U.S. Plastic Corporation GF PVC Ventilating & Bleed Valve Type 591 20821

The Ventilating and Bleed Valve Type 591 are primarily used where containers and pipes have to be aerated and/or vented. The float in the type 591 opens the valve if the level of the liquid falls. If the level of the liquid rises, the float is raised and pressed against a seal. The valve is then closed. For correct functioning, it is important that the valves Type 591 are installed vertically with the arrow pointing "up". Ventilating and bleed valves are mainly used for de-aerating of air, while filling piping systems and tanks, avoiding vacuum and discharging air pockets. Chief causes for air in piping systems include dissolved air being released into the system through pumps, valves, fittings and other pipe components, when filling containers and pipe lines, air inclusions may occur and pressure drops or temperature increases can release dissolved air. Positioning of the valves can be at absolute and temporary high points, after pumps or at turning points.