Process and E&I are developing P&IDs for an upcoming project. The picture below shows the preliminary drawing they have come up with. As I’m sure we all know by now, concentric reducers should not be used in pump suction lines unless the pump is a top suction pump, which this one is not. I’ve brought this point up to them along with discussing cavitation, but as of now they are not wanting to change what they have come up with. Their reasoning being the line size is too small for the flow switch insertion into the pipe and they want the flow switch to protect the pump (obviously).
Before I go back and argue some more, I was looking for some reinforcement that I should continue this argument and look for an alternative solution.
The pump will be used for offloading tanker trucks with refinery grade propane and sending it off to bullet storage tanks.
I believe you are justified in continuing the argument - from what I see, there’s a possibility in vapor accumulating in the segment containing the flow switch. Unless there is some nuance with pumping liquid propane that I am not aware of, I agree with your position as stated.
Snippet source https://www.eng-tips.com/viewthread.cfm?qid=427521