Typically, washing machine pressure switches have a large sensing diaphragm that's about 60mm or so in diameter and three quick-connect male terminals. One connection is common, while the others are for normally open (NO) and normally closed (NC) connections. A set-point adjustment mechanism is built in (it's directly controlled by the 'water level' knob) and the switch opens and closes with audible clicks.
Because they're not externally adjustable, they don't need to be located close to the control panel. Depending on your application, you might want your salvaged pressure switch to operate at pressures that are different to its standard range. That's not hard to do if you have a washing machine pressure switch, as they are quite easy to modify.In standard form, turning the adjustment control typically allows the trip pressure to be set to detect water depths anywhere from 9cm to 20cm. But if you remove the adjustment.