remember that dp switches on pumps prove that the pump is RUNNING. they do not prove that the pump is FLOWING. i have been to many jobs where the bas techs use dp switches to prove the pump is flowing (which is incorrect) and then start the chiller. i mostly don't like them on anything (pumps or chillers) because the piping to the switch does not have any flow in them and over time, crud fills up the piping making the switch fail.
a fun example with dp switches on pumps: close 1 isolation valve to the chiller (with the chiller off) then manually start the chilled water pump...the switch will make...do this in front of the bas tech and ask them to explain why this is happening. 95% of the bas techs will say that the switch has failed and needs replaced!
ifm effectors have been my favorite for about 5 years now....they are great if selected properly and installed properly.
"Right" is not the same as "Wise".
Don't step on my favorite part of the Constitution just to point out your favorite part.
Just because you can measure it, doesn't mean it is important. Just because you can't measure it, doesn't mean it isn't important.