Where to Put a Valve on the Pump

Posted: 7/28/2014

Valves on a pump control the flow of liquid through a pump.Valves on a pump control the flow of liquid through a pump. These help to regulate pressure within a pump and prevent against possible breakage. Any pump should have two valves attached; one at the inlet, or suction, and the other at the outlet, or discharge area.

Valves must be installed at the correct distance in order to insure maintenance and safety. This can be determined by using the width of each valve as a measure. For example, if a pump has a 1 inch inlet and ½ inch outlet, then a valve should be placed a minimum of 10 inches from the suction side and 5 inches away on the discharge.
When trying to control the flow of the pump, always regulate the flow using the valve on the outlet side. Using the valve on the suction side to regulate the flow greatly increases the chances of "starving the pump." This is when the level of liquid entering the pump is less than the pump is trying to put out. Starving the pump, after dry running, is the greatest danger to any magnetic drive pump.

The valve on the suction side should only be closed when the pump is turned off. Upon startup, the valve on the outlet should not be fully open, it should be partially closed to generate some extra backpressure.

The best valves to use with March Pumps are generally those which have minimum friction losses. Friction loss is the loss of energy, or "head," that occurs within a pipe due to viscous effects generated by the surface of the pipe. March Pump encourages the use of valves that are designed to keep friction losses at a minimum.

Popular choices are ball valves and gate valves. Ball valves are valves with a spherical disc which has a hole through the middle. This controls the amount of flow through the pump.

Gate valve

These can attain perfect shutoff of flow.


Gate valves are valves that open by lifting a "gate" or wedge out of the path of the liquid. These are primarily used to permit or prevent flow, but should not be used to regulate flow.

Solenoid valves

Conversely, valves such as solenoid valves (electromechanical valves controlled by an electric current through a solenoid, or helix coil), can be dangerous to plastic pumps because of how quickly they close. It is very possible they may cause water hammer. This is a pressure surge that occurs when a liquid is forced to stop or change direction suddenly, which can result in breaking the rear housing. If you are using a solenoid valve, increase the time it takes to close the valve to reduce the chance of water hammer from occurring.

Valves help maintain and regulate the usage of your pump. Be sure to use the best equipment for your needs.

If you have any questions, feel free to contact us at any time.

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