Common Air Duct Cleaning Terms

Access: The ability to gain entry to the interior of the air duct or HVAC component. Access Door: Fabricated metal barrier (hatch) by which a service opening is accessed or closed. Adhered Substance: A material, such as mastic, that is not removable by direct contact vacuuming. ACGIH: American Conference of Governmental Industrial Hygienists. Adhered Particulate: Any material not intended or designed to be present in an HVAC system, and which must be dislodged in order to be removed. Aerosols: Solid or liquid airborne particles. AIHA: American Industrial Hygiene Association. Air Duct: A passageway for distribution and extraction of air, excluding plenums not installed in accordance with SMACNA Standards (See ASHRAE Terminology of Heating, Ventilation, Air Conditioning & Refrigeration, 1991). Air Duct Covering: Materials such as insulation and banding used to cover the external surface of a duct. Air Duct Lining: Generally refers to fiberglass or other matting affixed to the interior surfaces of the air ducts for thermal insulation and noise attenuation. Air Filtration Device (AFD): A portable or transportable, self-contained blower assembly designed to move a defined volume of air equipped with one or more stages of particulate filtration. Depending on the mode of use, an AFD that filters (usually HEPA) and re-circulates air is referred to as an "air scrubber." One that filters air and creates negative pressure is referred to as a "negative air machine." Air-handling Unit (AHU): A packaged assembly, usually connected to ductwork, that moves air and may also clean and condition the air. Coils: Devices inside an HVAC system that temper and/or dehumidify the air handled by the HVAC system. These include heat exchangers with or without extended surfaces through which water, ethylene glycol solution, brine, volatile refrigerant, or steam is circulated for the purpose of total cooling (sensible cooling plus latent cooling) or sensible heating of a forced-circulation air stream. Collection Device: A HEPA-filtered machine designed primarily to collect debris, filter particulate and discharge air back to the indoor environment, or a fan driven non-HEPA-filtered machine that is designed to collect debris, and then filter particulate while discharging the air outside the building envelope. Ductwork: A system of passageways for distribution and extraction of air, excluding plenums not installed in accordance with SMACNA Standards. EPA: United States Environmental Protection Agency Duct Access Door: Fabricated metal barrier (hatch) by which a service opening is accessed or closed. HEPA: High Efficiency Particulate Air. To be called a true HEPA filter, or certified HEPA filter the filter must have a documented filtration efficiency of 99.97% at 0.3 micron-sized particles. HVAC System: The heating, ventilation, and air conditioning (HVAC) system includes any interior surface of the facility's air distribution system for conditioned spaces and/or occupied zones. This includes the entire heating, air-conditioning, and ventilation system from the points where the air enters the system to the points where the air is discharged from the system. IAQA: Indoor Air Quality Association Mold Contaminated: The presence of indoor mold growth and/or mold spores, whose identity, location and amplification are not reflective of a normal fungal ecology for an indoor environment, and which may produce adverse health effects and cause damage to materials, and adversely affect the operation or function of building systems. Porous HVAC System Surface: Any surface of the HVAC system in contact with the air stream that is capable of penetration by either water or air. Examples include fiberglass duct liner, fiber glass duct board, wood, and concrete. Thermal Acoustic Materials: HVAC insulation materials designed for sound and temperature control. UL: Underwriters Laboratories, Inc. Vacuum Collection Equipment: See "Collection Device." Visibly Clean: A condition in which the interior surfaces of the HVAC system are free of non-adhered substances and debris. Visual Inspection: Visual examination with the naked eye of the cleanliness of the HVAC system Wet Process Cleaning: Any method of mechanical cleaning of HVAC components that utilizes water and/or liquid chemicals as part of the process (i.e. power washing, steam cleaning, hand washing).