During a pump capacity test, if the pump pressure is correct but the nozzle flow is too high, what adjustment should be made?

• A. Open the discharge gate further
• B. Increase the throttle setting
• C. Close the discharge gate further and reduce the throttle setting
• D. Check the tank water level

Answer: (C)

Controlling pump capacity during a test is all about balancing the amount of water being delivered with the pressure at the nozzle by using two main controls: the discharge gate and the throttle. If the nozzle flow is too high but the pressure at the nozzle is already at the desired value, you want to reduce the overall output rather than push more water through. Closing the discharge gate further increases hydraulic restriction, which lowers the flow coming from the pump. At the same time, reducing the throttle setting slows the pump, further reducing flow and helping bring the nozzle flow down to the target level without overshooting the pressure. Opening the discharge gate or increasing the throttle would increase flow and make the nozzle flow problem worse. Checking the tank water level isn’t addressing the flow control issue in the discharge path.