EXCESS FLOW CHECK VALVES


 

EXCESS FLOW CHECK VALVES

EXCESS FLOW CHECK VALVES are safety mechanisms. They are to be installed in flow lines to and from pressure tanks, as near to the tank as possible. Their purpose is to shut off the flow of fluid from the tank in case of breakage or rupture of any flow line or fitting located on the outlet side of the valve.

Excess Flow Check Valves are normally open valves. They are to be positioned in the tank line or tank fitting so that high velocity of flow outward from the tank will force the valves to the closed position. Each valve design is rated for one particular maximum rate of flow. It will allow the passage of any rate of flow less than, and up to and including, this maximum flow rate. With an increase of velocity of flow, the valve will remain closed as long as this differential prevails. *It is evident that, if the valve is properly installed and the piping and fittings are properly sized for the installation, the valve automatically will close in case of breakage of the line or any fitting in the flow system on the side of the valve away from the tank unless the pressure in the tank is too low to maintain valve-closing velocity through the broken line. When repairs to the system are made and pressure closed in, the slight see page through the small orifice in the excess flow check valve head will, in time, allow pressures to equalize on both sides of the excess flow check valve and the excess flow check valve again will open to flow position and will be ready for further use. Flow lines should be as short and as free from bends and other flow restrictions as possible. Lines and fittings should not be reduced to smaller size than the size of the line for which the valve is intended as indicated by the last size code letter in the valve number.

 

SAFETY / PRESSURE RELIEF VALVES  THERMAL RELIEF VALVE    ATMOSPHERIC RELIEF VALVE   PRESSURE REDUCING VALVES / STATION   PRESSURE CUM VACUUM RELIEF VALVES  BREATHER VALVES    EXCESS FLOW  SHUT  OFF VALVES   UNDERGROUND SAFETY VALVES FOR WATER TANK /  WATER FLOW CANAL AS PER BS – 4558 : 1983 NON – RETURN VALVES  BALL VALVES DIAPHRAGM VALVES  NEEDLE  VALVES / MANIFOLDS/ THROTTLING VALVES   FLUSH BOTTOM VALVES