UL508A Barriers Used with Ventilation Openings

[JASON8102]

In the UL508A guidline for Industrial Control panels, section 22 discusses barriers used with ventilation openings. If anyone is familar with this standard, section 22.4 reads "A barrier of polycarbonate shall be at least .125" thick. A NONMETALLIC BARRIER OTHER THEN POLYCARBONATE SHALL BE AT LEAST .25" THICK." Like a filter material. Does this "nonmetalic" material need to meet UL94 flame rating? No where in section 22 does it discuss flame rating.

Jason Schultz
Mechanical Engineer
Yaskawa Electric America
"It's got to be 5pm somewhere!"

 

[7anoter4]

I'm not familiar with UL 508A standard, but I think the filter has to withstand the blowing pressure in a short-circuit case. The polycarbonate filter may be V0, V1 or V2 flame resistance. If a material would be less than V2 this could not be UL listed, whatever. But other plastics are not mechanical resistant as polycarbonate.This is my opinion.