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Re: That's It!!!...
"Using a spring-loaded check valve as a final pressure reduction is a sure
way to get a major overload of CO2 in the final 30 psi or so, if you have
not monitored and changed the tank."
As Dezi would say to Luci - " You've got a lot of 'splainin' to do! "
A spring-loaded check valve, correctly oriented, requires a certain minimum
amount of pressure in order to "crack", or open and allow fluid to flow.
Depending upon the design specifications of the valve, removing the input
pressure will either close the flow off (as the spring closes again) or does
nothing (if the spring requires a certain minimum amount of "back pressure"
in order to close solidly again and that minimum pressure is not present).
A check valve is not designed to act as a pressure reduction step - it is
there to prevent the backflow of aquarium water into the needle valve /
regulator and/or CO2 cylinder when there isn't a positive flow of gas moving
from the cylinder to the aquarium.
Several aquarium products companies, Dupla, Dennerle and ADA, market check
valves designed for use with CO2 injection systems for aquarium use. Only
Dupla gives any "specs" for their device. (Max. Pressure 3.00 bar, Min.
Pressure 0.15 bar). Several mail order companies sell check valves for use
in CO2 systems, but none of the ones I contacted have any idea of the design
specs of what they are selling.
Apparently, many people here either use no check valve at all, or else use a
regular "airline" type check valve (which may or may not be wise, depending
upon the unstated design specs of the valves and the conditions encountered
when they are used with pressurized CO2).
There are _many_ companies which market check valves and they are available
with a wide variety of specs - "max. and min. operating pressure", "cracking
pressure", and "reseating pressure", and in a wide variety of materials. One
(or more) of these might be perfect for use in an aquarium setting, if ONLY
we had a common knowledge of the requirements of such a valve under aquarium
If _anyone_ on this list has a better understanding of how a check valve
works, or how to select one for use with pressurized CO2 in an aquarium
setting, they are keeping the information to themselves. I asked for input
regarding the selection of check valves by their "specs" a while ago and
_nobody_ volunteered any information.