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HVAC Abbreviations Directory
American National Standards Institute. A set of specifications (envelope dimensions) for centrifugal pumps manufactured in the United States
Reduction or removal of a contaminant.
Atmospheric pressure added to gauge pressure.
Temperature measured from absolute zero
Degrees Rankine, where absolute 0°R. = -459.7°F, degrees Kelvin where absolute 0°K = -273.1°C.
Absolute Zero Temperature
Temperature at which all molecular motion ceases (- 460 F. and - 273 C.)
Substance with the ability to take up or absorb another substance.
Usually solid substance with the ability to take up or absorb another substance (usually in gas).
A material which, due to an affinity for certain substances, extracts one or more such substances from a liquid or gaseous medium with which it is in contact and which changes physically or chemically, or both, during the process. Calcium chloride is an example of a solid absorbent, while solutions of lithium chloride, lithium bromide, and the ethylene glycols are examples of liquid absorbents.
It is a device containing liquid for absorbing refrigerant vapour or other vapours. In an absorption system, it is that part of the low side used for absorbing refrigerant vapour.
The ratio of absorbed to incident radiation on a surface. It is the fraction of incident electromagnetic power that is absorbed at an interface, in contrast to the absorption coefficient, which is the ratio of the absorbed to incident electric field
The process in which a substance in one state is incorporated into another substance of a different state (e.g. liquids being absorbed by a solid or gases being absorbed by a liquid).
It is a process whereby a material extracts one or more substances present in an atmosphere or mixture of gases or liquids accompanied by physical change or chemical change, or both, of the material.
The process of one substance entering into the inner structure of another.
Absorption chillers differ from mechanical vapour compression chillers in the fact that they utilize a thermal or/and chemical process to produce the refrigeration effect necessary to provide chilled water. There is no mechanical compression of the refrigerant taking place within the machine as it occurs within more traditional vapour compression type chillers.
Refrigerator which creates low temperature by using the cooling effect formed when a refrigerant is absorbed by chemical substance.
AC ( Alternating Current )
The commonly available electric power supplied by an AC generator and is distributed in single or three phase forms. AC current changes its direction of the flow (cycles).
A motor (see motor definition) operating on a-c current that flows in either direction (AC current) there are two general types: induction, and synchronous.
The energy required to induce air to move at the entry to a system.
Acceptable indoor air quality
Indoor air that does not contain harmful concentrations of contaminants; air with which at least 80% of building occupants do not express dissatisfaction
Method for determining or restricting access to system and network resources.
Access control system
A dedicated special system for security.
A door provided in a unit casing, wall, floor, ceiling, duct, etc, to permit inspection, entrance, or availability to concealed parts or devices.
Opening in natural draft tower used for access to the cold water basin. It can be large enough for a man only, or large enough for mechanical equipment.
It is a storage chamber for low side liquid refrigerant, also known as surge drum or surge header; also, a pressure vessel whose volume is used in a refrigerant circuit to reduce pulsation.
Actual cubic feet per minute; the quantity or volume of a gas flowing at any point in a system. Fans are rated and selected on the basis of ACFM, as a fan handles the same volume of air regardless of density.
Actual cubic feet per minute; the quantity or volume of a gas flowing at any point in a system. Fans are rated and selected on the basis of ACFM, as a fan handles the same volume of air regardless of density. Also see ‘‘CFM’’ and ‘‘SCFM.’’
Air Changes Per Hour. The number of times that air in a house is completely replaced with outdoor air in one hour.
Any substance that donates a proton (H+) when dissolved in a solution. In water treatment, it usually means circulating water with a pH of less than 7.0. Sulfuric acid is the most common acid used to control cooling water pH.
The recognition and/or registration of an event (e.g. alarm) by an operator.
A function that allows a destination node to inform a sending node of the receipt of a protocol-data-unit.
A term used to identify the level of indoor radon at which remedial action is recommended.
In reference to the indoor air quality Tools for Schools Kit. The packet contains three components - an introductory memo, IAQ Backgrounder, and IAQ Checklist - to assist school personnel to implement an effective yet simple indoor air quality program in their school.
It is a form of aluminium oxide, which absorbs moisture readily and is used as a drying agent.
It is a form of carbon made porous by special treatment by which it is capable of absorbing various odours, anesthetics, and other vapours.
Specially processed carbon used as a filter drier; commonly used to clean air.
The amount of steel (iron) in the stator and rotor of a motor. Usually the amount of active iron is increased or decreased by lengthening or shortening the rotor and stator (they are generally the same length).
Active tracer gas release
Controlled release of a tracer gas by a pressurized system or pump.
That portion of a regulating valve which converts mechanical fluid, thermal energy or electrical energy into mechanical motion to open or close the valve seats
Field device that interfaces to control a plant process, operated electrically and pneumatically, or hydraulically. It influences the mass flow or energy flow
Mechanical device attached to a damper to move its blades. May be manual, electric, pneumatic, or hydraulic.
Connects and aligns the power end of an ANSI pump to the wet end.
Add On Heat Pump
Installing a heat pump in conjunction with an existing fossil fuel furnace. The result is a dual fuel system
Unique object identifier and/or device identifier within a system or combined systems.
Unique structured method for data point identification to address the information provided in BACS, consisting of a scheme and the semantics of the elements.
It is a thermodynamic process during which no heat is extracted from or added to the system.
Adjustable speed drive
A mechanical, hydraulic or electrical system used to match motor speed to changes in process load requirements
It is a material which has the ability to cause molecules of gases, liquids, or solids to adhere to its internal surfaces without changing the adsorbent physically or chemically. Certain solid materials, such as silica gel and activated alumina, have this property.
Substance with the property to hold molecules of gas or fluid without causing a chemical reaction
The capability of all solid substances to attract to their surfaces molecules of gases or solutions with which they are in contact. Solids that are used to adsorb gases or dissolved substances are called adsorbents; the adsorbed molecules are usually referred to collectively as the adsorbate. An example of an excellent adsorbent is the charcoal used in gas masks to remove poisons or impurities from a stream of air
The action, associated with surface adherence, of a material in extracting one or more substances present in an atmosphere or mixture of gases and liquids, unaccompanied by physical or chemical change. Commercial adsorbent materials have enormous internal surfaces.
Adhesion of a thin film of liquid or gases to the surface of a solid substance.
Assimilation of molecules or other substances onto the physical structure of a liquid or solid without chemical reaction.
The binding of gases to the adsorbent surface through chemical reaction after the physical adsorption.
Physical adsorption resembles the condensation of gases to liquids and depends on the physical, or van der Waals, force of attraction between the solid adsorbent and the adsorbate molecules
Act of combining substance with air.
Blowing or mixing of air through water to sweep out other dissolved gases and to equilibrate the water with primarily nitrogen, oxygen and carbon dioxide.
It is a process of exposing a substance or area, to air circulation.
An organism that grows only in the presence of free (molecular) oxygen.
It is an assemblage of small particles, solid or liquid, suspended in air. The diameters of the particles may vary from 100 microns to 0.01 micron or less; that is dust, fog, smoke.
A suspension of liquid or solid particles in air.
A suspension of liquid or solid particles in air.
Fan wheel design with airfoil-shaped blades.
They predict how capacity, head and horsepower are affected by changes in the centrifugal pump impeller diameter or shaft speed.
Annual Fuel Utilization Efficiency. A rating that reflects the efficiency of a gas furnace in converting fuel to energy. A rating of 90 means that approximately 90% of the fuel is utilized to provide warmth to your home, while the remaining 10% escapes as exhaust.
Age of air, local mean
The mean time it takes for supply air to reach a certain indoor point.
Age of air, room mean
Mean of all the local mean ages of air. symbol α
It is a device causing turbulent motion in a fluid confined in a tank.
Air Handler Unit. The air handler unit generally includes a blower or fan, heating and/or cooling coils, and related equipment such as controls, condensate drain pans, and air filters.
It is a device which automatically switches the air from one side of the ice tank to the other.
Introduction of new, cleansed, or recirculated air to conditioned space, measured by the number of complete changes per unit time.
The amount of air required to completely replace the air in a room or building; not to be confused with recirculated air.
Air change rate
Ventilation air flow rate divided by room volume. It indicates how many times, during a time interval, the air volume from a space is replaced with outdoor air
Air change rate, nominal
The nominal air change rate is equal to the ventilation flow rate divided by the room volume.
A method of expressing the amount of air leakage into or out of a building or room in terms of the number of building volumes or room volumes exchanged.
Air changes per hour (ACH)
Ventilation air flow divided by room volume. It indicates how many times, during one hour, the air volume from a space is replaced with outdoor air.
Device used for removal of airborne particulates and/or gases from the air. Air cleaners may be added to HVAC systems or stand-alone room units
Device used for removal of airborne impurities. A device that actively removes impurities from the air, including forced air filtration systems and electronic air cleaners. Air cleaners may be added to HVAC systems or stand-alone room units.
It is a device used to remove airborne impurities.
Air cleaner, electrostatic
A device that uses an electrical charge to trap particles traveling in the air stream
An IAQ controls strategy to remove various airborne particulates and/or gases from the air. The three types of air cleaning most commonly used are particulate filtration, electrostatic precipitation, and gas sorption
An indoor air quality control strategy to remove various airborne particulates and/or gases from the air. The three types of air cleaning most commonly used are particulate filtration, electrostatic precipitation, and gas sorption.
Air cleaning system
A device or combination of devices applied to reduce the concentration of airborne contaminants, such as microorganisms, dusts, fumes, respirable particles, other particulate matter, gases, and/or vapours in air.
Coil on some types of heat pumps used either as an evaporator or condenser.
Device used to control temperature, humidity, cleanliness and movement of air in a confined space.
Air Conditioner, Room
It is a factory-made, encased assembly designed as a unit primarily to provide free delivery of conditioned air to an enclosed space, room, or zone. It includes a prime source of refrigeration for cooling and dehumidification and means for circulating and cleaning air. It may also include means for ventilating and heating.
It is the process of treating air so as to control simultaneously its temperature, Humidity, cleanliness and distribution to meet the requirements of the conditioned space.
Treating air to meet the requirements of a conditioned space by controlling its temperature, humidity, cleanliness, and distribution.
Control of the temperature, humidity, air movement and cleaning of air in a confined space.
A form of air treatment in which temperature is controlled, possibly in combination with the control of ventilation, humidity and air cleanliness.
Air conditioning system
A combination of all components required to provide a form of air treatment in which temperature is controlled or can be lowered, possibly in combination with the control of ventilation, humidity and air cleanliness. (EPBD, 2002/91/EC)
Air Conditioning Unit
It is an assembly of equipment for the treatment of air so as to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the requirements of a conditioned space.
Air Conditioning Unit, Cooling (Heating)
It is a specific air-treating combination, consisting of means for ventilation, air circulation, air cleaning, and heat transfer, with control means for cooling (or heating).
Air Conditioning, Comfort
It is the process of treating air so as to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space.
Air Conditioning, Complete
It is the process of air conditioning in which the temperature and humidity are independently controlled.
Air Conditioning, Industrial
It is the process of air conditioning for other uses other than comfort.
Air Conditioning, Summer
It is the comfort air conditioning carried out primarily when outside temperature and humidity are above those to be maintained in the conditioned space.
Air Conditioning, Winter
It is the process of heating, humidification, air distribution, and air cleaning, where outside temperatures are below the inside room temperature.
Air Conditioning, Year Round System
It is a complete system, which ventilates, heats and humidifies in winter, cools and dehumidifies in summer, the air in the spaces under consideration and provides the deserved degree of air cleanliness and motion.
Any material in the atmosphere that affects persons and their environment (pollutant includes materials such as liquids, solids, aerosols, gases and odours). Term is used interchangeably with air pollutant.
Mechanism designed to lower temperature of air passing through it
It is a factory-encased assembly of element whereby the temperature of air passing through the device is reduced
Air Cooler Unit
It is specific air-treating combination consisting of means of air circulation and cooling.
Air Cooler, Dry
It is an equipment that removes sensible heat from the dehydrated air whenever it leaves the dehydrator at an elevated temperature
Air Cooler, Dry-Type
It is a forced circulation air cooler wherein heat transfer is not implemented a liquid spray during the operating period.
Mechanical air-moving device designed to limit the influx of unwanted air at a building opening.
A planar jet that provides a climate separation between zones with different conditions of indoor air quality and climate
An air distribution outlet or grille designed to direct airflow into desired patterns. Supply air terminal device, designed to direct airflow into desired patterns, usually placed in the ceiling, generally of circular, square or rectangular shape, and composed of divergent deflecting members.
Distribution of the air in a space, called the treated space, by means of devices, called air terminal devices, in a manner so as to meet certain specified conditions, such as air change rate, pressure, cleanliness, temperature, humidity, air velocity and noise level.
Distribution of the air in a space by means of air terminal devices, in a manner so as to meet certain specified conditions, such as air change rate, pressure, cleanliness, temperature, humidity, air velocity and noise level.
Air diffusion, displacement
Air diffusion where the mixing of supply air and indoor air is very low. Usually supply air is a few degrees cooler that room air and supply velocity low.
Air diffusion, mixing
Air diffusion where the mixing of supply air and room air is intended
The transportation of a specified air flow to or from the treated space or spaces, generally by means of ductwork.
A jet of air at specific conditions discharged at low velocity in a space in order to provide locally needed conditions.
Air Exchange Rate
The rate of air flow moving through a space, usually expressed in terms of room volume units per unit of time such as room air changes per hour
Air Exchange Rate
The rate at which outside air replaces indoor air in a space. Expressed in one of two ways: the number of changes of outside air per unit of time in air changes per hour (ACH); or the rate at which a volume of outside air enters per unit of time - cubic feet per minute (cfm).
Air extract, mechanical
The process of extracting air with the aid of powered air movement components, usually fans.
Air extract, natural
The process of extracting air by means of wind forces or density differences or a combination of the two.
Total amount of dry air and associated water vapor flowing through the tower, measured in cubic feet per minute at the exhaust from the tower and converted to standard air which has a density of 0.075 lb. per cu. ft.
Air flow rate, mass
Mass flow of air over specified time, usually expressed in kg/s or kg/h.
Air flow rate, volumetric
Volumetric flow of air over specified time, usually expressed in l/s or m3/h.
The space between magnetic poles or between rotating and stationary assemblies in a motor or generator.
The space between the rotating (rotor) and stationary stator member in an electric motor.
An-blower, filter and housing parts of a system. Fanblower, filter, heat transfer coil, and housing parts of a system. Also known as the blower section and part of the split system, this unit is commonly in your home or attic and blows the air through your house. This has to be matched with the condenser properly to assure maximum efficiency. This will contain your heating and evaporator coil.
Air handling unit
Assembly consisting of sections containing a fan or fans and other necessary equipment to perform one or more of the following functions: air circulation, filtration, heating, cooling, heat recovery, humidifying, dehumidifying and mixing of air, and necessary controls functions.
The measure of useful power required to move a given air rate against a given resistance. The ratio of air horsepower to fan input horsepower is the measure of fan efficiency.
Leakage of air into rooms through cracks, windows doors and other openings.
Air is coming into the stuffing box because of a negative suction pressure.
Opening in cooling tower through which air enters a tower. On induced draft towers, the air inlet is commonly called the louvered face.
It is a pipe which supplies the air requirements of the conditioned space. to the ice cans contained in the freezing tank.
Air leakage factor
The air leakage per unit envelope area.
Air leakage, internal
Air leakage between two air streams in an air handling component like heat recovery unit.
It is a pipe which carries air to the air laterals supplying ice cans contained in the freezing tank.
Result of the presence of air pollutants in the atmosphere.
Air Pressure Switch
Used on motors with blowers to measure the difference in pressure across the filter so as to detect a clogged filter.
Air Quality Standard
A government-mandated regulation that specifies the maximum contaminant concentration beyond which health risks are considered to be unacceptable.
Air quality, indoor (IAQ)
IAQ deals with the health and comfort of the air inside buildings and characterize the indoor climate of a building, including the gaseous composition, temperature, relative humidity, and airborne contaminant levels. IAQ is the expression for both the concentration of impurities in the air and an expression of how people signify their perception of the air (perceived air quality) in the form of e.g. smell and irritation (sensory measurements).
Air quality, perceived (PAQ)
Perceived air quality is an indoor air quality as it is perceived by humans.
Air Source Equipment
Heat pumps or air conditioners that uses the outdoor air to transfer heat to and from the refrigerant in the unit.
The layering of air within a space, due to density differences caused by temperature distribution of the air
Air supply, displacement
Air supply where the mixing of supply air and indoor air is at a minimum.
Air supply, mechanical
The process of supplying air with the aid of powered air movement components, usually fans
Air supply, mixed
The supply of mixed air.- see also mixed air
Air supply, natural
The process of supplying air by means of wind forces or density differences or a combination of the two.
Air Terminal Device
A device located in an opening provided at the boundaries of the treated space to ensure a predetermined motion of air in this space.
Air Terminal Device, Slot
A device with one or several slots with an aspect ratio of 10: 1 or more for each slot (the aspect ratio is the ratio of the length to the width of the closed rectangular opening). A slot may or may not have an adjustable member to vary the direction of the air jet(s) or air flow rate.
The distance an air jet travels upon leaving a diffuser before its velocity is reduced to a specific value, usually to the velocity which does not cause draft, 0,15-0,25 m/s depending on the temperature
Rate of speed of an airstream, expressed in FPM.
A valve, either manual or automatic, that is used to remove unwanted air from the highest point of a piping system.
It is the air surrounding an object.
Air that has been heated, cooled, humidified or dehumidified to maintain an interior space within the "comfort zone". (Sometimes referred to as "tempered" air)
Air removed from a space and discharged to outside the building by means of mechanical or natural ventilation systems.
The air in an enclosed occupiable space.
Air volume or flow that is set into motion by the primary air supplied to a space
The mixture of outdoor air and recirculated return air
Air taken from outside the building which therefore has not previously circulated through the ventilation system.
It is the air taken from outdoors and, therefore, not previously circulated through the system.
It is external air; atmosphere exterior to refrigerated or conditioned space and ambient (surrounding) air.
Conditioned and dehumidified outdoor air supplied to the terminal unit such as chilled beam, induction unit etc. through a duct from the air handling unit.
It is the returned air passed through the conditioner before being again supplied to the conditioned space.
A part of extract air which is not exhausted from the building, but it is recirculated back to spaces.
Air, Reheating of
In an air conditioning system, the final step in treatment in the event the temperature is too low.
It is the air returned from conditioned or refrigerated space.
It is the moist air in which the partial pressure of the water vapour is equal to the vapour pressure of water at the existing temperature. This occurs when dry air and saturated water vapour coexist at the same drybulb temperature.
Air volume flow rate extracted from a room and being supplied again to the same room after having been conditioned. (EN 13779) - also referred to as transfer air
It is the dry air at a pressure 760 mm Hg at 21°C temperature and with a specific volume of 0.833 m3/kg
Air delivered by mechanical or natural ventilation to a space, composed of any combination of outdoor air, recirculated air or transfer air.
Air moved from one indoor space to another.
Outdoor air which is supplied to a room for ventilation purposes.
Heat of compression, plus the heat of absorption, is transferred from refrigerant within coil to surrounding air, either by convection or fan or blower.
The distribution or movement of air.
The secondary airflow from the room induced into a terminal unit such as chilled beam, induction unit etc. by the primary air.
Factory-made encased assembly consisting of a fan or fans and other equipment to circulate, clean, heat, cool, humidify, dehumidify, or mix air.
Factory-made encased assembly consisting of a fan or fans and other equipment to circulate, clean, heat, cool, humidify, dehumidify or mix air.
Air-handling units, decentralised
In contrast to the central air-handling units, these units are allocated to a single room or group of rooms, supplying secondary air or outdoor air to that room.
Ak value (of an air terminal device)
Quotient obtained by dividing a measured air flow rate by a measured air velocity according to a specific process and a specific instrument
Warning of the presence of a hazard to a property or the environment, in security systems also to life.
A low form of plant life which generally requires sunlight and air for existence. Causes plugging of heat exchanger tubes and cooling tower distribution systems, and fill.
A low form of plant life containing chlorophyll that generally requires sunlight and air for existence. Many are microscopic but under favorable conditions can grow sufficiently dense to plug cooling tower distributors on the decks and to interfere with water splashing in the fill. Large masses often slough off the tower and plug heat exchangers or deposit in piping.
A toxic material that will kill algae. Some of the more commonly used algaecides are chlorine, copper sulfate and phenolic compounds.
A toxic material which will retard or prevent the growth of algae and slimes. Some of the more commonly used algaecides are chlorine, copper sulfate and phenolic compounds.
Normally in tablet form, placed in evaporator drain pan. Used to help slow the growth of bacteria.
Calculation that results in an output by evaluating input variable(s).
The centerline of the pump is perfectly aligned with the centerline of the driver (usually an electric motor).
An expression of the total basic anions (hydroxyl groups) that is present in a solution. It also represents, particularly in water analysis, the bicarbonate, carbonate, hydroxyl and occasionally the borate, silicate, and phosphate salts which will react with water to produce acid neutralizable anions.
A substance capable of causing an allergic reaction because of an individual's sensitivity to that substance.
Allergens and Pathogens
Biological material, including bacteria, viruses, fungi, mold spores, pollens, skin flakes and insect parts are ubiquitous in indoor environments. These particulates range from less than one to several microns in size. When airborne, they are usually attached to dust particulates of various sizes so that all sizes of airborne particulates may include them.
Character set that consists at least of decimal digits and letters.
Flow of electricity that constantly changes direction between positive and negative sides. Almost all power produced by electric utilities in the United States moves in current that shifts direction at a rate of 60 times per second.
The atmospheric altitude (height above sea level) at which the motor will be operating; NEMA standards call for an altitude not exceeding 3,300 ft. (1,000 meters) . As the altitude increases above 3,300 ft. And the air density decreases, the air’s ability to cool the motor decreases; for higher altitudes higher grades of insulation or a motor departing are required. DC motors require special brushes for high altitudes.
The height above sea level of a given location.
Immediate surroundings or vicinity.
The surrounding atmosphere; encompassing on all sides; the environment surrounding a body but undisturbed or unaffected by it.
The atmosphere which is adjacent to but not affected by the cooling tower. Generally, this means upwind of the tower, and the other areas where other heat producing equipment is located that supplies extraneous sources of heat to the air coming to the tower.
The air surrounding a building; outside air.
Ambient Air Temperature
Surrounding temperature, such as the outdoor air temperature around a building.
Ambient dew point
The ambient temperature in oF when dew begins to be deposited.
The heat or pressure in the area where the equipment is located.
The temperature of the surrounding cooling medium, such as gas or liquid, which comes into contact with the heated parts of the motor. The standard enema rating for ambient temperature is not to exceed 40 degrees Celsius.
Ambient wet-bulb temperature
The wet-bulb temperature that is measured in accordance with the definition of ambient. Readings are obtained by means of a mechanically aspirated psychrometer
Air Movement and Control Association.
A water-soluble, colorless, pungent gas with the formula NH3.
Positive ion with the formula NH4+ that forms when ammonia dissolves in water. It adds non-natural alkalinity to the water.
Ampere (A or Amp)
The primary unit of measurement of electrical current. One ampere of current is produced in a circuit by 1 volt acting through a resistance of 1 ohm.
An increase in the numbers or concentration of a microbe or its products through reproduction and growth of the microbe.
An organism that can grow under either aerobic or anaerobic conditions.
An organism that grows only in the absence of free oxygen (e.g.,sulfate reducing bacteria).
Continuous progression of a value with different point-by-point assignment of information.
Function for handling a measured value via an analog input.
Part of the hardware pertaining to a control device for measuring or positioning.
Function for delivering a manipulated variable or set point via an analog output.
Information containing a numerical represented quantity.
A threaded bolt embedded in a concrete basin or fitted to supported members, to which an anchor casting is attached.
A device for attaching the tower structure to the foundation; it does not include the anchor bolt. Also known as Column Anchor.
A device that reads air velocity, such as a wind vane. In fan applications, it is usually a spinning-vane-type instrument used to read low velocities at registers or grills.
A device which reads air velocity such as a wind vane. In fan applications, it is usually a spinning-vane type instrument used to read low velocities at registers or grills.
A negatively charged ion.
The process of relieving stress and brittleness in metals by heating
To soften the metal by heating it to a predetermined temperature somewhere below its melting point.
The total effects in energy use (measured in megawatthours) and peak load (measured in kilowatts) caused by all participants in the DSM programs that are in effect during a given year.
A positively charged electrode that, during electrolysis, attracts anions. formula NH3.
Area on a metal surface where electrons are given up and metal dissolves (corrosion).
An electrolytic action of affixing a protective coating or film, usually applied to aluminum
American National Standards Institute.
An agent that prevents foam from forming or reduces its presence.
An anti-friction bearing is a beating utilizing tolling elements between the stationary and rotating assemblies.
Agent that kills microbial growth.
American Petroleum Institute
In an AC circuit, the product of Volts x Amperes supplying a single-phase motor, or 1.732 x Volts x Amperes supplying a 3-phase motor; expressed in either volt- amps (VA) or kilovolt-amps (kVA), where 1000 VA = 1 kVA. See also ‘‘Real Power’’ and ‘‘Power Factor.’’
A set of functions that, together, form a logical unit supporting a process.
Object located within the BACS device’s application process.
Customized device fulfilling the requirements of a specified application.
The difference between the cold water temperature in degree F and the ambient or inlet wet-bulb temperature in degree F.
In an evaporative cooling device, combination consisting of means of air circulation and the difference between the average temperature of the cooling. circulating water leaving the device and the average wet-bulb temperature of the entering air. In a conduction heat exchanger device, the difference in temperature between the leaving treated fluid and the entering working fluid.
Accessories added to a fan for the purposes of control, isolation, safety, static pressure regain, wear, etc.
Air Purifying Respirator
Structure and means by which components and devices of a system are connected to intercommunicate.
It is the total plane area of the portion of a grille, face, or register bounded by a line tangent to the outer edges of the outer openings through which air can pass.
It is the total minimum area of the openings in an air inlet or outlet through which air can pass.
Area, gross floor
The total area of all the floors of a building, including intermediately floored tiers, mezzanine, basements, etc., as measured from the exterior surfaces of the outside walls of the building.
Area, internal gross
A term used in the United Kingdom, defined in the RICS Standard, for the area of a building measured to the internal face of perimeter walls at each floor level.
Area, net floor
A term used in the ISO standard to express the Interior Gross Area less the areas of all interior walls.
Area within the heated or cooled surface occupied for long periods. Normally the floor area within 1,0 m from external walls-windows and HVAC equipment and 0.5 m from internal walls.
Area of a building, next to the exterior walls, which has a different heating or cooling load than the rest of the building.
Area/space, living floor
Total area of rooms falling under the concept of rooms. (OECD Glossary of statistical terms)
Area/space, useful floor
Floor space of dwellings measured inside the outer walls, excluding cellars,non-habitable attics and, in multi-dwelling houses, common areas. (OECD Glossary ofstatistical terms)
Air-Conditioning and Refrigeration Institute is a nonprofit, voluntary organization comprised of heating, air conditioning and refrigeration manufacturers. ARI publishes standards for testing and rating heat pumps and air conditioners to provide you with a standardized measure of comparison.
Air Conditioning and Refrigeration Institute.
The portion of the magnetic structure of a DC or universal motor which rotates.
Armature Current, Amps
Rated full load armature circuit current.
Armature Inductance, Mho
Armature inductance in mill-henries (saturated).
The current that flows in the armature winding of a dc motor tends to produce magnetic flux in addition to that produced by the field current. This effect, which reduces the torque capacity, is called armature reaction and can effect the commutation and the magnitude of the motor’s generated voltage.
Armature Resistance, Ohms
Armature resistance is measured in ohms at 25 degree Celsius. (cold)
A measure of the ability of a device to remove ASHRAE standard test dust from test air. Also see ASHRAE dust.
The amount of particles of non-specific size captured by the filter. The arrestance describes how well an air filter removes larger particles (total mass) such as dirt, lint, hair anddust.
A class of silicate minerals composed of long, thin fibers.
A leading HVAC/R Association - American Society of Heating, Refrigerating and Air Conditioning Engineers. The trade association that provides information and sets standards for the industry.
American Society of Heating, Refrigeration, and Air Conditioning Engineers.
American Society of Mechanical Engineers.
The ratio of the width to the length
It is the ratio of the length of the core of a grille, face, or register to the width in air distribution outlets. In rectangular ducts, it is the ratio of width to depth.
It is production of movement in a fluid by suction created by fluid velocity.
American Society for Testing and Materials
American Society for Testing and Materials.
One atmosphere is approximately 14.7 PSI; 408" water gauge. Airflow is the result of a difference in pressure (above or below atmospheric) between two points.
At sea level, atmospheric pressure is 14.7 psi.
One atmosphere is approximately 14.7 psi, 408″ water gauge at sea level. Airflow is the result of a difference in pressure (above or below atmospheric) between two points.
One in which air movement through the tower is dependent upon atmospheric conditions, not induced by mechanical fans.
A number given to each element representing the number of protons in one atom of that element.
Weight (in grams) of 6.02x1024 atoms of a particular element. The weight of an atom of any element compared with that of oxygen that is considered to be 16.
It is the process of reducing to fine spray.
Absorption of sound pressure. Attenuation reduces the amplitude only of a sound wave while leaving the frequency unchanged.
The logical level on which the supervisory and processing functions for plant automation are performed. This level can also be assigned dialogoriented operating functions.
An organism that is capable of producing its own food through the use of chlorophyll and light.
Fan where the airflow through the impeller is mainly parallel to the axis of rotation. The impeller is contained in a cylindrical housing.
Fan where the airflow through the impeller is predominantly parallel to the axis of rotation. The impeller is contained in a cylindrical housing.
In-line air movement parallel to the fan or motor shaft.
In-line air movement parallel to the fan or motor shaft.
The force or loads that are applied to the motor shaft in a direction parallel the axis of the shaft. (such as from a fan or pump)
A mixture made up of two or more refrigerants with similar boiling points that act as a single fluid. The components of azeotropic mixtures will not separate under normal operating conditions and can be charged as a vapor or liquid.
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