How about an airflow meter from an automobile air intake. Most all have a
means of measuring air flow.
73
Gary K4FMX
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> On Behalf Of Dr. David Kirkby
> Sent: Friday, April 15, 2011 4:24 AM
> To: amps@contesting.com
> Subject: Re: [Amps] Airflow meter
>
> On 04/13/11 07:24 PM, Jim Barber wrote:
> > I wonder if a hand-held anemometer would have significant back
> pressure?
>
> I would not think it be very significant myself.
>
> > It's fairly easy to convert flow rate to volume if the duct size is
> known.
> > Inexpensive units go for 20-30 USD on eBay.
>
>
> My ex-boss (Prof. D. T. Delpy) used a technique for measuring air
> *velocity*,
> which I don't think is particularly relevant here, but I'll describe it
> since it
> is quite interesting. Although it used platinum wires, I suspect you
> could use
> copper, though I do see platinum would have some advantages.
>
> It was used for measuring the speed babies breathed out air, so had to
> have
> negligible restriction on the airflow. Using a plastic bag would not
> have been
> very good for this purpose!
>
> Going left to right there is:
>
> Source of air --- > heater ---- > thermometer
>
> 1) The source of air. This was the babies mouth.
>
> 2) Heater. This is a thin platinum wire through which a short pulse of
> high
> current is passed. I've no idea of the temperature the wire reached, but
> it's
> not important to know the temperature.
>
> 3) Thermometer. This is another thin platinum wire, forming part of a
> platinum
> resistance thermometer. This responds very rapidly to temperature
> changes.
>
> The time between heating the first platinum wire, and when the
> temperature
> increase was observed on the second is measured. Knowing the distance
> between
> the two wires and the time allows one to calculate the velocity.
>
> > The "Bagometer" method is straightforward as well; just curious about
> > alternatives.
>
> Well, above is a curious alternative, though not very useful in this
> application.
>
> I'd be surprised if this technique was not described in some medical
> journal by
> him, but a quick glance with Google Scholar was unable to unearth the
> paper.
>
> --
> A: Because it messes up the order in which people normally read text.
> Q: Why is top-posting such a bad thing?
> A: Top-posting.
> Q: What is the most annoying thing in e-mail?
>
> Dave
>
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