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Re: Aquatic Plants Digest V2 #871

>Okay... I've talked to the welding guys a bit, but still have a question
>that someone on the APD might know the answer to.  If I set a pressure
>regulator to 5psi and had a tube coming off of it that was stoppered,
>would the pressure in that line only reach 5psi?  Also, would the
>regulator effectively shut off the tank when the line pressure reached
>5psi?  (This is basically the same question.)  Now say that I took the
>stopper out of the end of the line so that the gas could flow freely out
>the end.  Would the regulator open back up to let a max. pressure of 5psi
>out, or would it let more out to try to maintain a pressure of 5psi in the

The regulator tries to keep the pressure set at its output to the specified
value by changing the flow rate.  For your 5psi, either stoppered or open,
the regulator will try to maintain the pressure in the line at 5psi.
Stoppered this is no problem.  The pressure at any point in the line will
be 5psi.  Open is another thing.  The flow rate necessary to maintain 5psi
will depend on the diameter of the tubing and its length(also if it has
kinks, etc.)  If the tank pressure is sufficient and the regulator
sufficiently capable, the pressure at the output of the regulator will be
5psi and will decrease over the length of the tube until it is at
atmospheric.  The drop will not be linear as most of it will occur near the
end of the tube.  Also all of these pressure values are referenced to
atmospheric and are not absolute.  The 5psi you speak of is 5psi above
atmospheric and is in actuality approximately 19psi(5psi + 14psi).

k5vkq at ix_netcom.com