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17-4 PH STAINLESS STEEL®: Is a martensitic precipitation/ age hardening stainless steel, offering high strength and hardness. 17-4 PH withstands corrosive attack better than any of the 400 series stainless steels, and in most conditions its corrosion resistance closely approaches that of 300 series stainless steel. 17-4 PH is primarily used as a stem material for butterfly and ball valves. 17-4 PH STAINLESS STEEL is a registered trademark of Armco Steel Company.

316 STAINLESS STEEL: An alloy of iron, carbon, nickel, and chromium. A nonmagnetic stainless steel with more ductility than 400SS. Austinetic in structure, 316 stainless steel has very good corrosion resistance to a wide range of environments, is not susceptible to stress corrosion cracking and is not affected by heat treatment. Most common uses in valves are stem, body and ball materials.

400 SERIES STAINLESS STEEL: An alloy of iron, carbon, and chromium. This stainless is normally magnetic due to its martensitic structure and iron content. 400 series stainless steel is resistantto high temperature oxidation and has improved physical and mechanical properties over carbon steel. Most 400 series stainless steels are heat-treatable. The most common applications in valves are for stem material in butterfly valves and backseat bushings and wedges in cast steel valves.

50 cycle OR 50 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 50 times a second.

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.

A.N.S.I. Standard: American National Standards Institute. A set of specifications (envelope dimensions) for centrifugal pumps manufactured in the United States.

A.N.S.I-1-: American National Standards Institute.  ANSI is a term often used in connection with the classification of flanges, ANSI class 150, 300, etc ANSI B73.1: this is a standard that applies to the construction of end-suction pumps. It is the intent of this standard that pumps of all sources of supply shall be dimensionally interchangeable with respect to mounting dimensions, size and location of suction and discharge nozzles, input shafts, base plates, and foundation bolts.

A.N.S.I-2-: American National Standards Institute: A private organization that helps to promote the standardization process that began in the United States in 1918.

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

ABS: Acrylonitrile Butadiene Styrene Class 4-2-2 conforming to ASTM D1788 is a time-proven material. The smooth inner surface and superior resistance to deposit formation makes ABS drain, waste, and vent material ideal for residential and commercial sanitary systems.  The residential DWV system can be exposed in service to a wide temperature span.  ABS-DWV has proven satisfactory for use from:40°F to 180°F. These temperature variations can occur due to ambient temperature or the discharge of hot liquids into the system. ABS-DWV is very resistant to a wide variety of materials ranging from sewage to commercial household chemical formulations. ABS-DWV is joined by solvent cementing or threading and can easily be connected to steel, copper, or cast iron through the use of transition fittings.

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: Atmospheric pressure added to gauge pressure.

Absolute Pressure-1-: Pressure above zero pounds per square inch.

Absolute pressure-2-: Pressure is measured in psi (pounds per square inch) in the imperial system and kPa (kiloPascal or bar) in the metric system. Most pressure measurements are made relative to the local atmospheric pressure. In that case we add a "g" to the pressure measurement unit such as psig or kPag. The value of the local atmospheric pressure varies,  it is not the same if you are at sea level (14.7 psia) or at 4000 feet elevation (12.7 psia). In certain cases it is necessary to measure pressure values that are less than the local atmospheric pressure and in those cases we use the absolute unit of pressure, the psia or kPa a.

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):  An electric current that reverses its direction at regular intervals. 2. A flow of electricity which reaches maximum in one direction, decreases to zero, then reverses itself and reaches maximum in the opposite direction. The cycle is repeated continuously. The number of such cycles per second is the frequency.

AC (Alternating Current)-1-:  The vibration of electrons to push an electric charge.

AC Motor: A motor (see Motor definition) operating on AC current that flows in either direction (AC current). There are two general types: induction and synchronous.

Acceleration: The rate at which velocity changes.

Acceptance Factor: Tank drawdown expressed in percentage. Example: The acceptance factor of a bladder tank with a pressure setting of 30/50 PSI is 31% (.31).

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

Accumulator: A fairly old term for a lead-acid battery, with a number of cells in series to ‘accumulate’ a higher voltage.

Accumulator-1-: Used in domestic water applications to stabilize the pressure in the system and avoid the pump cycling on and off every time a tap is opened somewhere in the house. The flexible bladder is pressurized with air at the pressure desired for achieving the correct flow rate at the furthest point of the house or system. As water is pulled from the tank the bladder expands to fill the volume and maintain the pressure. When the bladder can no longer expand the water pressure drops, the pressure switch of the pump is activated on low pressure, and the pump starts and fills the water volume of the accumulator. The bladder keeps the air from entering into solution with the water resulting in less frequent re-pressurization of the accumulator.

Acequia: Acequias are gravity-driven waterways, similar in concept to a flume. Most are simple ditches with dirt banks, but they can be lined with concrete. They were important forms of irrigation in the development of agriculture in the American Southwest. The proliferation of cotton, pecans and green chile as major agricultural staples owe their progress to the acequia system.

Acetal (POM): The Acetal resins are among the strongest and stiffest of all thermoplastics, and are characterized by good fatigue life, low moisture sensitivity, high resistance to solvents and chemicals, and good electrical properties. Because of these properties, Acetals often compete with nylons for many of the same applications. Acetals may be processed by conventional injection molding and extrusion techniques. The main area of application for Acetal is industrial and mechanical products. Acetal has good wear resistance, good chemical resistance, good dimensional stability, high strength and high stiffness. Some of the disadvantages are poor resistance to acids, subject to UV degradation, flammable, difficult to bond and has high specific gravity.

Acid Demand: A titration test used to determine proper amounts of acid (or pH decreaser) to reach correct levels. For example, to lower pH from 8.0 to 7.6, your pool may "demand" 2qts. of acid.

Acid: A substance that has a pH of less than 7, which is neutral. Specifically, an acid has more free hydrogen ions (H+) than hydroxyl ions (OH-).

Acid-1-: Liquid (muriatic acid) or dry granular (sodium bisulfate) substance used to lower the pool's pH (toward a more acidic condition) or to lower total alkalinity levels.

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

Acre-foot(acre-ft): The volume of water required to cover 1 acre of land (43,560 square feet) to a depth of 1 foot. Equal to 325,851 gallons or 1,233 cubic meters.

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 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.

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 Sludge: A wastewater treatment process that uses suspended microorganisms to digest the organic contents of wastewater.

Actuator: A device used together with radiant heat manifolds to control water flow through individual manifold branches. Actuators allow to use a single radiant heat manifold station to control multiple heating zones.

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 Base or Conversion Base: Same as conversion base. An adapter to convert current Nema "T" frame motors (which are smaller) to older Nema "U" frame motor mounting dimensions.

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

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: Connects and aligns the power end of an ANSI pump to the wet end.

Adapter-1-: Usually a fitting, used to transition from one type of connection to another. Examples: PEX to copper pipe adapter, sweat (solder) to thread adapter, threaded to CPVC adapter, etc.

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.

AFBMA: Anti-Friction Bearing Manufacturers Association - an organization of most bearing manufacturers that establishes standards for bearings. Armature The portion of the magnetic structure of a DC or universal motor which rotates.

Affinity laws: The affinity laws are used to predict the change in diameter required to increase the flow or total head of a pump. They can also predict the change in speed required to achieve a different flow and total head. The affinity laws can only be applied in circumstances where the system has a high friction head compared to the static head and this is because the affinity laws can only be applied between performance points that are at the same efficiency.

Affinity laws-1-: They predict how capacity, head and horsepower are affected by changes in the centrifugal pump impeller diameter or shaft speed.

Affinity Laws-2-:  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 Bleeder Assembly: Located on the top of the filter and sometimes accompanied by a pressure gauge, the bleeder is opened to release air trapped in the filter.

Air Bound: A condition occurring when a centrifugal pump body is filled with air and a vacuum can no longer be formed allowing water to flow into the pump.

Air Eliminator (aka Air Separator):  Device used in hydronic and radiant heating systems to remove excess air from the system. Unlike air vents and air purgers, air eliminators have very high efficiency and allow to remove even microscopic air bubbles from the system, which can help to extend the life of system’s components, reduce maintenance and system noise. Air eliminators are typically made from brass or bronze and come in sizes ranging from 3/4” to 2”.

Air entrainment (ingestion): Air in the pump suction can reduce the performance of a pump considerably. There are many causes of air entrainment; the air may be coming in at the suction tank due to improper piping or due to leakage in the pump suction line (assuming that conditions are such that low pressure is produced in the suction line). Leakage in a suction pipe under low pressure will cause air to enter the pump. Centrifugal pumps can be designed to handle more air if required.

Air Gap: Opening between the stator and rotor.

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 ingestion: Air is coming into the stuffing box because of a negative suction pressure.

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 Over: Motors designed for fan or blower service and cooled by the air stream from the driven fan or blower.

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.

Air Release Valve: The valve on top of a filter or separation tank which allows you to manually release the air out of the system. This reduces the risk of a filter or separation tank explosion.

Air Scoop: Usually made of cast iron, this fitting has an air chamber at the top, which slows down the velocity of water flowing though it and allows air bubbles to accumulate in the chamber. Top of the chamber is usually equipped with a 1/8” treaded hole, allowing to connect an Air Vent for further air purging.

Air Vent: A simple, automated air purging device which allows to remove excess air from hydronic heating systems. Most commonly used type of air vents are float type air vents. Typically installed at the highest point in the system, made from brass and available in connection sizes from 1/8” to 1/2“.

Air Volume Control: Maintains the air charge in a standard water storage tank. Pre-charged tanks do not require an air volume control.

Alarm Condition: Condition that warns operator of a problem with system, eg., high water alarm which will activate horn and light.

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.

Algae-1-: Over 20,000 species known to exist. Algae may form on your pool surfaces or it may bloom in suspension. We typically know algae to be green but it may also be yellow (mustard algae), black, blue-green, or any shade in between. It may form separate spots or seem to grow in sheets. Pink algae are not algae at all but a form of bacteria. Algae are living breathing organisms that need warmth, sunlight, and CO² to thrive.

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

Algaecide-1-: Meaning, to kill algae. Algaecides perform best as a backup to a routine sanitation program. They also help to kill airborne spores as they blow into the pool. A variety of algae treatment products are available including copper and silver compounds, poly-quat compounds, chlorine enhancers , and herbicides.

Algaestat: An algaecide kills algae, while an algaestat retards and prevents its genesis and growth.

Alignment: The centerline of the pump is perfectly aligned with the centerline of the driver (usually an electric motor).

Alkaline: Alkalis are best known for being bases (compounds with pH greater than 7) that dissolve in water. Alkaline is commonly used as a synonym for base, especially for soluble bases.

Alkaline-1-: Sometimes water or soils contain an amount of alkali (strongly basic) substances sufficient to raise the pH value above 7.0 and be harmful to the growth of crops.

Alkaline-Manganese Dioxide Cell: A type of primary cell which uses an anode of powdered zinc, a cathode of manganese dioxide and a potassium hydroxide electrolyte. Offers up to 8 times the capacity of carbon-zinc cells. Commonly called the alkaline battery.

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.

Alkalinity-1-: Alkaline refers to the condition where the water's pH is above 7.0 (neutral) on the pH scale. It is the opposite of acidic. Alkalinity is the amount of carbonates and bicarbonates in the water, measured in "parts per million" (PPM) of Total Alkalinity.

Alkalinity-2-: The capacity of water for neutralizing an acid solution.

Allowable pipe stress: The allowable or maximum pipe stress can be calculated using the ASME Power Piping Code B33.1. The allowable pipe stress is fixed by the code for a given material, construction and temperature from which one can calculate the allowable or maximum pressure permitted by code.

ALLOY 20Cb-3®: This alloy has higher amounts of nickel and chromium than 300 series stainless steel and with the addition of columbium, this alloy retards stress corrosion cracking and has improved resistance to sulfuric acid. Alloy 20 finds wide use in all phases of chemical processing. Commonly used as interior trim on butterfly valves.  ALLOY 20Cb-3 is a registered trademark of Carpenter Technology.

Alluvium: Deposits of clay, silt, sand, gravel, or other particulate material that has been deposited by a stream or other body of running water in a streambed, on a flood plain, on a delta, or at the base of a mountain.

Alternating current:  A current formed when electrons flow in one direction, followed by a flow in the opposite direction.

Alternative On-site System: an on-site treatment system other than a conventional septic tank and leach field design, i.e. sand mounds, sand filters, cluster systems, etc.

Alternator: Device designed for alternating the run cycle or duplexing of two motors automatically, which equalizes pump wear.

Altitude: General purpose motors are suitable for operation up to 3300 feet. Class F insulation is suitable to 9900 feet.

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 bronze: The most widely accepted disc material used in butterfly valves, aluminum bronze is heat treatable and has the strength of steel. Formation of an aluminum oxide layer on exposed surfaces makes this metal very corrosion resistant. Not recommended for high pH wet systems.

Aluminum Heat Transfer Plates: These plates are used in radiant heating systems to improve heat dispersion across the flooring surface. Manufactured from aluminum using either extrusion or stamping methods and are available for 3/8” and ½” PEX in various shapes and sizes.

Aluminum Sulfate: Also known as "alum;" this product is used as a flocculent which attracts suspended particles in the water together (green or cloudy pools). "Alum" sinks everything to the bottom which is then vacuumed to waste. A small amount of "alum" can also be used as a sand filter additive.

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

Aluminum:  A silvery white metal that is soft, light, and an effective conductor. Is a ductile member of the poor metal group of chemical elements.

Aluminum-1-: A non-ferrous metal, very lightweight, approximately one-third as much as steel. Aluminum exhibits excellent atmospheric corrosion resistance, but can be very reactive with other metals. In valves, aluminum is mainly used as an exterior trim component such as a handwheel or an identification tag.

Ambient heat/pressure: The heat or pressure in the area where the equipment is located.

Ambient temperature: That amount of heat surrounding the motor during operation.

Ambient: The temperature of the space around the motor. Most motors are designed to operate in an ambient not over 104°F.

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.

Ampere:  A unit of measurement that indicates the amount of current flowing in a circuit.

Ampere-hour (Ah): The unit used in specifying the storage capacity of a battery. A battery with 1Ah capacity can supply a current of one ampere for one hour or 0.5A for two hours, etc. 1Ah ist he equivalent of 3600 coulombs of electrical charge.

Ampere-Hour Capacity: The number of ampere-hours which can be delivered by a storage battery on a single discharge. The ampere-hour capacity of a battery on discharge is determined by a number of factors, of which the following are the most important: final limiting voltage; quantity of electrolyte; discharge rate; density of electrolyte; design of separators; temperature, age, and life history of the battery; and number, design, and dimensions of electrodes.

Amperes (amps) or A: Current flow at a specific load condition.

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.

Amps-1-: The unit of measure or electrical current flow.

Amtrol: Manufacturer of expansion tanks.

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:A negatively charged ion, which has more electrons in its electron shells than it has protons in its nuclei, is known as an anion due to its attraction to anodes.

Annealing: To soften the metal by heating it to a predetermined temperature somewhere below its melting point.

Anode: In a primary or secondary cell, the metal electrode that gives up electrons to the load circuit and dissolves into the electrolyte.

Anti Vortex Plate: An anti vortex plate prevents the formation of a vortex and therefore air entrainment into the pump by forcing any emerging vortex to go around a plate and then into the suction pipe. The swirling motion cannot be maintained and the vortex dissipates and cannot form if the path is too long and contorted. Source: NFPA 22, Standard for water tanks for private fire protection 2008 edition.

Antifreeze: In snow melting, hydronic and radiant heating systems, antifreeze is usually a food grade propylene glycol.

A-PEX: (also known as PEX-A):  PEX tubing manufactured using engel method of cross-linking. This type of PEX tubing also uses expansion connection system.

API 610: American Petroleum Industry, a pump standard adopted by the petroleum industry. The intent being to make pumps more robust, leak-free and reliable.

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

Appropriation doctrine: The system for allocating water to private individuals used in most Western states. The doctrine of Prior Appropriation was in common use throughout the arid west as early settlers and miners began to develop the land. The prior appropriation doctrine is based on the concept of "First in Time, First in Right." The first person to take a quantity of water and put it to Beneficial Use has a higher priority of right than a subsequent user. Under drought conditions, higher priority users are satisfied before junior users receive water. Appropriative rights can be lost through non-use; they can also be sold or transferred apart from the land. Contrasts with Riparian Water Rights.

Aquaculture: Farming of plants and animals that live in water, such as fish, shellfish, and algae.

Aquastat: A device, commonly used in hydronic and radiant heating systems, which allows to control system components (such as circulators) by reading the system water temperatures. Aquastats are usually available in either strap-on type (device attached to the external surface of the pipe) or well type.

Aqueduct: A pipe, conduit, or channel designed to transport water from a remote source, usually by gravity.

Aqueous Batteries: Batteries with water-based electrolytes.

Aquifer (confined): Soil or rock below the land surface that is saturated with water. There are layers of impermeable material both above and below it and it is under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer.

Aquifer (unconfined): An aquifer whose upper water surface (water table) is at atmospheric pressure, and thus is able to rise and fall.

Aquifer: A geologic formation(s) that is water bearing. A geological formation or structure that stores and/or transmits water, such as to wells and springs. Use of the term is usually restricted to those water-bearing formations capable of yielding water in sufficient quantity to constitute a usable supply for people's uses.

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).

Artesian water: Ground water that is under pressure when tapped by a well and is able to rise above the level at which it is first encountered. It may or may not flow out at ground level. The pressure in such an aquifer commonly is called artesian pressure, and the formation containing artesian water is an artesian aquifer or confined aquifer. See flowing well

Artificial recharge: An process where water is put back into ground-water storage from surface-water supplies such as irrigation, or induced infiltration from streams or wells.

ASME: American Society of Mechanical Engineers. The Boiler pressure power piping code B31.3 is a code that is often used in connection with the term ASME, the maximum pressure safely allowable can be calculated using this code.

ASME-1-: 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.

ASTM: American Society for Testing Materials.

Atmospheric Losses: Engine performance DECREASES with altitude. The higher the altitude, the less air there is available to support combustion. Maximum engine power DECREASES about 3.5% per 1000 feet of altitude.

Atmospheric pressure: At sea level, atmospheric pressure is 14.7 psi. All around us. If one end of a tube is placed in water and a perfect vacuum is applied to the other end, that 14.7 psi could hold a column of water 33.9 feet high. This is only obtainable at sea level and with a perfect vacuum. In reality, ALL centrifugal pumps can lift water no more than 26 feet at sea level. This drops off approximately 2 feet for each 1000 feet of altitude above sea level.

Atmospheric Pressure-1-:  The force exerted by the atmosphere on the earth's surface, which allows a centrifugal pump to operate. At sea level, the atmospheric pressure equals 14.7 PSI. As elevation increases, atmospheric pressure decreases, therefore pump performance also decreases.

Atmospheric Pressure-2-: 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.

Atmospheric pressure-3-:  Usually refers to the pressure in the local environment of the pump. Atmospheric pressure varies with elevation, it is 14.7 psia at sea level and decreases with rising elevation. The value of the local atmospheric pressure is required for calculating the NPSHA of the pump and avoiding cavitation.

Atom: Is 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.

Atom-1-: The smallest distinguishable unit of a material that maintains that material's characteristics.

Automatic Pool Cleaner: A device which agitates or vacuums debris from the walls and floor of the pool.

Automatic Pump: Refers to a pump that is controlled with a liquid level switch, pressure switch or control panel automatically for designed conditions.

Automatic Reset Overload: After the motor cools, this line-interrupting protector automatically restores power. It should not be used where unexpected restarting would be hazardous.

Available Capacity: The total battery capacity, usually expressed in ampere-hours or milliampere-hours that are available to perform work. This depends on factors such as the endpoint voltage, quantity and density of electrolyte, temperature, discharge rate, age, and the life history of the battery.

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.

Average discharge pressure: Usual average discharge pressure is 40 PSI - halfway between the 30-50 PSI pressure switch setting of most water systems. When the tank is installed away from the pump at a higher level, or when house or yard fixtures are above the pump and tank, a greater pressure is needed and a larger pump must be used.

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

Axial flow pump: Refers to a design of a centrifugal pump for high flow and low head. The impeller shape is similar to a propeller. They are used extensively in the state of Florida to control the water level in the canals of low lying farming areas. The water is pumped over low earthen walls called burms into the South Florida Water Management District  main collecting canals.