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RE: [APD] Re: Needle Valve / Metering Valve for CO2

James had some questions about CO2 valves and manifolds.

Yeah, you need separate valves for each aquarium. Putting a valve upstream
of the manifold would serve no real purpose, except to be able to shut off
the CO2 flow to the entire system. If I were to do that, I would definitely
not spend much money on one.

As far as a manifold is concerned, You can build you own very easily. You
can probably buy 1/4-inch brass fittings (tees and pipe nipples) at the
local Home Depot or Ace Hardware, or whatever store you have locally. Use a
little piping compound, or some Teflon tape (just be real careful and keep
the tape on the threads only). Also be careful and don't connect different
metals directly together. You could get into a corrosion problem.

I don't know why you can't make a manifold from PVC pipe, as long as it is
downstream of the regulator. Half-inch Schedule 80 PVC with glued joints is
rated for 850 psig. Schedule 40 is good for 600. If there is a threaded
piece in the manifold, cut the ratings in half (420 and 300, respectively).
It would be a simple matter of creating a manifold with as many tees as you
need. Threaded is good, because you can take it apart if you need to modify
it or fix a leak.

Unfortunately, I can't find a Swagelok S series valve (my preference) that
would be a good match. The only one (an angle valve, not a "straight
through") with an NPT fitting (pipe thread) on one side, has 1/8-inch tube
fittings on the other. If using tubing smaller that standard aquarium air
hose is OK with you, that would probably work just fine.

Fortunately, I wouldn't build my system with the valves directly on the
manifold. I would put a barbed fitting on the manifold, connect tubing to
the barbs, run the tubing to the tank, and put the valve on the tubing. If
done this way, the SS4 series Swagelok valve is a very good choice, since it
works just fine with standard aquarium airline tubing. It also gives you
faster response time when you make changes to the valve since you don't have
to wait for things to change in a long line downstream of the valve.

-----Original Message-----
From: aquatic-plants-bounces+d_guynn=sbcglobal.net at actwin.com
[mailto:aquatic-plants-bounces+d_guynn=sbcglobal.net at actwin.com]On
Behalf Of James Purchase
Sent: Friday, February 18, 2005 10:08 AM
To: aquatic-plants at actwin_com
Subject: [APD] Re: Needle Valve / Metering Valve for CO2

Way back on February 12th, I posted a question for the technical gurus on
CO2 equipment. Not one person seemed to notice, as I never got any
responses. Either all of the knowledgable people had left the list, or I was
being ignored. (the title of the message was "Needle Valve / Metering Valve
for CO2").

Then, low and behold, Chris Hott expressed his frustration in finding a
needle/metering valve, and he was getting answers. Hmmmm, maybe I ought to
take my new dual stage CO2 regulator and go play in another sandbox.....

But all kidding aside, I really would like some input.

I'll be moving in a few months and want to be able to have one CO2 cylinder
serve a number of tanks. I'll need a manifold to distribute the gas. As I
said in my earlier post:

Aquabotanic sells a 4Plex Manifold which apparently has built-in needle
valves. Could this be used down-stream from a higher quality metering valve
to distribute CO2 to multiple aquariums? Or would I need separate metering
valves for each additional aquarium?

So, what do you think? How good are the built in needle valves in this
manifold? Or am I going to have to spring for separate Nupro/Hoke/Parker
metering valves?


James Purchase

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