Re: [GSAS-Member] CO2 Systems

[pwallace@u.washington.edu]

Susan:

With your current system you are alternating the supply (high pressure side) 
between 0 and ~800 psi (pressure in CO2 tank).  Your low pressure side (Set 
~20psi) is getting confused and and goes to >20 psi each cycle (ie the low 
pressure side needs back pressure to correctly regulate.  When the pressure in 
the main tank drops (< ~100 psi) the low pressure is unable to regulate and 
"dumps" the remainder of the CO2 tank)*.   So the better place to shut off the 
tank is on the supply side (low pressure, after needle valve).  The high 
pressure side will be happy at ~800psi.  The low pressure side will remain 
fixed at ~20 psi. and the gas flow will vary from "on" to "off."

The cheapest way to accomplish this function is to install an on/off valve 
after the needle valve. (NOT a second needle valve.)

The most expensive way is to install a solenoid which can be placed on the same 
timer as the lights.

-Paul

*The chance of an EOT dump can be decreased by setting the low pressure at 
10-30 psi with a good needle valve to further reduce the flow to the desired 
rate.  Using the low pressure side to control the flow rate (~0psi) makes an 
EOT dump likely.  Always use good CO2 specific check valves.  Always tie down 
your CO2 tank as a tip over can destroy the regulator.  Do not dispose in fire.

> Is that hard on my regulator turning it off and on? Isn't that what a
> solenoid does?
>
> Susan


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