Low pressure switches for hydraulic & pneumatic applications

Factory preset switches are set to specific pressure points during manufacturing and cannot be changed after installation. Field adjustable switches allow you to modify the pressure set point using built-in adjustment controls after the switch is installed.

Factory preset switches (SM, MM, LM series) offer consistent performance and lower cost when your pressure requirements are fixed. Field adjustable switches (SQ, CJ series) provide operational flexibility for applications where pressure settings may need optimization or changes during system commissioning.

Identify your required switching pressure and ensure it falls within the switch’s adjustable range with adequate margin. The switch’s maximum operating pressure must exceed your system’s highest pressure, including pressure spikes.

For example, if you need switching at 50 PSI, choose a switch with a 2-120 PSI range rather than a 2-30 PSI range. This provides headroom for pressure variations and system transients while ensuring reliable operation.

Differential is the pressure difference between when a switch turns on versus when it turns off. This built-in delay prevents rapid on-off cycling as system pressure fluctuates around the set point.

For instance, a switch with 30 PSI set point and 20% differential will turn on at 30 PSI but won’t turn off until pressure drops to 24 PSI. Low pressure switches typically have 8-20% differential depending on the model, ensuring stable operation without contact chatter.

Yes, most low pressure switches work in both pneumatic (air) and hydraulic (fluid) applications. The key is selecting appropriate pressure ratings and diaphragm materials for your specific media and operating conditions.

Standard Buna N diaphragms handle most air and hydraulic fluid applications. For specialized fluids or extreme temperatures, alternative materials like Viton or EPDM may be required for optimal compatibility and lifespan.

Snap-action switches change states instantly when the set point is reached, while gradual switches slowly transition between on and off positions. This instant switching eliminates contact arcing and provides reliable, repeatable performance.

The snap-action mechanism moves exactly 0.040 inches to actuate electrical contacts, ensuring clean switching under all operating conditions. This design contributes to operational life exceeding one million cycles in most applications.

For basic adjustable switches, turn the adjustment knob clockwise to increase the set point or counterclockwise to decrease it. Always use a calibrated pressure gauge to verify your settings and make gradual adjustments.

For switches with locking mechanisms, first loosen the set screw with the appropriate tool (typically 5/64″ hex wrench), make your adjustment, then retighten the screw. Test the system through several pressure cycles to confirm stable, repeatable switching.

Temperature extremes can affect diaphragm flexibility and calibration accuracy, though most switches operate reliably from -20°F to +220°F. Vibration, contaminated media, and improper installation torque are the most common causes of premature failure.

Proper mounting, clean connections, and protection from pressure spikes significantly extend switch life. NEMA 4 and 13 rated enclosures provide protection against moisture and environmental contamination in most industrial applications.