A & I:  ACRONYM – Assembly and Installation.

A & R:  ACRONYM – Automation and Robotics.

A.A.B.A.:  Ambient Air Breathing Apparatus.

AB 1807 (Tanner):  A California state law (Health and Safety Code section 39650 et seq.) which became effective in January of 1984 and established the framework for California’s toxic air contaminant identification and control program.

AB 2588 (Connelly) Air Toxics “Hot Spots” Information and Assessment Program:  A California program (Health and Safety Code Section 44300 et seq.) which requires certain stationary sources to report the type and quantity of specific toxic substances they routinely release into the air.  The program identifies high priority facilities and requires facilities posing significant risks to notify all exposed individuals.

AB 2766 (Sher) Motor Vehicle Fee Program:  A program that permits air district and local governments to allocate vehicle registration surcharge fees to projects that reduce motor vehicle emissions such as zero-emission vehicles, bike lanes, and trip reduction programs.

Abatement:  The reduction of pollutant discharge by means of process modification, shutdown or addition of control equipment.  Corrective action to stop or clean up pollution or nuisance.  The reduction or elimination of pollution.

Above Grade:  The portion of a foundation wall or other building assembly above ground level.

Abrasion:  The wearing away of a solid surface by friction.  Damage caused by wearing, grinding, friction, or scraping.

Abrasion, Flex:  Fabric wear in a creased area caused by excessive bending, usually associated with cage contact used in bag house filtration.

Abrasion Resistance:  Ability of a fiber or fabric to withstand surface wear.

Abrasive Blasting Respirator:  A continuous flow air-line respirator constructed so that it will cover the wearer’s head, neck and shoulders.  It is designed to protect the wearer from inhalation of, impact of, and abrasion by materials used or generated in abrasive blasting.

Abrasive Cleaners:  Products that clean through abrasive or scouring action.

Abrasive Dust:  Coarse particles such as sand, metallic compounds, ceramic and glass, that can cause rapid wear on ductwork, air cleaners and fans.

Abridged Life Cycle Assessment (ALCA):  A simplified methodology to evaluate the environmental effects of a product or activity holistically, by analyzing the most significant environmental impacts in the life cycle of a particular product, process, or activity.  The abridged life cycle assessment consists of three complimentary components, restricted inventory analysis, abridged impact assessment, and improvement analysis, together with an integrative procedure known as “Scoping.”

ABS:  (Acrylonitrile butadiene styrene) Rigid black plastic pipe used only for drain lines. A common thermoplastic used to make light yet rigid molded products such as vacuum cleaners, helmets, automobile body parts, etc.  It has excellent impact resistance and durability.

Absolute:  A degree of filtration that guarantees 100% removal of suspended solids over a specified size found in the filtrate.

Absolute, AEC, or CWS Filter:  Obsolete term for HEPA filters.

Absolute Containment:  Capacity for completely retaining any specified substance. (In the present sense, the specified Class III safety cabinet is an example.)

Absolute Efficiency:  An arbitrary filter efficiency rating.

Absolute Filter:  See HEPA filter.

Absolute Filtration Rating:  The diameter of the largest hard spherical particle that will pass through a filter under specified test conditions. This is an indication of the largest opening in the filter cloth.

Absolute Humidity:  Air moisture content expressed in grains (or pounds) of water vapor per pound of dry air.  Amount of moisture in the air, indicated in grains per cubic foot.  The amount of water vapor present in a unit volume of air, usually expressed in kilograms per cubic meter (see Humidity and Relative Humidity).  The mass of water vapor per unit volume of air.  The humidity of the air measured by the number of grains of water vapor present in one cubic meter of air.

Absolute Micron Rating:  All (not just 98%) particles larger than the stated micron size have been removed from the fluid being filtered.

Absolute Pressure:  Pressure referred to as perfect vacuum.  It is the sum of gauge pressure (+ or -) and atmospheric pressure.  Abbreviated “psia” for pounds per square inch absolute.  One atmosphere (14.7 psi) greater than gauge pressure.

Absolute Temperature:  Temperature measured from absolute zero using an absolute temperature scale (e.g. Kelvin).  The temperature of a body referred to the absolute zero, at which point the volume of an ideal gas theoretically becomes zero. (Fahrenheit scale is minus 459.67°F / Celsius scale is minus 273.15°C).

Absolute Viscosity:  The force per unit area required to produce unit relative velocity between two parallel areas of fluid distance apart; also called coefficient of viscosity.

Absolute Viscosity (Dynamic):  The force in newton required to move a fluid layer of one square meter area and a thickness of one meter with a velocity of one meter per second.

Absolute Zero:  Temperature at which all molecular motion ceases (-460 °F, -273.15 °C, and 0 K).  The lowest temperature theoretically attainable on the Kelvin scale (approximately 273.16° C).

Absolute Zero Temperature:  The lowest temperature theoretically attainable on the Kelvin scale. Approximately -273.16o C.

Absorb:  A method to trap liquids or gases by causing them to penetrate into the absorbent material.

Absorbed Dose:  The absorbed dose is the energy deposited in an organ or tissue per unit mass of irradiated material.  The common unit for absorbed dose is the rad, which is equivalent to 100 egs per gram of material.  The international scientific community has adopted the use of different terms.  The SI unit of absorbed dose is the joule per kilogram (J kg-1) and its special name is the gray (Gy).  One Gy is the same as 100 rad.  Amount of energy imparted to matter by ionizing radiation per unit mass of irradiated material, in which the absorbed dose is expressed in units of rad or gray (l rad = 0.01 gray).

Absorbent:  A material which extracts one or more substances from a liquid or gaseous medium which it contacts and charges physically or chemically, or both (e.g. soled absorbent:  Calcium chloride, liquid absorbent: solutions of lithium chloride, lithium bromide, and ethylene glycols).  A substance with the ability to absorb another substance.

Absorber:  A kind of scrubber utilizing the absorption principle.  An object absorbing another object or radiation (e.g. the blackened surface within a solar collector, which absorbs the solar radiation converting it to heat.  These surfaces usually absorb solar radiation but do emit a limited amount of radiative heat because of the so-called spectral selective coatings applied to the surface).

Absorptance:The ratio of a solar energy absorbed to incident solar.  The ratio absorbed objects or radiation.  (For solar energy the ratio of absorbed to incident solar radiation on a surface).  Also called absorbtivity.

Absorptance of a Glazing Material:  In this context the absorption of solar energy in the glazing material occurring throughout the thickness of a glazing material.  The absorptance is the fraction absorbed related to the incident overall radiation (involving multiple reflections).  The absorptance is different for different wavelengths (colored glazing) and angles of incidence.  The transmittance + absorptance + reflectance = 1.

Absorptance of an Opaque Surface:  The ratio of the radiation absorbed at a surface relative to the incident radiation on that surface.  The absorptance is different for different radiation wavelengths and angles of incidence.  The absorptance of normally incident radiation however is always numerically equal to the emittance of the surface for the same wavelength.  ‘Black body’ is a theoretical perfect absorber with an absorptance of 1 for all wavelengths: a typical matt black paint has an absorptance of 0.97 for normal solar radiation and 0.95 for long-wave (thermal) radiation.  For any wave length and angle of incidence, for an opaque surface, absorptance + reflectance = 1.

Absorption:  (gen) The taking in, incorporation or reception of gases, liquids, light or heat.  (phys/chem.) Penetration of one substance into the inner structure of another (cf. adsorption, in which one substance is attracted and held on the surface of another). Occurs between a gas or vapor and a liquid.  (pharm.) The process of movement of a drug from the site of application into the extracellular compartment of the body.  A process where an object absorbs another object or radiation.  For example, a process whereby a material extracts one or more substances present in an atmospheric or mixture of gases or liquids accompanied by the material’s physical and/or chemical changes.  A solid material’s ability to draw in and hold liquid or gas.  In chemistry, is a physical or chemical phenomenon or a process in which atoms, molecules, or ions enter some bulk phase – gas, liquid or solid material.  This is a different process from adsorption, since the molecules are taken up by the volume, not by surface.  A more general term is sorption which covers adsorption, absorption, and ion exchange.  In physics, the taking up of light, heat, or other energy by molecules.  The absorbed energy is converted into heat.  Absorption in chemistry is the taking up of one substance by another. For example, a gas such as oxygen may be absorbed, or dissolved, in water.  In the HVAC industry heat energy is absorbed from the medium being cooled and transferred in the refrigerant.  Retention of liquids in the bulk of the fabric where the liquid is retained by filling up of void spaces, i.e. pores of the fiber, between fibers in a yarn and between yarns in the fabric.  The process by which a liquid adheres to the absorbent material but does not penetrate the fibers or particles themselves.  The process of one substance entering into the inner structure of another.  The uptake of water, other fluids, or dissolved chemicals by a cell or an organism (as tree roots absorb dissolved nutrients in soil.)  In physics, the taking up of light, heat, or other energy by molecules.  The absorbed energy is converted into heat; Absorption in chemistry is the taking up of one substance by another. For example, a gas such as oxygen may be absorbed, or dissolved, in water.  In the HVAC industry we absorb heat energy from the medium being cooled and transfer that energy in the refrigerant.

Absorption and Adsorption:  In addition to differences in boiling points, each type of hydrocarbon and impurity may have a preferred attraction to another substance or chemical.  Two processes, adsorption and absorption, take advantage of this attraction and are used to separate the various parts of fossil fuels and in particular natural gas.  Adsorption is the sticking or adhesion of liquids or gases to the surface of a solid or another liquid, similar to gum on a wall; where absorption is the taking up or surrounding of a substance by another substance, similar to how a sponge soaks up liquids and holds it within little pockets.  The transfer of molecules of gas or liquid from the outside to the interior of another material.

Absorption Cycle:  Absorption chillers differ from mechanical vapor compression chillers in that they utilize a thermal or 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 occurs within more traditional vapor compression type chillers.  Most commercial absorption chillers utilize lithium bromide (a salt) and water as the fluid pair.

Absorption Factor:  For solar radiation the fraction of solar radiation, transmitted through a glazing system that is absorbed inside the building.

A/C:  An abbreviation for air conditioner or air conditioning.
AC:  Abbreviation for alternating current, a type of electric current in which the polarity is constantly reversing causing the electron flow to reverse.  ACRONYM – An electrical current that periodically reverses its direction.  Standard in US and Canada is 60 cycles per second.  Europe and other countries is 50 cycles per second.  Alternating current.
AC or DC:  Abbreviation for equipment capable of operating on alternating or direct current.

A/C Air Filter (s):  A device which removes solid particulates such as dust, pollen, mold, and bacteria from air. Air filters are used in application where air quality is important, notably in building ventilation systems and in engines, such as internal combustion engines, gas compressors, diving air compressors, gas turbines and others.  Some buildings, as well as aircraft and other man-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spun fiberglass filter elements. Another method uses fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid-dynamics of the air-compressor part of the Gas Turbines.

Acapella: See mucus clearing device.
ACCA:  Air Conditioning Contractors of America.

Acceleration Loss:  The velocity pressure required to accelerate the air from rest to the duct velocity or slot velocity, whichever is higher.

Accelerator:  Any material added to stucco, plaster or mortar which speeds up the natural set.

Accent Lighting:  Accent lighting illuminates walls, reduces brightness and contrast between walls and ceilings or windows.

Acceptable Daily Intake (ADI):  The highest daily amount of a substance that may be consumed over a lifetime without adverse effects.

Acceptable Indoor Air Quality:  Air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction.

Acceptance Test:  A test made upon completion of fabrication, installation, repair, or modification of a system unit, component or part to verify to the user or owner that the item meets specified requirements.

Accepted:  Tested and certified by procedures stipulated by the authority having jurisdiction; refer to CSA Z94.4 for complete details.

Accepted Respirator:  A respirator tested and certified by procedures established by testing and certification agencies recognized by the authority having jurisdiction.

Access Panel:  An opening in the wall or ceiling near the fixture that allows access for servicing the plumbing/electrical system.

Accessible:  Can be approached or entered by the inspector safely, without difficulty, fear or danger.

A/C Circuit:  Alternating Current.  The flow of current through a conductor first in one direction, then in reverse.  It is used exclusively in residential and commercial wiring because it provides greater flexibility in voltage selection and simplicity of equipment design.

A/C Condenser:  The outside fan unit of the air conditioning system.  It removes the heat from the Freon gas and turns the gas back into a liquid and pumps the liquid back to the coil in the furnace.

Accredited Laboratory:  A laboratory having a certificate of accreditation meeting the requirements of ISO/IEC Guide 25 (or other equivalent standard, such as CSA Standard CAN/CSA-Z753) or accreditation by the Standards Council of Canada.

Accumeter:  The metering (flow control) device inside a Carrier centrifugal chiller.  Its unique design always feeds the cooler with liquid refrigerant, which has a much greater cooling capability than a gaseous refrigerant.

Accumulator:  A shell device installed in the suction line of a HVAC system to prevent liquids from entering the compressor.

Accuracy:  Closeness of the result of a measurement to the true value of the quantity measured.

Accurator:  A piston type metering device that feeds the proper amount of liquid refrigerant into the evaporator.

A/C Disconnect:  The main electrical ON-OFF switch near the A/C condenser.

ACE:  See “Air Change Effectiveness.”

Acetone:  A colorless, volatile, extremely flammable liquid ketone, CH3COCH3, widely used as an organic solvent.

A/C Filter (s):  A device which removes solid particulates such as dust, pollen, mold, and bacteria from air. Air filters are used in application where air quality is important, notably in building ventilation systems and in engines, such as internal combustion engines, gas compressors, diving air compressors, gas turbines and others.  Some buildings, as well as aircraft and other man-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spun fiberglass filter elements. Another method uses fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid-dynamics of the air-compressor part of the Gas Turbines.

A/C Filter Replacement:  Generally every 2 - 3 months, but you may want to change them more often. During periods where you are using your HVAC system continuously, we recommend changing monthly to maintain the best indoor air quality. The following chart should assist you:

"The most important maintenance task that will ensure the efficiency of your air conditioner is to routinely replace your air filters[...] air conditioner furnace filters may need more frequent attention if the air conditioner is in constant use, is subjected to dusty conditions, or you have fur-bearing pets in the house." - United States Department of Energy

A/C Filter Sizes:  Filter Size:  The size of a filter is listed by its length, height and thickness.  For example, a common filter size would be listed as 20x20x1.  20 inches wide by 20 inches high and 1 inch thick.  Nordic Pure has manufactured filters in the following sizes since 1960:
1 inch Air Filters:
10x20x1, 12x12x1, 12x18x1, 12x20x1, 12x24x1, 14x20x1, 14x24x1, 14x25x1, 14x30x1, 15x20x1, 16x16x1, 16x20x1, 16x24x1, 16x25x1, 18x18x1, 18x20x1, 18x24x1, 18x25x1, 20x20x1, 20x24x1, 20x25x1, 20x30x1, 24x24x1, 24x30x1, 25x25x1

2 inch Air Filters:
10x20x2, 12x20x2, 12x24x2, 14x20x2, 14x24x2, 14x25x2, 15x20x2, 16x16x2, 16x20x2, 16x24x2, 16x25x2, 18x18x2, 18x20x2, 18x24x2, 18x25x2, 20x20x2, 20x24x2, 20x25x2, 20x30x2, 24x24x2, 24x30x2, 25x25x2
4 inch Air Filters:
12x24x4, 16x20x4, 16x25x4, 18x24x4, 20x20x4, 20x24x4, 20x25x4, 24x24x4
Now we also carry 5 inch Honeywell Replacements: 16x25x5 and 20x25x5
1 inch Air Filters:
10 x 20 x 1, 12 x 12 x 1, 12 x 18 x 1, 12 x 20 x 1, 12 x 24 x 1, 14 x 20 x 1, 14 x 24 x 1, 14 x 25 x 1, 14 x 30 x 1, 15 x 20 x 1, 16 x 16 x 1, 16 x 20 x 1, 16 x 24 x 1, 16 x 25 x 1, 18 x 18 x 1, 18 x 20 x 1, 18 x 24 x 1, 18 x 25 x 1, 20 x 20 x 1, 20 x 24 x 1, 20 x 25 x 1, 20 x 30 x 1, 24 x 24 x 1, 24 x 30 x 1, 25 x 25 x 1

2 inch Air Filters:
10 x 20 x 2, 12 x 20 x 2, 12 x 24 x 2, 14 x 20 x 2, 14 x 24 x 2, 14 x 25 x 2, 15 x 20 x 2, 16 x 16 x 2, 16 x 20 x 2, 16 x 24 x 2, 16 x 25 x 2, 18 x 18 x 2, 18 x 20 x 2, 18 x 24 x 2, 18 x 25 x 2, 20 x 20 x 2, 20 x 24 x 2, 20 x 25 x 2, 20 x 30 x 2, 24 x 24 x 2, 24 x 30 x 2, 25 x 25 x 2
4 inch Air Filters:
12 x 24 x 4, 16 x 20 x 4, 16 x 25 x 4, 18 x 24 x 4, 20 x 20 x 4, 20 x 24 x 4, 20 x 25 x 4, 24 x 24 x 4
5 inch Honeywell Replacements:
16 x 25 x 5 and 20 x 25 x 5

ACFM:  ACRONYM – Actual Cubic Feet per Minute of gas volume at the actual conditions of temperature, pressure, moisture, elevation and gas composition.  See gas flow rate.

A/C Furnace Filter (s):  Air filters come in a variety of sizes and types. The primary distinction between one filter and another is the size of the filter (length, width and thickness) and the filter material or “media” that is used in the manufacture of the filter. Nordic Pure features all of the popular sizes of air filters. Nordic can also make a filter for your system if we do not stock your size. All custom filters can be ready to ship to you within ten days to two weeks and usually costs about the same as many of our competitor’s ready-made filters.  The air in a furnace or air conditioning system first enters the home through the air return where it passes through the air filter(s) and into the air handler, over the cooling coils or heat exchanger part of the HVAC system (where the air is either cooled or heated) and out through the ductwork into the home. The circulation throughout the HVAC system is accomplished through a powerful blower system (shown above). Because the air filter is the only device in the entire HVAC system capable of removing airborne impurities, it makes sense that frequent replacement of the air filter as well as careful consideration as to the type of air filter you use will directly impact the quality of your indoor air. Conversely, ignoring the HVAC systems air filter means you are allowing the entry of polluted air into the entire system, driving down operating efficiency, filling up ductwork with all dust, pollen, dust mites, etc. and other airborne pollutants while exposing the building’s inhabitants to polluted air. Though there are a wide variety of air filters, they are generally termed as disposable air filters or reusable air filters.  Reusable air filters sound good, in concept. After all, replacement costs can add up over time. The problem is that reusable air filters do not do as an efficient job as desired. To begin, reusable air filters are messy when removed from the HVAC system. Then there is the problem of finding a suitable area to clean the filters. Very often, highly toxic cleaners are required for adequate cleaning of reusable air filters. Once the chemical is used on the filter, it is absorbed into the filter and therefore a certain amount of the cleaner can be released back into the circulating air posing a potential health threat. Nordic does not endorse this type of filter and does not sell reusable filters.
Make-Your-Own Air Filters are designed to enable you to construct your own filter. Buyers for these types of media filters usually do so because their HVAC system does not accommodate standard sized air filters. The most common media for filtration is fiberglass. The handling of fiberglass is difficult as fibers from fiberglass can break off in the skin causing discomfort. Further, fiberglass provides only marginal filter effectiveness. Also, the make-your-own-filters often have no frames to use in securing the media material. As a consequence, the filters can often collapse necessitating a service call by an air conditioning professional. Nordic does not endorse the use of this type of filters. Our many years of manufacturing expertise has enabled us to manufacture a custom filter at about the same price as off-the-shelf air filters from competitors. The most significant difference is that the media material is much higher in quality and has a frame around the material and the media is attached to the frame with a support material insuring there are no collapsed filters.  Disposable panel air filters are the most commonly used type of air filter in furnaces, air conditioning systems or HVAC systems. Panel air filters, being disposable, solve the problems associated with handling dirty filters while insuring ease of removal/replacement. Disposable panel air filters use a variety of media for filtration. A “panel” air filter gets its name because the air filter is actually manufactured as a self-contained, one-piece “panel” that consists of the (a.) air filter media material, (b.) any internal structure that supports the air filter media material such as metal fabric, wire or even cardboard, and (c.) the box or frame in which the air filter media material and the media support material is attached to and housed within. The box or frame of a disposable panel air filter is rigid. The frame is normally constructed of cardboard, plastic or even metal and made to withstand the insertion of the filter into the HVAC system and keep its structural integrity while the HVAC system is operating.  The frame is defined by the length, width and thickness of the box housing the filter media.  The most common type of air filters on the market is panel air filters that use fiberglass as the filter media. Fiberglass filters are very cheap and do an effective job at removing only the largest of airborne particulates. In addition to its limited ability to filter finer particulate, fiberglass is very brittle and can cause harm when handled. Further, there is a potential for the fiberglass fibers to break off and enter passing air creating a serious health problem. Nordic does not endorse the use of fiberglass filters, both because of their limited ability to filter the air, especially smaller particulate and the health implications.  Pleated air filters are much like disposable panel air filters in that the filter media is housed in a rigid panel but the difference is that the media material used to filter the air, as well as the way the material is mounted into the air filter box or frame is different. The filter media used in pleated filters most often resembles fabric and has the capability of removing significantly smaller particulate from the air. Further, when the filter media is integrated into the filter, it is pleated to provide more surface area for filtration. This pleating adds more than double the surface area of un-pleated filters. The net effect is that you end up with a filter that removes more of the particulate in the passing air AND has at least twice as much surface area. Combined, pleated air filters provide a significantly higher level of filtration.  Electrostatic pleated air filters are a more highly evolved version of the pleated air filter. In addition to a higher quality media filter material and pleats for increased surface area for filtration, electrostatic pleated air filters are also electrostatic meaning that the filter media material is electrically charged so that the media material acts much like a magnet to draw more particulate into the media filter material for more efficient filtration. Another benefit of the electrostatic material is that it does not permit the growth of bacteria, often a problem with other filters. Nordic manufactures and sells only Electrostatic Pleated Air Filters in a wide variety of lengths and widths with thickness from 1" to 5".

ACGIH:  American Conference of Government Industrial Hygienists: a professional organization of industrial hygienists who work either in government or academe.  It publishes, does educational work, and sets various health standards, such as TLVs.  See TLV.  An organization that annually determines standards of exposure to toxic and otherwise harmful materials in the workroom air, commonly known as threshold limit value (TLV).  The American Conference of Governmental Industrial Hygienists is a professional society devoted to the development of administrative and technical aspects of worker health protection.  Membership is limited to professional personnel in governmental agencies or educational institutions engaged in occupational safety and health problems.  The ACGIH issues guidelines and recommendations in the form of Threshold Limit Values (TLVs) which are published annually.

ACH, Air Changes per Hour:  Air changes per hour.  The number of times that air in a house is completely replaced with outdoor air in one hour.
Acid:  Any chemical with a low pH that in water solution can burn the skin or eyes.  Acids turn litmus paper red and have pH values of 0 to 6.

Acid Aerosol:  Acidic liquid or solid particles that are small enough to become airborne.  High concentrations of acid aerosols can be irritating to the lungs and have been associated with some respiratory diseases, such as asthma.

Acid Deposition:  A complex chemical and atmospheric phenomenon that occurs when emissions of sulfur and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere, often far from the original sources, and then deposited on earth in either wet or dry form.  The wet forms, popularly called “acid rain,” can fall to earth as rain, snow, or fog.  The dry forms are acidic gases or particulates.  A comprehensive term for the various ways acidic compounds precipitate from the atmosphere and deposit onto surfaces.  It can include:  (1.) wet deposition by means of acid rain, fog, and snow; and (2.) dry deposition of acidic particles (aerosols).

Acid Etch:  A preparatory step for concrete sealing.  Diluted hydrochloric acid is applied to the concrete to etch the surface for better seal adhesion.

Acid Gases:  Gases which are acids, or produce acids when in contact with moisture.

Acid Rain:  A broad term used to describe several ways that acids fall out of the atmosphere.  A more precise term is acid deposition, which has two parts: wet and dry. Wet deposition refers to acidic rain, fog, and snow.  Dry deposition refers to acidic gases and particles.  Acid rain is primarily caused by the reaction of two common air pollutants, sulphur dioxide and nitrogen oxides, with water in the atmosphere.  A term used to describe several ways that acidic compounds fall out of the atmosphere, causing a variety of ground-level environmental effects.  These effects include damage to forests and soils, fish and other living things, and human health.  Acid rain also reduces how clearly we can see through the air, an effect called visibility reduction.  In the United States, about two-thirds of all sulfur dioxide and one-quarter of all nitrogen oxides come from electric power generation that relies on burning fossil fuels like coal.  Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds.  These acidic compounds fall to the earth as acidic rain, fog, and snow, or as dry deposited gases and particles that can be blown to the ground by the wind.

Acidity:  The quality, state or degree of being acid.  In oils, acidity denotes the presence of acid-type constituents whose concentration is usually defined in terms of neutralization number.

A-Coil:  A heat exchanger consisting of two diagonal coils that are joined together in a manner that looks like the letter “A.”

Acoustical:  Of or pertaining to sound.

ACP:  Association of Contingency Planners.  A national association with local chapters located around the country.

Acre:  43,560 square feet.

Acre Foot (AF):  The amount of water required to cover an acre one foot deep (325,861 gallons).  A family of five uses about one acre-foot of water per year.

AC Replacement:  A quality job begins with quality products. The Sansone Corporation is recognized as an award winning dealer for both Carrier and Trane, the two most popular brand names in America for reliable, efficient air conditioning. Since 1976, Sansone Corporation has been dedicated to carefully matching the comfort needs of residents, with an expanded choice of product innovations from these leading manufacturers, in order to satisfy both your comfort requirements and your budget.  From residential to commercial, there is no job that is too big or too small. If you’re ready for a new air conditioning system, let the courteous, Sansone installation consultants show you how you can start saving money right away and avoid the potentially higher service costs later. 

Four Things to Consider Before Buying a Heating and Cooling System

The following information has been provided by the Carrier website.

1. Efficiency  Efficiency ratings are like gas mileage – the higher the rating, the more efficient the product is. All products are given the following ratings, so you’ll know exactly what to expect from your investment.

SEER
(Seasonal Energy Efficiency Ratio)
This measurement gauges air conditioning cooling. All new models are required to have at least a 10.0 SEER rating. The Infinity 18 air conditioner receives up to 18.0 SEER.

ENERGY STAR®
Carrier Corporation has determined that certain products meet ENERGY STAR® guidelines for energy efficiency. Look for this logo on our Infinity and performance™Series products.  
2. Refrigerant  Freon®–22 Refrigerant
Since its debut in 1930, Freon refrigerant has been used in cooling systems. And while it’s still available, the Clean Air Act of 1990 prohibits the production of Freon–22-based air conditioners and heat pumps by 2010, and Freon–22 production by 2020. As Freon–22 production declines, its cost is predicted to rise. (Freon is a registered trademark of E.I. duPont de Nemours & Company.)
Puron® Refrigerant
Carrier was the first to introduce a new, non-ozone-depleting refrigerant called Puron – a full six years ahead of the competition — paving the way for the future. Puron refrigerant is chlorine-free, so it doesn’t damage the Earth’s ozone layer. And, as other refrigerants become less available, Puron refrigerant will be the refrigerant of choice for years to come.  
3. Comfort
Carrier specializes in creating a customized home comfort system with our broad selection of heating and cooling products. Your Carrier dealer can help you choose the best system for your home including Carrier-exclusive features that further enhance your indoor environment.
ComfortHeat™ Technology
ComfortHeat™ Technology accurately predicts the need for heating while cutting temperature swings in half, and provides a nearly continuous flow of warmth in low-capacity operation for a steadier, more consistent indoor temperature.

Infinity™ System
When a heat pump or air conditioner is combined with a variable-speed furnace or fan coil, the revolutionary Infinity System is the only system in the industry that allows you to control temperature, humidity, air quality, fan speed and ventilation; and even detects when your air filter needs replacing. It’s so advanced it automatically adjusts to your systems’ needs for peak efficiency and performance. It’s the ultimate control center for all of your home system components.
IdealHumidity™ Systems
IdealHumidity Systems automatically add or remove just the right amount of moisture to keep your home comfortable. IdealHumidity Systems can help you save on energy costs, too. When the humidity is right, you can feel comfortable at higher temperatures in the summer, and lower temperatures in the winter.

4. Sound  Carrier air conditioners are also quiet, thanks to the exclusive Silencer System™ that ensures extra-quiet performance by maximizing airflow while minimizing vibration. With sound ratings as low as 69 decibels (dB), Carrier’s Infinity™ Series air conditioners make less noise than a refrigerator.

A/C Replacement Filter (s):  Generally every 2 - 3 months you will want to replace your air filters, but you may want to change them more often. During periods where you are using your HVAC system continuously, we recommend changing monthly to maintain the best indoor air quality. The following chart should assist you:

“The most important maintenance task that will ensure the efficiency of your air conditioner is to routinely replace your air filters[...] air conditioner furnace filters may need more frequent attention if the air conditioner is in constant use, is subjected to dusty conditions, or you have fur-bearing pets in the house.” - United States Department of Energy
You can turn to Nordic Pure for all of your air conditioner filter replacement needs.  We manufacture an array of standard filter sizes and are able to custom make any size to match your unit. 

Acrolein:  An agent added to methyl chloride to make you aware of refrigerant leaks.

Acrylic:  A glassy thermoplastic material that is vacuum-formed to cast and mold shapes that form the surface of fiberglass bathtubs, whirlpools, shower bases, and shower stalls.  A synthetic polyermized fiber that contains at least 85% acrylonitrile.

Acrylics:  A family of plastics used for fibers, rigid sheets and paints.

Acrylonitrile:  A colorless, volatile, flammable liquid nitrile C3H3N used chiefly in organic synthesis and for polymerization.

ACT:  ACRONYM – Activate, Activation.

Action Level:  A concentration established by environmental protection agencies for a substance in a particular medium (water, soil, etc.) that may present a health risk or affect beneficial uses when exceeded.  If contaminants are found at concentrations above their action levels, measures must be taken to decrease the contamination.  A specific concentration of a toxic substance in the air established by OSHA that when reached makes the performance of certain procedures necessary, e.g., monitoring the air, notifying all employees affected.  (EPA’s current action level is 4 pCi/L.)

Action Packet:  In reference to the IAQ Tools for Schools Action Kit - contains numerous products to assist school personnel to implement an effective yet simple IAQ program in their school.

Action Plan:  A list of specific instructions drawn up by a health care professional for an asthmatic to follow.  The plan includes a normal schedule for asthma medicines, as well as what to do if peak flow readings or asthma symptoms become worse than usual.  These plans are split into zones (red, green, and yellow).  See:  Zones.

Activate:  To turn on, supply power, or enable systems, equipment, or devices to become active by normal operating controls.  Examples include turning on the gas or water supply valves to the fixtures and appliances and activating electrical breakers or fuses.

Activated Alumina:  A type of aluminum oxide that absorbs moisture (used in refrigerant driers).  An adsorption type desiccant.

Activated Carbon / Charcoal:  A form of carbon ‘activated’ by treatment with oxygen to have very high surface area, capable of removing many gases and odors from the air.  Activated Carbon is a specially treated carbon that has been exposed to heat around 800-900 degrees Celsius.  The great thing about activated carbon is that it has a large internal surface area and can trap a lot of impurities inside it.  Activated carbon is most commonly seen in simple tap water filters and fish tank filters, but is also used in some small air filters and has even been used in cigarette butts.

Activated Carbon:  Charcoal activated by heating to 1472-1652ºF a material of high adsorptive gases, vapors, organics, etc.  Has a large internal surface area.  Removes dissolved color, odor and taste from liquids or gases.  Commonly used in the pharmaceutical industry to remove organic contaminants.  A processed carbon used in filter driers, commonly used in air filters to clean the air.

Activated Carbon Filter:  See Gas-phase adsorber cell.  See also Adsorption.  Also see “Activated Charcoal.”

Activated Carbon/Zeolite Blend:  This is a blend of adsorbents used in some air purifiers that removes odors and certain chemicals from the air.

Activated Charcoal:  Activated Charcoal is used to remove odorous substances from air (in vacuum cleaners and air purifiers) and water (in water filters) through adsorption.  Activated charcoal is made by treating charcoal with oxygen, which has the effect of creating countless holes or pathways in the charcoal.  The result is a charcoal with an amazingly large surface area.  As air or water passes through the immense surface area of activated charcoal, odorous compounds are caught in the innumerable bonding sites.  Activated charcoal only removes specific impurities that are attracted to carbon while others will pass right through.  Activated charcoal filters stop working once all the bonding sites are filled with trapped impurities, requiring that the filter be replaced.  Activated charcoal filtration is sometimes referred to as carbon or active carbon filtration.

Activated Military Carbon Cloth:  A cloth impregnated with activated charcoal to remove odors and gasses.

Activated Sludge:  Sludge floc produced in raw or settled wastewater by the growth of zoogleal bacteria and other organisms in the presence of dissolved oxygen.

Active Cooling:  HVAC term for compressor driven air conditioning.

Active Diffuser:  An air supply outlet with a local fan to deliver air from the plenum through the diffuser into the conditioned space.

Active Height Control:  This is a feature of certain SEBO upright vacuums also referred to as Automatic Height Adjustment.  Electronic controls identify the floor and the height of the carpet nap.  The brush is then raised or lowered automatically depending upon the type of carpet or flooring for optimal cleaning performance.

Active HEPA Filter:  This is a Miele trade name for their HEPA (High Efficiency Particulate Air) filter that not only captures and retains tiny, lung-damaging particles (including dust mite feces and pollen), it also includes the same Generally Activated Charcoal filter (GAC) that the Active Air Clean filter uses to absorb odors.  This Miele filter conforms to the new stringent European standard for filtration (EN 1822) which means that it actually traps 99.99% of all particles as tiny as 0.3 of a micron.

Active Solar Techniques:  Mechanisms, such as flat-plate collectors, which are designed to actively collect the energy of sunlight and use it; for example, to heat a building or to heat water.

Active System:  A traditional HVAC system that uses mechanical means to artificially condition (cool, heat, ventilate) the air supply in a building and that draws power for these processes from electricity or gas.

Activity:  Activity is the rate of transformation or decay of a radioactive material.  The SI unit of activity is the reciprocal second (s-1) and its special name is the Becquerel.  Federal and state agencies in the United States use conventional units where activity is given in curies (Ci); 1 Ci = 3.7 x 1010 Bq.

ACTR:  ACRONYM – Actuator.

Actual Capacity:  Quantity of gas actually compressed and delivered to the discharge system at rated speed of the machine and under rated pressure conditions.

Actual Dimension (Lumber):  The exact measurement of lumber after it has been cut, dried and milled.

Actual Size:  The true size of the filter.  See Nominal Size.

Acute:  Sudden.  Brief, not ongoing.  Usually implies relatively high intensity.  Acute asthma symptoms may last a short time but are more severe than an individual’s usual symptoms.
Acute Effect:  Adverse effect on a human or animal which has severe symptoms developing rapidly and coming quickly to a crisis.  Also see “chronic effect.”

Acute Exposure:  A single exposure to a toxic substance which results in biological harm or death; usually characterized as lasting no longer than a day (24 hours).

Acute Health Effect:  Ahealth effect that occurs almost immediately (hours/days) after a single or brief/acute exposure.  The term is used to describe brief exposures and effects which appear promptly after exposure to a toxic agent.

Acute Toxicity:  Relatively short-term lethal or other effect, usually defined as occurring within four days for fish and macroinvertebrates and shorter times (two days) for organisms with shorter life spans.  The ability of a substance to cause poisonous effects resulting in severe biological harm or death soon after a single exposure or dose.  Any severe poisonous effect resulting from a short-term exposure.

AC Vent Filter (s):  Air Register Vent Filters are made of a self-charging electrostatic material that acts as a dust magnet for your vent register system.  Use them in bathrooms, bedrooms, kitchen, family room and RV/Motor Homes.  When air flows through the filter, dirt, dust, smoke, and pollen sized particles are trapped. Filtered air then passes back into your house.  Keeps dirt and objects from falling into ducts.  Air Vent Filters are designed to provide filtered air in your home.

Ad Hoc:  An ad hoc committee is one that is set up for a particular purpose.

Adaptive Model (Adaptive Approach):  For thermal comfort this is an approach to the study of thermal comfort starting from the observation that there are a range of actions which occupants can take to achieve thermal comfort, and that discomfort is caused by constraints imposed on the range of actions by social, physical or other factors (see also Adaptive Principle).  Over time this means that people are comfortable at the ‘usual’ or ‘average’ temperature which they experience.

Adaptive Opportunity:For thermal comfort:  the ability of a building to allow adaptation to broaden the band of temperatures at which the person could be comfortable.  Actions might include adding or removing a layer of clothing, changing posture, or adjusting the metabolic rate.  Spatial variation of temperature across the room, availability of a desk fan, and the presence of sun shading or openable windows would make the adaptive opportunities still greater.  These actions either alter the temperature which is required for comfort, or alter the room temperature towards that which the occupants will find comfortable.

Adaptive Principle: A principle which can be stated as: If a change occurs (in the thermal environment) such as to produce discomfort, people
react in ways which tend to restore their comfort.

Adaptive Processes:  The range of actions that man takes to achieve thermal comfort.

Adaptive Reuse:  Renovation of a building or site to include elements that allow a particular use or uses to occupy a space that originally was intended for a different use.

Adaptor:  A fitting that unites different types of pipe together, e.g. ABS to cast iron pipe.

Additive:  An additive is something that is added to a product, but which does not affect the product’s performance.  For instance, adding color to a Popsicle doesn’t change the Popsicle’s taste; therefore, color is an additive.  For those with allergies, additives can be a real problem.  Things like artificial color, dyes, fragrances, and preservatives are all potential allergens.

Add-on Control Device:  An air pollution control device such as carbon absorber or incinerator that reduces the pollution in exhaust gas.  The control device usually does not affect the process being controlled and thus is “add-on” technology, as opposed to a scheme to control pollution through altering the basic process itself.  See also pollution prevention.

Adenoidectomy:  Pronunciation (ad′ĕ-noy-dek′tŏ-mē).  An operation for the removal of adenoid tissue from the nasopharynx.

Adenoids:  Pronunciation (ad′ĕ-noydz).  Adenoids (or pharyngeal tonsils, or nasopharyngeal tonsils) are a mass of lymphoid tissue situated at the very back of the nose, in the roof of the nasopharynx, where the nose blends into the mouth.  Normally, in children, they make a soft mound in the roof and posterior wall of the nasopharynx, just above and behind the uvula.
Adenoids are part of the immune system. Like all lymph tissue, they trap infectious agents like viruses and bacteria, and they produce antibodies.  Since the adenoids are located at the back of the nasal airway, they provide defense against inhaled substances.  This function decreases with age as the adenoids shrink. Because adenoids do ordinarily shrink by late childhood, the problems caused by enlarged adenoids rarely occur in adults.

Adhesion:  Molecular attraction that holds the surfaces of two substances in contact.  The property of a coating or sealant to bond to the surface to which it is applied.

Adhesive Failure:  Loss of bond of a coating or sealant from the surface to which it is applied.

Adiabatic:  A change in gas condition where no heat is added or removed except in the form of work.

Adiabatic Compression:  A type of compression where no heat is transferred to or from the gas during the compression process.

Adiabatic Efficiency:  Ratio between measured shaft power and the adiabatic compression power, referring to measured mass flow.

Adjudication:  A determination of water rights for an entire stream or ground water basin.  Adjudication sets priorities of rights during shortages.

Administrative Control Measures:  Methods of controlling worker exposure to dangerous substances by limiting contact time with the substance.

Adrenalectomy:  Surgical removal of the adrenal glands.

Adrenergic:  Resembling some of the effects of adrenaline.  Medications called beta-adrenergic drugs are commonly used in asthma to help open up the airways (which is why they are called bronchodilators).

Adsorb:  A method causing a liquid or gas to condense on the surface only of an adsorbing material.

Adsorbent:  In addition to the adjectival meaning, the term describes any of several substances that collect gaseous pollutants.  Used both for measurement and control.

Adsorbent Filter:  A filter medium primarily intended to hold soluble and insoluble contaminants on its surface by molecular adhesion.

Adsorber:  A device for removing gases or vapors from air by means of preferential physical condensation and retention of molecules on a solid surface.  Adsorbers used in nuclear applications are often impregnated with chemicals to increase their activity for organic radioactive iodine compounds.

Adsorber Cell:  A modular replaceable adsorber element.
Adsorption:  Adhesion of a thin layer of molecules to a surface they contact.  Adhesion of molecules of liquids, gases, and dissolved substances to surfaces of solids; as opposed to absorption, taking of molecules of one substance directly into another substance.  Adsorption is a surface phenomenon; absorption is an intermingling or interpenetration of two substances.  Removal of a pollutant from air or water by collecting the pollutant on the surface of a solid material; e.g., an advanced method of treating waste in which activated carbon removes organic matter from waste-water.  Adsorption is often used to extract pollutants by causing them to be attached to such adsorbents as activated carbon or silica gel.

Adsorptive Filtration:  The attraction to, and retention of particles in, a filter medium by electrostatic forces, or by molecular attraction between the particles and the medium.

Advance Directives:  Legal documents including the Living Will and Durable Power of Attorney for Health Care.  A Living Will states what type of treatment you wish to receive in the event that you become physically or mentally unable to communicate your wishes.  A Durable Power of Attorney for Health Care authorizes another person to make medical decisions for you when you are unable to do so for yourself.  See also Living Will and Durable Power of Attorney for Health Care.

Advanced Reciprocating Compressor:  Type of compressor that uses a more efficient process for compressing refrigerant for better cooling efficiency.

Advanced Treatment:  A level of wastewater treatment more stringent than secondary treatment; requires an 85% reduction in conventional pollutant concentration or a significant reduction in non-conventional pollutants.  Sometimes called tertiary treatment.

Adverse:  Undesirable.

Adverse Health Effect (Occurrence):  Any abnormal, harmful, or undesirable effect (occurrence) on the physical, biochemical, biological, or behavioral well-being of a person that results from being exposed to pollutants in the environment.  A health effect from exposure to air contaminants that may range from relatively mild temporary conditions, such as eye or throat irritation, shortness of breath, or headaches to permanent and serious conditions, such as birth defects, cancer or damage to lungs, nerves, liver, heart or other organs.

Adversely Affect:  Constitute, or potentially constitute, a negative or destructive impact.

Advisory Level:  The level above which an environmental protection agency suggests it is potentially harmful to be exposed to a contaminant, although no action is mandated.

AEE (Association of Energy Engineers):  A trade organization for certification and information on energy efficiency, utility deregulation, facility management, plant engineering, and environmental compliance.

Aerated Pond (see Oxidation Pond):  A natural or artificial wastewater treatment pond in which mechanical or diffused-air aeration is used to supplement the oxygen supply.

Aeration:  Act of combining substance with air.  Passing air through a solid or liquid, especially a process promoting breakdown or movement of contaminants in soil or water by exposing them to air.  To combine or charge with gas.  Exposing water to the air; often results in the release into the atmosphere of gaseous impurities found in polluted water.

Aerator:  An apparatus that mixes air into flowing water.  It is screwed onto the end of a faucet spout to help reduce splashing.

Aerobic:  In the presence of oxygen.

Aerobic Bacteria:  Organisms which require oxygen to live.

Aerobic Treatment:  Process by which microbes decompose complex organic compounds in the presence of oxygen and use the liberated energy for reproduction and growth.

Aerodynamic Diameter:  The diameter of a unit density sphere having the same settling velocity in air as the particle in question of whatever shape and density.

Aerosol:  Aerosol is the term used to describe the dispersing of tiny particles of liquid in a volume of air approximately 100µ or smaller in size.  Example: dust, smoke, fog.  Aerosol sprays tend to be highly flammable and most often come as pressurized canisters.  (1.) Small droplets or particles suspended in the atmosphere, typically containing sulfur.  They are usually emitted naturally (e.g. in volcanic eruptions) and as the result of anthropogenic (human) activities such as burning fossil fuels.  (2.) The pressurized gas used to propel substances out of a container.  Particles of solid or liquid matter that can remain suspended in air from a few minutes to many months depending on the particle size and weight.

Aerosol Generator:  A device, used in conjunction with an aerosol photometer, which creates a polydispersed sub-micron aerosol to challenge integrity of HEPA filters and containment of safety cabinets.

Aerosol Photometer:  A device used to determine particle size and distribution in air by measuring the mass concentration of scattered light.

Aerosol Spectrometer:  A device used to determine particle size and distribution in air by measuring the range of color produced by passing a white light through a prism.

Aesthetically:  Tastefully; concerned with appearance.

Af:  Fan wheel design with airfoil-shaped blades.

AFCOM:  Association For Computer Operations Managers.  A national trade association.  AFCOM publishes a bi-monthly magazine The Computer Operations Manager.  (www.afcom.com/).

Affluent:  Fluid entering the filter or filter system.  Commonly described as influent, it is the opposite of effluent.

Afterburner:  In incinerator technology, a burner located so that the combustion gases are made to pass through its flame in order to remove smoke and odors.  It may be attached to or be separated from the incinerator proper.  An air pollution abatement device that removes undesirable organic gases through incineration.

Aftercooler:  Heat exchangers for cooling air or gas discharge from compressors.  Designed to reduce the temperature and liquefy condensate vapors.  Both air cooled and water cooled units are available.

Aftercooling:  The removal of heat from a gas after compression is completed.

After-treatment Device:  Engine pollutant emissions are generally reduced by engine modifications, fuel specifications or exhaust gas after treatment.  An after-treatment device is a component used to reduce engine pollutant emissions downstream of the combustion chamber.  Catalytic converters and particulate traps are examples of after-treatment devices.

AFUE – Annual Fuel Utilization Efficiency:  The ratio of annual output of useful energy or heat to the annual energy input to the furnace.  This is a measurement of the efficiency of a gas furnace.  The higher this rating is the more efficient the furnace will be.  It describes the percentage of heat produced for every dollar of fuel consumed.  Indicated as a percentage, your furnace’s AFUE tells you how much energy is being converted to heat.  For example, an AFUE of 90 means that 90% of the fuel is being used to warm your home, while the other 10% escapes as exhaust with the combustion gases.  The minimum percentage established by the DOE for furnaces is 78%.

AGA:  Abbreviation for American Gas Association, Inc.

Agenda 21:  A comprehensive blueprint for global action drafted by the 172 governments present at the 1992 Earth Summit organized by the United Nations in Rio de Janeiro, Brazil.

Agent:  Any biological, chemical or physical power, principle or substance capable of acting upon a subject organism, usually to its detriment.

Agglomerating Dust:  Dust particles that exhibit tendencies for particle growth, such as powdered milk, fertilizer, detergents, etc.

Agglomeration, Particle:  Multiple particles joining or clustering together by surface tension to form large particles, usually held by moisture, static charge or particle architecture.

Aggregate:  Crushed stone, slag or water-worn gravel that comes in a wide range of sizes which is used to surface built-up roofs.

Agitation:  In terms of vacuum cleaners, agitation is the brushing action on carpet fibers.  This can be from the fixed brush on a carpet and rug tool or from the revolving brush of a turbine or motorized power head.  Agitation is important in order to break surface tension to release fine soils as well as to remove more difficult surface soils such as pet hair.  Revolving brushes sometimes use “beater bars” to bring fine soils and dust up from carpet backing for removal.

Agonist:  When talking about drugs, this refers to a compound that stimulates or enhances activity of the cell receptors.

Agricultural Bi-products:  Products developed in agriculture but are not primary products.  These are often converted into building materials, such as straw used in wall panels or entire bales used as building blocks.

Agricultural Burning:  The intentional use of fire for vegetation management in areas such as agricultural fields, orchards, rangelands, and forests.  The regulation of agricultural burning is described in the Agricultural Burning Guidelines, Title 17, California Code of Regulations.

Agricultural Fibers:  Natural fibers, such as cotton, often used as insulation materials. <

Agricultural Residue:  Plant parts, primarily stalks and leaves, not removed from the fields with the primary food or fiber product.  Examples include corn stover (stalks, leaves, husks, and cobs); wheat straw; and rice straw.

AHAM:  An acronym for the American Home Appliance Manufacturers trade group, a company that tests and certifies air purifiers based on CADR (Clean Air Delivery Rate).  See “CADR.”

AHU (Air Handling Unit):  Equipment that includes a fan or blower, heating and/or cooling coils, regulator controls, condensate drain pans, and air filters.  An air handler, or air handling unit and often abbreviated to AHU, is a device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. Usually, an air handler is a large metal box containing a blower, heating and/or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to ductwork that distributes the conditioned air through the building, and returns it to the AHU. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served, without ductwork.  Small air handlers, for local use, are called terminal units, and may only include an air filter, coil, and blower; these simple terminal units are called blower coils or fan coil units. A larger air handler that conditions 100% outside air, and no recirculated air, is known as a makeup air unit (MAU). An air handler designed for outdoor use, typically on roofs, is known as a rooftop unit (RTU).

AHU Filters:  Air filtration is almost always present in order to provide clean dust-free air to the building occupants.  It may be via simple low-MERV pleated media, HEPA, electrostatic, or a combination of techniques.  Gas-phase and ultraviolet air treatments may be employed as well.   It is typically placed first in the AHU in order to keep all its components clean.

AIA:  American Institute of Architects.

AIHA:  American Industrial Hygiene Association.

Air:  A colorless, odorless, tasteless gas.  A mixture of individual gases.  The gaseous mixture surrounding the earth.  Standard density of dry air free of carbon dioxide (0°C, 101,325 kPa) is equal to 1,292 8 g/L.  Standard conditions for air in spectroscopy are 101,325 kPa, 15°C, 0.03% CO2, dry.  A mixture of gasses constituting a compressed fluid tied to the planet by gravitational attraction.  Air is 79.0% nitrogen, 20.9% oxygen, and less than 0.1% a mixture of carbon dioxide, argon, helium, and hundreds of other gasses originating from natural and man-made sources.  So called “pure” air is a mixture of gases containing about 78 percent nitrogen; 21 percent oxygen; less than 1 percent of carbon dioxide, argon, and other gases; and varying amounts of water vapor.  See also ambient air.

Air Actuator:  An elastomeric bellow with specially designed metal end closures used in place of pneumatic or hydraulic cylinders.  A device which induces action or motion with compressed air being the medium through which the power is transmitted.

Air Amplifier:  A component on a compressed air line designed to increase in magnitude the flow by releasing small amounts of compressed air at high velocity through an internal, ring shaped nozzle.  This column of air released through the front creates a vacuum behind, thus pulling ambient air through the rear and pushing ambient air in front.

Air Balance:  HVAC term for distributing air through a system to precisely match the required amount.  Meaning, as it applies to Class II cabinets, to adjust airflow volume so that air exhaust is equal to air intake and thereby eliminating (or minimizing) movement of outside air into the cabinet work area and vice versa through the face opening.

Air Barrier:  Any part of the building shell that offers resistance to air leakage.  The air barrier is effective if it stops most air leakage.  The primary air barrier is the most effective of a series of air barriers.  For buildings a material carefully installed within a building envelope assembly to minimize the uncontrolled passage of air into and out of a dwelling.  Induction of room air through the front opening of safety cabinets that contain hazardous aerosols.  The unidirectional movement of air past and parallel to the plane of an opening, and at a velocity greater than that on either side, thereby creating an impedance to transverse movement of airborne particulates through the opening.  Air barriers are systems of materials designed and constructed to control air flow between a conditioned space and an unconditioned space. The air barrier system is the primary air enclosure boundary that separates indoor (conditioned) air and outdoor (unconditioned) air. In multi-unit/townhouse/apartment construction the air barrier system also separates the conditioned air from any given unit and adjacent units. Air barrier systems also typically define the location of the pressure boundary of the building location. In multi-unit/townhouse/apartment construction the air barrier system is also the fire barrier and smoke barrier in inter-unit separations. In such assemblies the air barrier system must also meet the specific fire resistance rating requirement for the given separation.  Air barrier systems are assembled from “materials” incorporated in “assemblies” that are interconnected to create “enclosures.” Each of these three elements has measurable resistance to air flow. The minimum resistance or air permeances for the three components are:
Material       0.02 l/(s-m2)@ 75 Pa
Assembly   0.20 l/(s-m2)@ 75 Pa
Enclosure   2.00 l/(s-m2)@ 75 Pa

• Material:  0.02 l/(s-m2) @ 75 Pa
• Assembly: 0.20 l/(s-m2) @ 75 Pa
• Enclosure: 2.00 l/(s-m2) @ 75 Pa

Air Basin:  A land area with generally similar meteorological and geographic conditions throughout.  To the extent possible, air basin boundaries are defined along political boundary lines and include both the source and receptor areas.  California is currently divided into 15 air basins.