Pressure Switch, Connection Size : 1/4 Inch

A pressure switch (also used for vacuum and called a vacuum switch) consists of a switch mechanism that is connected to a bellows or diaphragm that reacts to system pressure. Some are adjustable and some are not. They are selected operating range and differential. Operating range is the pressure limits in which the switch will work. Differential is the difference between the cut-in and cut-out pressures. A popular switch found on many compressors will a range of 40 to 250 PSI and an adjustable differentia of 35 to 60 PSI. This means that the lowest pressure that the switch can be set to close at is 40 PSI, and the highest pressure it can be set to open at is 250 PSI. The differential that is actually available to use varies with the pressure range you’re actually working in. As pressure increases, available differential increases as well. Some switches have differentials as low as 5 PSI. The contact points in the switch are usually rated for the amount of current they can carry. Some switches are also horsepower rated.
When you replace a pressure switch it’s important to make sure the contacts are of the same configuration as the switch you have. Double Pole Single Throw (DPST) contacts are very common. These will have 4 terminal screws, two of which are labeled “Line” and two of which are labeled “Load” or “Motor”. Some pressure switches need to be able to signal whether they are open or closed. These commonly have contacts called Single Pole Double Throw (SPDT). There will be three terminals labeled “Common”, Normally Open” or “Normally Closed”. Cal Supply stocks a large selection of pressure switches for whatever you need.