Hoffman 401440 Radiator Steam Vent. Model 40 Air Valve. 1/8" Angle Connection. Air Valve (non-vacuum). Float-type vent For ordinary one-pipe system that doesn’t require proportional venting Single non-adjustable port 1⁄8" NPT angle connection Maximum operating pressure 6 psig (0.4 bar) Maximum pressure 10 psig (0.7 bar)