Pressure Switches- I

A pressure switch is one detecting the presence of fluid pressure. Pressure switches often use
diaphragms or bellows as the pressure-sensing element, the motion of which actuates one or more
switch contacts.
The “normal” status of a switch is the condition of minimum stimulus. A pressure
switch will be in its “normal” status when it senses minimum pressure (e.g. n applied pressure, or
in some cases a vacuum condition).If the trip setting of a pressure switch is below atmospheric pressure, then it will be “actuated” at atmospheric pressure and in its “normal” status only when the pressure falls below that trip point (i.e. a vacuum).