Series DHII Digihelic® Differential Pressure Controller

Series DHII Digihelic® Differential Pressure Controller

Series DHC Digihelic® Differential Pressure Controller

Series DHC Digihelic® Differential Pressure Controller

Series DH3 Digihelic® Differential Pressure Controller

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

The Series DH3 Digihelic® Differential Pressure Controller is a 3-in-1 instrument possessing a digital display gage, control relay switches, and a transmitter with current output all packed in the popular Photohelic® gage 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 1.5% full scale accuracy on ranges down to the extremely low 0.25" w.c. to 2.5" w.c. full scale. Ranges of 5" w.c. and greater maintain 0.5% F.S. 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.

Please see Series AT-DH3 ATEX/IECEx Approved Digihelic® Differential Pressure Controller for ATEX approved models.

For additional ranges, see Series DHC Digihelic® Differential Pressure Controller.

Product Applications

  • SCFM duct flow
  • Filter status
  • Duct or building static pressure
  • Damper and fan control
Starting at $462.00
Grouped product items
Model Description Availability* Qty Price
DH3-005 Differential Pressure Controller, range 0-2.5" w.c. 3-4 Weeks*
DH3-007 Differential Pressure Controller, range 0-10" w.c. 3-4 Weeks*


Air and non-combustible, compatible gases.
Wetted Materials:
Consult factory.
Housing Material:
Die cast aluminum case and bezel.
±1.5% for 0.25" and ±0.25" w.c. ranges. Ranges 0.5" to 5" w.c. and corresponding bi-directional (except ±2.5" w.c.) ±1%; All other ranges: ±0.5% @ 77°F (25°C) including hysteresis and repeatability (after 1 hour warm-up).
< ±1% per year.
Pressure Limits:
Ranges (uni- and corresponding bidirectional), ≤ 1 in w.c.: 9 psi; 2.5 and 5 in w.c.: 1.5 psi; 10 in w.c.: 3 psi; 25 in w.c.: 8 psi; 50 in w.c.: 15 psi; 100 in w.c.: 20 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). For 0.25" and ±0.25" w.c. ranges: ±0.03%/°F (±0.054%/°C).
Power Requirements:
12 to 28 VDC, 12 to 28 VAC 50 to 400 Hz.
Power Consumption:
3 VA max.
Output Signal:
4 to 20 mA DC into 900 Ω max.
Zero & Span Adjustments:
Accessible via menus.
Response Time:
250 ms (damping set to 1).
Backlit 4 digit LCD 0.4" height LED indicators for set point and alarm status.
Electrical Connections:
15 pin male high density D-sub connection. 18" (46 cm) cable with 10 conductors included.
Process Connections:
1/8" female NPT. Side or back connections.
Mounting Orientation:
Mount unit in vertical plane.
5" (127 mm) OD x 3-1/8" (79.38 mm).
1.75 lb (794 g).

Switch Type:
2 SPDT relays.
Electrical Rating:
1 A @ 30 VAC/VDC.
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
  • Full-scale accuracy of 1.5% or better even on extremely low ranges, and 0.5% for ranges above 5 in w.c. provide for greater measurement precision
  • Secure menu program provides access to device operation only for the right skill level
  • Optional stainless steel bezel is the same installation diameter as Magnehelic® gage and simplifies field upgrade to DH3 pressure controller

Product Literature


Catalog Pages

Product Data Sheet



Model Chart

EXAMPLE DH3 002 AT Series DH3-002-AT Digihelic® Differential Pressure Controller, range 0.25" w.c., with aluminum tag.
SERIES DH3     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.
0.25-0-0.25" w.c.
0.5-0-0.5" w.c.
1-0-1" w.c.
2.5-0-2.5" w.c.
5-0-5" w.c.
10-0-10" w.c.
Aluminum Tag
Certificate of Origin
Factory Calibration
NIST Certificate of Calibration
Brushed 304 Stainless Steel Bezel
Stainless Steel Tag


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. Series' 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. Series' EDA, DPG-200, DPT, and 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.
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.
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Model Description Availability* Price
A-298 Flat aluminum bracket for flush mounting Photohelic® & Capsuhelic® gages, 603A, 605, and 3000MR. 1-3 days*
A-301 Static pressure tip, for 1/4" metal tubing connection. 1-3 days*
A-302 Static pressure tip, for 3/16" and 1/8" ID plastic or rubber tubing. 1-3 days*
A-302F-A 303 SS Static pressure tip with mounting flange, for 3/16" I.D. rubber or plastic tubing. 4" insertion depth, includes mounting screws 1-3 days*
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A-489 4" 303 SS straight static pressure tip with flange, 1/4" hose barb. 1-3 days*
A-700 Power supply (0.5 A) 1-3 days*