Hi All,

Slightly off topic but is car related!

I have a requirement at work to measure air flow, so a combination of speed and volume.

I suddenly had a thought that an air flow meter could easily be connected on to the bits I need to measure to ensure all the air flows in to the meter.

When looking on ebay they seem to have 4 or 5 terminals but what meaningful data could I expect? Is it a resistance measurement? I am only looking for a comparison rather than a measurement.

It is airflow out of an injection mould ejection system. All help appreciated.

Thanks,
Steve

could you not use a peak flow meter?

The flapper type from an RV8 just has a pot connected to the moving flap so this would just read as a resistance. AFAIK the hotwire type work by measuring the current needed to maintain a wire in the air stream at a given temperature.

The flapper would be easier for you to use, bear in mind the air flow these are designed to measure though. A 3.5 will pull something like 9,000 litres a minute at max rpm (if I got the calc right).

An air flow meter would normally have two sensors. One to measure the air flow and one to measure the air temperature.
They both work by measuring resistance. It will be quite easy if you can get hold of the vane (flapper) type (as Toltec suggests) and use a multimeter to work out which two pins are measuring the resistance.