Measuring air flow

[Phil Hunter]

> I am looking for a bench setup capable of measuring air flow of up
> to 500 m³/hr accurately. Within 1% anyway. Use will be calibration
> check of AFMs. What kind of gauges are out there that won't cost
> an arm and leg.
> 
> FR Wilk

If you really want 1% accuracy, an LT1 MAF may not do it, but the
thunk occurs to me to use 3 in series, i.e., each air molecule
flows thru all 3 MAF's, then "average" the result. I _think_ this
is statistically correct, someone better at it than I can confirm
or deny.

The MAFs cost about $100 USD, 3.5" units are also available if you
need more airflow, cost ~$180, IIRC they are temperature compensated
so you don't have to deal w/ that source of error.

For measuring the MAF output, one source that may not come
immediately to mind is Amateur Radio, Ham's need to measure frequency
a lot and have many articles & projects on the subject. Often the
frequency is RF, but generally it is divided down to something a
uC can measure. A quick look at one of the main sites,
http://www.arrl.org , it looks as if many online articles are for
"members only" which is unfortunate, but you may be able to find
back issues of QST, CQ, and other magazines in your public library,
often the authors have kits available.

rgds,
philh
(digest)


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