Dwyer Pressure In-Electric Out Transducers

Dwyer Combination Magnehelic Gauge and Transmitter

Use as a direct replacement for your Magnehelic Gauges when automating. Provide visual readout for local monitoring and send a 4-20mA signal to your system—all with one combination unit!


  • Directly fits in the existing Magnehelic mount
  • Measures and controls very low differential pressure
  • Front adjustable zero span; adjustable to 0.05% of full span
  • Magnehelic dial face
  • Power: 12.3 to 35Vdc
  • Output: 4 to 20mAdc, 2-wire

Dwyer Photohelic Pressure Switch / Gauge

The photohelic units combine all the features of a magnehelic gauge and a pressure switch. Instead of buying a magnehelic gauge only, consider using a photohelic and get control plus indication. When automating, replace your magnehelic gauges with photohelic to provide feedback and status indication.

  • Positive, negative or differential pressure
  • Monitor and control filters, fans, building pressure and more …

How They Work:

Two photocell-actuated circuits and two DPDT relays permit both high and low alarms or limit controls. Relays are de-energized when gauge For Air Velocity Ranges: pointer is to the left of respective set points. Loss of electrical power or loss of pressure provides “fail-safe” protection.