What causes pump impeller damage?

Cavitation, air entrainment and recirculation all result in pitting damage on the impeller caused by the formation and subsequent collapse of vapor bubbles. The difference between them lies in the method by which the bubbles are formed and the location of the resultant impeller damage.

What happens if discharge valve of reciprocating pump is closed?

Closing the discharge valve increases the pressure but does not change the flow. Reciprocating pumps run at a much lower speed than centrifugal pumps. By increasing speed, the packing and sealing life of the machine can be compromised.

What can cause a centrifugal pump to seize?

A centrifugal pump can seize when there is excessive metal-to-metal contact at rotating to stationary interfaces like wear rings, center bushings, and throttle bushings. Pump seizure can cause a lot of damage and in some services create a significant safety or environmental hazard.

What causes centrifugal pump failure?

Centrifugal pumps, which are a common pump used in industry, are known to fail as a result of problems that arise within the fluid, such as cavitation, and mechanical faults, such as found in bearings and seals. Vibration monitoring has been found to be suitable in determining faults within pumps.

For what particular reason should the cargo pump be started against a closed discharge valve?

A closed discharge valve at startup or shutdown also prevents backflow from any static discharge head. Pumps that require less shut-off power and torque than at normal flow conditions are usually started against a closed discharge valve.

How is a centrifugal pump started with reference to discharge valve and suction valve position?

Ensure that the discharge valve of the pump is closed. If it may be open or partially open, then close it. Open the suction valve 100\%. Do pump priming by opening the vent valve and to release the air, when liquid starts oozing out of the vent then close the vent valve.