What will happen while starting if discharge valve of reciprocating pump is closed?

What will happen while starting if discharge valve of reciprocating pump is closed?

By closing the discharge valve, the starting current can be reduced. As we know, at the start of any motor, the current will be high. If we start the pump with discharge valve closed, it means there no discharge head and minimum resistance to the pump and so current drawn is minimum.

What happens when the discharge valve of a running positive displacement pump is closed?

A positive displacement pump operating against a closed discharge valve will continue to produce flow until the pressure in the discharge line has increased until the line bursts or the pump is severely damaged – or both. The relief valve can be internal or external.

What happens when discharge valve of a centrifugal pump?

If the discharge valve is closed and there is no other flow path available to the pump, the impeller will churn the same volume of water as it rotates in the pump casing. The vapor can interrupt the cooling flow to the pump’s packing and bearings, causing excessive wear and heat.

Is centrifugal pump a positive displacement pump?

A centrifugal pump is categorised as a non-positive displacement pump. Traps a certain amount of liquid and forces it from the suction to the discharge port. Flow rate remains constant as change in pressure.

Why centrifugal pump started with discharge valve closed?

Explanation Using Pump Characteristics >The discharge valve of the pump has to be closed during startup. This is maintained so, inorder to prevent sudden load on the power system, if the valve is open. If you look at the characteristics of the pump, the power required ,increases with flow rate.

When a centrifugal pump is started its delivery valve is kept?

The delivery valve connects the pump outlet and the delivery pipe. It remains closed before the pump is switched on. When the pump builds up its pressure, it is opened and can be used to control or vary the discharge.

What must you do before starting a centrifugal pump?

Every centrifugal pump must be primed, vented and full of liquid before it is started. The pump you are about to start must be properly vented and primed. The suction valve must be fully open.

When are centrifugal pumps used?

Centrifugal pumps are commonly used for pumping water, solvents, organics, oils, acids, bases and any ‘thin’ liquids in both industrial, agricultural and domestic applications. In fact, there is a design of centrifugal pump suitable for virtually any application involving low viscosity fluids.

Why is centrifugal pump negative displacement?

A centrifugal pump is categorised as a non-positive displacement pump. Traps a certain amount of liquid and forces it from the suction to the discharge port. Flow rate remains constant as change in pressure. The internal clearances allow higher viscosity handling.

What is a closed discharge?

If the discharge valve is closed when the pump is started, it means that there is no discharge head and minimum resistance to the pump, and therefore the output current is the smallest.