We have a two pump system with Mercoid Lead and Lag psw on each pressure tank. Two PLCs cause each pump to pump in turn. Lead switchs are set at 35 falling and 50psi riseing. Can anyone tell me what psis Lag switchs should be set at?

The two pumps are about 1/4 mile apart and the pressure tanks discharge into 6" main lines. At this time the First pump installed ocassionally runs at or near the same time as the second installed pump.

It appears that the psws were set by trial and error originally and the guy who really understood the system is no longer with the service co. All of my training says that psws should be calibrated, not field set and then you must keep records so that a psw can be replaced without the trial and error.

Thank you.

Ken