Question 141General Subjects - Assistant Engineer

The correct answer is A. Potable water pumps of the non-positive displacement type, such as centrifugal pumps, require a vacuum-priming system if located above the potable water storage tanks. This is because non-positive displacement pumps cannot create enough suction to lift water from below the pump level, so a vacuum-priming system is necessary to ensure the pump can be filled and primed. In contrast, positive displacement pumps like gear pumps can create enough suction to lift water from below the pump level, so they do not require a vacuum-priming system in that scenario (option B is incorrect). Similarly, non-positive displacement pumps located below the water storage tanks do not need a vacuum-priming system (option C is incorrect), as gravity can provide the necessary pressure for the pump to operate.