The materials included in this compilation are for the use of Dwyer Instruments, Inc. potential customers and current employees as a resource only. They may not be reproduced, published, or transmitted electronically for commercial purposes. Furthermore, the Company’s name, likeness, product names, and logos, included within these compilations may not be used without specific, written prior permission from Dwyer Instruments, Inc. ©Copyright 2014 Dwyer Instruments, Inc.

1. Differential Pressure
ATEX Enclosures
The materials included in this compilation are for the use of Dwyer Instruments, Inc. potential customers and current employees
as a resource only. They may not be reproduced, published, or transmitted electronically for commercial purposes.
Furthermore, the Company’s name, likeness, product names, and logos, included within these compilations may not be used
without specific, written prior permission from Dwyer Instruments, Inc. ©Copyright 2014 Dwyer Instruments, Inc.

2. Overview
Magnehelic®
AT22000
Photohelic®
AT3A3000
AT23000MR
Digihelic®
AT2DH3
Switches
AT21823
AT11910
AT1ADPS
Transmitters
AT2MS
AT2605

3. ATEX Housing Rating
II 2 GD Ex d IIC Gb T6, -50°C≤Ta≤+60°C
Ex tb IIIC Db T85°C
ATEX flame proof against:
Gas, Vapors, Mist, Dust
Alcohol, Aromatics, Propane, Methane, Ketones, Wood
Dust, Coal Dust, etc

4. ATEX Housing Rating
Limits damage and propagation of fire in the
event of failure or combustion
Contains and quenches any flame
Gases/dust may be present but not all the time
Temperature ratings
Gases: ambient temperatures up to 60 °C
Dust: ambient temperatures up to 85 °C

5. ATEX Housing Options
Enclosure options:
Blind or glass top
SS or brass pressure connections
Overpressure relief valve

6. Magnehelic®
Series AT22000
Gage differential pressure
indication with scale
ranges from 60 Pa (0.25
INWC) to 30 kPa (120
INWC)

7. Photohelic®
Series AT3A3000
Offers gage differential
pressure indication
with 2 DPDT latching
relays in scale ranges
from 60 Pa (0.25
INWC) to 30 kPa (120
INWC)

8. Photohelic®
Series AT23000MR
Gage differential pressure
indication with 2 SPDT
relays in scale ranges from
60 Pa (0.25 INWC) to 30
kPa (120 INWC)
Low Voltage Power

9. Digihelic®
Series AT2DH3
Digital differential pressure
indication with 2 SPDT relays
and an adjustable 4 to 20 mA
output, in scale ranges from 60 Pa
(0.25 INWC) to 35 kPa (100
INWC)
Display measurement modes for
pressure, air velocity, and
volumetric flow

10. Switches
Series AT21823
Differential pressure switch
with set point ranges from
17 Pa (0.07 INWC) to 21
kPa (85 INWC)
SPDT rated 15 A @ 120-
480 VAC
±2% FS repeatability

11. Switches
Series AT21900
Differential pressure switch
with set point ranges from
17 Pa (0.07 INWC) to 4.9
kPa (20 INWC)
SPDT rated 15 A @ 120-
480 VAC
±3% FS repeatability

12. Switches
Series AT2ADPS
Differential pressure switch
with set point ranges from
20 Pa (0.08 INWC) to 5 kPa
(20 INWC)
SPDT rated 1.5 A @ 240
VAC
Indicating set point
adjustment knob

13. Transmitters
Series AT2MS
Digital differential pressure
indication with analog output, in
scale ranges from 25 Pa (0.1
INWC) to 5 kPa (25 INWC)
Display measurement modes for
pressure or air velocity
Analog outputs
4 to 20 mA, 0 to 5 V, or 0 to 10 V

14. Transmitters
Series AT2605
Gage differential pressure
indication with 4 to 20 mA
output, in scale ranges from
60 Pa (0.25 INWC) to 500 Pa
(2 INWC)

15. Applications
Hazardous Area Air Flow Measurement:
Coal Mine Ventilation Air Flow
Wastewater Treatment Ventilation
Oil Refinery Ventilation

16. Applications
Air Scrubber Monitoring
Maintain DP across scrubber for efficiency

17. Applications
Coal Power Plant Dust Collection
Log DP for environmental agencies and
control filter cleaning

18. Applications
Hazardous area HVAC systems:
Filter monitoring
Blower vacuum monitoring
Fan pressure indication
Duct static, room, or building pressures