Series AT23000MR/3000MRS ATEX/IECEx Approved Photohelic Switch/Gauge

Brand: Dwyer Instruments, LLC

Using solid state technology, the Series AT23000MR / AT23000MRS ATEX/IECEx Approved Photohelic® Switch/Gauges combine the functions of a precise, highly repeatable differential pressure switch with a large easy-to-read analog pressure gauge.

Gauge reading is unaffected by switch operation and will indicate accurately even if power is interrupted. AT23000MR series employ versatile electromechanical relays with low amperage ratings-ideal for dry circuits.

For applications requiring high cycle rates, choose AT23000MRS models with SPST (NO) solid state relays. Easy to adjust set point indicators are controlled by knobs located on the gauge face (accessible opening case after de-energizing instrument).

All models provide both low and high limit control. Compatible with air and other non-combustible, non-corrosive gases, they can be used in systems with pressures to 25 psig (1.725 bar). Optional construction is available for use to either 35 psig (2.42 bar) or 80 psig (5.51 bar).

Important notes for installation:
  • Cables must be fitted through 1/2" NPT cable gland or ATEX/IECEx conduit (not supplied with instrument).
  • Make sure after cabling to close tight cover and cable gland, in order to keep IP66 rating (IP65 with option OPV, overpressure relief valve).
  • Open cover only after de-energizing instrument.
  • Attention: Check local safety rules and warnings on unit and manual for a correct use of the instrument in hazardous area.
  • Gauge reading unaffected by switch operation and will continue to read pressure even during power loss
  • Zero and range adjustments outside of gauge means no disassembly in normal service
  • Solid-state design allows for switching in high cycle rate applications without degradation
  • 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



  • ± 2 % of Full Scale at 21.1° C (70° F)
  • ± 4 % of Full Scale on -00 Models
  • 3 % of Full Scale on -0, -60 Pa

Adjustment Type

  • Adjustable Knobs on Face Behind Enclosure Cover

Approvals & Certifications

  • IECEx
  • ATEX
  • CE

Cover Material

  • Blind
  • Glass Cover

Electrical Connectors

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

Enclosure Finish

  • Texture Epoxy Coat RAL7038

Enclosure, Body Material

  • Aluminum

Environmental Protection

  • IP65 with Option OPV
  • IP66


  • 0.01 mA (AC) Min.
  • 1.0 Amp (AC) - Max.


  • Air
  • Non-Combustible, Compatible Gases

NPT Connection

  • 1/8” NPT Female

Power Requirement

  • 24 Vdc, Regulated ± 10 %

Process Connection Material

  • Brass

Sensor Orientation

  • Diaphragm in Vertical Position

Set Point - Decreasing

  • Inches WC: 0 to 2
  • Pa: 0 to 500

Set Point - Increasing

  • Inches WC: 0 to 2
  • Pa: 0 to 500


  • Dial: 4” (101.6 mm)

Supply Voltage

  • 20 to 280 Vac (47 to 63 Hz)

Switch Type

  • Each Set Point Has 1 Form C Relay (SPDT)

System Pressure

  • bar: 5.5
  • kPa: 550
  • psig: 80 (For hp Version. 35 psig for MP Version & 25 psig for Standard Version)

Temperature Range

  • -6.7° to 48.9° C (20° to 120° F)
  • Case: -60° to 60° C (-76° to 140° F)

  • Hazardous Area Pressure Measurement and Switching
  • Pneumatic Conveying
  • Air Conditioning Systems
  • Clean Rooms
  • Fume exhaust Systems

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