Groth Corporation”s new line of relief valves is designed for environments too corrosive for metallic or fiberglass devices. Constructed of nonmetallic, corrosion-resistant materials, the valves feature an all-polymer internal construction for harsh chemicals, such as Chlorine, Ethylene Dichloride, Hydrochloric Acid and other corrosive materials. Polymer valves operate in a similar fashion to their metal and fiberglass counterparts. They protect low-pressure atmospheric storage tanks from excessive pressure and/or vacuum and limit fugitive emissions by preventing constant tank “breathing” to atmosphere. The nonmetallic pressure and/or vacuum relief valves are available in vent-to-atmosphere or pipe-away configurations.