Question 146General Subjects - Assistant Engineer

The correct answer is A) 40 psig cut-in for pump start and 55 psig cut-out for pump stop. The reasoning is that the "lag" potable water pump should be set to start at a slightly lower pressure than the "lead" pump, in order to allow the lead pump to meet the water demand first before the lag pump activates. This helps to minimize the cycling of the pumps and ensures efficient operation of the system. Setting the lag pump to 40 psig cut-in and 55 psig cut-out, compared to the lead pump's 45 psig cut-in and 55 psig cut-out, achieves this desired pressure differential. The other options are incorrect because B) and C) do not have the appropriate pressure differential between the lead and lag pumps, while D) has the lag pump starting at a higher pressure than the lead pump, which is not the desired configuration.