Water Terms Glossary

Don't know what a specific term or abbreviation means? Check out our list of commonly used industry terms below for help.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

60 cycle OR 60 hertz power - This uniform waveform, when applied to a set of coils of wire, sets up a magnetic field that changes from positive to negative 60 times a second.

Abrasion Hazard - A sharp or rough surface that could scrape the skin upon contact or through normal activity.

Absolute Filter Rating - Filter rating meaning that 99.9 percent of essentially all of the particles larger than a specified micron rating will be trapped on or within the filter.

Absolute Pressure - Pressure above zero pounds per square inch.

Absorption - The process of one substance actually penetrating into the structure of another substance. This is different from adsorption in which one substance adheres to the surface of another.

AC - Alternating Current - The vibration of electrons to push an electric charge.

Acceleration - The rate at which velocity changes.

Accessible - Easily exposed for inspection and the replacement of materials and/or parts with the use of tools.

Acidic - The condition of water or soil, which contains a sufficient amount of acid substances to lower the pH below 7.0.

Across the line starting of a motor - When the pump turns on, the full locked rotor amperage is drawn to start the motor.

Action Level - The level of lead or copper which, if exceeded, triggers treatment or other requirements that a water system must follow.

Activated Carbon - A form of elemental carbon whose particles have large surface area with adsorptive qualities, primarily used to remove chlorine, objectionable tastes and odors and numerous toxic organic compounds from water. Produced by heating carbonaceous substances, bituminous coal or cellulose-based substances such as wood or coconut shell, to 700 degrees Centigrade or less in the absence of air to form a carbonized char and then activating or oxidizing at 800 to 1000 degrees Centigrade with oxidizing gases such as carbon dioxide or steam to form pores, thus creating a highly porous adsorbent material.

Activated Carbon Block - A blend of fine activated carbon, water and a suitable binders (such as polyethylene or similar material) that is mixed and molded and hardened or extruded to a cartridge filter of any size and shape. Occasionally specialized media are added along with activated carbon to provide customized performances of specific contaminants such as lead.

Acute Health Effect - An immediate (i.e. within hours or days) effect that may result from exposure to certain drinking water contaminants (e.g., pathogens).

Adapter Bracket - Connects the driver (motor, engine, etc.) to the volute case while helping to enclose the sealing mechanism, impeller, and possibly the bearings (depending on the style of pump).

Adapter Bracket and Volute Case - The stationary components of a pump.

Adsorption - Attachment of a substance to a solid (or liquid) surface by non-specific means (as with carbon filtration techniques).

Aeration - The process of adding air to a water supply for the purpose of oxidation (of materials such as iron, manganese, etc.).

Aerobic - To oxygenate. Using molecular oxygen. Growing or occurring only in the presence of molecular oxygen, such as aerobic organisms.

Affinity Laws - With the same impeller: If you double the diameter, the flow doubles; the head generated by the impeller is related to the square of the liquid exit velocity; the change of horsepower is related to the cube of the change in the velocity of the liquid.

Air Induction System - A system whereby a volume of air (only) is induced into hollow ducting built into a spa floor, bench or other location. The air induction system is activated by a separate air power unit (blower).

Air Or Gas Entrainment - The entrapment of localized air or gas bubbles and pockets that are created at the discontinuity between an impinging jet flow and the receiving pool of water.

Air Over Water Tanks - An air over water tank allows the air and water to touch and mix. These tanks need some sort of air make up system to continually replace tank air that mixed with the flow of water out of the tank.

Air Pump Assist Backwash - The compressing of a volume of air in the filter effluent chamber (by means of an air compressor or by the water pressure from the recirculating pump) which, when released, rapidly decompresses and forces water in the filter chamber through the elements in reverse, dislodging the filter aid and accumulated dirt, carrying it to waste.

Algae - Green, black or brown microscopic plant life which is nourished by sunlight. A group of single-celled plants, which includes both seawater and fresh water varieties.

Algaecide - A chemical or process for killing algae. An algaestat is an agent for preventing their growth.

Alkalinity - A measurement of the quantity of chemicals present in water, which can neutralize acids. These include carbon dioxide, bicarbonate, carbonate and hydroxides. pH conditions which exceed 7.0.

Alum - A flocculating agent. Potassium and ammonium alum are the most common types used in the treatment of pool water. Aluminum sulphate is often used with gravity sand filters.

Aluminum Sulfate - An aluminum salt commonly used as a flocculent by municipal water treatment facilities.

Ambient Temperature - The amount of heat surrounding the motor during operation.

Amperage - Also called current or Coulombs, is the amount of electrical energy flowing through an appliance at any given time. This measurement is expressed in units called amperes, often shortened to amps.

Amperes - The measurement of current flowing through an electrical circuit.

Amphoteric - A substance, such as aluminum, capable of acting as either an acid or base.

Amps - short for amperes - An electrical measurement of motor performance where current (amps) = voltage (volts) divided by resistance (ohms). Amps is a measure of the flow of electricity.

Anaerobic - A condition in which there is no air or no available free oxygen. Sometimes relates to microbes, which can exist without oxygen.

Analog meter - Has a needle and a range select dial. Infinity is on the left side and zero on the right, and is used to measure electrical properties of circuits and components.

Anions - See ion.

ANSI - American National Standards Institute - A private organization that helps to promote the standardization process that began in the United States in 1918.

Apparent Power - Calculated by a formula involving the “real power” that is supplied by the power system to actually turn the motor.

Aquifer - A natural underground geologic formation or group of formations in rocks, sand, gravel, and soils containing enough ground water to supply wells and springs.

Area - The space on a flat plane bordered by two lines that can be measured in two directions (Length x Width = Area).

ASME - American Society of Mechanical Engineers - A professional organization which promotes advances in engineering, along with professional development, education, and engineering safety. Many ASME standards have been adopted as legal codes in nations all over the world.

Atmospheric Pressure - The pressure energy produced by the atmosphere at earth's surface, measured and expressed as pounds per square inch (psi) or inches of mercury (in Hg). The weight of the atmosphere at a given point on earth. Atmospheric pressure equals about 14.7 PSIA at sea level and decreases as the altitude increases.

Atom - Made up of a nucleus with protons and neutrons and electrons moving around the nucleus in orbits. Atoms have an equal number of protons and electrons.

AVC - Air Volume Control - A device that maintains the air charge in a standard water storage tank. Pre-charged tanks do not require an air volume control. In an air over water tank with Jet Pumps an AVC is placed on the tank to insert air into the tank and keep the pressure correct and to compensate for absorption. Submersible pumps installed with an air over water tank use bleeder orifices to maintain air pressure in the tank and help prevent the tank from becoming water-logged.

Axial Cam Pump - A type of pump that uses a rotating cam to pressurize water for high pressure cleaning purposes.

Back to top

Backflow - A reverse flow in water pipes. A difference in water pressures pulls water from sources other than the well into a home’s water system, for example waste water or flood water. Also called back siphonage.

Backwash - The process of flow reversal to clean a filter and to restore it to the normal clean condition for filtering with a minimum resistance to flow through the media.

Backwash Cycle - The operating time, after the filter cycle, required to completely clean the filter.

Backwash Piping - The pipe extended from the backwash outlet of the filters to a terminus at the point of disposal.

Backwash Rate - The rate of application of water through a filter during the cleaning cycle expressed in gallons per minute per square foot of effective area.

Bacteria - Any of a class of microscopic living organisms having round, rod-like spiral or filamentous single cell or non-cellular bodies, often aggregated into colonies or mobile by means of flagella. Living in soil, water, organic matter or the bodies of plants and animals and being autotrophic (self-generative), saprophytic (digests chemicals already in their environment) or parasitic. Some are helpful and some are harmful. “Good” bacteria aid in pollution control by consuming and breaking down organic matter and other pollutants in septic systems, sewage, oil spills, and soils. However, “bad” bacteria in soil, water, or air can cause human, animal, and plant health problems.

Bactericide - Material capable of inhibiting or destroying bacteria. Function is known as bactericidal.

Bacteriostatic - Material capable of reducing the rate of bacterial growth. Sometimes confused with bactericidal.

Ball or Globe Valve - These valves can be adjusted but are less susceptible to cavitation than a gate valve.

Basic Pump Components - The driver (most likely an electric motor) supplies the power necessary to rotate or spin an impeller; the volute case and seal plate, which direct the water to where you want it to go and builds the pressure to drive the water in the direction desired; the impeller moves the water and adds velocity.

Basket Strainer - A device which acts as a filter for a flow of liquid or slurry. Large particles are trapped in the strainer and not allowed to continue through the system.

Bather - Any person using a pool, spa or hot tub and adjoining deck area for the purpose of water sports, recreation or related activities.

Bearings - Three types generally used in electric pump motors: ball; sleeve; Kingsbury.

Beginners Area - Those water areas in pools, spas and hot tubs which are three feet or less in water depth.

Belt - Or Chain-Drives - a mechanism for transferring mechanical power between two places and is a common means of motivating large agricultural pumps.

Best Available Technology - The water treatment(s) that EPA certifies to be the most effective for removing a contaminant.

BHP - Brake Horsepower - the measured quantity of energy that must be supplied by the driver for the pump to operate successfully at the given conditions.

Bill Of Materials (BM) - List of parts that are assembled into a pump at the factory.

Binders - When used in reference to cartridge filters, refers to chemicals used to hold, or bind, short fibers together in a filter. Also may refer to various chemicals used to bind polymeric compounds in products such as plastic bottles.

Biofilm - An aggregation of active, multi-layered microbes found on surfaces and in particular inside tubing and pipes. May be difficult to remove by chemical means due to multiple layers and lack of fluid dynamics at surfaces where it resides.

Bipolar Transistor - A type of transistor with three terminals that is made from a doped semiconductor material; a specific kind of transistor used to send currents in two different directions. Its primary purpose is for use in electrical devices to amplify or change electrical signals.

Black Water - Raw human sewage.

Black Wire - Only hooked up to a circuit breaker and would tell a U. S. electrician that the wire may not be safe to touch as it may have live voltage on it.

Blinding - The fouling or plugging of pores in a membrane, usually by a gel-like substance.

BOD - Biochemical Oxygen Demand - A measure of the amount of oxygen required by bacteria for stabilizing material that can be decomposed under aerobic conditions. BOD is a commonly used determinant of the organic strength of a waste.

Body Feed - The continuous addition of small amounts of filter aid during the operation of a diatomaceous earth filter.

Booster Pump - A pump that adds pressure to existing pressure in a water system.

Booster Pump System - A system whereby one or more hydrojets are activated by the use of a pump which is completely independent of the filtration and heating system of a spa. In other uses it is generally a pump and pressure tank controlled by a pressure switch or other device.

Booster Station - A pumping system used to amplify water pressure.

Bowl-Style Construction - Features multi-vane diffusers in bowls that thread or bolt together for ease of assembly and disassembly. Bowl-style submersible turbines use mixed flow impellers rather than radial flow, as they work more efficiently with the bowl-style diffuser.

Brackish Water - Water containing between 1000 and 15000 mg/l of dissolved solids is generally considered to be brackish.

Brake Horsepower (BHP) - The measured quantity of energy that must be supplied by the driver for the pump to operate successfully at the given conditions.

Breakthrough - The first appearance in the effluent of an adsorbate of interest under specified conditions.

Bridge or Bridge Rectifier - A set of solid state diodes that convert AC power to DC power.

Bridging or Salt Bridging - The caking of salts in a dry water softener tank which causes failure of the liquid or brine beneath the dry salt to become saturated. The net result of bridging is insufficient salt to properly regenerate the resin.

Brine - (Same as Reject Water) - One of two streams of fluids generated by a Distiller or Reverse Osmosis unit. It contains the impurities removed from the feed water. Characteristically, 30,000 to 300,000 ppm.

Bromide - A compound of bromine. Two of the salts, Sodium and Potassium Bromide, are sometimes used to produce a disinfectant or algaecide.

Bromine - An element which is sometimes used in pool water purification. A dark, heavy, reddish-brown liquid in its normal state. Closely related to chlorine.

Butterfly Valve - From a family of valves called quarter turn valves, the butterfly is a metal disc mounted on a rod. When the valve is closed, the disc is turned so that it completely blocks the liquid flow. When the valve is open, the disc is rotated a quarter turn so that it allows unrestricted liquid passage.

Back to top

Capacitor - A storage device for electrical energy.

Capacitor Start Motor - Similar to the split phase motor except that there is a capacitor in series with the start winding; the start windings must be disconnected from the circuit after the motor reaches about two-thirds of its running speed to keep it from over heating both the start windings and capacitor. The capacitor start motor is more costly than the split phase and is typically available from 1/4 to 3 HP. It has a higher starting torque (200-400% of run torque) and requires less starting current (400-575% of run current) because of the starting capacitor.

Capacitor Start/Capacitor Run (CSCR) Control Box - Uses a starting capacitor and a running capacitor in line; makes much less noise and will add durability to the pump motor.

Capacitor Start/Capacitor Run (CSCR) Motor - Has a run capacitor always in series with the start (auxiliary) winding and a start capacitor, connected by a normally closed switch. The cap start/cap run motor is the most costly: are usually available from 1/2–15 HP and offer high starting and breakdown torque while providing smoother running characteristics at higher horsepower ratings.

Capacitor Start/Induction Run (CSIR) Control Box - Uses a capacitor to provide more starting torque out of a three-wire CSIR motor than with a two-wire Split Phase motor but is noisier and less durable. It is less expensive and therefore the more popular control box sold in the market today.

Capacity or Flow Rate - The amount of water a pump will put out or a tank will hold; the volume of liquid that passes a given point in a specified unit of time.

Carbon - With an atomic number of 6, carbon is a naturally abundant nonmetallic element which forms the basis of most living organisms.

Carcinogen - Any substance which tends to produce cancer in an organism.

Carrier Frequency - The nominal frequency of a transmitted carrier wave when the modulation is zero. The higher the modulating frequency, the more resolution each PWM pulse contains OR the smoother the output waveform and the higher the resolution.

Cartridge - Depth Type - A replaceable porous filtering element with a medium not less than three-fourths inch (3/4”) thick that relies on penetration of particulates into the medium to achieve their removal.

Cartridge - Surface Type - A replaceable porous filtering element with a medium less than three-fourths inch (3/4”) thick that relies on the retention of particulates on the surface of the cartridge to achieve their removal.

Cartridge Filter - A filter that utilizes a porous cartridge as its filter medium.

Cations - See ion.

Cavitation - A condition that occurs in pumps when the water/liquid entering the pump is changed from a liquid state to a gaseous state and back to liquid that is generally caused by too high of flow rate or from pipe that is too small for the flow rate. The formation of vapor bubbles in areas of low pressure in a liquid. It is not air in the liquid. It does not happen just in pumps. The act of cavitation itself does not cause any damage.

Cavitation Damage - The pitting or wearing away of a solid surface caused by the collapse of vapor bubbles created by low pressure prior to the damage.

Cellulase - An enzyme, which causes the decomposition of cellulose.

Cellulose Acetate - A synthetic polymer derived from naturally occurring cellulose and widely used in the fabrication of membranes. The polymers used for reverse osmosis membranes may be diacetate, triacetate or blends of these materials.

Centrifugal Force - A force that tends to move something from the center to the outside of a rotating body.

Centrifugal Pump - A type of kinetic energy pump that uses centrifugal force (slinging motion) to deliver water in a steady stream to create pressure. The pump consists of three basic components: The driver i.e. motor, PTO or engine; the stationary part, known as the pump body; and the rotating part, known as the impeller.

Centrifuge - A mechanical device that uses centrifugal or rotational forces to separate solids from liquids.

Channeling - The greater flow of liquid through passages of lower resistance which can occur in fixed beds or columns of particles (carbon, etc.) due to non-uniform packing, irregular sizes and shapes of the particles, gas pockets, wall effects and other causes.

CHECK or Foot Valve - A device that keeps water/liquid flowing one way through a pump or piping system.

Chemical Feeder - Any device to feed chemicals, but usually one feeding alum, acid, filter aid, algaecide, or soda ash. Included in this category are proportioning pumps, injector type feeders, pot type feeders, operating from a pressure differential, and dry type feeders.

Chloramines - Chemical complexes formed from the reaction between ammonia and chlorine. They are presently being used to disinfect municipal water supplies because unlike chlorine, they don't combine with organics in the water to form potentially dangerous carcinogens such as trihalomethanes (THM). Retains its bactericidal qualities for a longer time than free chlorine does. Chloramines can exist in three forms, the proportions of which depend on the physical and chemical properties of the water: Monochloramine; Dichloramine; Nitrogen Trichloride. Water containing chloramines must not be used for fish or kidney dialysis applications.

Chlorinated Hydrocarbons - A group of organic chemicals formed by reacting petroleum-derived chemicals with chlorine. Such chemicals include pesticides (insecticides) and herbicides and are frequently potent carcinogens.

Chlorinator - A device to feed, regulate the flow, and measure the amount of chlorine gas introduced into the water being treated.

Chlorine - An element, normally a gas, which is liquefied under pressure and stored in steel cylinders. Used as a disinfectant and algaecide when it is introduced in water solution into a pool or spa. A very toxic biocide. A halogen element isolated as a heavy irritating greenish-yellow gas of pungent odor, used as a bleach, oxidizing agent, and a disinfectant in water purification.

Chronic Health Effect - The possible result of exposure over many years to a drinking water contaminant at levels above its MCL.

Clear Water - Rain water runoff collected in a sump or collection basin.

Closed Impeller - Impellers designed to completely enclose the vane area with two shrouds. The front shroud is designed to incorporate an "eye" or entrance to the impeller. The back shroud is designed to incorporate either a tapped or keyed hub allowing the impeller to be attached to the driver. By enclosing the impeller vanes on both sides, the velocity of the water moving through the vanes is increased, thus enabling the impeller to produce higher head. It is the most efficient impeller type but is prone to clogging due to its closed design. Closed impellers are used in jet pumps, submersible well pumps, and some sump pumps that do not need to pass any solids or stringy material.

Coagulant - A chemical which causes dispersed colloidal particles to become destabilized, thereby aiding in their removal during municipal water treatment. Aluminum and iron salts are commonly used for this purpose.

Coagulation - A practice common in municipal water treatment in which a chemical (coagulant), most commonly alum, is added to water in order to destabilize colloidal particles by neutralization of their electrical charges. Coagulation is used, together with flocculation, as a process for colloid removal.

COD - Chemical Oxygen Demand - The amount of oxygen consumed to completely chemically oxidize organic water constituents to inorganic end products.

Code - The code letter imprinted on a motor identification label that provides the locked rotor KVA (kiloVolt Amps) per horsepower value.

Coliform - A group of related bacteria whose presence in drinking water may indicate contamination by disease-causing microorganisms.

Collection Pit - An in-ground or above ground basin used to collect rain or surface water, sewage, or animal wastes. Also called a sump crock or sump pit when used with submersible or pedestal sump pumps.

Colloidal Mineral - Colloid - Un-dissolved, sub micron-sized, suspended particles which are well dispersed in a solution and will not readily settle out on standing. Most colloidal minerals are held in suspension by their tiny size and/or a static electrical charge. Many colloidal minerals claim to be organic due to the fact that they come from prehistoric mineral deposits such as humic shale and that some of the minerals are bound to carbon.

Community Water System - A water system which supplies drinking water to 25 or more of the same people year-round in their residences.

Compaction - The undesirable physical compression of a reverse osmosis or ultrafiltration membrane which results in reduced flux rates. The phenomenon is accelerated at higher temperatures and pressures.

Compliance - The act of meeting all state and federal drinking water regulations.

Concentrate - The portion of a feed stream that retains the ions, organics and suspended particles that were rejected during the cross flow filtration or purification process. Associated with water cooled distillers and reverse osmosis systems.

Concentric - The shape of a pipe or fitting meaning perfectly round.

Condensate - Water obtained through distillation by evaporation and subsequent condensation.

Conductivity - A measure of the ability of an aqueous substance to transmit an electric current. The conductivity imparted to water by dissolved solids is a function of both the amount and composition of the salts and the temperature of the water.

Conductor - A material that contains movable electric charge, metal copper being among the best

Confining Layer - Layer of rock that keeps the ground water in the aquifer below it under pressure. This pressure creates springs and helps supply water to wells.

Contacts - As related to pumps, contacts are the connecting points for electrical flow used in a pressure switch. When sufficient water pressure has been achieved, the contacts open, thus turning off the pump. If water pressure drops to a preset level, the contacts close, thus sending electricity to the pump to restore desired pressure.

Contaminant - Anything found in water (including microorganisms, minerals, chemicals, radionuclides, etc.) which may be harmful to human health.

Control Box - A device which contains electrical components necessary for starting and running 3-wire, single phase submersible motors.

Convertible Jet Pump - A type of jet pump able to be converted from a shallow well to a deep well application by attaching a conversion jet kit consisting of a Nozzle, a Venturi, and a Body or Housing.

Corrosion - The etching or oxidation of a material by chemical action. Corrosion and Scale Deposits add up to a reduction in flow area, an increase of the velocity of the liquid, and an increase in head loss due to friction.

Corrosion Resistant Material - A material with exceptional resistance to the corrosion factors to which it is subjected.

Cross Connection - Any actual or potential unprotected connection between a drinking (potable) water system and any source of contamination (pool or other non-potable water) whereby back flow to the potable water system could occur. Appropriate protection may be vacuum breakers, air gaps or other methods.

Cryptosporidium - A microorganism commonly found in lakes and rivers which is highly resistant to disinfection. Cryptosporidium has caused several large outbreaks of gastrointestinal illness, with symptoms that include diarrhea, nausea, and/or stomach cramps. People with severely weakened immune systems (that is, severely immuno-compromised) are likely to have more severe and more persistent symptoms than healthy individuals.

Current - The movement or flow of an electrical charge, matter, carried by electrons along a path (conductor, wire). It moves very slowly, about an inch an hour. Current is measured in terms of Amperes or Amps.

Cutout Point - The setting at which a pressure switch opens its contacts so that a pump stops pumping.

Cutwater - The thin portion of a centrifugal pump's volute closest to the impeller. Close tolerances between the cutwater and the impeller forces a higher volume of water out of a pump than loose tolerances.

Cyanuric Acid - A chemical used for chlorine stabilization.

Back to top

D.E. - Diatomaceous Earth - A type of filtration media. Can also stand for Dual Element when talking about electrical fusing.

Darcy, Weisbach Head Loss Tables - Based on the head loss in clean, new pipe, these values are used by fluid engineers when designing pumping systems.

Datum Plane - The centerline of the impeller eye in an above-ground horizontal pump; the eye of the first stage or bottom impeller in a submersible pump. This can be closely estimated as being at the same height as the top of the suction screen.

DC - Direct Current - A one-way push of electrons, electric charge.

Dead Head - The point on a pump performance curve where the unit is pumping zero GPM - also known as Shut-off Head.

Decks - Those areas surrounding a pool, spa or hot tub that are specifically constructed or installed for use by bathers.

Deep Areas - Portions of a pool, spa or hot tub having water depths in excess of five feet (5’).

Deep Well Jet Pump - A type of jet pump able to lift water less than 70'. It has two pipes leaving it - the suction pipe and the drive pipe.

Deionization - Removal of ions from water by exchange with other ions associated with fixed charges on a resin. First, positively charged ions are removed, by a cation exchange resin, in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively charged ions are removed, by an anion exchange resin for a chemically equivalent amount of hydroxide ions. The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange.

Demineralization - The process of removing minerals from water e.g. deionization, reverse osmosis and distillation.

Desalination - The removal of dissolved inorganic solids (salts) from a solution such as water to produce a liquid which is free of dissolved salts. Desalination is typically accomplished by distillation, reverse osmosis or electrodialysis. A common source water may be seawater.

Design Rate of Flow (Design Filter Rate) - The average rate of flow in a system which is used for design calculation (usually the flow in gallons per minute divided by the effective filter area in square feet).

Dialysis Dementia - A severe, often fatal encephalopathy which has been attributed to accumulation in the brain of aluminum from dialysate prepared with inadequately purified water. May include consumption of tap water with high levels of alum used in most municipal water treatment processes.

Diatomaceous Earth (D.E.) - Porous silica from skeletal remains of one-celled plants, which when properly graded, acts as a precoat filter media for water filtration.

Diatomaceous Earth Filter - A filter that utilizes a thin layer of diatomaceous earth as its filter medium that periodically must be replaced.

Diffuser - The portion of a volute case from the cutwater to the pump flange. In submersibles, a piece, adjacent to the impeller exit, which has multiple passages of increasing area for converting velocity to pressure.

Digital Meter - Has an LCD display, a range select dial, and is used to measure electrical properties of circuits and components.

Direct Connection or Dead Short - Electricity takes the shortest direct route through the motor, coil or other component; nothing is restricting the current flow.

Directional Inlet Fitting - An inlet fitting which provides adjustment in direction and flow rate to produce proper distribution of incoming water.

Discharge - The pump orifice where water exits the pump.

Discharge Head - The total head, including static head and friction head, on the discharge side of the pump.

Disconnect Box - An on/off switch placed between the control box and power distribution (breaker) panel and permits power to be disconnected from a device for service purposes.

Disinfectant - A chemical (commonly chlorine, chloramine, or ozone) or physical process (e.g., ultraviolet light) that kills microorganisms such as bacteria, viruses, and protozoa.

Disinfection - A process for the destruction of bacteria. The process may be physical, as with heat or ultraviolet irradiation, or chemical, as with chlorination.

Dissolved Solids (Total Dissolved Solids) - TDS - Includes colloidal and suspended particles at sizes far less than one micron in diameter. Associated with evaporation processes such as distillation.

Distance - The straight line separation between an object and a reference point.

Distillation - Vaporous state liquid is condensed on a cool surface, collected and stored. Most contaminants do not vaporize and therefore do not pass to the condensate. Removes nearly 100 percent of salts and those organics that do not have a vaporizing temperature near or below that of the distilled liquid. Usually combined with carbon filtration to remove balance of remaining organics with vaporization temperatures below that of water.

Distilled Water - Water which has been purified by passing through an evaporation-condensation cycle; it generally contains less than 5 ppm of dissolved solids.

Distribution System - A network of pipes leading from a treatment plant to customers' plumbing systems.

Distributor (Top or Bottom) - The device in a filter designed to divert the incoming water to prevent erosion of the filter media.

Diving Area - That area of a pool designed for diving. (NOTE: Diving Areas are defined in detail in various standards and regulations such as NSPI, Public and Residential Pool Standards, AAU, FINA, etc.).

Diving Board - A board especially designed to produce diver spring action when properly installed on an anchor (base) and fulcrum. (The term diving board includes non-spring types).

Diving Platform - Usually used for the standard 5-meter and 10-meter official diving platform.

Diving Tower - This term is usually used for the 3-meter (10-ft.) springboard support.

Dole Flow Valve - This is an excellent valve to use as there is nothing to turn or adjust. This means that when you put it in no one else can play with it. It helps to keep the pump set right where the professional puts it. Because of the nature of this valve it only allows a flow at a certain GPM.

Double Pipe - In a jet pump application means that there are two pipes going all the way down to the jet pump. This is a closed system. The industry standard has the suction pipe over the drive pipe.

Double Pipe or Single Pipe System - Refers to the well size and how the well can be entered.

Double Pole Single Throw Circuit Breaker - The only safe method of connecting a 230VAC water pump. It consists of two separate circuit breakers within a housing and both are controlled by one single lever.

Downthrust - The general direction of the thrust is toward the impeller eye. In sub turbines installed vertically this direction is down. Is the normal operating mode of the pump.

Drain - An outlet at the deep point of a vessel or trough through which waste water passes.

Drawdown - The difference between the static water level and the pumping water level in a well. Also can refer to the per cycle capacity rating of a pressure tank at a given pressure range. Occurs when the pump starts running.

Drawdown Level - The water level in a well measured while the pump is pumping at full capacity. Less than normal water level in the tank causes the pump to run more frequently and for shorter durations. More than normal water level in the tank causes the pump to run less frequently and for longer durations to replace the high quantity of water in the tank.

Drive or Pressure Pipe - Usually the smaller of two pipes connecting a jet pump to the down-well venturi, it carries the water from the pump to the venturi.

Dry Niche - A normal weatherproof fixture placed in an opening behind the pool wall which illuminates the pool through a watertight window in the pool wall.

Dual Voltage Motors - A type of single or three phase motor that can be configured to operate on two or more voltage levels. Dual voltage motors allow the same motor to be used in many applications.

Duplex System - A sewage or effluent system that uses two pumps to control the water level in the storage chamber via float switches and a control box.

Back to top

Eccentric- The shape of a pipe or fitting meaning off-center, not exactly circular in shape.

Eccentric Reducer - Also called a Bell reducer, is a pipe fitting designed with the smaller outlet off center to the larger end, allowing it to align with only one side of the inlet. The eccentric reducer must be installed with the straight side up to prevent trapping air at the pump suction. Eccentric reducers eliminate noise and isolate vibration in the pipeline, reduces stress, eliminates electrolysis and protects against start-up surges.

Eff. % or Pump Efficiency (percent) - The difference between the LHP (Liquid Horsepower) and BHP (Brake Horsepower). LHP is the amount of HP required to get a certain flow and head out of the pump. BHP is the cost to make that happen. Pump efficiency is always going to be less than one because you can never get more out then you put in. It is a ratio of flow and head out vs. electricity in. Efficiency % is about what goes in vs. what you get out OR what I use verses what I loose OR the wattage we use or pay for vs. the wattage used to accomplish our task.

Effective Filter Area - Permanent Medium Type: The effective filter area is the filter surface that is perpendicular to the flow direction. Cartridge Filter: The total effective filter area shall be the cartridge area that is exposed to the direct flow of water. This excludes cartridge ends, seals, supports and other areas where flow is impaired.

Effluent - Sewage or waste water which has undergone some pretreatment. Effluent water may contain small solids and/or stringy material (lint, hair, etc.). Effluent is generally defined as 3/4” solids or less.

Ejector - A device consisting of a body, nozzle, and venturi tube that increases the pressure output of a jet pump. The nozzle increases the velocity of the water, then the venturi tube converts the velocity to pressure.

Ejector Package - When supplied for use with a jet pump, its components include a housing, a venturi, and sealing components. When water is pushed through the venturi, a low pressure region is created that siphons external water into the water flow, which is then delivered to the system water supply.

Ejector Vane - Located on the back side of the impeller, the ejector vane creates positive pressure that prevents debris from collecting around the shaft seal.

Electric Motor (Squirrel Cage Induction Type) - A motor whose name is derived from the similarity between the motor windings (which may use conductive bars connected together at both ends by shorting rings forming a cage-like shape) and a squirrel cage/hamster wheel. These are the most common type of industrial AC electric motors, being rugged and requiring neither a separate DC power source nor ship-rings. They are constant speed devices when energized by a constant frequency AC supply.

Electrical Charge - Movement of electrons into another orbit.

Electrical Energy - A wave that moves along columns of electrons around a conductor. The energy itself is contained in the electromagnetic fields connected to those electrons and moves very fast (almost the speed of light), used up when it reaches a load.

Electrical Relay - A switch operated by electricity. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and most have double throw switch contacts. Can be controlled using low power and can control multiple loads.

Electricity - Energy resulted from the presence of charged particles.

Electrolysis - Decomposition of metal due to flow of electrical current.

Electromagnetic Force - The movement of electrical energy along a path around a conductor (wire).

Electronic Relay - Senses the pump motor amp draw and the normally closed switch opens, disconnecting the wire going from the relay to the capacitor taking the start windings out of the circuit.

Electrons - A stable negatively charged elementary particle with a small mass that is a fundamental constituent of matter and orbits the nucleus of an atom

Elevation - The vertical distance between the level where fluid enters a pipe and the level where it leaves; is measured from the datum plane to the highest point. It is associated with the discharge side of a pump and must be added to the Total Discharge Head if the inlet is lower than the outlet and subtracted if the inlet is higher. As a rule of good installation practice, however, pipes should slope continuously upward from the inlet to the outlet to prevent entrapment of air.

Empty Bed Contact Time - A measurement of the duration of contact between water and the media through which it is flowing, typically used in reference to carbon beds.

Endotoxin - Bacterial lipopolysaccharide, a substance released from the cell walls of gram-negative bacteria when the organism is broken down.

Energy - Cannot be created or destroyed, only converted.

Engine Driven Pump - A type of pump which uses an electric or hydraulic motor as its driver or motive force.

Enhanced-Flow STEP System - A private sewage system that requires a pump. An Effluent Pump lifts a predetermined volume of collected septic overflow to a distribution box or manifold for gravity flow to an absorption field. Enhanced-Flow Systems have the advantage of flexibility in locating the absorption field as well as improved performance compared to strictly gravity flow systems. By pumping a predetermined volume each cycle, the absorption field has time to stabilize between cycles. Loss of effectiveness in hard soils and high water tables and progressive plugging of drain holes and absorption areas are disadvantages.

Equilibrium - The condition where the forces applied to an object are in balance.

Equivalent Length Of Pipe - Pipe fittings and valves were tested and values assigned for the head loss measured through them. Instead of assigning a factor, as in the "K" factor method, an "equivalent length of pipe in linear feet" value was assigned.

Exemption - State or EPA permission for a water system not to meet a certain drinking water standard. An exemption allows a system additional time to obtain financial assistance or make improvements in order to come into compliance with the standard. The system must prove that: (1) there are compelling reasons (including economic factors) why it cannot meet a MCL or Treatment Technique; (2) it was in operation on the effective date of the requirement, and (3) the exemption will not create an unreasonable risk to public health. The state must set a schedule under which the water system will comply with the standard for which it received an exemption.

Explosion Proof - A type of motor enclosure that resembles a TENV or TEFC motor with the added protection that the atmosphere cannot get into the motor and sparks in the motor cannot get out into the atmosphere.

Back to top

Face Piping - The piping with all valves and fittings which is used to connect the filter system together as a unit. This includes all valves and piping necessary for the filter plant to perform the functions of filtering or backwashing, either by the plant as a whole or any unit operating singly.

Factor Of Safety - The ultimate load divided by the safe load or the ultimate strength divided by the allowable stress.

Feed Water - Water under pressure entering a purification system or an individual piece of purification equipment, such as an ultra filter, distiller or reverse osmosis system.

Feet Of Head - A basis for indicating the resistance in a hydraulic system, equivalent to the height of a column of water that would cause the same resistance (100 feet of head equals 43 pounds per square inch). The total head is the sum of all resistances in a complete operating system. The principal factors affecting a head are vertical distances and the resistance caused by friction between the fluid and pipe walls.

Ferric Iron - Small solid iron particles containing trivalent iron, usually as gelatinous ferric hydroxide or ferric oxide, which are suspended in water and visible as "rusty water". Ferric iron can normally be removed by filtration. Also called "precipitated iron".

Ferrous Iron - A divalent iron ion, usually as ferrous bicarbonate which, when dissolved in water, produces a clear solution. It is usually removed by cation exchange water softening. Also called "clear water" iron.

Fibrewound Tank - A tank body made from polyethylene plastic fibers wound around a mandrel.

Filter - A device that separates solid particles from water by recirculating the water through a porous substance (a filter medium element). Permanent Medium Filter: A filter that utilizes a medium that under normal use will not have to be replaced. Diatomaceous Earth Filter: A filter that utilizes a thin layer of diatomaceous earth as its filter medium that periodically must be replaced. Cartridge Filter: A filter that utilizes a porous cartridge as its filter medium.

Filter Agitation - The mechanical or manual movement to dislodge the filter aid and dirt from the filter element.

Filter Aid - A type of finely divided media used to coat a septum type filter, usually diatomaceous earth or volcanic ash. (NOTE: Alum, as used on the bed of a sand filter, is also referred to as a filter aid).

Filter Cartridge - A filter which operates through a disposable cartridge. These are of two general types: The surface or area type where the suspended matter is removed at the surface, and the depth type in which the interstices vary from large to small in depth.

Filter Cycle - The operating time between cleaning or backwash cycles.

Filter Diatomite - One designed to filter water through a thin layer of filter aid such as diatomaceous earth or volcanic ash. Diatomite filters may be of the Pressure, Gravity, Suction or Vacuum type.

Filter Element - A device within a filter tank designed to entrap solids and conduct water to a manifold, collection header, pipe or similar conduit. A filter element usually consists of a septum and septum support.

Filter Media - The finely graded material which entraps suspended particles (sand, anthracite, diatomaceous earth, etc.).

Filter Rock - Graded, rounded rock and/or gravel used to support filter media.

Filter Septum - That part of the filter element consisting of cloth, wire screen or other porous material on which the filter cake is deposited.

Filter, Gravity - Sand - A filter with a layer of filter media (usually silica sand) supported on graded gravel through which water flows by gravity.

Filter, Pressure - Sand - A sand filter enclosed in a tank to operate under pressure.

Filter, Sand - A type of filter media composed of hard sharp silica, quartz, or similar particles with proper grading for size and uniformity.

Filter, Vacuum (Suction) - A filter which operates under a vacuum or from the suction side of a pump.

Filtrate - The portion of the feed stream that has passed through the membrane or filtering media.

Filtration Flow - The rate of flow in volume per time (gallons per minute, gallons per hour), through the filter system installed per manufacturer’s instructions with a new, clean filter medium.

Filtration Rate - The rate of filtration of water through a filter during the filter cycle expressed in US gallons per minute per square foot of effective filter area.

FINA - The Federation Internationale de Natation Amateur - The governing body for intercollegiate competition including the Olympic games.

Final Dispersal - The movement of effluent water to the ground for absorption and filtration.

Finished Water - Water that has been treated and is ready to be delivered to customers.

First Affinity Law - With the same impeller, if you double the diameter, the flow doubles.

Fixture Unit Value - An assigned value for flow created by plumbing fixtures. The value assumes the likelihood of any given plumbing fixture operating at the same time and the amount of wastewater it may create.

Flange - A device used to couple to a pipe on the suction or discharge of a pump.

Flocculating Agent - A compound, such as one of the alums, which forms minute flakes in water which attract or enmesh small suspended particles.

Flocculent - Chemical which, when added to water, causes particles to coagulate into larger groupings that settle out easier. Aluminum compounds are common catalysts in this process.

Flooded Suction - The condition where the water supply is above the pump.

Floor Slope - The slope in the pool floor, usually expressed in feet (or inches) of vertical rise in feet (or inches) of horizontal distance.

Flow Inducer Sleeve - A sleeve attached to a submersible pump to force water to pass around it and enter the pump's suction intake from below the motor for cooling purposes.

Flow Rate - The volume of liquid that passes a given point in a specified unit of time. Capacity is also commonly used to designate Flow Rate when working with pumps. Example - GPM (Gallons per minute), GPH (Gallons pre Hour), or GPD (Gallons per day).

Flow Rate or Capacity - The volume of liquid that passes a given point in a specified unit of time.

Flow Restrictors - Valves or bends in a pipe system that restricts the flow of liquid.

Flow Velocity - A quantitative expression of the rate of linear motion at which water passes through a pipe or conduit.

Fluidization - A process by which particles are suspended by an upward flow of liquid, such as may occur during back washing of ion exchange resin or carbon media.

Fluoride - A salt of hydrofluoric acid which may occur naturally in water supplies or be added by municipal processes for the prevention of dental caries. Fluoride is considered toxic in most medical settings and has been implicated with a wide range of physiological disorders including renal bone disease.

Flux/Flux Rate - The rate per unit of area at which water passes through a semi-permeable membrane, such as those used for ultrafiltration or reverse osmosis.

Flyweight - A weight mounted on the side of a rotor designed to snap outward as the motor reaches a critical speed.

Foot or Check Valve - A device that keeps water/liquid flowing one way through a pump or piping system; A foot valve is a modified check valve that has a screen on the suction end to prevent debris from entering the pump or pipe.

Force - An applied effort that tends to attempts to move something.

Fouling - The deposition of insoluble materials, such as bacteria, colloids, oxides and water-borne debris, onto the surface of a media such as water softening resins, reverse osmosis or ultrafiltration membrane. Fouling is associated with decreased flux rates and may also reduce the rejection rates of reverse osmosis membranes.

Four-Pole Motor - Motors with two pairs of running windings that usually run at 1750 rpm.

Fourth Float - Used in a duplex system, when called for in specifications, to activate the alarm. In this case the Lag Float only activates the lag pump.

Frame - The dimensional standard or physical set of members that are used on a motor.

Freeboard - The clear vertical distance between the top of the filter medium and the lowest outlet of the upper distribution system in a permanent medium filter.

Friction - The resistance to motion of two objects or surfaces that touch.

Friction Loss - The loss of pressure or head due to the resistance to flow in the pipe and fittings. Friction loss is influenced by pipe size and fluid velocity, and is usually expressed in feet of head; a form of energy, which is another name for head.

Friction Loss Calculation - Based on the type of pipe to be used, the size of the pipe, the average flow rate, and the length of the pipe.

Friction Loss Charts - A table showing resistance to water movement within various types of piping material. All charts are not the same - Pentair uses the Williams and Hazen chart.

Full Load Amps (FLA) - The FLA is the amperage rating at the motor nameplate horsepower rating and at its rated (nominal) voltage. This is usually the point of maximum efficiency and maximum power factor for the motor. This is where the motor prefers to run.

Fulvic Acids - Acidic substances which are found in humic (organic) soils and which may become suspended in water. A component in the production of chloramines.

Fungus - A parasitic plant which produces no chlorophyll and is dependent on other life forms for its existence.

Back to top

Galvanic Action - Creation of an electrical current by electrochemical action.

Gas Or Air Entrainment - The entrapment of localized gas or air bubbles and pockets that are created at the discontinuity between an impinging jet flow and the receiving pool of water.

Gasket or O-Ring - A plastic or rubber ring or flat plastic or paper device used in machinery as a seal against air, oil, or high pressure.

Gate Valve - This is probably the least effective of all the valves as it is more prone to cavitation damage and can easily be adjusted by the end user.

Gauge Pressure (PSIA) - Pressure above atmospheric pressure.

Generator - A device used to create electrical energy. When operating, a generator will cause a flow of electrical charge.

Giardia Lamblia - A microorganism frequently found in rivers and lakes, which, if not treated properly, may cause diarrhea, fatigue, and cramps after ingestion.

Glauconite Sand - A mineral which is frequently used in depth filters.

Governor - A device that maintains a constant engine speed; a spring loaded device which is mounted under the canopy on the motor shaft designed to regulate rotational speed or momentum.

GPD - Gallons Per Day - A flow rate measurement.

GPG - Grains Per Gallon - Equivalent to 17.1 milligrams/liter of calcium carbonate.

GPH - Gallons Per Hour - A flow rate measurement.

GPM - Gallons Per Minute - A flow rate measurement.

Gratuitous Harmonics - Annoying and potentially harmful signals generated by variable frequency drives (VFD) that are transmitted into a dwellings electrical network. Modern VFD devices use improved power components to minimize this effect.

Gravity Feed Systems - These private systems use gravity as the means to move the water from one side of tank to the other or from the septic tank to the effluent tank and then to final dispersal.

Gray Water - Non-toilet household wastewater (sinks, showers, laundry, etc.) that is sometimes recycled especially for use in gardening or for flushing toilets.

Grinder Pump - A sewage pump designed to chop or cut solids, which are mixed with the water to become slurry.

Ground Water - The water that systems pump and treat from aquifers (natural reservoirs below the earth's surface).

Gutter Fitting (Gutter Drain) - A drainage fitting used in the overflow gutter.

Back to top

H-O-A (Hand-Off-Auto) - A toggle switch which allows you to choose how you want the pump to run. Hand means you turn it on and off. Off means nothing will happen because the pump(s) are turned off. Auto means that the float switches are being used to turn the pump(s) on and off.

Handhold/Handrail - A permanently installed device that can be gripped by a bather for the purpose of resting and/or steadying him/herself. Is not limited to but may be located within or without the pool, spa or hot tub or as part of a set of steps or deck-installed equipment.

Hardness - The amount of calcium and magnesium in the water in grains per gallon, (expressed as calcium carbonate).

Head - short for "Feet Of Head" - A term used to define water pressure in vertical feet. Or a term representing the energy content of a liquid, expressed as the height of an equivalent vertical column of water. a. This is expressed in feet of head. b. This can apply to both sides of a pump; the suction side and discharge side. c. It is also used to express the total losses in a pumping system (Total Dynamic Head). Used interchangeably with PSI (pounds per square inch). Head is a result of what happens when we start the pump and create a flow.

Health Advisory - An EPA document that provides guidance and information on contaminants that can affect human health and that may occur in drinking water, but which EPA does not currently regulate in drinking water.

Heavy Metals - Metallic elements with high atomic weights, such as mercury, chromium, cadmium, arsenic, and lead. Even at low levels these metals can damage living things. They do not break down or decompose and tend to build up in plants, animals, and people causing health concerns.

Hermetic - Completely sealed, especially against the escape or entry of air.

Hertz - One cycle of AC electric flow.

Hi-Rate Permanent Media Filter - A swimming pool water filter capable of water flows of up to 20 GPM for 10 hours. Offer the best combination of economy, performance, durability, and ease of maintenance.

High Static Water Level - The ground water elevation without any influence from pumping.

Homogeneous Membranes - See membranes.

Horizontal Run - The horizontal distance between the point where fluid enters a pipe and the point at which it leaves.

Horsepower - 'One horsepower' is defined as the ability to move 33,000 pounds one foot in one minute (or to move 550 pounds one foot in one second). It is a measure of work performed.

Hose Connector - The fitting used to connect the hose to the wall or pump fitting (usually a combination hose sleeve and nut).

Hot Tub - A spa constructed of wood with sides and bottom formed separately; and the whole shapes to join together by pressure from the surrounding hoops, bands or rods; as distinct from spa units formed from plastic, concrete, metal or other materials.

Hydraulic Shock - A damaging condition that occurs when a column of liquid changes direction quickly and increases in velocity. Also called Water Hammer. Weakest point in system will break. Causes can be sudden loss of power to the driver, valve closing too quickly, valve closing too slowly allowing backflow.

Hydrogen Sulfide - A toxic gas that is detectable by a strong "rotten egg" odor. Associated with high levels of bacterial decay. Commonly found together with iron and manganese contaminants.

Hydrojets - A fitting that bleeds air and water creating a high velocity, turbulent stream of air enriched water.

Hydrologic Cycle - The term used to describe how water travels through the environment by evaporation, condensation and precipitation. Identical process is observed in steam distillation systems.

Hydrolysis - A chemical process resulting from reactions with water; frequently used in reference to the breakdown of polymers.

Hydrophilic - Pertaining to a substance, which readily absorbs water ("water-loving").

Hydrophobic - Pertaining to a substance, which does not readily absorb water ("water-hating").

Hydrotherapy Inlet Fitting - A special high velocity air entraining inlet fitting to produce a massage effect.

Hydrotherapy Spa or Hot Tub - A unit that may have a therapeutic use which is not drained, cleaned or refilled for each individual. It may include, but not be limited to, hydrojet circulation, hot water and cold water mineral baths, air induction bubbles or any combination thereof. Industry terminology for a spa includes, but is not limited to, “therapeutic pool,” “hydrotherapy pool,” “whirlpool,” “hot spa,” etc.

Hypochlorinator - A device used to feed, control and measure a solution of sodium or calcium hypochlorite into a water being treated. There are three general types: The positive displacement type which is usually a motor driven unit, the aspirator type actuated by a pressure differential created within the hydraulic system, and the metering type connected to the pump suction using an orifice which is opened and closed by a timing mechanism.

Hypochlorite, Calcium - A compound of chlorine and calcium used in powder or granulated form usually containing 70% to 80% available chlorine by weight which is released in water solution to act as a germicide or algaecide.

Hypochlorite, Sodium - A compound usually containing 5% to 16%, or more, available chlorine by weight, in a caustic soda solution, which releases chlorine when added to pool water.

Back to top

ID Run Failure - The correct information about the motor was not entered into the PID.

Impeller - The bladed member of the rotating assembly of the pump which applies the principal force to the liquid being pumped.

Influent - The inflow or entering water to a filter or other device.

Inlet - The fitting through which the filtered water passes to the pool (filtered water inlet), or the fitting through which raw water passes to the pool (raw water inlet).

Inorganic Contaminants - Mineral-based compounds such as metals, nitrates, and asbestos. These contaminants are naturally-occurring in some water, but can also get into water through farming, chemical manufacturing, and other human activities. EPA has set legal limits on 15 inorganic contaminants.

Insulated Gate Bipolar Transistor (IGBT) - Solid state devices used to switch the DC bus on and off at specific intervals.

Insulator - A material that does not allow a very good movement of electrons; rubber & paper

Inverter - A circuit that inverts DC voltage back to AC.

Iodine - An element related to chlorine and bromine used as a disinfectant, both in its natural solid form and in iodide compounds. When iodides are used, chlorine is normally employed to free the elemental iodine.

Ion - An atom or molecule having either a positive or negative electrical charge. Positively charged ions are referred to as cations and ions having a negative charge are termed anions.

Ion Exchange - A process by which certain ionized chemicals present in water are replaced with other ionized chemicals temporarily attached to resin particles. The exchange process is made only for ions having the same charge.

Iron - A very common element often present in ground water in amounts ranging from 0.01 to 10.0 ppm(mg/l). Iron may be found in three forms: in soluble forms such as in ferrous bicarbonate; bound with a soluble organic compound; or as suspended ferric iron particles. Iron above 0.3 mg/l is objectionable to water because of staining of laundry and plumbing fixtures.

Iron Bacteria - Bacteria which thrive on iron and are able to actually use ferrous iron (as found in water or steel pipes) in their metabolic processes to incorporate ferric iron in their cell structure and to deposit gelatinous ferric hydroxide iron compounds in their life processes.

Back to top

Jammed Impeller - Occurs when some type of debris is pulled in the suction port that stops motor rotation.

Jet Package - An accessory kit sold with jet pumps. Can consist of ejector, extra nozzles and venturis, bushings and reducers, pipe adapters and foot valves, and packing leathers. Also known as Ejector package or Injector package.

Jet Pump - A centrifugal pump with a jet (venturi) attached, either at the pump (shallow well) or in the well (deep well). While the centrifugal part of the pump uses centrifugal force and the atmosphere to work, the jet uses hydraulics and the atmosphere. The jet has no moving parts. jet pumps primary function is to increase pressure (shallow or deep well), or help draw water from a deeper depth (deep well only).

JTU (Jackson Turbidity Unit) - A visual means of measuring water clarity based upon the amount of light passing through a tube of water.

Jump Board - A mechanism that has a coil spring, leaf spring or comparable device located beneath the board which is activated by the force exerted in jumping on the board.

Back to top

K-factor - Values assigned to fittings, such as elbows, tees, strainers, valves, etc., based on testing measured head loss.

Kingsbury Type Bearing - A type of thrust bearing that floats on a cushion of lubricant; used in submersible pump motors; requires that the motor be up to a minimum speed (typically 1800 RPM) within one second to sustain cooling.

Back to top

Ladder, Deck - A ladder for deck access from outside the pool, spa or hot tub.

Ladder, Double Access - A ladder that straddles the pool wall of an aboveground pool and provides pool ingress and egress.

Ladder, Limited Access - Any ladder with provision for making entry inaccessible when a pool, spa or hot tube is not in use (i.e., swing-up, slide-up or equivalent).

Lag Float - A panel float that activates an alarm in a simplex system or the alarm and lag pump in duplex systems.

Laminar - Non-turbulent fluid flow. Associated with fluid dynamics and designs of fluid tubing and pipelines.

Langelier Saturation Index - A calculated number used to predict the calcium carbonate (CaCO3) stability of a water; whether a water will precipitate, dissolve, or be in equilibrium with, calcium carbonate. It is sometimes erroneously assumed that any water that tends to dissolve calcium carbonate is automatically corrosive. Langelier saturation index = pH - pH, where pH = actual pH of the water, and pH, = pH at which the water having the same alkalinity and calcium content is just saturated with calcium carbonate.

Laws Of Nature - If you want something, you have to pay for it.

Leach Field - A subsurface land area with relatively permeable soil designed to receive pretreated wastewater from a septic tank or intermediate treatment unit. The soil further treats the wastewater by filtration, absorption, and microbiological degradation before the water is discharged to ground water.

Lead Float - A panel float that activates a pump in a simplex system or the lead pump in a duplex system.

Lift - Associated with the suction side of a pump.

Lift-Out Guide Rail System - A device used to move heavier pumps up and down in a pit or basin.

Lignin - A polysaccharide found in the cell walls of plants; a breakdown product of decaying vegetation, which may be present in surface water supplies.

Liner - A membrane that acts as a container for the water.

Liner, Expandable - A liner that is constructed of a material that has the capability of stretching into a greater depth of irregular shape other than the original construction dimensions.

Liner, Hooper - The liner that is used to obtain greater depth by geometrical pattern construction on the liner bottom or floor to fit a predetermined size and shape.

Liquid End - A series of impellers and diffusers stacked together and mated to an electric motor to form a submersible pump.

Liquid Horsepower - The energy added by the spinning impeller.

Load - An area where electrical energy is used or consumed (converted). Load is what is doing the work we want: a light bulb, power saw, or pump motor.

Lopes or Loping - A condition where a diesel engine fires rapidly at top dead center (tdc), so piston, rod, and crank accelerate rapidly. As the piston moves away from the combustion, it slows down until it reaches tdc and fires again. Then it accelerates and repeats the cycle. A diesel engine requires the use of a rubber coupling.

Low-Pressure Pipe LPP Distribution Systems - A private sewage system that requires a pump. An Effluent Pump lifts a predetermined volume of collected septic overflow and distributes it throughout the absorption area at a uniform pressure. The advantage of flexibility in locating the absorption field is inherent. In addition, the uniform distribution minimizes plugging and is significantly more effective in hard soils and high water tables. LPP distribution fields may be smaller in area than those used in other types of septic systems. Absorption fields can be located on sloping ground or on uneven terrain that would be unsuitable for gravity flow systems

Lower Distribution System (Underdrain) - Those devices used in the bottom of a permanent medium filter to collect the water during the filtering and to distribute the water during the backwashing.

Back to top

Magnetic Field - A region of space surrounding a magnetized body or current-carrying circuit in which the resulting magnetic force can be detected.

Magnetic Starters - A system or device required with three phase motors for motor control.

Main Outlet - The outlet fitting at the bottom of a swimming pool through which water passes to the recirculating pump (often erroneously referred to as the “main drain”.

Make-Up Water - Fresh water used to fill or refill the pool, spa, hot tub, or potable water system.

Maximum Contaminant Level (MCL) - The highest level of a contaminant that EPA allows in drinking water. MCLs ensure that drinking water does not pose either a short-term or long-term health risk. EPA sets MCLs at levels that are economically and technologically feasible. Some states set MCLs which are more strict than EPA's.

Maximum Contaminant Level Goal (MCLG) - The level of a contaminant at which there would be no risk to human health. This goal is not always economically or technologically feasible, and the goal is not legally enforceable.

Mechanical Shaft Seal - A type of shaft seal used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements and is able to be replaced in the field.

Mechanically Operated Centrifugal Switch - An electric switch that operates using the centrifugal force created from a rotating shaft. The switch is designed to activate or de-activate as a function of the rotational speed of the shaft. In single-phase, split-phase induction motors, the switch is used to disconnect the starting winding of the motor once the motor approaches its normal operating speed. The centrifugal switch consists of weights mounted to the shaft of the motor and held near the shaft by spring force. At rest, levers attached to the weights press a low-friction, non-conductive plate against a set of electrical contacts mounted to the motor housing, closing the contacts and connecting the starting winding to the power source. When the motor approaches its normal operating speed, centrifugal force overcomes the spring force and the weights swing out, raising the plate away from the electrical contacts. This allows the contacts to open and disconnects the starting winding from the power source; the motor then continues operating solely using its running winding. Motors using such a centrifugal switch make a distinct clicking noise when starting and stopping as the centrifugal switch opens and closes.

Membranes - Thin films constructed of cellulosic or synthetic materials, which are designed to provide selective transport of solutes. Widely used for hemodialysis, micro filtration, ultrafiltration and reverse osmosis, membranes may be either homogeneous or asymmetric. Homogeneous membranes have a uniform structure or cross-section while asymmetric membranes have a dense "skin" which overlays a porous substructure.

Methemoglobinemia - The presence in blood of methemoglobin, a substance related to normal oxyhemoglobin, but having no oxygen-carrying capabilities and induced by exposure of blood to certain toxic chemicals, such as nitrites.

Mg/l - Milligrams per liter - A measure of concentration of a dissolved substance in a liquid. A concentration of one mg/l means that one milligram of a substance is dissolved in each liter of water. For practical purposes, this unit is equal to parts per million (ppm) since one liter of water is equal in weight to one million milligrams. Thus, a liter of water containing 10 milligrams of calcium has 10 parts of calcium per one million parts of water or 10 parts per million (10 ppm).

Micro Filtration - The separation or removal from a liquid of particulates and micro-organisms in the size range of 0.1 to 2 microns in diameter.

Micro Porous - In the context of water purification, membranes having an average pore size, which is between 0.1 and 1.0 micron in diameter.

Microfarad - A measurement of capacitance (electrical storage capability). Capacitors or condensers have a range listed on the casing (15-22 MFD, example) showing the capacity it can handle. They will also show the maximum voltage they can handle (370V, example).

Microhm - A measurement of electrical resistance equal to one millionth of an ohm. The unit of measurement for testing the electrical resistance of water to determine its purity. The closer water comes to absolute purity, the greater its resistance to conduction of an electrical current. Absolute pure water has a specific resistance over 18 million ohms (megohms) across one centimeter of water at a temperature of 78 degrees Fahrenheit.

Micron - A unit of linear measure. It is one millionth of a meter, or one thousandth of a millimeter. The smallest particle than can be distinguished by the naked eye would be about 40 microns across.

Micron Rating - A measurement applied to filters or filter media to indicate the particle size at which a substantial percentage of suspended solids above that size will be removed. As used in the water treatment industry standards, this may be an absolute rating or a nominal rating.

Microorganisms - Tiny living organisms such as bacteria, algae, diatoms, parasites, plankton, and fungi, which can be seen only with the aid of a microscope. Some microorganisms can cause acute health problems when consumed in drinking water. Also known as microbes.

Microwatt-Seconds Per Square Centimeter - A unit of measurement of intensity and retention, or contact time in the operation of ultraviolet (U/V) systems.

Milliliters/Minute - A common measurement for the flow rate of small RO systems. Usually measured with a graduate cylinder. One thousandth of a liter per minute. Milliliters/min x.38 = gal/day.

Minimum Basin Size - The minimum size for a sewage basin to prevent the pump from cycling on and off too frequently. Minimum pump run time should be between 15 seconds and 2 minutes. The longer the pump runs the better for the pump.

Minimum Flow - The amount of flow required to keep solids in suspension in a piping system. When moving sewage or effluent water with solids, bigger piping is not better. Pipe that is too large will cause the flow velocity to slow down and the solids will settle out in the pipe.

Mixed Bed - The intermixing of two or more filter or ion exchange products in the same vessel during a service run. The most common use is in ion exchange systems having a 40/60 percent cation to anion resin bed such as that for a deionization polisher system. In filtration, there may be an intermixing of two or more media in a single tank with each stratified into separate layers.

Mixed Flow Pump - Functions as a compromise between radial and axial flow pumps, the fluid experiences both radial acceleration and lift and exits the impeller somewhere between 0-90 degrees from the axial direction. As a consequence mixed flow pumps operate at higher pressures than axial flow pumps while delivering higher discharges than radial flow pumps. The exit angle of the flow dictates the pressure head-discharge characteristic in relation to radial and mixed flow.

Mod Media - Short for Modular Media - A type of filtration system. Consists of filters within filters - interchangeable and replaceable.

Model Number - Identification nomenclature for a product. Also called Model or Catalog Number or Product Number or Material Number.

Monitoring - Testing that water system operators must perform to detect and measure contaminants. A water system that does not follow EPA's monitoring methodology or schedule is in violation, and may be subject to legal action.

Monovalent Ion - A cation or anion having a single electrical charge.

Motor Canopy - The protective wrapper surrounding the electrical elements of a motor.

Motor Pad - A rubber or other resilient material placed underneath an electric motor. The pad cushions the motor to reduce noise and vibration transmission to the mounting surface.

MSDS - Material Safety Data Sheet - Required by law for products with potential for pollution or health risks(examples = paint, petroleum products).

MTBE - Methyl Tertiary Butyl Ether - A volatile organic chemical (VOC) used as an octane-enhancing lead substitute and more recently as an oxygenating agent in gasoline to reduce carbon monoxide emissions from automobiles. MTBE is volatile, flammable and highly soluble in water. During refueling and gasoline production, MTBE is volatilized to the atmosphere where it dissolves into the atmospheric moisture and returns to earth as precipitation, polluting our water supplies. Since MTBE does not adsorb well with organic matter in soils it is easily washed away. In surface water, MTBE volatilizes into the air. While in ground water, MTBE persists and moves freely. MTBE occurrences in ground water above 40 ppb have so far been attributed to point source contamination such as underground gasoline tank leaks, overflows, etc. EPA has tentatively classified MTBE as a potential human carcinogen.

MULTIPLE FILTER CONTROL VALVE - A multi-port valve with at least four positions for various filter operations, which combines in one unit the function of two or more single direct flow valves (Dial Selector Valve).

Multistage Pump - All the pumps or stages use a common shaft instead of individual motors (like a submersible turbine or a line shaft turbine).

Muriatic Acid - A commercial name for hydrochloric acid. Used for lowering the pH and alkalinity of pool water.

Back to top

Nanofiltration - A membrane treatment process, which falls between reverse osmosis and ultrafiltration on the filtration/separation spectrum. The nanofiltration process can pass more water at lower pressure operations than reverse osmosis, can remove particles in the 300 to 1,000 molecular weight range such as humic acid and organic color bodies present in water, and can reject selected (typically polyvalent) salts. Nanofiltration may be used for selective removal of hardness ions in a process known as membrane softening.

NCAA - National Collegiate Athletic Association - The governing body for intercollegiate competition and the recording agent for college swimming records.

NEC - National Electric Code - A document listing various codes and regulations that counties and townships work off of to set their standards. Also used by NEMA.

NEMA - National Electric Manufacturers Association - Sets standards that must be adhere to by a manufacture if they want this rating. Some of the standards are bolt hole pattern, shaft length, bell housing size, etc.

Net Positive Suction Head - NPSH - Static pressure on the suction side of a pump, must be high enough to prevent the water entering the impeller from boiling. There are two types of NPSH - NPSHR and NPSHA.

Net Positive Suction Head Available - NPSHA - The amount of head available to the pump to overcome the NPSHR. NPSHA should be a larger number than NPSHR. NPSHA is affected by atmospheric pressure changes, altitude, pipe and fitting sizes, and elevation to the liquid being pumped.

Net Positive Suction Head Required - NPSHR - The amount of head required by the pump to keep the liquid being pumped in a liquid state. The only way NPSHR can be changed is by changing the pumps' rotational speed or its impeller diameter.

Neutralization - The addition of either an acid to a base or a base to an acid to produce a more nearly neutral solution. The use of alkaline or basic materials to neutralize acidity of some water is common practice in water processing to prevent corrosion of metallic home plumbing.

Neutrons - A component of an atom. Neutrons have no charge at all.

Nitrate - An anion comprised of one nitrogen atom and three oxygen atoms. Nitrates are considered toxic in hemodialysis water and are also harmful to infants when consumed orally. Plant nutrient and fertilizer that enters water supply sources from fertilizers, animal feed lots, manures, sewage, septic systems, industrial wastewaters, sanitary landfills, and garbage dumps are nitrates.

Nominal Filter Rating - Filter rating indicating the approximate size particle, the majority of which will not pass through the filter. It is generally interpreted as meaning 85 percent of the particles of the size equal to the nominal filter rating will be retained by the filter.

Non-Transient, Non-Community Water System - A water system which supplies water to 25 or more of the same people at least six months per year in places other than their residences. Some examples are schools, factories, office buildings, and hospitals which have their own water systems.

Nonswimming Area - Any portion of a pool, spa or hot tub where water depth, offset ledges or similar irregularities would prevent normal swimming activities.

Nozzle - An ejector part/device that increases the velocity of the liquid flowing through it by creating a partial vacuum at it's throat. Atmospheric pressure causes the increase in velocity.

NPS Discharge - Nonpoint Source pollution: nutrients, sediments, toxic substances, and pathogens that degrade waterways. NPS occurs mainly through storm water runoff.

NSF - National Science Foundation - A U.S. government-funded agency which provides fundamental research and education in all the non-medical fields of science and engineering.

NTU - Nephelometric Turbidity Unit - An instrumental means of measuring water clarity based upon the intensity of light scattered by suspended individual particles (suspended solids) that are generally invisible to the naked eye, similar to smoke in air.

Nucleus - Can have as many as seven layers or orbits of electrons moving around it.

Back to top

ODP - Open Drip Proof - a type of motor enclosure.

Off Float - A panel float that turns pump off.

Ohmmeter - Device used to check the resistance of the flow of electricity.

On-Site System - A natural system or mechanical device used to collect, treat, and discharge or reclaim wastewater from an individual dwelling without the use of a community-wide sewer. The system includes a septic tank and leach field.

ON/OFF Float Switch - A device commonly used with sump or other types of drainage pumps that sense water level and turns the pump motor on if the level exceeds the high level setting and off when the water level drops below the low level setting.

Open Impeller - Impellers designed with open blades or vanes, both front and back.

Open or Infinity - The flow of electricity is so small that the meter cannot sense it; there is no flow taking place.

Operating Pressure - The manufacturer's specified range of pressure expressed in pounds per square inch (PSI) in which a water processing device or water system is designed to function.

Operating Temperature - The manufacturer's recommended feed water or inlet water temperature for a water treatment system.

Organic Contaminants - Carbon-based chemicals, such as solvents and pesticides, which can get into water through runoff from cropland or discharge from factories. EPA has set legal limits on 56 organic contaminants.

Orifice Plate - A disc, placed in a water flow line, with a concentric sharp-edged circular opening in the center, which creates a differential pressure to measure flow and to operate feeders and instruments or other hydraulic equipment.

Osmosis - The natural tendency of water to pass through a semi-permeable membrane, so as to equalize concentrations on both sides of the membrane.

Osmotic Pressure - The force (pressure) resulting when two liquids, having different solute concentrations, are separated by a semi-permeable membrane. For every 100 ppm, an osmotic "back pressure" of 1 psi is generated and this "back pressure" must be overcome in the reverse osmosis process.

Osteodystrophy - Abnormal bone development which, in renal patients, may be attributed to parathyroid gland dysfunction and is characterized by high serum phosphorus and alkaline phosphates and low serum calcium levels.

Osteomalacia - A softening of bone due to an accumulation of osteoid and reduced mineralization, which may cause fractures with minimal stress.

Osteoporosis - Demineralization of bone, which may cause fractures with minimal stress.

Overflow Gutter - The gutter around the top perimeter of the pool which is used to skim the surface of the water and to carry off the waste, or to collect it for return to the filters (sometimes incorrectly referred to as “scum gutter” or “spit trough”).

Overflow System - Refers to removal of pool surface water through the use of overflows, surface skimmers and surface water collection systems of various design and manufacture.

Overload Protector - A device that interrupts the flow of current in an electric circuit if the flow becomes sufficiently high to constitute a danger.

Oxidants (Oxidizing Agents) - Chemicals, which provide oxygen and accept an electron in an oxidation-reduction reaction. Free chlorine and chloramines are oxidants, which are widely used for disinfection.

Oxidizing Filters - Filters that use a catalytic media, such as managanous oxides or potassium permangenate, to oxidize iron, manganese and other impurities from water.

Ozone - An extremely active oxidizing agent and bacteriocide, which consists of three oxygen atoms. It is formed by the action of a high voltage electrical field on oxygen or air (such as occurs during an electrical storm). Some degree of ozone can also be produced by certain types of ultraviolet lamps.

Back to top

Pancake-Style Submersible Turbines - Have radial flow impellers with multi-vane diffusers enclosed in an outer sleeve.

Parts Per Million (ppm) - The standard measure of total dissolved solids. Parts of dissolved material in one million parts of water. (eg. one pound of mineral salts dissolved in a million pounds of water would be on part per million).

Pascal (pa) - A unit of pressure equal to one Newton of force per square meter. One thousand pascals equal one kilopascal (KPa); a kilopascal equals 0.145 pounds per square inch. Alternatively, 1 psi = 6895 Pa = 6.895 kN/sq.m = 0.0703 kg/

Pathogens - Micro-organism that can cause disease in other organisms or in humans, animals and plants. They may be bacteria, viruses or parasites and are found in sewage, in runoff from animals and in water used for swimming. Fish and shellfish contaminated by pathogens, or the contaminated water itself, can cause serious illness.

Performance Curves or Pump Curves - A graph-type representation of an operating characteristic of a pump; shows how such a characteristic varies as a function of a single parameter (for example, total head vs. capacity) The "family" or composite graph makes it easier to judge whether a pump model will be useful for the pumping requirements.

Permanent Medium Filter - A filter that utilizes a medium that under normal use will not have to be replaced.

Permanent Split Capacitor (PSC) Motor - A motor that has a run type capacitor in series with the start winding (now referred to as the auxiliary winding) but does not require a switch to disconnect it. The PSC motor is less costly than the cap start motor because a switch is unnecessary and is available from 1/4 to 1-1/2 HP: starting torque is low (30-150% of run torque) and requires the lowest starting current of any design (less than 200% of run current).

Permeable - Allowing some material to pass through.

pH - A measurement of water acidity or alkalinity using a scale of 0 to 14. 7 = neutrality, numbers less than 7 = acidity, numbers greater than 7 = alkalinity. Relative acidity or alkalinity of a substance, such as water, as indicated by the hydrogen ion concentration.

Phase Angle - The difference between the phase of a sinusoidally varying quantity in a multi-phase motor and the phase of a second quantity which varies sinusoidally at the same frequency. Also known as phase difference.

Phenols - Weak aromatic acids, which are indicative of industrial pollution of water supplies. When combined with chlorine, they produce an objectionable taste and odor.

Pinching Hazard - Any configuration of components that would pinch or entrap the fingers or toes of a bather.

Poles - A method of classifying motors by the number of "poles" or pairs of windings.

Polyamide - A synthetic polymer of the nylon family used in the fabrication of reverse osmosis and ultrafiltration membranes.

Polymers - A chemical compound with many repeating structural units.

Polysulfone - A synthetic polymer used to fabricate reverse osmosis and ultrafiltration membranes, which are characterized by extreme thermal stability and chemical resistance. Popular in dental waterline filtration systems.

Polyvalent Ion - A cation or anion having a multiple electrical charge.

Polyvinyl Chloride (PVC) - A thermoplastic piping material produced by the polymerization of vinyl chloride.

Pool Boiler - A type of pool heater operating as an Indirect Type, but using steam instead of hot water in the closed system.

Pool Depth - The vertical distance between the floor level and or which is inclined 45° or less from horizontal. The normal or operating water level when the pool is in use.

Pool Floor - That portion of the pool interior which is horizontal or which is inclined 45° or less from horizontal.

Pool Heater - A device through which pool water is circulated to increase the temperature of the water. In the Direct Type, the heat is transferred directly to the pool water circulating tubes. The Indirect Type utilizes a separate enclosed system which is directly exposed to heat generator and which heats the pool water by circulating the steam or hot water around the tubes of a heat exchanger through which the water circulates. The heat generator is considered part of every heater.

Pool Wall - The sides of a pool above the floor which are vertical at the top and coved at the bottom, or which are inclined to the pool no more than 45° from the vertical.

Pools - Above ground/Portable Swimming Pool - A removable pool of any shape that is deeper than forty-two inches (42”) or holds more than 2,500 gallons of water or has a water surface area in excess of 150 square feet. The aboveground pool frame is located entirely above ground and may be readily disassembled for storage and reassembled to its original integrity.

Pools - In Ground Swimming Pool - Any pool, spa or hot tub whose sides rest in partial or full contact with the earth.

Pools - Non-Permanently Installed Swimming Pool - One that is so constructed that it may be readily disassembled for storage and reassembled to its original integrity.

Pools - On-Ground Swimming Pool - Any pool, spa or hot tub whose sides rest fully above the surrounding earth and that has a deep area below the ground level.

Pools - Public - Any pool, other than a residential pool, which is intended to be used for swimming or bathing and is operated by an owner, lessee, operator, licensee or concessionaire, regardless of whether a fee is charged for use.

Pools - Public Class A - Competition - Any pool intended for use for accredited competitive aquatic events such as FINA, AAU, NCAA, N.F., etc. The pool may also be used for recreation.

Pools - Public Class B - Any pool intended for public recreational use.

Pools - Public Class C - Any pool operated solely for and in conjunction with lodgings such as hotels, motels, apartments, condominiums, etc.

Pools - Public Class D - Special Purpose - Any pool operated for medical treatment, water therapy or non-recreational functions.

Pools - Public Type VI thru Type X - Public Pools suitable for the installation of diving equipment by type. Diving equipment classified at a higher type may not be used on a pool of lesser type (i.e., Type VIII equipment on a Type VI pool).

Pools - Residential - A residential pool shall be defined as any constructed pool, permanent or non-portable, that is intended for noncommercial use as a swimming pool by not more than three-owner families and their guests and that is over twenty-four inches (24”) in depth, has a surface area exceeding 250 square feet and/or a volume over 3,250 gallons. Residential Pools shall be further classified into types as an indication of the suitability of a pool for use with diving equipment.

Pools - Residential - Type I thru Type V Diving Equipment - Residential pools suitable for the installation of diving equipment by type. Diving equipment classified at a higher type may not be used on a pool of lesser type (i.e., Type III equipment on a Type II pool).

Pools - Residential - Type Q - Any residential pool where the installation of diving equipment is prohibited.

Pools - Wading - A pool that may range in water depth from two feet (2’) to zero feet (0’) for wading.

Pore - An opening in a membrane, which allows certain components to pass through, but not others.

Potable Water - Any water, such as an approved domestic water supply, which is bacteriologically safe and otherwise suitable for drinking.

Potassium Permanganate - An oxidizing agent commonly used for the regeneration of manganese green sand iron filters and occasionally used as a disinfectant.

Power - The rate at which work is expended.

Power Factor - Reactive Power / Apparent Power; electric utilities prefer power factors as close to 100% as possible, and sometimes charge penalties for power factors below 90%.

PPB (Parts Per Billion) - (equivalent to micrograms per liter). Unit used for the measurement of the concentration of a chemical or other substance in a liquid.

PPM (Parts Per Million) - (equivalent to milligrams per liter). Unit used for the measurement of the concentration of a chemical or other substance in the pool, spa or hot tub water, where this concentration is expressed in terms of “n” molecules of substance per one million molecules of water.

Precharge - The air put into a pressure tank to make it operate within a specific pressure range

Precharged Tank - A water storage tank pre-charged with air at factory featuring a vinyl bag to separate water from air which prevents waterlogging. This tank design provides greater drawdown than standard tanks. Pre-charged tanks do not require air volume control.

Precoat - The coating of filter aid on the septum of a diatomite type filter at the beginning of each filter cycle.

Precoat Feeder - A device used to feed a calculated amount of filter aid at the start of a diatomaceous earth filter cycle - following the cleaning operation.

Pressure - The effect produced by the application of force over the surface of an enclosed area.

Pressure Differential - The difference is pressure between two parts of a hydraulic system (influent and effluent of a filter, suction and discharge of a pump, the up and down-stream sides of a venturi or orifice).

Pressure Drop - Sometimes referred to as "delta P", it is the decrease in hydrostatic force (pressure) due to the effects of friction or restrictions on a flowing liquid.

Pressure Head - The vertical distance (in feet) equal to the pressure (in PSI) at a specific point. The pressure head is equal to the pressure in PSI times 2.31 ft.

Pressure Switch - Electrical/pneumatic device used to turn the pump on and off.

Pressurized Dosing System - A method of delivering effluent to a leaching field in intermittent doses. Requires a 2-1/2 to 4 foot squirt at the end of the system.

Primacy State - A State that has the responsibility and authority to administer EPA's drinking water regulations within its borders. The State must have rules at least as stringent as EPA's.

Priority Pollutants - Those pollutants that pose the most serious health hazards determined by the EPA (Environmental Protection Agency).

Private System - An on-site septic system.

Private Water System - An on-site drinking water system made up of a pump, a storage tank and accessories to operate the system automatically. When a faucet is opened in the system, air pressure in the upper part of the tank forces the water to flow out of the tank and into the system. Water pressure falls as the water flows out of the tank. When pressure drops to the cut-in setting of the pressure switch, the switch closes the circuit and the pump starts and runs until system pressure rises to the cut-out setting.

Product Water - The purified water stream from equipment, such as distillation, reverse osmosis and ultra filter units.

Proton - A stable elementary particle of the baryon family that is a component of all atomic nuclei and carries a positive charge equal to that of the electron's negative charge.

Protozoa - One-celled animals, usually microscopic, that are larger and more complex than bacteria. May cause disease.

PSI - An abbreviation for “pounds per square inch” (see “Feet of Head”).

PSIA - Pounds per Square Inch Absolute (above zero PSI).

PSIG - Pounds per Square Inch Gauge (above atmospheric pressure).

Public Notification - An advisory that EPA requires a water system to distribute to affected consumers when the system has violated MCLs or other regulations. The notice advises consumers what precautions, if any, they should take to protect their health

Public Water System (PWS) - Any water system which provides water to at least 25 people for at least 60 days annually. There are more than 170,000 PWS's providing water from wells, rivers and other sources to about 250 million Americans. The others drink water from private wells. There are differing standards for PWS’s of different sizes and types.

Pump And Dump Dosing System - Pumps a predetermined amount of effluent to a distribution box where it will gravity feed through the leaching system.

Pump Curves - Performance Curves - A graph-type representation of an operating characteristic of a pump; shows how such a characteristic varies as a function of a single parameter (for example, total head vs. capacity)

Pump Efficiency - The ratio of the water (output) power to the shaft (input) power. Pump efficiency is plotted on performance curves in most cases using what are known as "Iso-Efficiency Curves" When selecting pumps, try to keep the efficiency within 5% of the Best Efficiency Point.

Pump Flange - An external rib, or rim (lip), for strength and for attachment to another object, such as the flange on the end of a pipe or valve. By using flanges, pipes can be assembled or disassembled very easily.

Pump Strainer - A device, placed on the suction side of a pump, which contains a removable strainer basket designed to trap debris in the waterflow with a minimum of flow restriction (sometimes referred to in the past as a “Hair and Lint Trap”).

Pumping Level - The lowest water level reached during pumping operation.

Pumping Water Level - The water level in the well when the pump is running and the system is operating as it was designed or as the well driller has tested it. .

Puncture Hazard - Any surface or protrusion that would puncture a bather’s skin under casual contact.

Pyrolosis - A breakdown process which occurs when organic matter is subjected to elevated temperatures.

Back to top

Quaternary Ammonia - A series of compounds of ammonia in solution used as algaecides and germicides which reduce the surface tension of the water.

Back to top

Radial Flow - The flow pattern in which water flows from the outside of a filter element to the center core. For example, a replaceable particulate or carbon cartridge filter unit.

Radial Flow Impeller - A pump component in which the liquid enters the eye of the impeller axially and is turned by the impeller vanes and shroud to exit perpendicular to the axis of the pump shaft.

Radionuclides - Any man-made or natural element that emits radiation and that may cause cancer after many years of exposure through drinking water. Can be very long lasting as soil or water pollutants.

Radon - A colorless, odorless naturally occurring radioactive gas formed by the breakdown or decay of radium or uranium in soil or rocks like granite. Radon is fairly soluble in water, so well water may contain radon.

Rate Of Flow (GPM) - The measurement of the volume of flow per unit of time expressed in gallons per minute.

Rate Of Flow Indicator - A device to indicate the rate of flow in a pipe line (sometimes referred to as a “rate-of-flow meter”).

Rated Pressure - That pressure that is equal to or less than the designed pressure and appears on the data plate of the equipment.

Raw Water - Water in its natural state, prior to any treatment for drinking.

Real Life Head - If you need to move the water up 30 feet, that is defined as 30 feet of head. Or if you need to have 10 PSI at the end of your pipe, that is 23.1 feet of head.

Real Power - Used strictly to develop a magnetic field within the motor.

Recharge Area - The land area through or over which rainwater and other surface water soaks through the earth to replenish an aquifer, lake, stream, river, or marsh. Also called a watershed.

Recirculating System - The entire system including the suction piping, pump, strainer, filter, face piping and return piping.

Recovery (Percent Recovery) - A measurement applied to distillation, reverse osmosis and ultrafiltration equipment, which characterizes the ratio of product water to feed water flow rates. The measurement is descriptive of distillation reverse osmosis or ultrafiltration equipment as a system and not of individual membrane elements. Expressed as a , recovery is defined as: % Recovery = (Product flow rate/Feed flow rate) x 100.

Regeneration - Carried out using either an acid or alkali to remove the accumulated cations or anions, respectively from a filtration media. At the same time, the cation exchanger takes on hydrogen ions, to restore them to the original hydrogen or hydroxide form, respectively.

Rejection (Percent Rejection) - A measure of the ability of a reverse osmosis membrane to remove salts. Expressed as a percentage, rejection is defined as: Rejection = (l-Product concentration/Feed concentration) x 100.

Removable - Capable of being disassembled with the use of only simple tools such as a screwdriver, pliers or wrench.

Residual - Usually refers to chlorine residual, or the amount of measurable chlorine remaining after treating water with chlorine. Free residual differs from combined residual in that it is not combined with ammonia or other elements or compounds, and is a more effective disinfectant.

Resin - Specially manufactured polymer beads used in the ion exchange process to remove dissolved salts from water.

Resistance - Impedes the flow of electrons, and is measured in Ohms.

Return Piping - That part of the pool, spa or hot tub piping between the filter and the vessel through which filtered water passes.

RO - Reverse Osmosis - The process of removing, or separating, all particles and solids down to the smallest invisible salt particle from liquids. Reverse osmosis uses intense pressure to force liquids through a membrane or filter with holes so small that no particles can get through at all, and only the pure liquid remains.

Rotor - The part of the motor that moves. It consists of a stack of metal stampings called "laminations" that are bound together, having a series of slots that may be injected with molten aluminum or wrapped with copper or aluminum wire.

Rotor Speed - Based on the frequency or hertz that the electric energy is moving. One Hertz is one complete cycle of AC electric power.

Run Capacitor - Placed in line with the starting coil to smooth out the flow of electricity, making the motor run quieter by eliminating mechanical vibration caused by the turning rotor.

Ryznar Index - A modification of the Langelier index used to calculate the degree of calcium carbonate saturation and to predict the likelihood of scale formation from a water supply.

Back to top

Safety Line - A continuous line not less than 1/4 inch in diameter, which is supported by buoys and attached to opposite sides of a pool which is supported by buoys and attached to opposite sides of a pool to separate the deep and shallow ends.

Salt Passage Rate - A measurement of the passage of salts through a reverse osmosis membrane. Salt passage is related to rejection by: % Salt passage = 100 - % Rejection.

Sample - The water that is analyzed for the presence of EPA-regulated drinking water contaminants. Depending on the regulation, EPA requires water systems and states to take samples from source water, from water leaving the treatment facility, or from the taps of selected consumers.

Sanitary Survey - An on-site review of the water sources, facilities, equipment, operation, and maintenance of a public water systems for the purpose of evaluating the adequacy of the facilities for producing and distributing safe drinking water.

Saturated Zone - The underground area below the water table where all open spaces are filled with water. A well placed in this zone will be able to pump ground water.

Scale Deposits - Corrosion and Scale Deposits add up to a reduction in flow area, an increase of the velocity of the liquid, and an increase in head loss due to friction.

Scaling - Usually used in reference to distillation or reverse osmosis equipment, scaling is the precipitation of sparingly soluble salts, such as calcium carbonate, onto the surface of a distiller boiler or reverse osmosis membrane. Scaling is associated with decreased flux and reduced reverse osmosis rejection rates. Scaling also affects to a slight degree the efficiency of distillation processes.

Scrubbing or Scouring Velocity - A velocity of water moving fast enough to remove particles trying to cling to the pipe and keep the solids moving in the pipe. Minimum of 2 feet per second.

Second Affinity Law - With the same impeller, the head generated by the impeller is related to the square of the liquid exit velocity; if you increase the speed of the water the head will increase by the square of the change.

Secondary Drinking Water Standards - Non-enforceable federal guidelines regarding cosmetic effects (such as tooth or skin discoloration) or aesthetic effects (such as taste, odor, or color) of drinking water.

Sediment - Very small debris, such as sand, rust, or silt, that settles to the bottom of a tank or vessel.

Sedimentation - The process by which solids are separated from water by gravity and deposited on the bottom of a container or basin.

Self Priming Pump - A centrifugal pump having the capability of dispersing a certain amount of air from its pump body, assuming the pump has been primed initially, when operating under a suction lift; to free itself of entrained gas without losing prime; and to continue normal pumping operation without attention..

Semi-Open Impeller - Also know as a vane impeller, it has only one shroud. The other side of the impeller is in close contact with the pump volute case. The vanes of the impeller are spaced far enough apart to pass solids.

Semipermeable - Descriptive of a material, such as a reverse osmosis or ultrafiltration membrane, which allows the passage of some molecules and prevents the passage of others.

Septic Tank - A container used to collect wastewater from a house. Generally they have two compartments and are watertight. The larger compartment is for the raw sewage and the second compartment for effluent water. The second compartment can also be used as a pump chamber.

Septum - That part of the filter element consisting of cloth, wire screen or other porous material on which the filter medium or aid is deposited.

Service Factor - A factor indicating the degree to which an electric motor can be operated over the specified horsepower without danger of overloading or failure. In other words, it is the actual horsepower of the motor.

Service Pressure - The range of pressure in the pressure tank during the pumping cycle, usually expressed in pounds per square inch gauge (P.S.I.G.).

Setting - The vertical distance from the level at which the discharge pipe leaves the well to the bottom of the pump or jet assembly in the well.

Sewage - Raw wastewater from residential, commercial or industrial sites. Sewage from residential sites is generally defined as 2” or less solids and commercial sites are 3” or 4” solids.

Sewage Pump - A pump designed to pump black water (effluent).

Shallow Well - A type of jet pump OR a well having less than 25' of lift.

Shallow-Well Jet Pump - A dedicated pump that will work to a maximum depth of about 25 feet. The jet is either attached or pre-cast into the pump body.

Short-Cycling - The water pump turns on and off too rapidly or too frequently.

Shut-off Head - The total head created by a pump that is running against a closed discharge.

Silicon Controlled Rectifier (SCR) - A solid state device containing a gate that acts as the "turn-on" switch that allows the device to fully conduct voltage.

Silt Density Index - A measurement of the rate at which a 0.45 ~m filter disc is plugged under standardized test conditions. Silt density index (SDI) determinations are used to estimate the rate at which various water supplies will cause fouling or plugging of reverse osmosis or ultrafiltration membranes.

Silver Protein - A solution containing silver ions, such as Argyrol, used as a germicide.

Simplex System - A sewage or effluent system that uses a single pump to control the water level in the storage chamber. Most residential systems are simplex systems. Most simplex systems use an automatic pump with a piggy–back float to turn them on and off, some use a panel.

Single Or Double Pipe System - Refers to the well size and how the well can be entered.

Single Phase Protection (SPP) Device - Senses the power factor as heat builds up in the motor and shuts it down when the preset limit is reached.

Single Pipe - In a jet pump application means there is only one pipe going down into the well. The jet is attached to it and has leathers above the intake. These leathers act as a seal to ensure that well water will only enter through the suction.

Single-Phase Motor Designs - Motors that are most common to centrifugal pumps.

Skimmer Weir - The horizontal surface over which the water flows to the circulating system (usually self-adjusting for water level changes).

Slip - The difference between the rotor speed and the rotating magnetic field in the stator. Slip is what allows a motor to turn.

Slip Resisting - A surface that has been so treated or constructed as to significantly reduce the chance of a bather from slipping. The surface should not be an abrasion hazard.

Slurry - A suspension of diatomaceous earth in water used for body feeding in D.E. filters.

Slurry Feeder - A device to feed a variable amount of filter aid during the filter cycle.

Snifter Valve - A valve in a water system that allows air to enter or escape, and accumulated water to be released.

Sodium Bisulfate - A dry chemical commonly used to lower pH in water. Also called soda ash.

Sodium Carbonate - A dry chemical commonly used to raise pH in water.

Soft Start - Bringing a motor up slowly to its full running amps instead of starting the motor with locked-rotor in-rush current.

Soft Water - Water containing less than 1 grain per gallon dissolved calcium and magnesium salts. Definition of where “softness” starts may vary depending on individual viewpoints

Sole Source Aquifer - An aquifer that supplies 50 percent or more of the drinking water of an area.

Solute - Dissolved particles in a solvent

Sorbent - See adsorption.

Source Water - Water in its natural state, prior to any treatment for drinking.

Sp or Specific Gravity of Liquid - The ratio of the mass of a solid or liquid to the mass of an equal volume of distilled water at 4°C (39°F) or of a gas to an equal volume of air or hydrogen under prescribed conditions of temperature and pressure. Also called relative density.

Spa - A hydrotherapy unit of irregular or geometric shell design. (SEE “HYDROTHERAPY SPA” OR “HOT TUB”)

Spa - Inground - A Spa whose sides reside partially or fully below the natural ground level.

Spiral Casing or Volute - A pump component that has a gradually expanding water passageway from the tongue or cut water of the volute to the discharge.

Spiral Wound Membrane - The most common practical configuration of membranes for RO systems.

Split Phase Motor - A type of electric motor that has a start winding and a run or main winding separated by 90 degrees and the windings are wired in parallel. The split phase motor is a low cost design and is available from 1/20 to 1-1/2 HP and is usually found on low-end centrifugal pumps. It produces low starting torque (100-175% of run torque) and requires a very high starting current (700-1000% of run current).

Spray Rinse, Mechanical - A fixed or mechanically movable spray system which directs a stream of water against the filter surface, causing the filter aid and accumulated dirt to dislodge into the empty tank.

Springboard - A board especially designed to produce diver spring action when properly installed on an anchor (base) and fulcrum. (The term diving board includes non-spring types).

Squirrel Cage Induction Type Electric Motor - A motor whose name is derived from the similarity between the motor windings (which may use conductive bars connected together at both ends by shorting rings forming a cage-like shape) and a squirrel cage/hamster wheel. These are the most common type of industrial AC electric motors, being rugged and requiring neither a separate DC power source nor ship-rings. They are constant speed devices when energized by a constant frequency AC supply.

SSE - Sump, Sewage and Effluent pumps.

Start Winding - A second set of coils connected in series with a capacitor.

Starting Switch or Governor or Relay - A device designed to open its contacts when the motor reaches a critical speed, removing the start capacitor from the circuit.

Static Discharge Head - Another name for elevation. It is the distance between the datum plane and the highest point you are pumping to.

Static Electricity - An imbalance of protons (positive charged particles) and electrons (negative charged particles); a separation of negative and positive charges, caused by the intimate contact and then separation of two dissimilar insulating materials.

Static Head - The vertical distance between the free level of the source of the supply and the point of free discharge, or to the level of the free surface of the discharged water.

Static Or Standing Water Level - The undisturbed level of water in the well before pumping.

Static Suction Head - Is located on the suction side of the pump and is the distance between the datum plane and the water. It can be expressed as a positive or negative number depending if the pump has to lift the water.

Stator - The part of the motor that does not move. It consists of a stack of metal stampings called "laminations" that are bound together with a series of slots that contain the windings of the motor. Stator also includes the starting windings in a single phase motor.

Stator Slots - Slots in the stator for the coils of wire that will cause the magnetic field that rotate the rotor.

STEP Pump (Septic Tank Effluent Pump) - A pump designed to pump gray or effluent water.

STEP System (Septic Tank Effluent Pump) - An effluent pump transfers septic tank effluent, collected in the pump chamber to a distribution box or manifold for gravity flow to an absorption field or sewer line. The advantage of this method compared to other gravity systems is that the absorption field or sewer line can be located at a higher elevation than the septic tank. Disadvantages are common with all gravity systems, i.e. progressive plugging of the drain holes and absorption areas, and minimal effectiveness in hard soils or high water tables.

Steps - Riser/tread or series of risers/treads extending down from into the deck with the bottom riser/tread terminating at the pool

Sterilization - A physical or chemical process that reduces the number of organisms to a safe predetermined level (see also disinfection).

Straight Centrifugal Pump - The common name for non self-priming pumps. When air enters the eye of the impeller and voids the low pressure area in the impeller, this type of pump immediately loses its prime and must be manually re-primed.

Sub Turbine - The driver is close coupled to the pump end and submerged with it, eliminating the need for a long line shaft extending down from the surface. A sub turbine can be installed in any position, from vertical to horizontal.

Submergence - The vertical distance between PUMPING LEVEL and the bottom of the pump or jet assembly. Submergence must be sufficient to insure that the suction opening of the pump or jet assembly is always covered with water, while maintaining enough clearance from the bottom of the well to keep it out of sediment (at least 10 feet clearance is recommended).

Submersible Pump - A multi-stage centrifugal pump with a waterproof electric motor mounted below the pump end.

Bleeder Orifices - A device used where submersible pumps are installed with an air over water tank to maintain air pressure in the tank to help prevent the tank from becoming water-logged.

Submersible Turbine Pump - A number of centrifugal pumps plumbed together. The discharge on one pump is plumbed directly into the suction of the next pump. That adds pressure energy to the liquid.

Submersible Turbine Pump Stage - Consists of an impeller, a multi-vane diffuser, a common shaft for all the stages, and fasteners and spacers (depending on the exact style of construction).

Suction - Where the water enters the pump

Suction Head - The total head on the suction side of the pump, including suction lift and friction head.

Suction Inducer Sleeve - A sleeve surrounding a pump that forces the air or gas to rise in the well, allowing only water to enter the pump suction.

Suction Leak - An escape of liquid from, or insertion of air into, the piping system going into a pump.

Suction Lift - The condition where the water supply is below the pump.

Suction Piping - The part of the pool, spa or hot tub piping through which water passes from the vessel to the pump.

Superficial Velocity - A quantitative expression of the rate of linear motion with which water passes through a vessel used to house particles, such as ion exchange resin or carbon media.

Surface Attraction - Another form of resistance to flow in any liquid. A liquid will attach itself to any surface and cannot be moved.

Surface Skimmer or Recirculating Overflow - A device designed to continuously remove surface film and water and return it through the filter as part of the recirculation system, usually incorporating a self-adjusting weir, a collection tank and a means to prevent air lock of the pump (sometimes referred to as a “recirculation overflow,” or a “mechanical” or “automatic skimmer”).

Surface Skimmer System - This term encompasses perimeter type overflows, surface skimmers and surface water collection systems of various design and manufacture.

Surface Water - The water that systems pump and treat from sources open to the atmosphere, such as rivers, lakes, and reservoirs.

Surge Arrester - Another type of pump protection; protects the pump and controller if someone down line shuts off a piece of equipment that uses lots of power.

Surge Chamber - A storage chamber within the pool recirculating system used to absorb the water displaced by bathers.

Surge Tank - A type of pressurized water storage vessel. Surge tanks typically have large areas of stagnation that offer opportunistic bacteria a favorable environment for multiplication. Commonly found in reverse osmosis systems. Requires periodic sanitation to ensure control of bacterial growth.

Suspended Solids - Includes settle-able particles less than one micron in diameter.

Swimming Area - That area of a pool in excess of 3 feet in depth which is devoted to swimming.

Switch Frequency - Same as carrier frequency; the higher the frequency, the more resolution each PWM pulse contains OR the smoother the output waveform and the higher the resolution.

System Head Demand - A method of evaluating the Total Head requirements of an entire pumping system.

Back to top

Tamperproof - Meaning that tools are required to alter or remove portions of the equipment.

Tank - A steel, plastic, or fibrewound vessel designed to store pressure or water.

Tannin - Any of a group of water soluble, natural organic phenolic compounds that are produced by metabolism in trees and plants and are part of the degradation-resistant fulvic acid materials formed during the decomposition of vegetation. Tannins occur in water or in almost any location where large quantities of vegetation have decayed. Tannins can impart a faintly yellowish to brown color to water. Tannin molecules tend to form anions in water above pH 6 and can be treated with anion exchange resins. Below pH 5, tannins are better treated with activated carbon.

Taste And Odor - A type of filter that makes water smell and taste better.

TDH - Total Dynamic Head - The total amount of head required by the system. The amount of head the pump must produce to properly operate the system.

TDSL - Total Dynamic Suction Lift - Equivalent to Head.

TEFC - Totally Enclosed Fan Cooled - A type of motor enclosure. Larger motors have a fan to blow air over the outside of the motor housing.

TENV - Totally Enclosed Non-Vented - A type of motor enclosure.

Terminal Board - The place where the power is connected to the motor, and in most cases is where the voltage selection is made.

Thermal Limit - The maximum internal operating temperature in an electric motors, determined by the class of insulation used.

Thin Film Composite - A membrane made with a polyamide-based polymer consisting of three layers: a polyester support web, a micro porous polysulfonic inter layer, and an ultra-thin barrier coating on the top surface.

Third Affinity Law - With the same impeller, the change of horsepower will be related to the cube of the change in the velocity of the liquid; if you increase the speed of the water the horsepower required to affect that change will be cubed.

Three Phase Motor - A type of electric motor that does not have starting windings; coil sets are in groups of three instead of two.

Three States of Water - Liquid; Vapor or gas; Solid.

Thyristor - Same as SCR: a solid state device containing a gate that acts as the "turn-on" switch that allows the device to fully conduct voltage.

Time - The measure of delay between two events.

Titratable Alkalinity - The quantity of hydrogen ions (H+), which must be added to a sample of alkaline water in order to establish a condition of neutrality.

TNS - Test, Normal, Silence - A toggle switch used to turn the alarm on for a test, normal means the alarm is on and when the float that runs it is in the up position it turns the alarm on. Silence means the audio and visual alarm has gone off and you're working on it and don't want to hear the audio anymore.

Torque - A turning or twisting effort that results from a force being applied to a rigid object at a radial distance from the center of rotation. Torque = (force) times (radial distance)

Torque - A twisting or turning effort that results from a force being applied to a rigid object at a radial distance from the center of rotation.

Total Discharge Head - The total pressure or head the pump must develop on the discharge side. It is the sum of the elevation, the service pressure, and the friction loss. Of course, all of these measurements must be expressed in the same units, usually feet of head, before adding them together.

Total Dissolved Solids - The sum of all ions in a solution, often approximated by means of electrical conductivity or resistance measurements. Total dissolved solids (TDS) measurements are commonly used to assess distiller and reverse osmosis unit performance. It is important to note that a test measuring the electrical conductivity of the water sample provides only an estimate of the TDS present, as conductivity is not precisely proportional to the weight of an ion and nonconductive substances cannot be measured by electrical tests.

Total Dynamic Head - The total amount of resistance to flow against which a pump must work OR the sum of all the losses the pump must overcome to make the system work. Its components are Suction Head (Static suction lift, Suction side friction loss, Draw down) and Discharge Head (Static discharge head ((or elevation)), Discharge side friction loss, Head or pressure required at the point of usage.

Total Dynamic Head (TDH) - The sum of the static head or lift, plus the head needed to overcome friction in the piping and head required to operate the system.

Total Effective Length Of Pipe - The sum of straight pipe lengths plus fitting friction loss, which has been converted into straight lengths of pipe.

Total Organic Carbon - A measurement of the total mass of dissolved carbon in a water sample, excluding that originating from carbon dioxide and carbonates.

Total Static Head - Consists of the physical dimension of the static discharge head plus or minus the static suction head.

Total Suspended Solids (TSS) - A measure of the amount of suspended solids found in wastewater effluent. The particles, which can be removed from a solution by filtration, usually specified as the matter which will not pass through a 0.45 micron pore-diameter filter.

Toxic - Meaning that a given substance has an adverse physiological affect on man.

Transient, Non-Community Water System - A water system which provides water in a place such as a gas station or campground where people do not remain for long periods of time. These systems do not have to test or treat their water for contaminants which pose long-term health risks because fewer than 25 people drink the water over a long period. They still must test their water for microbes and several chemicals.

Tread Contact Surface - Foot contact surfaces of a ladder, step, stair or ramp.

Treads, Recessed - A series of vertically spaced cavities in the pool, spa or hot tub wall creating tread areas for step-holes.

Treatment Technique - A required process intended to reduce the level of a contaminant in drinking water.

Turbidity - A measurement of the amount of suspended solids (colloids) in a solution. Caused by stirred-up sediment, silt, clay, etc. Turbidity blocks light rays and makes the water opaque. Turbidity is measured in Nephelometric Turbidity Units (NTU). Potable water should not exceed 0.3 NTU. Turbidity cannot be directly equated to suspended solids because white particles reflect more light than dark-colored particles and many small particles will reflect more light than an equivalent large particle.

Turbine Bowl - A component of a submersible pump that houses an impeller. Often stacked in multiple stages.

Turnover - The period of time (usually in hours) required to circulate a volume of water equal to the pool, spa or hot tub capacity.

Two Sides To A Pump - Suction Side (How does that water get in there?) - the pump moves the water so that the low pressure has to be filled from another source. If we get the pressure low enough at the eye of the impeller, the atmosphere will push the water from our source to the pump; Discharge Side - the side that moves the water away from the pump.

Two-Pole Motor - Motors with one pair of running windings that run at 3450 rpm.

Types Of Suction Lift - Negative lift, meaning that the pump is above the water and has to have the water pushed up to it by the atmosphere; Positive lift, meaning that the pump could be submersible or has water above it.

Back to top

Ultra Filters - A membrane based filtration system in which the pore sizes range from 0.002 to 0.1 microns.

Ultraviolet (Uv) Light - Radiation (light) having a wavelength shorter than 3900 angstroms, the wavelength of visible light and longer than 100 angstroms, the wavelengths of x-rays. This wavelength puts ultraviolet light at the invisible violet end of the light spectrum. UV light is used as a disinfectant. Water treated by ultraviolet light should be free from particulate materials or turbidity so as to prevent micro-organisms from being shielded from the incident UV radiation.

Underdrain - The distribution system at the bottom of the filter which collects the water uniformly during the filter cycle, and which distributes the backwash water uniformly during the cleaning operation. Normally applies to sand filters.

UNDERWATER LIGHTS - A light designed to illuminate a pool from beneath the water surface.

Universal Gravitation Constant - The acceleration of a free falling body in the gravity field of the Earth. g = 32.2 feet/second/second

Unsaturated Zone - The area above the ground water level or water table where soil pores are not fully saturated, although some water may be present.

Upper Distribution System - Those devices designed to distribute the water entering a permanent medium filter in a manner so as to prevent movement or migration of the filter medium. This system shall also properly collect water during filter backwashing unless other means are provided.

Upthrust - A submersible turbine pump run with an extremely high flow rate and very low discharge head causes the thrust direction up. This happens when the impellers are not generating enough downward thrust.

Utility Pump - An inexpensive pump similar to a sump pump except that it is not automatic.

Back to top

Vacuum - A measure of pressure below atmospheric pressure. When the impeller rotates, it creates a vacuum in the eye of the impeller, which allows atmospheric pressure to push the water into the vacuum.

Vacuum Wall Fitting - The fitting in the wall of the pool just below the water level to which is attached the hose for the underwater suction cleaner.

Vaned Diffuser - Has gradually expanding passageways all the way around.

Vapor Pressure - The pressure that is required to keep water in a liquid state at that temperature

Variable Frequency Drive (VFD) - Circuitry that runs a motor from 0 to 60 Hz.

Variable High-Speed Drive (VSD) - Circuitry that runs a motor from 30 to 80 Hz.

Variable Torque Pump - The torque required is proportional to rotational velocity of the impeller.

Variance - State or EPA permission not to meet a certain drinking water standard. The water system must prove that: (1) it cannot meet a MCL, even while using the best available treatment method, because of the characteristics of the raw water, and (2) the variance will not create an unreasonable risk to public health. The State or EPA must review, and allow public comment on, a variance every three years. States can also grant variances to water systems that serve small populations and which prove that they are unable to afford the required treatment, an alternative water source, or otherwise comply with the standard.

Velocity - The measurement of the motion of liquids, expressed in feet per second.

Venturi or Venturi Tube - A tube having a constricted throat which causes differences in pressure and can be used to operate feeding devices, instruments and to measure flow. When used in conjunction with a nozzle, it converts the velocity of the liquid being pumped to pressure.

Vertical Wall - Shall refer to the wall up to a positive 11° angle towards the pool’s interior from plumb.

Violation - A failure to meet any state or federal drinking water regulation.

Virus - The smallest infectious microorganism, made of RNA or DNA, in a protein shell, which grow only in other, living cells. They are 0.004 to 0.1 microns in size and about 100 times smaller than bacteria.

Viscosity - The resistance of a fluid to flowing freely, caused by friction from its molecules OR a measure of how strongly molecules cling to each other. The higher the viscosity of the liquid, the higher the resistance to flow and the greater the head loss.

VOC or Volatile Organic Compound - A category of water contaminants.

Voltage - Electric potential similar to pressure but not a form of energy

Voltage Loss - The amount of electricity used to force current(amps) to where it needs to go. This can be caused various ways such as too small of wire, too long of a run, etc.

Volts - An electrical measurement of motor performance where voltage(volts) = current(amps) x resistance(ohms). Volts measures the pressure of electricity.

Volume - The amount that something will hold OR the contents of a space that is formed by lines that can be measured in three directions (length x width x height). In a pipe the formula is (Area x length).

Volute Case - A pump component that encloses the impeller and converts the high velocity energy created by the impeller into pressure energy. It is spiral shaped, similar to a snail's shell.

Vortex Impeller - Special class of semi-open impeller that creates a vortex in the water and spins the solids to the outside of the water vortex. A vortex impeller stands away from the pump volute case in order to pass solids. Special advantage of a vortex impeller is that it is not prone to clogging with stringy material. does not allow solids to pass through the impeller but forms a whirlpool under the impeller which moves solids up and away.

Vulnerability Assessment - An evaluation of drinking water source quality and its vulnerability to contamination by pathogens and toxic chemicals.

Back to top

Wading Area - That area less than 3 feet in depth devoted to activity of non-swimmers.

Wall Slope - The inclination from vertical in a pool wall, expressed in degrees or in feet (or inches) of horizontal distance in a given depth in feet (or inches).

Walls - The interior pool wall surfaces consisting of surfaces from the plumb to a 45° slope.

Water Hammer - The shock wave or series of waves caused by the resistance of inertia to an abrupt change of water flow through a water piping system. Water hammer may produce an instantaneous pressure many times greater than the normal pressure. For this reason, many building codes now require the installation of a "water hammer arrestor" or accumulation device to absorb shock waves and prevent damage to appliances such as washing machines as well as water treatment components such as reverse osmosis membranes.

Water - A very common organic solvent that weighs 8.334 pounds per gallon when fresh.

Water Horsepower - The energy added by the spinning impeller.

Water Line - Overflow System - The water line shall be at the top of the overflow rim.

Water Line - Skimmer System - The water line shall be at the midpoint of the operating range of the skimmers.

Water Slinger - A rubber or plastic washer installed on motor shaft to prevent water from entering the motor from seal leakage.

Water Softener - A pressurized water treatment device in which hard water is passed through a bed of cation exchange media for the purpose of exchanging calcium and magnesium ions for sodium or potassium ions, thus producing a "softened" water which is more desirable for laundering, bathing and dish washing. This cation exchange process was originally called zeolite water softening or the Permutit Process. Most modern water softeners use a sulfonated bead form of styrene/divinylbenzene (DVB) cation resin.

Water Table - The upper level of the saturated zone. This level varies greatly in different parts of the country and also varies seasonally depending on the amount of rain and snowmelt.

Water-Logged Pressure Tank - A condition in an air over water tank where the trapped air volume required for most efficient pump operation has leaked out of the tank, which will cause pump motor burnout. Symptoms are the pump runs in very short bursts and turns on and off frequently; the pump runs every time a faucet is opened; water pressure surges while the shower or a faucet is running; pump runs all the time but the water pressure is low. Waterlogging is a symptom of a ruptured or leaking air bladder.

Watershed - The land area that catches rain or snow and drains it into a local water body (such as a river, stream, lake, marsh, or aquifer) and affects its flow, and the local water level. Also called a recharge area.

Wattmeter - Instrument designed to measure load, in Watts (or Kilowatts).

Watts - A measurement of electrical power where watts = volts x amps. One watt is the rate of energy expended when a steady current of one amp flows under a pressure of one volt. 1HP = 746 Watts. Also known as Joules per second

Well Cap - A tight-fitting, vermin-proof seal designed to prevent contaminants from flowing down inside of the well casing.

Well Casing - The tubular lining of a well. Also a steel or plastic pipe installed during construction to prevent collapse of the well hole.

Wellhead - The top of a structure built over a well. Term also used for the source of a well or stream.

Wellhead Protection Area - The area surrounding a drinking water well or well field which is protected to prevent contamination of the well(s).

Wet Niche - A watertight and water cooled unit submerged and placed in a niche in the pool wall.

White Wire - Only hooked to the neutral bar and would tell an electrician that the wire was safe to touch.

Williams and Hazen Head Loss Tables - Based on the head loss in ten-year old pipe.

Wiring Diagram - Shows how the pump is wired for voltage.

Work - The amount of energy expended to move something times the distance the object is moved.

Back to top