[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Check valves for CO2
> Date: Tue, 26 Sep 2000 14:11:03 -0500
> From: zxcvbob <bob at area51online_net>
>
> James Purchase <jpurch at interlog_com> sez:
> > I suppose that they are concerned about water from an aquarium getting
> > sucked backwards and into things like Needle/Regulating Valves and/or
> > Regulators.
>
> I don't trust check valves, and I doubt that they are really
> necessary...
> Check valves are used on welding regulators or torches to prevent having
> oxygen and fuel gas mix in the regulator or tank, possibly causing an
> explosion. Check valves are used in plumbing to keep contaminated
> water out of the fresh water supply lines. Why do we use them again?
If water gets back to the equipment, water + CO2 = carbonic acid which is mildly
corrosive. I think that's the reason El Cheapo check valves melt down when used
for CO2.
A check valve might be useful for more than keeping water from siphoning or
being pushed back by under pressure. I've seen a phenomenom I can only speculate
about.
We had a Tetra CO2 bell setup some time ago as a trial. Airline ran from the top
of the bell to a small CO2 tank. I would squirt some CO2 in twice a day to keep
the bells full. It wasn't very successful.
However, I did note that when the bells were empty (i.e., all the CO2 diffused
into the water), the water would slowly move back up the airline toward the CO2
tank. If I waited long enough, the water would get as far as the tank. There was
no pressure from the water in the bell - the water had to go up and over the
tank rim.
I figure the CO2 in the airline was continuing to diffuse into the water in the
airline and the water was being pulled back up the line by the relative vacuum
created.
I tried a check valve to block it and it did, until the guts melted.
George Booth in Ft. Collins, Colorado (booth at frii_com)
http://www.frii.com/~booth/AquaticConcepts/