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Re: Aquatic Plants Digest V3 #8
First time responding, hope I do this right.
CO2 is typically filled as a liquid and at 70F will have a vapor pressure of
around 850 psia.
The most common type of regulator uses a spring and diaphragm to control the
outlet pressure. Optimal pressure therefore flow control from the regulator
is achieved by operating the regulator at an outlet pressure that the spring
was designed for. Regulators come in pressure ranges.
Find out from your regulator sales person what pressure the regulator was
desinged for and set it for that if you want to minimize "drift"( of your
setting.) If this isn't possible put at least 10 psig on the outlet to "load"
the regulator and give stable control. If at 10 psig the regulator pressure
is unstable increase the pressure setting until the output pressure stabilizes
over time.
For the flow rates that are discussed you need the fine control needle valves
mentioned. Also at these flow rates the heat transfer between the ambient and
the cylinder to vaporize the required CO2 is more than enough to prevent the
cylinder and or fittings from becoming cold. (never operate the cylinder
upside down, the regulator is not designed for liquid)
The pressure in your cylinder will stay constant until you have vaporized the
last of the liquid CO2, then it will start to decrease as you remove the
remaining gas.
If you are concerned about leaking fittings, make a soap solution and put it
on the joints in question. It will bubble if there are any leaks.
Tim