"For positive pipeline protection against damaging pressure surges." The operating principle of this valve is the same as the CONVENTIONAL Air and Vacuum Valve, with one exception ... Hydraulically Controlled Air and Vacuum Valves are normally open (because the heavy cast float is not buoyant), and slowly close, only after spilling a regulated volume of water to prevent a pressure surge. This valve provides excellent pipeline protection against primary and secondary surge pressures which usually occur when filling or draining a pipeline. The closing time of this valve is variable and adjustable by means of a hydraulic control system.
Immediate Availability thru 16 Weeks
Sizes 4" thru 20". Ratings 125# and 250# class.

Vacuum Relief/Air Inlet Valves are a normally closed valve and any time the System Pressure becomes Negative - IT OPENS IMMEDIATELY - allowing air into the system to prevent a vacuum forming. When system pressure returns to positive, the Vacuum Relief/Air Inlet Valve closes air tight. Standard VP,/AlVs are designed to open with a minimal 1/4 PSI pressure differential across the orifice. Higher or lower relief settings are available to suit the application. Rated 250# class available.
Availability immediate thru 16 weeks.
Sizes 3" thru 36".