“Vapor tight” means equipment or a system where there is no loss of vapors, as determined by ensuring that the concentration of vapors at a potential leak source is not equal to or greater than 100 percent of the LEL when measured with a combustible gas detector, calibrated with hexane or equivalent, at a distance of one inch from the source.

Source. (See Revision Note #1 and Revision Note #2 at chapter heading for Env-Or 500) #10229, eff 11-17-12; ss by #13458, eff 10-7-22 (formerly Env-Or 502.36)