3. Water & Environmental

Which anemometer is best for low speed air flow?

Anemometers are used to measure air flow in environmental studies or site monitoring.

Some applications may be measuring relatively slow or low velocity air flow – which anemometer is best to accurately measure these?

Hot wire anemometer monitoring HVAC system
Measuring low velocity air flow needs an anemometer sensitive at lower ranges – a hot wire anemometer should be selected

For low air flow or low velocity applications, a hot wire anemometer should be selected as these are more sensitive at lower air flow rates.

The sensor of the anemometer has a fine wire which is heated to above the ambient temperature.

Any air flow over the wire then cools it slightly – this cooling changes the resistance of the wire, which is related back to the air flow speed or velocity.

Hot wire anemometer
The ET-961 Hot Wire Anemometer

This is different to a vane anemometer which operates like a windmill – the air flow turns the vanes on the propellor, which is related back to air speed. These are better in higher air speed applications such as environmental monitoring as they cannot read very low air speeds, but are fine for use at higher speeds.

For more information on anemometers, both hot wire and vane type, just follow the links above or contact us;