Question 460Steam Plants - Assistant Engineer

The correct answer is B) Flashing at the suction side of the pump. When a centrifugal main feed pump is operated at shutoff head with the recirculating line closed, the pump will be running against a closed discharge valve. This creates a high-pressure condition at the pump discharge, which can cause the fluid on the suction side of the pump to vaporize or "flash". This flashing at the suction side of the pump can lead to pump cavitation and damage. The other answer choices are incorrect because: A) a decreased water level in the DC heater is not directly related to the pump operating at shutoff head, C) excessive diaphragm seal wear in the feed water regulator is not a consequence of the pump operating at shutoff head, and D) an increased water level in the steam drum is also not a direct result of the pump operating at shutoff head.