Question 146General Subjects - Assistant Engineer70% to pass
Suppose the pressure switch used to control the "lead" potable water pump is set at 45 psig cut-in for pump start and 55 psig cut-out for pump stop. What would be an appropriate setting for the "lag" potable water pump?
AI Explanation
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.
Related Questions
#144 What design feature is used to minimize potable water wastage associated with hot water distribution piping for a potable water system? #145 What are the operating characteristics of a "waterlogged" potable water system hydro- pneumatic header tank that needs to be recharged with compressed air? #147 What statement is true concerning the term "isochronous" as it applies to prime mover speed control governors? #148 Which term represents the ability of a speed control governor to maintain prime mover speed without hunting? #149 What is meant by the term "dead band" as it applies to prime mover speed control governors?