Re: CO2 regulator

>From: krandall at world_std.com (Karen A Randall)
>Date: Sat, 13 Jan 1996 20:39:00 -0500
>Subject: CO2 flow meter
>Subject: CO2 flow meter
>> I believe the flow meters are used in welding applications
>> where an inert gas is required to prevent oxidation of the hot
>> metal. The flow rates are much higher than those required for
>> aquaria. When I was making inquiries, the price for these thing
>> was quite high and comparable to that for regulators. Most
>> regulators with gauges are designed for compressed oxygen
>> and the welding supply guy told me that the acidic CO2 gas
>> will corrode them. 
I converted an old oxygen regulator to use as a CO2 regulator. According to
the people I dealt with at the welding supply company, the only real
difference between an oxygen regulator and a CO2 regulator is the nipple
that connects to the bottle. I also changed the low side gauge to one with
lower readings. The high side gauge did not need to be changed as both Co2
and Oxygen regulators come with gauges that read in the same pressure range.
My high side gauge reads up to 4000 psi with the CO2 pressure showing 800
psi. They also mentioned nothing about corrosion being a problem with CO2 as
opposed to oxygen.(They did however caution against trying to convert a
regulator from acetylene to CO2 use, as there is residue left over in a
regulator from acetlyene use.) I suppose there could be some internal
difference in the regulator that I'm not aware of, but all of the welding
regulators I've ever seen have been made of brass, whether they were set up
for acetylene, oxygen, or CO2. So far, I've had no problems with it at all.

>The regulators I have (made by two different companies) are 
>specifically designed for CO2 use.
>> A gauge won't tell you much because
>> compressed CO2 is a liquid with a constant gas pressure (for
>> any given temperature) and this won't change until the
>> the liquid CO2 in the tank is all gone. From that point it
>> is a very short time before you need to re-fill the tank.
>Actually, the gauges are quite useful.  The tank pressure gauge,as 
>you mentioned, does not start to go down until the liquid CO2 is 
>used up.  Still, at the rate I use CO2 in my 70G tank, I have at 
>least a couple of days notice that I need a new tank.
>The out flow gauge is useful to bring the flow down as low as 
>possible before feeding to the needle valve.
>> I don't have bottled CO2 (relying upon the little yeasties)
>> but I think many people keep a second smaller 5 lb bottle
>> on hand while they take their larger one in for a refill.
>A lot of people only _use_ 5 lb tanks.  A 5 lb tank is as heavy a 
>tank as I want to tote around, and as big as I can easily hide 
>under my tanks.  It also lasts over 9 months on my 70G tank, so 
>it's not like I have to run down for refills frequently ;-)  
>Besides, even a 5 lb tank will set you back about $50.

Wow! $50 to refill a 5 lb. bottle? I only paid $10.55 to have a 15 lb.
filled here in Arkansas.


Jay Bickford

Fort Smith, Arkansas