Home / FAQs / What are ATCO’s pressure ratings? These are ratings for our standard products:
Rated Positive Pressure:
10” w.g. per UL 181
Recommended Operating Pressures:
6” w.g. pos., 4”-12” dia., 4”w.g. pos., 14”-20” dia.; ¾” neg., all dia.
Velocity:
5,000 FPM
Flame Spread/ Smoke Developed:
25 max/ 50 max
Standard Lengths:
25’