Dwyer Series DH Digihelic Differential Pressure Controller

The Digihelic® controller allows 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 4-20 mA process output. In velocity of flow modes, a square root output is provided on the 4-20 mA signal to coincide with the actual flow curve. 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 damping 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® controller is the only instrument you will need for all your pressure applications.

Features & Benefits

  • SCFM Flow in Ducts
  • Air Flow for Industrial Ovens
  • Filter Status
  • Clean Room Pressure
  • Fume Hood Air Flow
  • Medical Room 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: Ranges ≤2.5″ w.c. = 2 psi; 5″: 5 psi; 10″: 5 psi; 25″: 5 psi; 50″: 5 psi; 100″: 9 psi.
Temperature Limits: 32 to 140°F (0 to 60°C).
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:

High Voltage Power = 100 to 240 VAC, 50 to 400 Hz or 132 to 240 VDC.

Low Voltage Power = 24 VAC ±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.
Agency Approvals: CE, UL