Sensitive Differential Switches

Sensitive differential switches are the perfect for those needing a sensitive, low pressure switch at an affordable price. These switches sense very low pressures, such as less than an inch of water, (Range = 0.25 inches of water to 35 inches of water). For a frame of reference, a trumpet player blows 55 inches of water (or 2 Psi) on average, so these switches are very sensitive.

Our sensitive differential switch can be setup to sense either pressure, vacuum, or the difference between two sources of pressure or vacuum. 


Wide variety of options available to meet original equipment manufacturers product requirements.


Highly stable with good repeat accuracy. All switches are 100% tested at high & low settings, & at proof pressure.


Remote operation with complete electrical isolation. UL Recognized. Costs less than conventional controls.


Presair switches are designed & manufactured in Eau Claire, Wisconsin, U.S.A.

Presair’s sensitive single pole switches can be adapted to pressure or vacuum switches, or as differential pressure switches. These switches are field adjustable or can be factory set from 0.25 inches of water to 35 inches of water.

The switches can respond to rapid pulsing & their gold-plated silver contacts will handle low level switching currents

These “slow make, slow break” switches can respond to rapid pulsing & the gold plated silver contacts will handle low level switching currents. Optional adjustable air bleeds can be supplied on either side of the diaphragm for pulse-sensing application safe edges or bellows.

Product Specifications

  • 0.25 – 15 inches of water Adjustable Range. Factory set options available.
  • SPST
  • Rating: 750 ma @ 250 VAC to 5 ma @ 3 VDC; 1 AMP @ 250 VAC to 5 ma @ 3 VDC.
  • UL / cUL Recognized for 100,000 operations.

Part Number Configurations

Here is a complete list of part number configurations already listed in our catalog. Click on a part number below for more information.

Other custom part number options are available. Please contact us with your requirements for more information.

Common Applications

The sensitive differential switches are commonly found in medical & industrial applications where little pressure or vacuum needs to be sensed.


Cross Reference

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D Series


6753 Series

Huba Controls

604 Series


PSW20 Series


0.25 to 35 inches of water

Max. Operating Pressure = 8 PSI



750 mA @ 250VAC

UL / cUL Recognized

Made in U.S.A.

Frequently Asked Questions


How do I adjust the switch’s set point?

Turn the small hex screw clockwise or counter clockwise to adjust the switch’s set point. See illustrations here.

How do I sense vacuum versus pressure?

The D1000 units come with 2 different air ports. Port B (Normally Open) senses pressure and Port A (Normally Closed) senses vacuum. See an illustration and further explanation here.

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