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RE: low pressure regulators



In response to a recent posting regarding the differences between high
pressure CO2 systems (using a sintered glass diffuser) and low pressure
systems (using a bell container or bioball reactor), Dave Gomberg made
passing comment about a "low pressure regulator":

>The regulator serves to reduce the pressure from about 800 psi in the tank
>to a more manageable number.  If you have an Eheim diffusor (or other high
>pressure appliance) then the regulator can supply the needed pressure (say
>15 psi) directly and stablely.  This is how a "high pressure" system works.
> If your appliance is designed for low pressure (like a canister fileter
>intake or a bell container or one of the bio-ball devices or ... then you
>have a major problem.  The regulator will not function stablely at the .2
>to 1.3 psi required by these devices.  You must add a second low-pressure
>regulator to drop the 15 psi of the first stage to a few tenths of a psi
>needed by your appliance.   This is a very difficult and experimental
>setup.  Many try to use a needle valve in place of the low pressure
>regulator.  The problem is that most needle valves are not designed to the
>nano-flows that we use or the high pressure drops we need.  The regulator
>releases CO2 as needed to maintain the output side pressure.
>For more details, see the page in my sig.

OK, I've checked the web-page, and I can understand the logic, but what is
this "experimental" regulator that he's talking about? Who makes one, what
are it's specifications and how much do they cost? And why, if this is the
proper way to set up a "low pressure" system, does EVERY commercial
manufacturer who sells purpose designed CO2 devices recommend the
regulator-needle-valve combination?

James Purchase
Toronto