DWYER Series AT-DH3 Approved Digihelic® Differential Pressure Controller

RM 0.00


Series AT-DH3 Approved Digihelic® Differential Pressure Controller

Digihelic® Pressure Control in Flameproof ATEX/IECEx Enclosure

The Series AT-DH3 ATEX/IECEx Approved 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 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 4-20 mA process output. In velocity or flow modes, a square root output is provided on the 4-20 mA signal to coincide with the actual flow curve. Flameproof enclosures are available in aluminum and can include a glass window for viewing process information and set point status on the digital display.

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 area.


Product Applications

  • Hazardous area pressure measurement and transmitter



  • 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



  • Service: Air and non-combustible, compatible gases.
  • Wetted Materials: Consult factory.
  • DH3 Housing Material: Die cast aluminum case and bezel.
  • Housing Material: Aluminum.
  • Finishing: Texture epoxy coat RAL7038.
  • Accuracy: ±1.5% for 0.25 in w.c. and ±0.25 in w.c ranges. Ranges 0.5 in w.c. to 5 in w.c. and corresponding bi-directional (except ±2.5 in w.c.) ±1%; all other ranges: ±0.5% @ 77°F (25°C) including hysteresis and repeatability (after 1 hour warm-up).
  • Stability: < ±1% per year.
  • Pressure Limits: See pressure limit chart.
  • Temperature Limits: 32 to 140°F (0 to 60°C) (Note: Product temperature limits differ from case).
  • Compensated Temperature Limits: 32 to 140°F (0 to 60°C).
  • Thermal Effects: 0.020% /°F (0.036/°C) from 77°F (25°C); For 0.25 in and ±0.25 in w.c. ranges: ±0.03%/°F (±0.054%/°C).
  • Power Requirements: 12-28 VDC, 12-28 VAC 50 to 400 Hz.
  • Power Consumption: 3 VA max.
  • Output Signal: 4-20 mA DC into 900 Ω max.
  • Zero and Span Adjustments: Accessible via menus in safe zone only.
  • Response Time: 250 ms (damping set to 1). Without considering delay caused by Exd flame arrestors (up to 30 s from FS to zero depending model and ranges with STD pressure ports) about 15 s with LD pressure ports on very low ranges.
  • Display: Backlit 4-digit LCD 0.4″ height LED indicators for set point and alarm status.
  • Process Connections: 1/8″ NPT female brass (SS optional).
  • Electrical Connections: Two 1/2″ NPT female. Cable gland not included.
  • Electrical Wiring: Screw terminal.
  • Mounting Orientation: Mount unit in vertical plane.
  • Enclosure Rating: IP66.
  • Dial Size: 5″ (127 mm) OD x 3-1/8″ (79.38 mm).
  • Weight: 12.3 lb (5.6 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.
  • Switch Type: 2 SPDT relays.
  • Electrical Rating: 1 A @ 30 VAC/VDC.
  • Set Point Adjustment: Adjustable via keypad on face in safe zone only.