Air and Gas Flow Meters

Velocity is the air or gas speed at a point, in metres per second. Volume flow is the amount passing per hour, in cubic metres per hour, calculated by multiplying velocity by the duct's cross-sectional area. A transmitter usually gives you velocity, and the volume figure comes from the duct size you enter.

A vane wheel probe handles flue and process gas up to 500 °C on the ZS25, or 350 °C on the ZS30. For dustier stacks, an S-type pitot tube with a differential pressure transmitter copes better with particulate than a rotating vane. Tell us the gas temperature and dust load and we'll recommend one.

Yes. Several Höntzsch instruments come in ATEX versions: vane wheel probes for Zone 0/20 or 1/21, vortex probes for Zone 2/22, and the flowtherm Ex handheld for Zone 1 and 2. Confirm your zone and gas group before ordering, since sensor and transducer ratings can differ on the same probe.

Most probes here need a process connection or an insertion point in the duct wall, sized for the sensor. Portable meters such as the EMA200 or flowtherm units use a small port for spot readings, and a pitot tube traverse only needs one or two access points rather than a full instrument mounting.

A vane wheel probe reads velocity directly from a spinning rotor and suits a wide range up to 500 °C. A thermal probe reads the cooling effect of gas on a heated element and suits very low, laminar flows. A vortex probe counts shed eddies and has no moving parts, giving a wide 1:80 turndown.

A pitot tube or flow grid measures differential pressure, not flow directly. You pair it with a transmitter such as the Halstrup-Walcher P 26.2 or the Produal DPT-Flow, which converts that pressure into a velocity or volume flow signal using the duct's known cross-section.

A vortex probe such as the Höntzsch VA40 suits compressed air and process gas lines, reading from 0.5 up to 40 m/s with a wide turndown. For portable spot checks on compressed air, the flowtherm handheld units accept the same sensor range on a temporary basis.