Series DH3 Digihelic Differential Pressure Controller

Brand: Dwyer Instruments, LLC

The SERIES DH3 Digihelic® Differential Pressure Controller is a 3-in-1 instrument possessing a digital display gauge, control relay switches, and a transmitter with current output all packed in the popular Photohelic® gauge style housing. Combining these 3 features allows the reduction of several instruments with one product, saving inventory, installation time and money. 

The Digihelic® controller is the ideal instrument for pressure, velocity and flow applications, achieving a 1% full scale accuracy on ranges down to the extremely low 0.25 inches WC to 2.5 inches WC full-scale. Ranges of 5 inches WC and greater maintain 0.5% Full Scale accuracy. Bi-directional ranges are also available. 

The Series DH3 Digihelic® controller allows the selection of pressure, velocity or volumetric flow operation in several commonly used engineering units. 2 SPDT control relays with adjustable deadbands are provided along with a scalable 4-20 mA process output. 

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 reading; digital damping for smoothing erratic process applications; scaling the 4-20 mA process output to fit your applications range and field calibration.
  • 3-in-1 instrument allows the reduction of several instruments with one product, saving inventory, installation time and money
  • Full scale accuracy of 1% even on extremely low ranges, and 0.5% for ranges above 5 inches WC provide for greater measurement precision
  • Secure menu program provides access to device operation only for the right skill level



  • ± 0.5 % at 25° C (77° F) Including Hysteresis & Repeatability, (After 1-Hour Warm-Up)

Adjustment Type

  • Adjustable Via Keypad on Face

Approvals & Certifications

  • CE

Compensated Temperature

  • 0° to 60° C (32° to 140° F)


  • 3 VA, Max.


  • Backlit 4-Digit LCD 0.4” Height LED Indicators for Set Point & Alarm Status

Electrical Connectors

  • 15-Pin Male High Density D-Sub Connection
  • 18” Cable (46 cm) with 10-Conductors Included (4” & 10” Cables Available)

Electrical Rating

  • 1 A at 30 Vdc/Vac

Enclosure, Body Material

  • Bezel
  • Die Cast Aluminum Case


  • Air & Non-Combustible, Compatible Gases

NPT Connection

  • 1/8” NPT Female


  • 4-20 mA DC Into 900 ohms, Max.

Power Requirement

  • 12-28 Vac, 50/400 Hz

Response Time

  • 250 milliseconds (Damping Set to 1)

Sensor Orientation

  • Mount Unit in Vertical Plane

Set Point - Decreasing

  • Inches WC: 0 to 25

Set Point - Increasing

  • Inches WC: 0 to 25


  • Gauge: 5” (127 mm) O.D. x 3-1/8” (79.38 mm)

Span & Zero Adjustments

  • Accessible Via Menus


  • < ± 1 % Per Year

Switch Type

  • 2 SPDT Relays

Temperature Range

  • 0° to 60° C (32° to 140° F)

Thermal Drift

  • ± 0.054 %/°C (± 0.03 %/°F)
  • 0.036/°C (0.020 %/°F) from 25° C (77° F)

  • SCFM flow in ducts
  • Filter status
  • Static pressures in ducts or buildings
  • Damper control
  • Fan control
show more