Category
Air Differential Pressure Transmitters
Measure differential pressure across filters, fans, ducts and clean rooms with transmitters from Produal, Beck and Halstrup-Walcher.
An air differential pressure transmitter measures the small pressure difference, often just a few pascals, across a filter, fan or clean room, and needs a low range and stable zero that liquid DP sensors don't. This page covers models from Produal, Beck and Halstrup-Walcher, including Modbus versions for BMS.
21 Products · AIR
2-wire Differential Pressure Transmitter DPT-2W
Airflow Transmitter DPT-Flow-MOD
Differential Pressure Transmitter 982R
Differential Pressure Transmitter 984
Differential Pressure Transmitter 985
Differential Pressure Transmitter 985-MODBUS
Differential Pressure Transmitter DPT-Dual-MOD
Differential Pressure Transmitter DPT-Priima
Differential Pressure Transmitter DPT-Priima-MOD-AZ-D
Differential Pressure Transmitter DPT-R8
Differential Pressure Transmitter P 29.2
Differential Pressure Transmitter P 34
Selection guide
Air Differential Pressure Transmitters Guide
How an air differential pressure transmitter works
The transmitter senses pressure at two ports, often only a few pascals apart, and outputs a proportional signal. Because the span is so small, the sensor's zero stability matters as much as its accuracy: a transmitter built for bar-range liquids would drift too much to hold a 10 Pa clean room reading, which is why air and gas DP transmitters use dedicated low-range sensors.
How to choose an air differential pressure transmitter
- Clean room accuracy: the Produal DPT-Priima gives ±0.4% ±0.4 Pa, with ranges down to ±25 Pa, for pressure differences as small as 10 to 15 Pa.
- Airflow calculation: the DPT-Dual-MOD and DPT-Flow-MOD calculate airflow from fan or duct pressure, with Modbus RTU output.
- Fan and VAV control: the DPT-Ctrl and DPT-Ctrl-MOD hold a fan, VAV system or damper at constant pressure or flow.
- Precise low ranges: Halstrup-Walcher P 26, P 34 and PU/PI measure from 10 Pa, with the P 34 compact enough for a control cabinet.
- Industrial ranges: Beck 984, 985 and 990 offer selectable ranges and 0 to 10 V or 4 to 20 mA outputs, with a local display on the 990.
- Simple alarm only: differential pressure switches, including the Beck 930 and 911.82, are listed on their own page. They trip a contact instead of giving a continuous signal.
- Hazardous areas: see flameproof differential pressure transmitters in the ATEX & Flameproof category.
For water and other liquids, see liquid differential pressure transmitters.
FAQ
Common questions
What accuracy do I need for clean room pressure monitoring?
Clean room pressure differences are often only 10 to 15 Pa, so a high-accuracy transmitter matters more than a wide range. The Produal DPT-Priima gives ±0.4% ±0.4 Pa, with ranges down to ±25 Pa, which keeps a small pressure cascade stable between rooms and corridors.
Can an air differential pressure transmitter calculate airflow?
Yes. Models such as the Produal DPT-Flow-MOD and DPT-Dual-MOD calculate air volume from the measured fan or duct pressure, and output it over Modbus RTU alongside the raw pressure reading, so a BMS doesn't need a separate calculation.
Is there a differential pressure controller for fans, not just a transmitter?
Yes. The Produal DPT-Ctrl and DPT-Ctrl-MOD hold a fan, VAV system or damper at a constant pressure or flow set point, rather than just reporting the value for another controller to act on.
What's the smallest range an air DP transmitter can measure?
Halstrup-Walcher's P 26, P 34 and PU/PI measure from 10 Pa, and the Produal DPT-Priima reaches ranges down to ±25 Pa at high accuracy. Below that, a dedicated draft pressure transmitter is built for furnace and boiler-scale readings.
Do you have an ATEX version of the air differential pressure switch?
Yes. The Beck 930 Ex is adjustable from 20 to 5000 Pa for Ex zones 1, 2, 21 and 22, covering both gas and dust hazardous areas, alongside the standard Beck 930 for non-hazardous installations.
Which models offer Modbus output for a BMS?
Several Produal and Beck models, including the DPT-Dual-MOD, DPT-Flow-MOD, DPT-Ctrl-MOD, DPT-Priima-MOD-AZ-D and the Beck 985-MODBUS, give Modbus RTU alongside or instead of an analogue output.
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