Dwyer Series AT2DH3 Differential Pressure Controller

Part Number: Series AT2DH3 Category:

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The ATEX/IECEx approved Series AT2DH3 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 ATEX/IECEx approved 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 to 20 mA process output. In velocity or flow modes, a square root output is provided on the 4 to 20 mA signal to coincide with the actual flow curve. Flame-proof enclosures are available in aluminum and can include a glass window for viewing process information and set point status on 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 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.

Product Applications

  • Hazardous area pressure measurement and switching

Service : Air and non-combustible, compatible gases.

Wetted Materials : Consult factory.

Housing Material : Die cast aluminum case and bezel.

Accuracy : < 5 in w.c. (except ±2.5 in w.c.): ±1%; All other ranges: ±0.5% at 77°F (25°C) including hysteresis and repeatability (after 1 hour warm-up).Stability:< ±1% per year.

Pressure Limits : Ranges ≤ 2.5 in w.c.: 25 psi; ±2.5″, 5 in w.c.: 5 psi; 10 in w.c.: 5 psi; 25 in w.c.: 5 psi; 50 in w.c.: 5 psi; 100 in w.c.: 9 psi.

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).

Power Requirements : 12 to 28 VDC, 12 to 28 VAC 50 to 400 Hz.

Power Consumption : 3 VA max.

Output Signal:4 to 20 mA DC into 900 Ω max.

Zero & Span Adjustments : Accessible via menus in safe zone only.

Response Time : 250 ms (damping set to 1).

Display : Backlit 4 digit LCD 0.4″ height LED indicators for set point and alarm status.

Electrical Wiring : Screw terminal.

Mounting Orientation : Mount unit in vertical plane.

Dial Size : 5″ (127 mm) OD x 3-1/8″ (79.38 mm).

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:12.3 lb (5.6 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


Switch Type : 2 SPDT relays.Electrical Rating:1 A @ 30 VAC/VDC.

Set Point Adjustment : Adjustable via keypad on face in safe zone only.

  • 3-in-1 instrument allows the reduction of several instruments with one product, saving inventory, installation time and money
  • Flame-proof 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

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