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Re: Needle valves and nutrients

> Date: Mon, 11 Dec 2000 06:29:47 -0800
> From: Jonathan Peakall <jpeakall at mcn_org>
> Subject: Needle valves and nutrients
> I do have a needle valve Tom, and it has never helped in an "end of
> tank" situation. In fact, I had a near tragedy. Thus I put on the
> propane regulator. I am using the good valve from M3. Are there valves
> out there that will prevent "end of tank" disasters? I'd rather use a
> needle valve alone, as then I could use the check valve again. I hate to
> think of ruining my regulator setup some day *shudder*.

Get a cheap low-pressure check valve from the LFS and forget the
spring-and-ball Eheim unit. A cheap plastic one with a silicone rubber flap
will protect quite well. You don't really need it, for chance of back
siphoning is negligible in most systems, not going into a pump or other
possible high-pressure point.

There's no reason for an end-of-tank dump if your are actually *using* a
needle valve. Having one in the line, in series with an Eheim (12 psi) check
valve, for example could be essentially the same as not even having it there
at all.

The Eheim is still controlling flow and will dump a lot of gas with a tiny
pressure rise at the regulator. Get rid of it. You should not see much
change in the bubble rate, if you set it with the needle valve and then
adjust the primary regulator up and down by a few psi.

When working properly, a small change in the needle valve should have a
significant change in bubble rate. A small change in the pressure-regulator
setting should have essentially no effect on the bubble count. Hence, a
small rise in pressure as the tank empties does not dump lots of gas.



           Wright Huntley, Fremont CA, USA, 510 612-1467 
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