Dwyer AT23000MR/3000MRS Photohelic® Switch/Gauge

Dwyer AT23000MR/3000MRS Photohelic 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).

Dwyer AT23000MR/3000MRS Photohelic Features

  • 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

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.

Dwyer AT23000MR/3000MRS Photohelic Specification

Service Air and non-combustible, compatible gases.
Wetted Materials Consult 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 Limits 20 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 Requirements 24 VDC, regulated ±10%.
Electrical Wiring Screw terminals.
Mounting Orientation Diaphragm in vertical position.
Dial Size 4″ (101.6 mm).
Set Point Adjustment Adjustable knobs on face behind enclosure cover. Follow instructions and safety warnings to open cover.
Switch Specifications (3000MR)
Switch Type Each 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 Type Each setpoint has a solid state relay.
Switching Voltage 20 to 280 VAC (47 to 63 Hz).
Switching Current 1.0 amp (AC) max., 0.01 mA (AC) min., (2) SPST NO.
Enclosure Rating IP66. IP65 with option OPV, overpressure relief valve.
Housing Material Aluminum.
Finishing Texture epoxy coat RAL7038.
Pressure Connections 1/8″ NPT female brass (SS optional). In presence of acetylene it is necessary to use SS.
Electrical Connections Two 1/2″ FNPT. Cable gland not included.
Weight 12.5 lb (5.7 kg).
ATEX Certificate BVI 14ATEX0072.
Agency Approvals ATEX 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

Another Article:

%d bloggers like this: