Quote Originally Posted by petersonra View Post
seals are threaded. if you have one on the D1 side how come no hazardous gases can get into the conduit leading to the non-hazardous side?
Yes, and not only that you can place a reducer in the seal.[Sections 501.15(A)(4) and 501.15(B)(2) (my idea BTW)] Remember, the seal is only to minimize, not prevent, the passage of flammables [Section 501.15 IN No.1] By the time all the packing and sealing compound in the seal is considered, minimizing passage in a properly installed seal is well covered. This has been confirmed by both manufactures and UL. Of course, a Division 2/unclassified seal doesn't have to be explosionproof in the first place, but there aren't supposed to be any flammables in the first place either under normal operating conditions.