When attack lines are used intermittently during pump operations, how does a pump operator ensure the pump does not overheat?

• A. Open the pump bypass valve
• B. Increase engine RPM
• C. Close the bypass valve
• D. Open the discharge valve

Answer: (A)

When attack lines are used intermittently, the pump can heat up because flow through the pump drops between bursts. Opening the pump bypass valve creates a recirculation loop that keeps water moving through the pump even when no water is being discharged to a nozzle. This continuous circulation carries heat away from the pump and its bearings, helping prevent overheating and keeping the pump operating within safe limits.

Closing the bypass stops this cooling loop, which lets heat build up. Increasing engine RPM would actually raise heat production rather than prevent overheating. Simply opening the discharge valve doesn't establish the necessary recirculation path to cool the pump when there isn’t constant flow through the lines.