Series DH Digihelic® Differential Pressure Controller

3 in 1 Instrument: Gage, Switch and Transmitter, Square Root Extractor for Air Flow

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.

NIST CALIBRATION available in Product Configurator.

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

Models & Ordering

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Shipping Information

All shipping times are dependent on product availability at time of shipment.

Although we make every effort to ensure a continuous supply of our products, occasional circumstances may force us to temporarily run out of a product, or have shipping delays. Should this occur, customers will be notified soon after placement of any orders for such products and, if applicable, items will be put on backorder. For orders requiring expedited shipment, our customer service team can be contacted to confirm product availability

COVID-19 Update: Due to high customer demand, lead time on some products may be up to two weeks. While this is a developing health situation, we are working continuously to take the necessary measures to ensure that the products you need are available with minimal interruption.

Build Your Custom Part. Use our Product Configurator

Model Description Usually Ships* Price Order
Ships: Next Day
Price: $559.00
Differential pressure controller, selectable engineering units: .2500" w.c., 6.350 mm w.c., 0.635 cm w.c., 0.467 mm Hg, 0.623 mbar, 62.28 Pa, 0.623 hPa, 0.114 oz/in². Next Day* $559.00 Order
Ships: Next Day
Price: $559.00
Differential pressure controller, selectable engineering units: 1.000" w.c., 25.40 mm w.c., 1.868 mm Hg, 2.491 mbar, 249.1 Pa, 0.249 kPa, 2.491 hPa, 0.578 oz/in². Next Day* $559.00 Order
Ships: Next Day
Price: $430.00
Differential pressure controller, selectable engineering units: 5.000" w.c., .4167 ft w.c., 127.0 mm w.c., 12.70 cm w.c., .1806 psi, .3678" Hg, 9.342 mm Hg, 12.45 mbar, 1245 Pa, 1.245 kPa, 12.45 hPa, 2.890 oz/in². Next Day* $430.00 Order
Ships: Next Day
Price: $430.00
Differential pressure controller, selectable engineering units: 10.00" w.c., .8333 ft w.c., 254.0 mm w.c., 25.40 cm w.c., .3613 psi, .7356" Hg, 18.68 mm Hg, 24.91 mbar, 2491 Pa, 2.491 kPa, 24.91 hPa, 5.780 oz/in². Next Day* $430.00 Order
Ships: Next Day
Price: $430.00
Differential pressure controller, selectable engineering units: 25.00" w.c., 2.083 ft w.c., 635.0 mm w.c., 63.50 cm w.c., .9032 psi, 1.839" Hg, 46.71 mm Hg, 62.27 mbar, 6227 Pa, 6.227 kPa, 62.27 hPa, 14.45 oz/in². Next Day* $430.00 Order
Ships: Next Day
Price: $430.00
Differential pressure controller, selectable engineering units: 50.00" w.c., 4.167 ft w.c., 1270 mm w.c., 127.0 cm w.c., 1.806 psi, 3.678" Hg, 93.42 mm Hg, 124.5 mbar, 12.45 kPa, 124.5 hPa, 28.90 oz/in². NOTE: velocity & volumetric flow not available. Next Day* $430.00 Order
Ships: Less Than 1 Week
Price: $430.00
Differential pressure controller, selectable engineering units: 100.0" w.c., 8.333 ft w.c., 2540 mm w.c., 254.0 cm w.c., 3.613 psi, 7.356" Hg, 186.8 mm Hg, 249.1 mbar, 24.91 kPa, 249.1 hPa, 57.80 oz/in². NOTE: velocity & volumetric flow not available. Less Than 1 Week* $430.00 Order

Can't find what you need? Build Your Custom Part. Use our Product Configurator


Air and non-combustible, compatible gases.
Wetted Materials:
Consult factory.
Housing Material:
ABS plastic, UL approved 94 V-0.
±0.5% at 77°F (25°C) including hysteresis and repeatability.
< ±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.
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.
1/8 DIN.
Panel Cutout:
1.772 x 3.620 in (45 x 92 mm).
14.4 oz (408 g).
Serial Communications:
Modbus® RTU, RS485, 9600 Baud.
Agency Approvals:

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


Model Number Description Usually Ships* Price Order
A-266 Digihelic® controller surface mounting bracket. Next Day $31.00 Order
Communication software CD. DIGIHELIC LINKS Communication software CD. Next Day $57.00 Order
Mini-Node™ RS-485 to USB converter. MN-1 Mini-Node™ RS-485 to USB converter. Next Day $84.00 Order
A-203 Clear PVC tubing, 1/8" ID x 1/4" OD, lengths to 100'. Next Day $1.80 Order


Model Chart

EXAMPLE DH 002 B Series DH-002-B Digihelic® Differential Pressure Controller, range 0.25" w.c., with barb fittings.
SERIES DH     Digihelic® Differential Pressure Controller
RANGE   002
  0.25" w.c.
0.5" w.c.
1" w.c.
2.5" w.c.
5" w.c.
10" w.c.
25" w.c.
50" w.c.
100" w.c.
0.10-0-0.10" w.c.
0.25-0-0.25" w.c.
0.50-0-0.50" w.c.
1.00-0-1.00" w.c.
2.50-0-2.50" w.c.
5.00-0-5.00" w.c.
10.00-0-10.00" w.c.
Barb Fittings
NIST Certificate of Calibration

Product Literature


Catalog Pages




A customer would like to get switching capability, local pressure indication, and a 4-20 mA output signal all in one device. Do we have a product to offer them?
Yes. The DH, DHII or DH3 possess high/low set points, digital gage display and 4-20 mA full scale output signal for air and compatible gas. The EDA, DPG-200, DPT and the MDPC possess high/low set points, digital gage display and 4-20 mA full scale output signal for compatible fluids.
Your Magnehelic gauge doesn't come with a calibration certificate, do you have any documentation for these gauges to meet these needs?
We have 3 options: (1) We can supply a Certificate of Conformance at no charge if you request that certificate at the time of order. The Certificate of conformance would state that each Magnehelic gauge is calibrated to meet the specifications stated on the spec sheet. (2) We offer a factory calibration “-FC” as an option that is a certificate of the standard calibration points at the time of manufacture, for a small fee. (3) We can also provide a NIST-traceable calibration for an extra charge per gage if that is required. To get the NIST-traceable calibration, you would simply add a “-NIST” to the end of your part number. NIST-traceable calibrations will come with the 6 point calibration certificate. We recommend “periodic calibration” for our Magnehelic, though we leave the specific time-frame up to the end user, since different organizations have different requirements (i.e. government groups often require more frequent calibrations.) If you choose to have the NIST traceable calibration done, the NIST group (the National Institute of Standards and Technology) dictates yearly calibration and it will be printed on the certificate.
Looking for information on the RS-232 Serial Communications Digihelic Links™ Communications Software, Modbus protocol®. Specifically command format, commands available, and controller responses?
Click on Modbus® to download this list of protocol.
I am using DH3 Digihelic differential pressure controllers for my applications. The instruction says that "the Alarm can be reset by the RESET key on the front panel, or an external reset switch". For the second case (reset by external reset switch), could you let me know how to do it? The instruction doesn't provide any related detail. Thanks in advance.
Unfortunately, contrary to what was printed in the instruction manual, the DH3 does not have the ability for the alarm to be reset via an external reset switch, mainly due to the limited number of pins available in the electrical connector. This feature is only available in the DH and DHII series Digihelics.
I have a digihelic DH007. and I would like to know is: could I filter the output relay signal (set point)? Does the delay or dampening functions work on the output or just on the alarms?
You can use the Dampening sub menu to stabilize the display from instabilities due to things such as vibration and excessive pressure fluctuations. This dampening feature will adjust the amount of readings which are averaged for each display update. The Digihelic DP controller does not have a feature like the “ALDL” Alarm delay for the relay output though. However, if you use the dampening feature, it will not fluctuate as much and therefore would not cause the reading to surpass the set point and activate the switch unless it truly is reading that pressure.

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