1986sv Civacon Vapor Vent Valve For Manholes Psi(36.6% similar) In case of a rollover, the poppet will not open under surge. Meets world class. Allows maximum payload. Durable and corrosion resistant for long life. Poppet seals internal vapor pressure better. Lightweight, one-piece aluminum construction. Stainless steel trim is corrosion resistant. The 1986 SVS...(March 7th, 2019)