What is the function of a discharge valve in the pump panel, and why must it be opened in a controlled sequence?

• A. It controls water temperature
• B. It blocks air from entering
• C. It is decorative
• D. It controls water flow; opening too quickly with no prime can cause air to enter and loss of prime, so you open gradually after priming.

Answer: (D)

The main idea you’re testing here is how the discharge valve controls water flow and why its opening must follow a careful sequence during starting. The discharge valve regulates how much water leaves the pump and enters the discharge system, shaping the flow that the pump will deliver. In fire pump operation, you prime the pump to remove air from the suction side. If you open the discharge valve too quickly before the pump is primed, air can be drawn into the pump, the prime can be lost, and the pump may fail to deliver water. Opening the valve gradually after priming lets the pump build pressure smoothly, prevents air entrainment, and avoids water hammer, ensuring a steady, reliable discharge flow.