Description The OPW 523V-2253 Pressure Vacuum Vent is designed to protect the tank vent lines against intrusion and blockage from water, debris or insects. A normally closed poppet in the valve opens at a predetermined pressure or vacuum setting to allow the tank to vent. Key Features A Variety of Pressure/Vacuum Settings - 3" water column, 1 oz., 8 oz,. 12 oz., pressure settings and 8" water column or 1/2 oz. vacuum settings are factory preset and tested. Reliable Service - A self-guided poppet assembly ensures consistent seating of the pressure/vacuum valve. Corrosion-Resistant Construction - Duratuff® composite body assures a long service life. Easy Installation - The 523V is available in 2" and 3" threaded versions or slip-on models that provide for attachment to the vent line with allen head screws and radial sealing "O-ring". Complies with NFPA 30 Requirements - For venting gasoline vapors upward. High Maximum Flow Rate - 7,000 scfh at 2 psi pressure drop. 40-Mesh Stainless Steel Wire Screen - Helps prevent debris and insects from entering the tank vent lines.