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Pressure switches are control devices that open or close an electrical contact when a preset pressure level is reached. Due to their simplicity, they are widely used in both safety and automation applications. From pump protection to industrial process safety, they play a critical role in ensuring reliability.

WORKING PRINCIPLE

When pressure is applied on the diaphragm, it causes mechanical movement that actuates an electrical mechanism. This mechanism results in the opening or closing of contacts. The fundamental principle is based on the relationship between pressure, force, and area:

Formula: P = F / A

Where P: Pressure (Pa), F: Force (N), A: Area (m²).

STRUCTURAL FEATURES

Body materials: stainless steel, brass, plastic
Diaphragm materials: NBR, EPDM, stainless steel
Contact types: NO (normally open), NC (normally closed), SPDT
Electrical connection options and IP protection classes

TYPES

Mechanical pressure switches
Electronic/digital pressure switches (with display, microprocessor controlled)
Vacuum switches
Differential pressure switches

SELECTION CRITERIA

Measurement range (bar, psi)
Maximum operating pressure
Contact rating (AC/DC values)
Process connection (threaded, flanged)
Environmental conditions (temperature, vibration, humidity, ATEX certification)

ADVANTAGES AND LIMITATIONS

Advantages:

Simple and reliable operation
No energy required for mechanical types
Cost-effective
Wide application range

Limitations:

Lower accuracy in mechanical types
Wear and calibration needs
Higher cost for electronic models

APPLICATION AREAS

Pump and compressor protection
Pressure safety in hydraulic and pneumatic systems
Boilers and steam systems
Water treatment plants
HVAC and automotive applications

STANDARDS

IEC 60947 (low-voltage switchgear)
EN 60947-5-1 (switches)
ATEX certifications (for explosive atmospheres)

CONCLUSION

Pressure switches are cost-effective, reliable, and widely used control devices in critical applications. When properly selected, they provide indispensable protection for equipment and ensure process safety.