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RE: 2 questions

>Does anyone have any idea what constitutes "non leaking high pressure
>tubing" that is suitable for CO2?  I used to make auto parts and have
>worked with all sorts of tubing with a myriad of pressure, temperature
>and chemical resistance properties.  Going back to some of the tubing
>suppliers we used to use I have seen a lot of tubing with all sorts of
>pressure ratings and made of all sorts of materials but few list CO2 as
>a suitable gas.  I have also seen both here in APD and on the web where
>tubing is sold reference to CO2 resistant or low loss tubing.

The CO2 resistant tubing sold in some of the pet supply places is usually 
Norprene, although this comes from others -- I haven't checked it myself. 
Silicone tubing is pretty much the standard low-pressure tubing used by a 
lot of people. Silicone tubing holds up pretty well, is very inexpensive, 
and doesn't leak too much CO2. The vinyl stuff gets hard, cracks, and has 
all the usual problems of the vinyl tubing.

>What materials are suitable and unsuitable for CO2 (both hard and soft)?
>Since the stuff is going to run through my home I certainly do not want
>it leaking.

The leaking isn't anything to be concerned about. The concerns most have 
are over loss of CO2 and the *economic impact* rather than spillage and 
messes. A lot of your CO2 is going to come out of your tank naturally 
anyway, so a little bit diffusing through the tubing isn't any big deal in 
terms of the gas getting into the room. IMHO, the amount of loss through 
the tubing on a *low pressure* system isn't worth the expense of the CO2 
resistant tubing.

The rigid stuff is usually copper refrigeration tubing since that is easy 
to get from places like Home Depot (it's sold in rolls starting at 10 
feet). That won't leak, but it's a lot harder to work with than the 
flexible tubing -- you need to solder or use compression fittings, bend 
carefully (preferably with a bending tool to make neat bends), and it 
doesn't allow for easy changes. I wouldn't use copper tubing unless you 
either need to build some kind of distribution setup for many tanks, have a 
very long (50+ feet) run of low pressure tubing, or for some reason need to 
run high pressure CO2 for a longish distance.

For the typical one-tank setup silicone is plenty good enough, or you can 
spend a bit more money to get the CO2 resistant stuff. There really isn't 
much need to consider other materials except for special cases like fish 
rooms and the like -- and often times not even then.

Waveform Technology
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