Joints of duct techniques shall be created substantially airtight by means of tapes, mastics, liquid sealants, gasketing or other authorized closure units. Closure units made use of with rigid fibrous glass ducts shall adjust to UL181A and shall be marked181A-P for strain-delicate tape, 181A-M for mastic or 181 A-H for https://daven888ngy0.loginblogin.com/profile