Question 294General Subjects - QMED

The correct answer is D) the discharge valve is closed off and there is no change in the discharge pressure. When the discharge valve is closed off on a centrifugal fire pump, the pump will simply circulate the water back to the suction side, and there will be no change in the discharge pressure. This is because the pump is not able to push water through a closed discharge valve, and the system is essentially in a closed loop. The other answer choices are incorrect because they do not accurately describe the behavior of the centrifugal fire pump when the discharge valve is slowly closed. Closing the suction valve (A and B) or the relief valve lifting (C) would not be the expected response to slowly closing the discharge valve.