Series AT2DH3 ATEX/IECEx Approved DH3 Differential Pressure Controller

Brand: Dwyer Instruments, LLC

The ATEX/IECEx approved Series AT2DH3 Digihelic® Differential Pressure Controller is a 3-in-1 instrument possessing a digital display gage, control relay switches, and a transmitter with current output.

Combining these three features allows the reduction of several instruments with one product, saving inventory, installation time and money. 

The ATEX/IECEx approved Digihelic® controller is the ideal instrument for hazardous area pressure, velocity and flow applications by allowing for the selection of pressure, velocity or volumetric flow operation in several commonly used engineering units.

Two SPDT control relays with adjustable dead bands are provided along with a scalable 4 to 20 mA process output. 

In velocity or flow modes, a square root output is provided on the 4 to 20 mA signal to coincide with the actual flow curve. Flame-proof enclosures are available in aluminum and can include a glass window for viewing process information and set point status on digital display.
  • 3-in-1 ATEX approved instrument allows the reduction of several instruments with one product, saving inventory, installation time and money
  • Flame-proof ATEX enclosure with optional glass window and aluminum housing protects the device in hazardous areas while giving local visibility to process pressure and set point status



  • ± 0.5 % at 25° C (77° F) Including Hysteresis & Repeatability, (After 1-Hour Warm-Up)

Adjustment Type

  • Adjustable Via Keypad on Face in Safe Zone Only

Approvals & Certifications

  • IECEx
  • ATEX

Compensated Temperature

  • 0° to 60° C (32° to 140° F)


  • 3 VA, Max.

Cover Material

  • Blind Glass Top Cover


  • Backlit 4-Digit LCD 0.4” Height LED Indicators for Set Point & Alarm Status

Electrical Connectors

  • 1/2” NPT Female (Cable Gland Not Included)
  • Screw Terminal

Electrical Rating

  • 1 A at 30 Vdc/Vac

Enclosure Finish

  • Texture Epoxy Coat RAL7038

Enclosure, Body Material

  • Aluminum
  • Die Cast Aluminum Case & Bezel

Environmental Protection

  • IP65


  • Air & Non-Combustible Compatible Gases

NPT Connection

  • 1/8” NPT Female


  • 4-20 mA DC Into 900 ohms, Max.

Power Requirement

  • 12-28 Vac, 50/400 Hz

Response Time

  • 250 milliseconds (Damping Set to 1)

Sensor Orientation

  • Mount Unit in Vertical Plane

Set Point - Decreasing

  • Inches WC: 0 to 100

Set Point - Increasing

  • Inches WC: 0 to 100


  • Dial: 5” (127 mm) O.D. x 3-1/8” (79.38 mm)

Span & Zero Adjustments

  • Accessible Via Menus in Safe Zone Only


  • < ± 1 % Per Year

Switch Type

  • 2 SPDT Relays

Temperature Range

  • -60° to 60° C (-76° to 140° F)

Thermal Drift

  • 0.036/°C (0.020 %/°F) from 25° C (77° F)

  • Hazardous Area Pressure Measurement and Switching
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