CO2 bottle pressure falls no idea why?

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befus

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Just back into kegging. In my first beer life I recall no issues at all and a C02 only got filled once in five years, a 10 pounder at that. This time I have a 20# bottle which showed 500 pounds garage (50's) temp when I hooked it up to the Birdman system. I transferred everything to the fridge and over a week or so the pressure has fallen to under 300#s. I have put soapy water on everything I can find (connectors,hoses, clamps, regulator parts, etc) and see no leaks at all, new o-rings all around ,btw. At this rate I will be out of gas in another week. Any ideas? Hooked a second keg up yesterday and did everything again.............no bubbles. Any sneaky leak locations I might be missing?
 
The high pressure gauge doesn't tell you how much gas is left in the tank. What it tells you is the pressure inside the tank, which will essentially be the vapor pressure of CO2 as long as there's still liquid CO2 present. Once the liquid CO2 runs out and the tank is nearly empty, the pressure will start dropping fast. The vapor pressure of CO2 is temperature dependent, which is probably why it dropped when you moved it into the fridge. The only way to know how much gas is in the tank is to weigh it, and subtract the tare weight of the tank.
 
One chart ought to do it...

VP%20curve%20fit.jpg


Cheers!
 
Check the visual aid above. It's like leaving a basketball outside in freezing temps.

Not really, that's gas expanding/contracting. This is the vapor pressure of a volatile liquid varying with temperature. One is linear, the other isn't. I like my chart (attached) a little better than day trippr's, but only because it's zoomed out a bit and it clearly shows the non-linearity. I made this from data available via Wikipedia.

Regardless, if you're reading 300 psi and you aren't keeping the tank at 0 deg F, you have a leak. Did you remember the washer between the tank and regulator? Are you leaving the tank open?

VLE.gif
 
Not really, that's gas expanding/contracting. This is the vapor pressure of a volatile liquid varying with temperature. One is linear, the other isn't. I like my chart (attached) a little better than day trippr's, but only because it's zoomed out a bit and it clearly shows the non-linearity. I made this from data available via Wikipedia.

Regardless, if you're reading 300 psi and you aren't keeping the tank at 0 deg F, you have a leak. Did you remember the washer between the tank and regulator? Are you leaving the tank open?

Ah! I see now! I wondered why it changed so drastically...
 
Regardless, if you're reading 300 psi and you aren't keeping the tank at 0 deg F, you have a leak. Did you remember the washer between the tank and regulator? Are you leaving the tank open?

It was a new regulator and if it didn't have a washer in it, I didn't put one (or have one) in. I do leave it open (on?) all the time. Is this bad? Right now I am carbing up another keg and thought I'd have to leave it on in any case.
 
No, leaving it open all the time is fine. I was just checking because if you have it hooked up to an actively carbing keg and you don't leave it open, the pressure will drop as CO2 is absorbed by the beer.

Some regulators have a built in o-ring, others don't. If yours doesn't you definitely need the washer. Maybe post a picture or link or model?
 
I lost gas in 2-3 tanks rather quickly. The guy at the gas store gave me a free new washer of a different style and I checked my connections ALL OVER and even replaced the QD on one keg that seemed ot be problematic and now I'm getting 4-5 kegs off a tank, carbed and served.
 
No, leaving it open all the time is fine. I was just checking because if you have it hooked up to an actively carbing keg and you don't leave it open, the pressure will drop as CO2 is absorbed by the beer.

Some regulators have a built in o-ring, others don't. If yours doesn't you definitely need the washer. Maybe post a picture or link or model?

New Taprite regulator came win the fridge kit from Birdman. I would just think if there were a leak I'd see signs of it with all the soapy water I have brushed on this thing. Gonna hook and unhook everything one more time, checking for leaks at each step......sigh.
 
The taprites usually have an integrated o-ring (I think...) so you shouldn't need a washer.
 
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