Fans are rated and selected on the basis of ACFM, as a fan handles the same volume of air regardless of density. ABSORPTION: the process of one substance entering into the inner structure of another. ADSORPTION: adhesion of a thin film of liquid or gases to the surface of a solid substance. AEROSOL: an assemblage of small particles, liquid or solid, suspended in air. The diameter of the particles may vary from 100 microns down to 0.01 micron or less, e.g., dust, fog, smoke. AGGLOMERATE: the grouping of smaller particles into a larger mass. AIR BALANCING: the process of regulating airflow to achieve the desired flow throughout the duct system. AIR CURTAIN: a mechanical device designed to limit the flow of unwanted air in a particular area. AIR FLOW: in-line movement of a stream of air. AIR VELOCITY: rate of speed of an airstream, expressed in feet per minute. AMBIENT: immediate surroundings or vicinity. AMCA: Air movement and control association. ARC-OVER: term used to describe the electrical current jump or sparking between areas of opposite potential. ARC-TRACKING: term used to describe the groove or track in an insulator as a result of arc-over. This track allows for a collection point for conductive material and results in more frequent arc-over conditions. ASHRAE: American Society of Heating, Refrigeration, and Air Conditioning Engineers. ASHRAE TEST STANDARD 52: test used to compare efficiencies of filters designed to collect dust particles. Includes standards for Atmospheric Dust Spot and Arrestance Testing. ASPECT RATIO: the relationship of width to length. ATTENUATION: adsorption of sound pressure. Attenuation reduces the amplitude of a sound wave without altering the frequency. AXIAL FLOW: in-line air movement parallel to the fan or motor shaft. BACKDRAFT DAMPER: damper used in a system to prevent airflow in a given direction. BALLING: term used to describe the infrequent buildup of airborne material on the tips of the spiked ionizers. Bl FAN: describes a fan with backwardly-inclined blades. BLOW THROUGH: contaminate that passes through a collector, usually as a result of high velocity or heavy loading. BREAK HORSEPOWER {BHP}: the amount of mechanical energy consumed in a system. BRIDGING: the buildup of collected material across two or more collector plates resulting in arc-over. CAPTURE VELOCITY: air velocity necessary to overcome opposing air currents or natural airflow and cause contaminated air, fumes, or particles to flow in a desired pattern. CARTRIDGE FILTER: pleated cellulose, synthetic fibers or a combination of the two used to collect air borne particulate matter. Typically a cylindrical tube with the airstream drawn from the outer surface inward with the filtered air exiting through the core of the filter. May be cleaned with a reverse pulse of compressed air to extend the collection life of the cartridge. CFM: Cubic feet per minute; the volume of airflow for a given fan or system. CLOSED LOOP: a system employing a filtered and recycled cleaning medium to flush collected material off the ionizer-collector cell surfaces. COALESCE: the gathering of smaller liquid particles into a larger grouping. CONVEYING VELOCITY: the air velocity required In a duct system to maintain entrapment of a specific material. COLLECTOR CELL: assembly containing the ionizer, repelling and collector plates, which collect and remove particulate matter from the contaminated airstream. COLLECTOR PLATE: portion of a cell used to attract and retain a particle from the airstream. CONTAMINATE: any material or gas, fume, vapor or particle that pollutes an airstream. CONTROL CABINET: electrical enclosure used to house, power supply, clock/timer, PLC, wash controls and terminal strips. CSA- CANADIAN STANDARDS ASSOCIATION: sets safety standards for equipment used in Canada. DAMPER: a device used to modulate airflow throughout a system. dbA: sound-pressure level in accordance with the “A” scale of measurement. DEW POINT: the temperature at which condensation begins to form when air is cooled. DFT: dry film thickness. DILUTION VENTILATION: mixing of contaminated air with uncontaminated supply air to obtain a desirable contaminate level. D.O.P.: Dioctylphthalate aerosol, material used to test efficiency of a very high efficient filter. Typically used as a standard to test equipment used to collect ultra fine particles or oil mists. DUST: air suspension of particles of any solid material. Typically refers to particles or aerosols smaller than 100 microns. DWELL TIME: the amount of time that a particle has to travel past a collector plate in a cell. EFFICIENCY: a comparison of the amount of material entering verses leaving an air cleaner. ELECTROSTATIC PRECIPITATOR (ESP): a highly efficient air cleaner used to collect: solids and liquids. This filter consists of two elements an ionization section and a collecting plate section. In the ionization section, small diameter wires or speciall...