Co2 Tank Pressure?

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I just got my chest freezer setup for kegging. 2 on tap, room for 1 for carbonating. All the gas is set up and I have a new Cornelius 2 gauge regulator.
The "serving/carbing" gauge is 0-30psi. the "tank" gauge is 200-1800psi. I turn on the bottle and it says the tank(20#) has 600 psi. in it and according to the "tank gauge" this is at the top end of the grey"fill the tank zone". I just bought the tank(filled) a day or two ago has been shut off until now. So I guess my question is what is the pressure of a new 20# tank supposed to be?

Thanks
 
oops just re read and you abviously didn't carb with it. I'd call the distributor and complain a little. was the top shrink wrapped? The place I do my tank exchange shrink wraps the tops when they are full so they don't mix em up with a returned tank. sounds like you might have gotten a tank someone returned before it got filled.
 
There is a direct pressure/temperature relationship with compressed CO2. Compressed CO2 is in a liquid/vapor state. As the temperature goes down, so does the pressure. A temp increase will result in an increase in pressure. That is why it is important to keep the tanks away from any heat source, to avoid blowing the relief!

The pressure will stay the same, at a given temperature, until all of the liquid in the tank has been vaporized. Once only vapor exists, the pressure will drop rapidly.

When a CO2 cylinder is filled and the tank is not cold, the guy filling it has to bleed off some of the head pressure in order to completely fill the tank. In doing this the tank will get really cold and the pressure will drop. Give the tank a chance to stabilize at whatever temperature that it will be living in. Here is a chart that shows the relationship between pressure and temperature for compressed CO2.

CO2_liquid_gas_chart.gif
 
CO2 pressure is deceiving, so memorize john's chart. The pressure/temperature relationship is non-linear and pressure has nothing to do with the amount of CO2 in the tank. That is why it is sold be weight. There will be a test in the morning.

Also, you will probably have to adjust the regulator several times if you put the CO2 tank in the chest.
 
The one thing that the tank pressure gauge is good for is knowing when your tank is bone freaking dry (or nearly so). The high pressure gauge will drop rapidly once almost all the CO2 in the tank is depleted.

This only aids in troubleshooting, but is not a 'how full' gauge of any real value (as Mr 42 said).
 
IN one week, mine went from Red Zone to Green Zone just due to the weather change.

Are you storing your tank in your freezer?
 
The best way to tell the approximate amount of CO2 left is to put it on a scale or do the good-enough-test by picking it up. The tare weight is punched on the side so subtract that amount for the gross weight and you have the weight of the remaining liquid CO2 in the tank.
 
I wouldn't worry too much. You can see my regulator (the one on the left) reads just over the red-zone for this freshly filled 30#'r.

This is the day after I got it filled. Now, three months, five forced kegs and three served to completion kegs later, along with miscellaneous activites (pressurizing cleaned kegs...etc) my gauge is at exactly the same spot.

I won't start worrying until it starts to drop. But like Korkob said, when I do start worrying, I'll worry in a hurry.

My_Regulator.JPG
 
Thank you all soooo much for the responses. It was around 48 deg.F in my garage yesterday so around 600psi. seems about right according to Johnsma22's handy dandy Co2 pressure at temp. chart. BTW I'm ready for the POP Quiz!

Thanks!!!!
 
This is a super helpful thread. I've been wondering why my gauge was ALWAYS at 800, even considered buying another regulator ... but my room temp was about 66 degree so that chart basically explains it! :mug:
 
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