Category
Vane Wheel Flow Meters (Höntzsch)
Vane wheel probes for accurate air and gas velocity measurement, including hazardous-area versions.
A vane wheel flow meter reads velocity from the speed of a small rotor in the flow, giving high accuracy without a pressure transmitter. The Höntzsch ZS25 covers 0.4 to 120 m/s up to 500 °C, the ZS30 covers low velocities of 0.3 to 3.0 m/s up to 350 °C, and an ATEX ZG5 Ex-d version suits explosive atmospheres.
3 Products · Vane Wheel Flow Meter
Selection guide
Vane Wheel Flow Meters (Höntzsch) Guide
How a vane wheel flow meter works
A small rotor sits directly in the gas or liquid path, and the passing flow spins it at a speed proportional to velocity. Because the rotor reads velocity directly, rather than through a pressure difference, it needs no separate transmitter to interpret its signal, and there's no rotor wear affecting the reading the way a worn bearing might on other rotating instruments. The design handles heavy-duty conditions and high temperatures well, since it has no fine geometry to foul with dust the way a thermal element can.
ZS25 or ZS30?
- ZS25: for high velocity and high temperature. It reads 0.4 to 120 m/s in air and gases, or 0.04 to 10 m/s in water, at working temperatures up to +500 °C, suited to hot process air, dryers and ovens.
- ZS30: for low velocities only, 0.3 to 3.0 m/s, at up to +350 °C, used to monitor laminar airflow in pharmaceutical sterilising tunnels. Don't interchange the two: the ZS30's low-velocity design isn't rated for the ZS25's higher temperature or speed range.
- ZS25 ZG5 Ex-d / ATEX: for explosive atmospheres, with the sensor suitable for Category 1 (Zone 0 and 20) and the transducer for Category 2 (Zone 1 and 21). Confirm which component your installation needs rated at which category, since they differ.
How to choose a vane wheel flow meter
- Temperature: match the ZS25's 500 °C or ZS30's 350 °C limit to your process, and don't assume one covers the other's range.
- Velocity: pick the ZS25 for a wide 0.4 to 120 m/s span, or the ZS30 specifically for slow, laminar monitoring.
- Hazardous area: choose the ZG5 Ex-d version and check both sensor and transducer category ratings against your zone.
For very low, non-laminar-specific flows, see thermal flow meters. For general ATEX flow options, see our ATEX & Flameproof category.
FAQ
Common questions
What is a vane wheel flow meter?
It's a probe with a small rotor that spins in the gas or liquid stream at a speed proportional to velocity, giving a direct reading without a separate pressure transmitter. Höntzsch vane wheel probes handle gases, liquids and high temperatures, and suit both fixed process monitoring and hot, demanding environments.
What velocity range does the ZS25 cover?
It reads 0.4 to 120 m/s in air and gases, and 0.04 to 10 m/s in water, at working temperatures up to +500 °C. That wide span and high-temperature rating make it suitable for hot process air, dryers and ovens where other probe types would struggle.
What's the difference between the Höntzsch ZS25 and ZS30?
The ZS25 covers a wide 0.4 to 120 m/s range up to 500 °C, for general and high-temperature duty. The ZS30 is built specifically for low velocities of 0.3 to 3.0 m/s, up to 350 °C, for laminar flow monitoring such as pharmaceutical sterilising tunnels. Don't interchange them; their ranges don't overlap safely.
Can a vane wheel probe be used in Zone 0?
The ZS25 ZG5 Ex-d sensor is suitable for Category 1, covering Zone 0 and 20. Its transducer, however, is only rated for Category 2, Zone 1 and 21, so confirm which part of the installation sits in which zone before specifying, since the two components carry different ratings.
How hot can the gas be for a vane wheel flow meter?
The ZS25 works up to +500 °C, and the ZS30 up to +350 °C. These are different probes for different duties, so check which one matches both your temperature and your velocity range rather than assuming the higher-temperature model also suits low, laminar flows.
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