The 2 differnt types i bought and i have no idea how they really work, but with the help of the internet I found out that one of them is from a dishwasher and not from a washing machine. With a multimeter I made a continuity tests and it looks like that one is having 1 trip points and the other is having 2 trip points.
With the contiuty test you can test the pins how they respond and if the work. You just have to measure two pins and them blow into the switch, if the switch works you hear a click from the switch and the continuity will change from 1 to a 3 digit number and vice verce. Those pins will later be connected to the solenoid valve or water pump and send the signal to water our plants :)
Here is small video that explains pressure switches.
youtube pressure switch video