Centrifugal Pump troubleshooting ! Imran

Pump troubleshooting by Mohammad Imran

SUBJECT: The pump works for a while and then loses suction 10-12

A couple of things you must keep in mind when troubleshooting centrifugal pump problems:

• The centrifugal pump always pumps the difference between the suction and discharge heads. If the suction head increases, the pump head will decrease to meet the system requirements. If the suction head decreases the pump head will increase to meet the system requirements.
• A centrifugal pump always pumps a combination of head and capacity. These two numbers multiplied together must remain a constant. In other words, if the head increases the capacity must decrease. Likewise if the head decreases, the capacity must increase.
• The pump will pump where the pump curve intersects the system curve.
• If the pump is not meeting the system curve requirements the problem could be in the pump, the suction side including the piping and source tank, or somewhere in the discharge system.
• Most pumps are oversized because of safety factors that were added at the time the pump was sized. This means that throttling is a normal condition in most plants, causing the pump to run on the left hand side of its curve.