Vent Check 43 7 Vent Check Valve, AERO 1.1 For on-deck venting of tanks containing ballast, lub, oil, etc. Reality tested according to IACS requirements. Approved by major classification societies. Featuring these fine qualities: - realistic fluid-based pressure drop curves - pressure loading and impact tested floats - specially-designed seats with zero-leackage performance - tested and approved, submerged at inclinations up to 40 - optimal motion in closing operation