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Series DH Digihelic® Differential Pressure Controller

3 in 1 Instrument: Gage, Switch and Transmitter

The Dwyer Series DH 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 3 features allows the reduction of several instruments with one product, saving inventory, installation time and money. The Digihelic® is the ideal instrument for pressure, velocity and flow applications, achieving a 0.5% full scale accuracy on ranges from 5 to 100 in. w.c. See Larger Image

The Digihelic® allows the selection of pressure, velocity or volumetric flow operation in several commonly used engineering units. 2 SPDT control relays with adjustable dead bands are provided along with a scalable 4-20 mA process output. The Series DH provides extreme flexibility in power usage by allowing 120/220 VAC and also 24 VDC power which is often used in control panels.

Programming is easy using the menu key to access 5 simplified menus which provide access to: security level; selection of pressure, velocity or flow operation; selection of engineering units; K-factor for use with flow sensors; rectangular or circular duct for inputting area in flow applications; set point control or set point and alarm operation; alarm operation as a high, low or high/low alarm; automatic or manual alarm reset; alarm delay; view peak and valley process readings; digital dampening for smoothing erratic process applications; scaling the 4-20 mA process output to fit your application's range; Modbus® communications; and field calibration.

With all this packed into one product it is easy to see why the Digihelic® is the only instrument you will need for all your pressure applications.

  • Dust Collection Bag Filters
  • SCFM Flow in Ducts
  • Air Flow for Industrial Ovens
  • Filter Status
  • Clean Room Pressure
  • Fume Hood Air Flow
  • Pharmaceutical or Bio-Medical Glove Box Pressures
  • Static Pressures in Ducts or Buildings
  • Damper Control
  • Fan Control

Service: Air and non-combustible, non-conducting compatible gases.
Wetted Materials: Consult Factory.
Housing Material: ABS plastic, UL approved 94-V-0.
Accuracy: ±0.5% at 77°F (25°C) including hysteresis and repeatability.
Stability: < ±1% per year.
Pressure Limits:
3 X range.
Temperature Limits: 32 to 140°F. (0 to 25°C).
Compensated Temperature Limits: 32 to 140°F. (0 to 25°C).
Thermal Effects: 0.020%/°F (0.036/°C) from 77°F (25°C).
Power Requirements: High Voltage Power = 100 to 240 VAC, 50 to 400 Hz or 132 to 24 VDC. Low Voltage Power = 24 VDC ±20%.
Power Consumption: Low Voltage Power = 24 VDC - 130 mA max. High Voltage Power = 100 to 240 VAC, 132 to 240 VDC - 7VA max.
Output Signal: 4-20 mA DC into 900 ohms max.
Zero & Span Adjustments: Accessible via menus.
Response Time: 250 ms.
Display: 4 digit LCD 0.4" height. LED indicators for set point and alarm status.
Electrical Connections: Screw terminals.
Process Connections: Compression fitting for use with 3/16" OD x 1/8" ID tubing.
Enclosure Rating: Face designed to meet NEMA 4X (IP66).
Mounting Orientation: Mount unit in horizontal plane.
Size: 1/8 DIN.
Panel Cutout: 1.772 x 3.620" (45 x 92 mm).
Weight: 14.4 oz (408 g).
Serial Communications: Modbus® RTU, RS485, 9600 Baud.

Switch Type: 2 SPDT relays.
Electrical Rating: 8 Amps at 240 VAC resistive.
Set Point Adjustment: Adjustable via keypad on face.


The Mother Node™ converter is an easy solution for utilizing the Digihelic's® RS-485 serial communication and connection to virtually any PC.

351-9N - Silver RS-232 to RS-485 Converter with DB9F Connector.
352-9N - Gold RS-232 to RS-485 Converter with DB9F Connector

One Control for all your Pressure Applications
  1. Compact 1/8 DIN housing reduces panel space.
  2. Set Point status LED indicators display set point activation. Allows user to view process status from a distance.
  3. "Hot Key" saves time by allowing instant access to set point and alarms. Set points/alarms can be easily adjusted with arrow keys.
  4. Menu Key scrolls through menus to adjust settings. 5 simple menus allow for quick set-up and reduced installation time.
  5. Adjustable Clip for panel mounting.
  6. Set Point 2 or alarm output (SPDT). Selectable direct acting control relay with adjustable deadband or high, low or high/low alarm.
  7. 4-20 mA process output. View process remotely or send signal to PLC. Alleviates purchase of separate transmitter.
  8. 24 VDC power supply. Universal power supply eliminates options, inventory and ordering mistakes.
  9. Remote Reset Switch for alarm. Acknowledge alarm from remote location. For users that need quick alarm reset from a distance.
  10. RS-485 serial communications. View, record, and adjust control settings remotely from a computer with Modbus® protocol.
  11. Durable Compression Fittings for 3/16" OD x 1/8" ID plastic tubing. Secures tubing in harsh applications where vibration & temperature fluctuations occur.
  12. Set Point 1 output (SPDT). Direct or reverse acting control relay with adjustable deadband.
  13. 120-240 VAC power supply. Reduce inventory and eliminate lead times with universal power supply.
  14. Enter a menu or store a value. From home display press to view full scale range.
  15. Reset Button for clearing an alarm when alarm is set for manual operation.
  16. Alarm LED indicator shows alarm activation status. View alarm status from a distance.
  17. Selectable engineering units in pressure, velocity or flow, programmed on one unit. Alleviates time consuming conversions and flow charts.
Series DH Digihelic® Pressure Controller Models:
Pressure Units - Inches w.c. Pressure Units (ft w.c.) Pressure Units - mm w.c. Pressure Units - cm w.c. Pressure Units - psi Pressure Units - in. Hg Pressure Units - mm Hg Pressure Units - mbar Pressure Units - Pa Pressure Units - kPa Pressure Units - hPa Pressure Units - oz in.
 DH-002 0.25 6.350 0.635 0.467 0.623 62.28 0.623 0.144
 DH-004 1.000 25.40 2.540 1.868 2.491 249.1 0.249 2.491 0.578
 DH-006 5.000 .4167 127.0 12.70 .1806 .3678 9.342 12.45 1245 1.245 12.45 2.890
 DH-007 10.00 .8333 254.0 25.40 .3613 .7356 18.68 24.91 2491 2.491 24.91 5.780
 DH-008 25.00 2.083 635.0 63.50 .9032 1.839 46.71 62.27 6227 6.227 62.27 14.45
 DH-009* 50.00 4.167 1270 127.0 1.806 3.678 93.42 124.5 12.45 124.5 28.90
 DH-010* 100.00 8.333 2540 254.0 3.613 7.356 186.8 249.1 24.91 249.1 57.80
Series DH Digihelic® Pressure Controller-Bi-Directional Ranges Models:
Model Number Range
 DH-012* 0-25-0-0.25" w.c.
 DH-014* 1.0-0-1.0" w.c.
 DH-015* 2.5-0-2.5" w.c.
 DH-016* 5-0-5" w.c.
Model Number Description
 351-9N Silver RS-232 to RS-485 Converter with DB9F Connector
 352-9N Gold RS-232 to RS-485 Converter with DB9F Connector
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