Dwyer Magnehelic AT2DH3

Important notes for installation

  • Cables must be fitted through 1/2″ NPT cable gland or ATEX 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.

Please see SERIES DH3 for non-ATEX approved.


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) Case: -58 to 140°F (-50 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 ohms 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).


Switch Type: 2 SPDT relays.

Electrical Rating: 1 amp @ 30 VAC/VDC.

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

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 Approved Products from Comhas with ECN: NEMKO 10ATEX1096.

Agency Approvals: CE 0470 II2 GD Ex d IIC Gb T6; -50°C ≤ Ta ≤ +60°C Ex tb IIIC Db T 85°C.