Flow Meter
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Would anyone know where to get an inexpensive flow meter. Just needed for normal
temperature water and would have to measure about 1/2 gal per minute. I don't
want to construct one myself and would like to buy one off the shelf. Signal
output is not that important as something can always be figured out, but
something in the $10.00 range is needed to keep costs down.
Hank
temperature water and would have to measure about 1/2 gal per minute. I don't
want to construct one myself and would like to buy one off the shelf. Signal
output is not that important as something can always be figured out, but
something in the $10.00 range is needed to keep costs down.
Hank
Comments
water for a fountain or live well.
********
> Would anyone know where to get an inexpensive flow meter. Just needed for
normal temperature water and would have to measure about 1/2 gal per minute.
I don't want to construct one myself and would like to buy one off the
shelf. Signal output is not that important as something can always be
figured out, but something in the $10.00 range is needed to keep costs down.
Plastic flow sensors/switches are good to 100 PSI typically and
BRass/Composit ones are for higher pressures.
A simple on/off flow switch (industrial quality) is around $50. The Rotary
type ran about twice that.
The switch uses a paddle or magnet that gets pushed near a reed switch when
the flow is at or above the trip point. It is cheaper, but if the water has
any minerals in it can deposit on the paddle and make it stick or fail in the
active state. You will not know it has failed until disaster strikes. Any
place there is turbulence in the water, the minerals can leach out of the
water and start a deposit. Using all distilled water will prevent this, but
may not be practical.
The rotary type outputs pulses as the rotary paddles pass the switch or
sensor. You count the number of pulses per unit of time for the flow rate.
This is also easier to detect failure, as no pulses means no water flow or a
sensor jam/failure
When working with water flows one must think of the consequences of a sensor
failure. Is the water cooling something expensive? Life Threatening? Don't
skimp on a safety device.
A source we use on Plasma Torch cooling systems is made by GEMS
http://www.gemssensors.com/
There is also a company named Proteus that make s sensors, but I don't know
the web site. They are more reliable (and more $$$) than the GEMS
Hope this helps
Alan Bradford
Plasma Technologies
the fuel injectors and pressure regulator and 1 to measure the flow leaving
the pressure regulator and going back to the tank.
off the shelf units are about $200.00 us and i need 2!.
that hurts.
so
put a small coil above the 5/16" rubber fuel line, feed it with a square
wave of say oh about 1 mhz. put another coil on the bottom of the hose below
the top one. then feed this coil to the input of a freq to voltage
converter, then feed the f2v converter to a 12-16 bit a2d converter, now
read the a2d converter and what should we have?
has anyone tried this?
good/bad idea?
any ideas about the coils for this purpose?
how about it people?
can we make this work?
normdoty@h...
>From: "Hank Hagquist" <hankster@h...>
>Reply-To: basicstamps@yahoogroups.com
>To: <basicstamps@yahoogroups.com>
>Subject: [noparse][[/noparse]basicstamps] Flow Meter
>Date: Sun, 5 May 2002 18:33:45 -0400
>
>Would anyone know where to get an inexpensive flow meter. Just needed for
>normal temperature water and would have to measure about 1/2 gal per
>minute. I don't want to construct one myself and would like to buy one off
>the shelf. Signal output is not that important as something can always be
>figured out, but something in the $10.00 range is needed to keep costs
>down.
>
>Hank
>
>
>
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>
>
_________________________________________________________________
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for the government (SPR project among others).
An electromagnetic flow meter can be done, but there are a few things
you have to watch for.
1) The fluid has to be at least slightly conductive.
2) The recovered signal is very small.
3) The recovered signal is riding on the huge excitation voltage you are
applying (noise).
4) It is easier to work with if the head is actually in the fluid to
measure the voltage. Otherwise, you are expecting inductive coupling in
both directions which gives you even less signal and more noise.
5) If you are using coils the pipe has to be non conductive.
1MHz is probably too high. If I recall, we used an 18kHz excitation and
used switched capacitor filters to recover the signal. Your noise is all
common mode, so it is easy to reject, but all of this requires careful
design.
Al Williams
AWC
* Floating point A/D
http://www.al-williams.com/awce/pak9.htm
>
Original Message
> From: norman doty [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=qiKP0NkOs9ebTqfMB6PNQwWYJG2BXhWwgh53wfqw_Eox8nYRcRtsxwCk7NJejS-Ld92cTZlSyPY6Fzbc]normdoty@h...[/url
> Sent: Sunday, May 05, 2002 6:29 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Flow Meter
>
>
> ive been trying to design/build 2 flow meters, 1 to measure
> the fuel feeding
> the fuel injectors and pressure regulator and 1 to measure
> the flow leaving
> the pressure regulator and going back to the tank.
>
> off the shelf units are about $200.00 us and i need 2!.
>
> that hurts.
> so
>
> put a small coil above the 5/16" rubber fuel line, feed it
> with a square
> wave of say oh about 1 mhz. put another coil on the bottom of
> the hose below
> the top one. then feed this coil to the input of a freq to voltage
> converter, then feed the f2v converter to a 12-16 bit a2d
> converter, now
> read the a2d converter and what should we have?
>
> has anyone tried this?
> good/bad idea?
> any ideas about the coils for this purpose?
> how about it people?
> can we make this work?
>
> normdoty@h...
>
>
>
> >From: "Hank Hagquist" <hankster@h...>
> >Reply-To: basicstamps@yahoogroups.com
> >To: <basicstamps@yahoogroups.com>
> >Subject: [noparse][[/noparse]basicstamps] Flow Meter
> >Date: Sun, 5 May 2002 18:33:45 -0400
> >
> >Would anyone know where to get an inexpensive flow meter.
> Just needed
> >for
> >normal temperature water and would have to measure about 1/2 gal per
> >minute. I don't want to construct one myself and would like
> to buy one off
> >the shelf. Signal output is not that important as something
> can always be
> >figured out, but something in the $10.00 range is needed to
> keep costs
> >down.
> >
> >Hank
> >
> >
> >
> >To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> >from the same email address that you subscribed. Text in
> the Subject
> >and
> >Body of the message will be ignored.
> >
> >
> >Your use of Yahoo! Groups is subject to
> >http://docs.yahoo.com/info/terms/
> >
> >
>
>
>
>
> _________________________________________________________________
> Chat with friends online, try MSN Messenger: http://messenger.msn.com
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
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http://docs.yahoo.com/info/terms/