[boapiu]

Getting ready to bring one more keg online and had to disconnect one. Hooked up a Co2 dispenser thingy to make the beer available but as a few days passed it seems the keg that was cut from the Co2 bottle began to lose carb!? Is this possible or my imagination? The keg had been fully carbonated and consumed for a couple weeks (maybe less)  while connected to the tank. my question is whether or not beer in a keg can lose carbonation if it is disconnected from the Co2 bottle. Seems as though it has already absorbed as much as it can and should hold it. Hummmmmm.
Ps. I plan to implement some kind of distribution plumbing so I can keep all three kegs hooked up,in the future.

[tschmidlin]

The most obvious thing to check is if the keg leaks at all.  If it wasn't leaking before, it may be that the gas in poppet didn't seat right when you took off the gas.

[bluesman]

I recently had a keg of Pilsner that was fully carbonated do the same thing. I discovered that the in post poppet was not fully seating, so I replaced the poppet which fixed the problem.

Try leak testing all of your connections including the lid to determine the source of the leak. I use a spray bottle of starsan solution.

[The Professor]

I've had this happen on occasion as well.
Usually the leaks are at the gas poppet,  but I've had at least one instance where after a short investigation the problem actually turned out to be the relief valve, the little 'plug' inside having worn down a bit.   I wound up taking it apart at adding a schmeer of silicone to that little 'plug' inside the valve that makes the seal (aided by the spring in the valve).  After curing the silicone caulk as reassembly , there were no problems with the leak.

Lately though, I have been  double-checking the gas poppet whenever I disconnect the gas. 
Usually, just pushing it in momentarily and letting it reseal itself does the trick.  And if there is still any uncertainty, a drop of water on the top of the post where the poppet is tells the tale immediately.

[euge]

I always place my fingertip gently over the poppit. If there is a leak you will feel it form a bubble against the tip of your finger. This only works for the poppit BTW. A few squirts of starsan solution can find a leak just as well...

And thanks Professor I have some leaky relief valves.

BTW a little lube/oil on the poppit-head helps smooth things and less likely hood of sticking.

[boapiu]

so what i am gathering is that the Co2 in solution will not (somehow) go out of solution, once the gas in has been disconnected - so long as there is no leak. in other words, the beer will not go flat even if i disconnect the gas in. i have leak checked using starsan and there are no bubbles. once i sort out the gas lines thru some manifold arrangement all the kegs will be connected all the time.
NEW Question? Should i be using 5/16 or 1/4 inch for gas in? i have 1/4 for the tap. or does it depend on the length of tubing?
thanks for the help.

[mainebrewer]

The internal diameter of the gas line doesn't matter. I used 5/16 because that's what I had around and its easier to get on and off the barbs.

[Kit B]

Just thinking, but...
Is it possible that some of the co2 was used to generate carbonic acid & no longer took on gaseous form?

[tschmidlin]

When CO2 dissolves in the beer it creates carbonic acid.  When you take the pressure off, the some of the carbonic acid comes out of solution, leaving behind the H2O and coming out as CO2.  It's a reversible process.

I've been assuming that the keg had already reached equilibrium with respect to the amount of gas dissolved in the beer, so as long as the same pressure remains on the keg.

Were you pulling beers off of the disconnected keg?  That will cause the remaining beer to lose carb.  That or a leak are the only two things that would cause the beer to go flat.

Also, as was said above, the size and length of the gas hose doesn't matter.

[boapiu]

Pulling beers off the keg - yes. That must be it. I continued to draw beers until the pressure wouldn't allow. It was during that time I got the impression the beer was less carbonated. Now I have one of those portable Co2 cartridge devices to use in this situation until I get the manifold set up for three kegs. Unfortunately, with lots of guests coming for turkey day, I may not have anything left in my kegs. Thanks for solving the dilemma.

[tschmidlin]

Pulling beers off the keg - yes. That must be it. I continued to draw beers until the pressure wouldn't allow. It was during that time I got the impression the beer was less carbonated.

Well, that would do it.  When the beers stopped pouring it was because there wasn't enough pressure left in the keg to push the beer to the faucet.  Every time you pulled a pint CO2 was coming out of solution to reach equilibrium in the keg (you changed the beer volume to head space volume ratio) so it was losing carb the whole time.

In the future you can just switch the gas line back and forth between kegs and it will be fine.  Before I got my manifold I would just swap the gas connects to whatever kegs I was pouring from, and would make sure that every keg had pressure at the end of the night.  Your portable CO2 will work also.