Pressure switch

Another type of pressure switch detects mechanical force; for example, a pressure-sensitive mat is used to automatically open doors on commercial buildings.

The resulting motion is applied, either directly or through amplifying levers, to a set of switch contacts.

Such switches are useful when the difference is significant, for example, to detect a clogged filter in a water supply system.

The switches must be designed to respond only to the difference and not to false-operate for changes in the common mode pressure.

For example, rubber diaphragms are commonly used in contact with water, but would quickly degrade if used in a system containing mineral oil.

Pressure sensitive mats can be used to detect persons walking over a particular point, as part of a security alarm system or to count attendance, or for other purposes.