The minimum flow line helps prevent which pump condition?

• A. Deadhead operation
• B. Cavitation
• C. Air lock
• D. Overheating

Answer: (A)

A pump line that maintains a minimum flow is there to keep the pump from running with almost no liquid flow, i.e., to prevent deadheading. By recirculating a small amount of pumped fluid back to the suction or around the pump, it ensures there is always some flow through the pump. This keeps the bearings and seals cooled and lubricated and avoids the high head and heat that can occur when flow is nearly zero. Cavitation, air lock, and overheating can be related issues in some situations, but the line’s primary purpose is to prevent deadheading by guaranteeing a minimum circulating flow.