Pump Valve Investment Casting

Pump control valves
A pump control valve is normally closed to prevent reverse flow when the pump is off. It then opens at a controlled rate of speed just after pump start, gradually accelerating the fluid to minimize pressure surges. To initiate a normal pump shutdown, the pump control valve is closed against a running pump at a controlled rate of speed, gradually decelerating the fluid to minimize pressure surges. Upon seating, a limit switch on the pump control valve turns off the pump. When an electrical power failure occurs during pumping, the pump control valve automatically closes, usually at a faster than normal rate to minimize backflow.

Pump & control valve interface
A pump and control valve interface is a preprogrammed controller that properly sequences and controls the pump and pump control valve startup and shutdown procedure for normal operation. It includes a special sequence with a time delay to protect the pumping system from damage due to mechanical, hydraulic or power failure.

Check valves
Check valves are used to prevent the backflow of fluid through the pump by closing before flow reversal can occur. Check valves are installed on clean and dirty applications. Various closure devices are available that include air cushion, oil control, bottom buffers, lever and weight, external lever and spring or internal spring.

Surge relief valves
Surge relief valves are typically installed downstream of the check or pump control valves on the pump discharge header with the valve inlet connected to the side outlet of a tee and the valve outlet piped back to the sump. The normally closed surge relief valve opens quickly when the system pressure rises above its adjustable relief-pressure setting, allowing fluid to be discharged from the system through the open surge relief valve to a controlled, contained location—typically some form of sump. While the surge relief valve is open, the system is no longer contained, fluid compression is limited and surge pressure is controlled. The valve will remain open as long as the system pressure exceeds the valve’s relief-pressure setting. The valve will slowly begin to close at an adjustable rate as the surge pressure subsides and the system pressure falls below the valve’s relief-pressure setting.

Air valves
Air release valves remove small air pockets that form at the high points of a pipeline and restrict flow. Air and vacuum valves expel large amounts of air when filling the pipeline and admit air to relieve a vacuum when draining the pipeline.

Isolation valves
Isolation valves are typically one of three types—butterfly, plug or knife gate. Selection of an isolation valve depends on various factors including full flow requirements, media type and solids content, temperature, etc. An isolation valve will usually be located after the pump control valve or check valve to isolate both the valve and the pump for maintenance capability. An isolation valve is also required for the pressure relief valve.