Should The Outlet Valve Be Closed When Starting A Sanitary Centrifugal Pump?

Sanitary Centrifugal Pump, this annoying little goblin, needs to pay attention to a lot of things when starting. Should the outlet valve be closed when the centrifugal pump is started? Shocking! The answer is...

When the centrifugal water pump is started, there is no water in the outlet pipe of the pump, so there is no pipe resistance and lifting height resistance. After the centrifugal pump is started, the centrifugal pump head is very low and the flow rate is very large. At this time, the pump motor (shaft power) output is very large (according to the pump performance curve), which is very easy to overload, which will damage the pump motor and line. Therefore, the outlet valve must be closed when starting to make the pump operate normally.

If an axial flow water pump is used, the situation is the opposite. It must be started with the valve open. At this time, the motor power is the minimum. Due to the lack of resistance in a short period of time, it will operate at a large flow rate, often causing pump vibration, noise, and even motor overload, which will burn the motor. Closing the outlet valve is equivalent to artificially setting the pipe resistance pressure. After the pump operates normally, slowly start the valve to allow the pump to gradually work normally along its performance curve.

Two points must be ensured before starting the centrifugal pump:

1. Fill the pump casing with water to form a vacuum;

2. The gate valve on the outlet pipe must be closed so that the pump does not form a flow, which can reduce the motor starting current and facilitate the smooth start of the pump. As the pump starts smoothly, the gate valve should be opened slowly and in time.

The centrifugal pump lifts the water by the suction force of the vacuum formed by the centrifugal force of the impeller. Therefore, when the centrifugal pump is started, the outlet valve must be closed first and water must be filled. The water level must exceed the impeller part and the air in the centrifugal pump must be discharged before it can be started. After starting, a vacuum is formed around the impeller, sucking the water upward, and it can open automatically to lift the water. Therefore, the outlet valve must be closed first.