Joints of duct techniques shall be produced significantly airtight via tapes, mastics, liquid sealants, gasketing or other accepted closure systems. Closure devices employed with rigid fibrous glass ducts shall adjust to UL181A and shall be marked181A-P for pressure-sensitive tape, 181A-M for mastic or 181 A-H for heat-delicate tape. Closure systems https://chandral677kfy0.wikilowdown.com/user