If my memory serves me right, the term used to be applied to air filters. The Class 1 or Class 2 had to do with the amount of smoke which would be generated when a flame was applied to the filter. I think that a Class 1 filter had a metal frame and element and Class 2 had non metal, but again that's from what I recollect from years back, dealing with UL 478 which I believe had references to Class 1 and 2 filters.
Gabriel Roy Hughes Network Systems MD ----------------------------------------- snip --------------------------------------------------- Does anyone know what is meant by the term : system shall have a minimum fire rating of UL CLASS 2? Fred Schumacher Unisys Corp
