Adding uncarbed keg to manifold

[Mack]

I'm curious about folks' opinions on the matter - when I add a new keg to my keezer, with an 8-way manifold and 5 kegs already connected & carbed to proper level, is there a loss of pressure across the board as the new carb comes up to serving pressure?

Scenario:

5 kegs perfectly pouring, manifold set at 10.7 psi.

Pressure fermented keg (10.5psi during fermentation) added 2 days after cold crash (obviously the pressure drop and the temp drop are synchronous) to the manifold.

Almost immediately I lose pour tempo and "perceived head" on my other beers.

Anyone else have this "problem"?

My most simple solution is to utilize a second regulator to bring the new keg up to serving pressure (which i often do), though I prefer the "set it and forget it" method.

 

[day_trippr]

I would expect a very short period of time - measured in seconds - where the system pressure would be lower than "set point" as a result of connecting the new keg, but that's it. My keezer holds six kegs, and over the last two weeks have been cycling through the kegs with kicks being replaced by freshies, and connecting a fresh keg never affects the pour quality of kegs already being dispensed.

I do have a dedicated conditioning fridge, so kegs are always fully carb'd before they hit the keezer. But I wouldn't imagine that makes a significant difference wrt tapped kegs being affected when a freshie is connected, because the CO2 absorption rate of an uncarb'd keg is going to be glacial. I would suspect something else is going on...

Cheers!

 

[Broken Crow]

That's actually a practical example of something I've wondered about:
In the beverage dispensing industry, when a bar or restaurant installs a dispensing system it is standard practice to use a larger gas supply line than the liquid dispensing lines so as to allow more than one tap to be used at a time without losing pressure and creating foam. Though at least with EVABarrier, most homebrewers follow the defacto standard of using 5mmID gas line and 4mmID liquid line. For the homebrewer who doesn't use multiple taps at once, this issue never arises...though often, I'll be pouring myself an ale while my GF is pouring a cider off the same gas supply, I'm using 5mmID gas line and 3mmID liquid line and there has never been a slow down in the pour.
What size lines are you using?

 

[Mack]

I'm using the old standard 5/16 gas line, after having nothing but issues and leaks with a duotight system.

@day_trippr the difference is that my newly added kegs although "cold" are NOT carbonated. I'm not saying that I am experiencing a complete "flat" beer, just that I have noticed over the last half dozen or so kegs that each time a new uncarbonated keg is added to the mix, over the next couple of days I will notice less head on the other taps being pulled from. If indeed "something else is going on", I can't figure it out, there is no gas loss from the system other than what is now being shared with an under carbonated beer. My point: why wouldn't adding 5 gallons of basically 0 psi liquid to a system with 10-20 gallons of pressurized liquid effect it? So many emphatically suggest that the co2 disperses at it's own whim, so obviously it will be equalized across all of the kegs on the same gas line, won't it?

If I force carb on the secondary regulator and then add to the primary serving manifold, there is no noted loss of carbonation / foam / head from the other taps. Although, I have had the brain fart moment when I forgot to purge the 50 psi force carbed keg down to serving pressure and it DID over carb 2 other kegs on the system before I realized and purged them all over a couple days back down to serving pressure.

 

[Indian_villager]

Depends on your setup. I really recommend adding check valves to the gas lines going to each keg so that you don't back feed gas. This way if you have a contamination or a sour you don't risk the rest. I made the mistake once of having an overfilled keg that shot a bunch of beer back into the manifold. If you have the check valves, when your manifold dips in pressure to fill the new keg the check valves on all the other kegs should seat causing the pressure in them to only drop negligibly.

 

[mac_1103]

My point: why wouldn't adding 5 gallons of basically 0 psi liquid to a system with 10-20 gallons of pressurized liquid effect it? So many emphatically suggest that the co2 disperses at it's own whim, so obviously it will be equalized across all of the kegs on the same gas line, won't it?

Yes it will be equalize, but it is the pressure in the headspace that will be equalized (at whatever pressure you set your regulator for). The regulator can't tell (and shouldn't care) how much CO2 is dissolved in the beer in each keg. As CO2 is absorbed into the beer in a new keg, the regulator should supply additional gas to maintain headspace pressure in all of the connected kegs. I would be very interested to hear an explanation for CO2 coming out of solution in a beer carbonated to (for example) 2.3 volumes at 40F if there is 10 PSI of CO2 pressure in the headspace. Because I can't think of one.

 

[lumpher]

The other kegs will lose pressure for a couple seconds while they're all equalizing, but the regulator will have them all back up to full pressure quickly. Like Mac says, headspace pressure is all that is affected, and that for a few seconds. I can't think of any reason why the other kegs would be affected like that. 10.5 psi is 10.5 psi, whether warm or cold. I'm not saying it's the same amount of co2; it's not, but we're talking pressure, not volume.

 

[day_trippr]

My point: why wouldn't adding 5 gallons of basically 0 psi liquid to a system with 10-20 gallons of pressurized liquid effect it?

Let's say you had a keg of beer but the head space was actually at some negative pressure. When you hook the keg up to your gas distribution system, there'll be a rush of CO2 to that keg to bring it's head space pressure up to match the regulator setting.

And I suppose if your distribution system lacks check valves, that rush of gas would be a blend of regulator-provided gas plus whatever evacuates the head spaces of the connected kegs in time to join the party - which will be over in seconds, not minutes.

Once the system is back at equilibrium, you should not notice any difference in dispensing the other kegs - and why would you? The uncarbonated fluid in the new keg isn't going to change its carbonation level in any short order - it'll literally take a couple of weeks for a full corny keg to reach a typical carbonation level (2.1~2.5 volumes)...

Cheers!