Vent Valves as Flame Arresters

NFPA 30 recognizes that a conservation vent valve (pressnre-vacnnm valve) is an alternative to a flame arrester nnder certain circnmstances. This recognition is based on tests hegnn in 1920 and is snpplemented hy many years of experience. 

The concepts of the National Electrical Code (NEC) gronps and the Maxi-mnm Experimental Safe Gap (MESG) are important criteria in the selection and specification of dry type flame arresters. These are explained below. 

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