This is a “Square D” pressure switch, connected to a schedule 80 plastic PVC “T”, ready to insert into the pressure line just after the pump.
In case you are taken with this concept, the above photo shows the ordering data.
An oversized look at the guts of the switch. There are two sets of contacts, each with many times the surface area of the usual marine pressure switches. You can use the two sets in parallel, or save one set for later use. The contacts can be cleaned with a flat file. The springs are used to set the cut-in and cut-out pressure.
Switch installed. It works great, and the pump is operating at a much higher flow rate, indicating the old switch probably had a voltage drop across it, reducing voltage and therefore motor speed. Switches like this can be bought in industrial supply houses for about US$35.
Posted by Steve Dashew (April 10, 2008)