Pressure Switches — Precision Pressure Monitoring & Protection for Industrial Processes
Pressure switches are one of the most critical safety and control devices used in industrial systems. Their primary function is simple yet essential — detect pressure rise or drop and open/close an electrical contact to protect equipment, interlock processes, or maintain set pressure ranges.
NPK Industries supplies a full range of mechanical, electromechanical, and industrial-grade pressure switches from globally trusted brands such as Baumer, Indfos, and Danfoss. These switches are used across dairy, food & beverage, chemical, boiler & steam systems, water treatment, HVAC, compressors, pumps, hydraulic systems, and general utilities.
What is a Pressure Switch?
A pressure switch is an instrument that monitors pressure in a system and triggers an electrical switching action when a set threshold is reached.
It consists of:
- Sensing Element → diaphragm, piston, bourdon tube, bellows
- Actuation Mechanism → spring-loaded mechanism
- Electrical Microswitch / SPDT / DPDT contact
- Adjustment knob / calibration screw
- Enclosure → IP rated, industrial housing
Working Sequence:
- Process pressure is applied to the sensing element
- Pressure overcomes spring force
- Mechanical displacement activates the microswitch
- Output contact → NO closes or NC opens
- Control system receives ON/OFF signal
This makes pressure switches essential for cut-out, cut-in, pump control, compressor protection, boiler safety, refrigeration systems, and general automation interlocks.
Working Principle of Pressure Switches
Most industrial switches operate on the spring-and-diaphragm principle:
Step-by-step:
- Pressure enters via process port
- Diaphragm or piston deflects proportional to pressure
- Deflection compresses the calibration spring
- Once the set point is reached → switch snaps
- Microswitch toggles state:
- NO → → closes
- NC → → opens
- On pressure fallback (differential/hysteresis), the switch resets
- Types of sensing elements:
Sensing Element | Suitable For | Notes |
Diaphragm | Air, water, hygienic lines | Most common |
Piston | Oils, hydraulic systems | High pressure |
Bellows | Steam, gas | Good repeatability |
Bourdon tube | Industrial ranges | Rugged |
Electrical Switching:
- SPDT / 1-NO-1-NC
- DPDT (dual switching)
- Micro-switch ratings: 5A, 10A, 15A
- Optional gold-plated contacts for low-level signals
Accuracy & Repeatability:
Typical: ±1% to ±3% of FS
Set-Point Adjustment:
Pressure Switches We Offer (Brand-wise Details)
Baumer Pressure Switch Series – UT6, CNI10, ZPPW, ZPDW
Baumer provides robust, precise, and long-life switches preferred by industries that require consistent performance.
UT6 – General Industrial Pressure Switch
- Rugged metallic design
- Diaphragm-based sensing
- IP65/67 enclosure
- High repeatability for pumps, compressors, industrial air lines
CNI10 – Compact Pressure Switch
- Extremely compact
- Suitable for OEM machines
- Adjustable set point
- Ideal for pneumatic systems & utility skids
ZPPW – Heavy-Duty Pressure Switch
- Designed for steam, oil, hydraulic systems
- Piston/bellows mechanism
- High pressure ranges
ZPDW – Differential Pressure Switch
- For filter choking, AHU monitoring, blower safety
- Air & gas compatible
- Adjustable differential