A pressure switch is a device that operates an electrical contact when a specified set of fluid pressure is attained on its input. The switch could be set up to make contact as the pressure rises or falls. Pressure switches are commonly used in industry to monitor and control systems that employ pressured fluids automatically.
Another sort of pressure switch measures mechanical force; for example, in commercial buildings, a pressure-sensitive mat is used to automatically open doors. Security alarm applications, such as pressure-sensitive floors, also use similar sensors.
Types of Pressure Switch
Mechanical Pressure Switch
A spring and a diaphragm, or piston, are used in a mechanical pressure switch to control the pressure at which the micro-switch is triggered. The spring is the force that opposes the input pressure, and its pretension can be modified with a set screw or knob. The pressure at which the switch creates an electric contact is precisely proportional to the spring pretension. The switch returns to its original state when the pressure drops.
Hysteresis is the difference between the switch point and the reset point. This is sometimes represented as a percentage of the switch point value, such as 20%. The hysteresis is determined by the manufacturer, and it is not changeable by the user for most mechanical switches.
Normally open (NO), normally closed (NC), and changeover (SPDT) connections are the most common types of contacts on these pressure switches. Both NO and NC operations are covered by the changeover connections.
The mechanical pressure switch can handle higher voltages and amperages than an electronic pressure switch. They can be used to adjust the contact for a pressure increase or decrease. An article on how to alter mechanical pressure switches may be found here.
Electronic Pressure Switch
An electrical pressure sensor is used in an electronic pressure switch to detect changes in inlet pressure. To set up the switching function, they have digital displays. The switch point can be factory-programmed or configured on-site to meet the application’s needs. Switch point, output signals, hysteresis, delay time, and other functions can be customised by the user to meet their specific needs.
Electronic pressure switches are ideal for automated and controlled equipment systems with programmable functions, digital displays, flexibility, precision, ingress protection, and stability.
Where Are Pressure Switches Used?
- Air compressor pressure switches are used to monitor and manage the air pressure in HVAC, gas cylinders, air pumps, and other systems.
- Engines employ oil pressure switches as an actuator or sensor to detect when the engine’s oil pressure falls below a predefined level.
- Furnace pressure switches are used as safety devices in both industrial and domestic applications. They detect negative pressure at the furnace’s startup and shut it off if the air pressure is too low.
- Well pump pressure switches are used in both residential and commercial structures to get water from the well and guarantee that the system is not over-pressurized.
- Water flow is automatically regulated by water pump pressure switches in residential, commercial, and agricultural applications.
- Vacuum pressure switches monitor the system’s vacuum or negative pressure. Residential boilers, electric heaters, air compressors, and transmission systems all contain them.