Strike Section 510.5 of the International Mechanical Code in its entirety and insert a new Section 510.5 into the Mechanical Code in its place to read as follows:
Incompatible materials and common shafts. Incompatible materials, as defined in the International Fire Code, shall not be exhausted through the same hazardous exhaust system. Hazardous exhaust systems shall not share common shafts with other duct systems, except where such systems are hazardous exhaust systems originating in the same fire area.
Exception: The provisions of this section shall not apply to laboratory exhaust systems where all of the following conditions apply:
(No change to conditions 1 through 5)
(No change to conditions 7 through 8.2)
D.C. Mun. Regs. tit. 12, r. 12-E510