Series-AT-DHCConfiguration

Supported Applications

The Series AT-DHC ATEX/IECEx Digihelic® Differential Pressure Controller is a 3-in-1 instrument combining a digital display gage, control relay switches, and a transmitter with current and voltage outputs. Designed for hazardous area applications, the series supports pressure, velocity, and volumetric flow monitoring in air and non-combustible, compatible gases.

Operating Conditions & Performance

The Series AT-DHC operates within an ambient temperature range of -4 to 158°F (-20 to 70°C). Accuracy is specified as ±0.5% FSO for all ranges, except the 0.5 in w.c. range at ±1% FSO and ranges at or below ±0.25 in w.c. at ±1.5% FSO. Stability is rated at less than ±1% per year FSO with thermal effects of 0.02% FS / °F (0.036% FS / °C). The response time is 400 ms when damping is set to 0.

Pressure limits vary by port/valve configuration: VS0 and VL0 support up to 10 kPa; VS1, VL1, and VS2 configurations range from 15 kPa to 40 kPa depending on whether one or both pressure ports are connected. The unit is not position sensitive.

Approvals & Compliance

• ATEX Certificate: INERIS 21ATEX0033X
• IECEx Certificate: IECEx INE 21.0064X
• Compliance Ratings: ATEX: CE 0080 II 2G Ex db IIC T5, T6 Gb -60°C≤Tas≤+50°C (T6) -60°C≤Tas≤+60°C (T5); II 2D Ex tb IIIC T75°C Db; IECEx: Ex db IIC T5, T6 Gb -60°C≤Tas≤+50°C (T6) -60°C≤Tas≤+60°C (T5) Ex tb IIIC T75°C Db.

Configuration Options

The series offers configurable measurement ranges in inches of water column, Pascals, and millimeters of water column. Available unidirectional ranges include 0.25 to 100 in w.c., while bidirectional options extend from ±0.25 to ±100 in w.c. Specific metric models cover 60 Pa to 250 Pa (unidirectional) and ±6 mm w.c. to ±25 mm w.c.

Outputs & Communication

• Analog Outputs: Scalable 4-20 mA (4-wire); selectable voltage outputs of 0-10 V, 0-5 V, 1-5 V, and 2-10 V (4-wire).
• Digital Communication: BACnet MS/TP or Modbus® RTU with supported baud rates from 9600 to 115200.
• Control Relays: Two SPDT relays rated at 1 A @ 30 VAC/VDC with adjustable deadbands and set points accessible via menus in the safe zone only.

Housing & Connections

• Enclosure: Flameproof aluminum housing with texture epoxy coat RAL7038. An optional glass window allows viewing of process information and set point status on the backlit LCD display.
• Process Ports: 1/8" female NPT ports located on the side or back; unused ports must be sealed with pipe plugs (Accessory A-330).
• Electrical Connection: 15 pin male high density D-sub connector with an included 18" (46 cm) cable containing 15 conductors. The enclosure provides two 1/2" NPT female entries for field wiring.

Enclosure Ratings by Configuration

• Standard: IP66
• Versions VS1, VS2, and VL1: IP65

Key Product Differences

The Series AT-DHC is distinguished from the standard Dwyer Digihelic® line by its ATEX/IECEx hazardous area approvals and flameproof aluminum enclosure. While the internal electronics share similar performance characteristics with non-hazardous models, the AT-DHC series requires calibration adjustments (zero and span) to be performed in a safe zone only.

Model numbers follow the format AT---DHC-<RANGE>-<COVER>-<PORT/VALVE CONFIGURATIONS>-<CABLE ENTRY>. Specific configurations such as VS1, VS2, and VL1 result in different pressure limits (e.g., 40 kPa max for one port connected on VS2) compared to the standard VS0 or VL0 configurations.