Dwyer Series AT23000MR/3000MRS Photohelic® Switch/Gage

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

Gage 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 gage 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 IP66rating (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.


  • Gage reading unaffected by switch operation and will continue to read pressure even during power loss
  • Zero and range adjustments outside of gage 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


  • Hazardous area pressure measurement and switching
  • Pneumatic conveying
  • Air conditioning systems
  • Clean rooms
  • Fume exhaust systems


ServiceAir and non-combustible, compatible gases.
Wetted MaterialsConsult factory.
Accuracy±2% of FS at 70°F (21.1°C). ±3% on -0, -60 Pa and ±4% on -00 models.
Pressure Limits-20 in Hg to 25 psig (-0.677 bar to 1.72 bar). MP option: 35 psig (2.41 bar), HP option: 80 psig (5.52 bar).
Temperature Limits20 to 120°F. (-6.67 to 48.9°C). Option LT low temperature to -20°F (28.8°C); (Note: Product temperature limits differ from case).
Power Requirements24 VDC, regulated ±10%.
Electrical WiringScrew terminals.
Mounting OrientationDiaphragm in vertical position.
Dial Size4" (101.6 mm).
Set Point AdjustmentAdjustable knobs on face behind enclosure cover. Follow instructions and safety warnings to open cover.
Switch Specifications (3000MR) 
Switch TypeEach setpoint has 1 Form C relay (SPDT).
Relay Contacts(resistive load) 1 Form C rated 1.0 A @ 30 VDC, 0.3 A @ 110 VDC or 0.5 A @ 125 VAC. Gold over clad silver - suitable for dry circuits.
Switch Specifications 
Switch TypeEach setpoint has a solid state relay.
Switching Voltage20 to 280 VAC (47 to 63 Hz).
Switching Current1.0 amp (AC) max., 0.01 mA (AC) min., (2) SPST NO.
Enclosure RatingIP66. IP65 with option OPV, overpressure relief valve.
Housing MaterialAluminum.
FinishingTexture epoxy coat RAL7038.
Pressure Connections1/8" NPT female brass (SS optional). In presence of acetylene it is necessary to use SS.
Electrical ConnectionsTwo 1/2" FNPT. Cable gland not included.
Weight12.5 lb (5.7 kg).
ATEX CertificateBVI 14ATEX0072.
Agency ApprovalsATEX Compliant CE 1370 Ex II 2G Ex d IIC T6 Gb / II 2D Ex tb IIIC T85°C Db, -60°C=Tamb=+60°C IECEx Compliant: Ex d IIC T6 Gb / Ex tb IIIC T85°C Db

Download Data Sheet: Series AT23000MR/3000MRS Photohelic® Switch/Gage

Ref: dwyer-inst.com
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