Dwyer Series DH Digihelic® Differential Pressure Controller

The 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. The Digihelic® controller is the ideal instrument for pressure, velocity and flow applications, achieving a 0.5% full scale accuracy on ranges from 0.25 to 100 in. w.c.

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.

Product Applications

  • SCFM duct flow
  • Industrial ovens air flow
  • Filter status
  • Clean room pressurization
  • Fume hood air flow
  • Surgical and medical room pressurization
  • Damper and fan control

Service : Air and non-combustible, 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 in 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 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 Ω 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 1/8″ ID X 1/4″ OD tubing (3.175 mm ID x 6.35 mm OD). Optional barbed fitting for 3/16″ 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 in (45 x 92 mm).

Weight : 14.4 oz (408 g).

Serial Communications : Modbus® RTU, RS485, 9600 Baud.

Agency Approvals : CE, UL.


Switch Type : 2 SPDT relays.

Electrical Rating : 8 amps at 240 VAC resistive.

Set Point Adjustment : Adjustable via keypad on face.

  • 3-in-1 instrument allows the reduction of several instruments with one product, saving inventory, installation time and money
  • Velocity of flow modes, a square root output coincides with the actual flow curve for greater precision
  • Power usage of 120/220 VAC or 24 VDC provides flexibility to incorporate device in control panel
  • Secure menu program provides access to device operation only for the right skill level
  • Modbus® communications supports Process and HVAC system integration and control

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