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Re: CO2 regulators

Shawn Prescott wrote to explain that dual-stage regulators are *not* a
necessity for CO2 as it is stored under pressure as a liquid, which finally
awoke something that's been scratching at the back of my mind during most of
this debate. So I offer some food for thought and inevitable discussion.

I believe that the "requirement" to move up to two-stage regulation is
dependent upon the compressibility of the gas involved. As has been pointed
out, any gas that compresses to a liquid state will remain at a constant
pressure until such time as no liquid remains. When enough has been
exhausted, *then* the internal pressure begins to vary and become hard to
control. In our predicament, it's the end-of-tank dump that has us worried
about controlling every iota of pressure until the tank is "literally"

That "end-of-tank" scenario is the constant state of a tank of gas that
*doesn't* compress to a liquid. Its internal pressure is dictated by the
amount of compressed gas remaining, and fluctuates downward with use. So,
after each use (or during prolonged sessions), the first stage must be
re-adjusted to bring the line within the operating range of the secondary.

Think of things that don't use a secondary regulator: the "beer tap" already
discussed, Liquid Propane tanks for cooking and heating (hey, and it's
inflammable at that!), butane/propane lines that run the "standard" Bunsen
burner network of a classroom (where the safety of an entire building is at

Now think of gasses that *do* use a secondary regulator, oxygen being a
prime example.

After that, think really hard about the situation that has us believing we
"need" the precision of multi- stage regulation. *That* should determine if
the added cost is necessary for your own particular circumstance...


David A. Youngker
nestor10 at mindspring_com