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Dwyer Instruments
Dwyer Digihelic II Differential Pressure Controller
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DHII Digihelic II: ±0.5%; 4–20 mA; 2× SPDT; Modbus; NEMA 4/IP66. RFQ range.
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Key parameters
Measuring range
Differential air/gas ranges from 0–0.1 in w.c. class through 0–100 in w.c. and bi-directional ±0.1…±10 in w.c. (model chart DHII-001…017)
Accuracy
±0.5% at 77 °F (25 °C) including hysteresis and repeatability (after 1 hour warm-up)
Output
4–20 mA DC into 900 Ω max; 2× SPDT relays 8 A @ 240 VAC resistive; Modbus RTU RS-485 9600 baud
Supply
High voltage 100–240 VAC 50–400 Hz or 132–240 VDC; low voltage 24 VDC ±20%
Protection
NEMA 4 / IP66 (designed to meet)
Ambient temperature
32 to 140 °F (0 to 60 °C); compensated same span
Fits low differential air/gas control where you need a Dwyer Digihelic II (DHII)—±0.5% accuracy at 25 °C, 4–20 mA output, dual 8 A SPDT relays, Modbus RTU RS-485, and NEMA 4 / IP66 class housing across ranges from about 0–0.1 in w.c. through 0–100 in w.c. and bi-directional spans.
Key advantages
- Accuracy — ±0.5% at 77 °F (25 °C) incl. hysteresis/repeatability
- Output — 4–20 mA into 900 Ω max
- Relays — 2× SPDT 8 A @ 240 VAC resistive
- Comms — Modbus RTU RS-485 9600 baud
- Enclosure — NEMA 4 / IP66 class
Typical applications
- Cleanroom ΔP control.
- Filter ΔP alarms.
- HVAC differential monitoring.
Selection guide
- Range / bi-directional
- HV vs LV supply
- Modbus vs relays only
Common mistakes
- Wrong pressure units.
- Ignoring 1-hour warm-up.
- Overpressuring low ranges.
When to RFQ / what to tell us
- Range, supply, outputs.
- Quantity, ship-to.
Request a Quote · Get selection help
Specs
| Spec | Value |
|---|---|
| SKU | 40986 |
| Brand | Dwyer Instruments |
| Model | DHII Digihelic II |
| Product type | Differential Pressure Controller |
| Measuring range | Differential air/gas ranges from 0–0.1 in w.c. class through 0–100 in w.c. and bi-directional ±0.1…±10 in w.c. (model chart DHII-001…017) |
| Accuracy | ±0.5% at 77 °F (25 °C) including hysteresis and repeatability (after 1 hour warm-up) |
| Output signal | 4–20 mA DC into 900 Ω max; 2× SPDT relays 8 A @ 240 VAC resistive; Modbus RTU RS-485 9600 baud |
| Supply voltage | High voltage 100–240 VAC 50–400 Hz or 132–240 VDC; low voltage 24 VDC ±20% |
| IP rating | NEMA 4 / IP66 (designed to meet) |
Documents
FAQ
Q: Accuracy? A: ±0.5% at 25 °C including hysteresis and repeatability.
Q: Relays? A: Two SPDT, 8 A @ 240 VAC resistive.
Q: What should I send for a quote? A: Range/supply, quantity, ship-to.
Links
| Parameter | Value |
|---|---|
| Measuring range | Differential air/gas ranges from 0–0.1 in w.c. class through 0–100 in w.c. and bi-directional ±0.1…±10 in w.c. (model chart DHII-001…017) |
| Accuracy | ±0.5% at 77 °F (25 °C) including hysteresis and repeatability (after 1 hour warm-up) |
| Output | 4–20 mA DC into 900 Ω max; 2× SPDT relays 8 A @ 240 VAC resistive; Modbus RTU RS-485 9600 baud |
| Supply | High voltage 100–240 VAC 50–400 Hz or 132–240 VDC; low voltage 24 VDC ±20% |
| Protection | NEMA 4 / IP66 (designed to meet) |
| Ambient temperature | 32 to 140 °F (0 to 60 °C); compensated same span |
| Display | 4-digit backlit LCD 0.6 in height; LED set-point/alarm indicators |
| Approvals | UL; CE |
| Mounting | Surface/vertical plane mount; 1/8 in female NPT process ports; 1/2 in conduit fittings |
| Sensor type | Differential pressure controller (gage + dual relays + transmitter) |
| Notes | Series DHII Digihelic II NEMA 4 package of Digihelic controller features. Specs from Dwyer Bulletin B-31 IOM on assets.dwyeromega.com. |
| Weight | 2 lb 10 oz (1.19 kg) |