DWYER Series AT-A3000 ATEX/IECEx Approved Photohelic® Pressure Switch/Gage

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Series AT-A3000 ATEX/IECEx Approved Photohelic® Pressure Switch/Gage

Photohelic® Switch/Gages in Flameproof ATEX/IECEx Enclosures

Flameproof approved Series AT-A3000 ATEX/IECEx Approved Photohelic® Pressure Switch/Gage functions as versatile, highly repeatable pressure switch combined with a precise pressure gage employing the time-proven Magnehelic® gage design. The Photohelic® switch/gage measures and controls positive, negative or differential pressures of air and compatible gases. Two photo-transistor actuated, DPDT relays are included for low/high limit control. Easy-to-adjust set point indicators are controlled by knobs located on the gage face (accessible opening case after de-energizing instrument). Set points can be interlocked to provide variable dead band which is ideal for control of fans, dampers, etc. Gage reading is continuous and unaffected by switch operation, even during loss of electrical power. Flameproof enclosures are available in aluminum with a glass window which allows for viewing of set point needles and process pressure.

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 maintain IP66 rating.
• 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 areas.


Product Applications

  • Hazardous area pressure measurement and transmitter
  • Air conditioning systems
  • Clean rooms
  • Fume exhaust systems



  • Service: Air and non-combustible, compatible gases.
  • Wetted Materials: Consult factory.
  • Housing material: Aluminum.
  • Finishing: Texture epoxy coat RAL7015.
  • Accuracy: ±2% of FS at 70°F (21.1°C); ±3% on -0 and ±4% on -00 models.
  • Pressure Limits: See pressure limit chart on catalog page.
  • Temperature Limits: 20 to 120°F (-6.67 to 48.9°C) LT low temperature option to -20°F available (Note: Product temperature limits differ from case).
  • Dial Size: 4″ (101.6 mm).
  • Mounting Orientation: Diaphragm in vertical position.
  • Set Point Adjustment: Adjustable knobs on Photohelic® gage face behind enclosure cover. Follow instructions and safety warnings to open cover.
  • Switch Type: Each set point has 2 form C relays (DPDT).
  • Repeatability:±1% of FS.
  • Electrical Rating: 10 A @ 28 VDC, 10 A @ 120, 240 VAC.
  • Electrical Wiring: Screw terminals.
  • Power Requirements: 120 VAC, 50/60 Hz; 240 VAC and 24 VAC power optional.
  • Enclosure Rating: IP66 (IP65 for versions VS1, VS2, VL1).
  • Process Connections: 1/8″ NPT female brass (SS optional).
  • Electrical Connections: Two 1/2″ NPT female. Cable gland not included.
  • Weight: 19.8 lb (9 kg).
  • ATEX Certificate: INERIS 21ATEX0033X.
  • IECEx Certificate: IECEx INE 21.0064X.
  • Agency Approvals: ATEX Compliant: CE 0080 EX II 2G Ex db IIC T5, T6 Gb -60°C ≤Ta ≤+50°C (T6) -60°C ≤Ta ≤+60°C (T5) II 2D Ex tb IIIC T75 °C Db;
    IECEx Compliant: Ex db IIC T5, T6 Gb -60°C ≤Ta ≤+50°C (T6) -60°C ≤Ta ≤+60°C (T5) Ex tb IIIC T75°C Db.



  • Saves inventory, installation time, and money by consolidating several instruments into one ATEX/IECEx approved product
  • Flameproof 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
  • Increased response time at low pressures with LD port configuration