If no water is being used for an extended time and the line must remain under pressure, the pump will ______?

• A. Cool
• B. Overheat
• C. Stall
• D. Shut down

Answer: (B)

Pumps rely on flowing fluid to carry away the heat they generate. If no water is being drawn from the line but the line must stay under pressure, the pump ends up working against almost no discharge flow—a deadheaded condition. The hydraulic energy stays inside the pump, and the usual cooling effect of moving water is lost, so heat from mechanical and hydraulic losses builds up. With little or no flow to remove that heat, the pump temperature rises and it overheats. If there were meaningful flow, cooling would keep things cooler; stalling describes a condition where the pump can’t move the load, and shutting down would be a protective action, not a direct result of a pressurized but unused line.