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Air Filter Units
UL 900
1 Scope

1.1 These requirements cover tests to determine the amount of smoke generated and the combustibility of air filter units of both washable and throwaway types used for removal of dust and other airborne particles from air circulated mechanically in equipment and systems installed in accordance with the Standards for Installation of Air Conditioning and Ventilating Systems, NFPA 90A (Other Than Residence Type), Installation of Warm Air Heating and Air Conditioning Systems, NFPA 90B (Residence Type), the International Mechanical Code, the International Fire Code, and the Uniform Mechanical Code. These requirements also cover media intended for assembly into air filter units.

1.2 Since the smoke generation of an air filter unit, as well as its combustibility, depends upon the nature and quantity of the material collected by the filter, the test requirements of this standard, for classification purposes, apply only to air filter units in a clean condition. Consequently, when filters are susceptible to the accumulation of combustible deposits, it is intended that maintenance and inspection practices should be followed as proposed in Appendix B of NFPA 90A.