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Paul,
As long as the area for exhausting the gas is larger than the area =
feeding the gas you should maintain an ambient pressure around the sensor. =
This would not be the case if the flow was great enough that resistance =
around the exhaust ports caused a back pressure. Certainly there may be =
micro-changes in pressure as you would get with any compressible fluid =
flow but these are not great enough to be significant. The sensors aren't =
designed for use above 1atm and by keeping the flow reasonable and using a =
vented adapter the area around the sensor stays at ambient pressure. =
Unless you're blasting gas through the line the error from pressure is =
negligible.
C.
Chris Elmore
College of Liberal Arts
Univ. of SC
(803) 777-1534 office
(803) 348-3055 mobile
Please use this address for all email: chris@sc*.ed*
>>> Paul Braunbehrens <Bakalite@ba*.co*> 08/17 11:47 AM >>>
I guess this doesn't make sense to me. If gas is flowing, how can=20
the pressure be ambient? What is the error induced by having a=20
higher PP due to a flow over the element versus a resing pressure.=20
It seems to me that if the flow is off by 10% you'd get a 10% reading=20
error, although in practice this doesn't seem to bear out. Sorry if=20
these are stupid questions, but I'd rather ask some of those than tox=20
on o2.
Thanks.
Chris Elmore wrote:
~
>Paul,
> For flow rate, get a needle valve from the brass fittings=20
>section at Lowes and use a flow meter to calibrate it. Once it's=20
>calibrated epoxy the adjustment shaft and you're set to go- total=20
>cost: about $5. You can even oxygen clean it if that makes you=20
>happy. Flow rate doesn't really matter as long as you have enough to=20
>purge the lines and move the gas over the sensor but not enough to=20
>produce back pressure. Sensors measure partial pressure so you have=20
>to keep the pressure at ambient. If you can hear gas flowing that's=20
>enough.
>C.
--=20
Paul Braunbehrens mailto:Bakalite@ba*.co*=20
http://www.daw-mac.com Mailing list for digital audio on the mac
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