If I force carbonate my keg, and after that I close my CO2 cilinder valve and plug my gas line into my gas in quick disconnect. Would this make my CO2 regulator to work as a spunding valve and let me regulate the CO2 pressure inside my keg? This things works in both flow ways?

If not, there is a way to properly measure the psi inside the keg without buying a pressure gauge for that? That's my plan on future, but for now I need to force carbonate (fast way) a keg, but don't want to take much time in trial and error when go dispensing my beer to get a perfect pouring. There is about 6 hours to my event, not enough time to the 'set it and forget' method. My kegs are pin lock, and doesn't have a pressure relief valve, what makes adjusting pressure when serving a little more difficult.

  • Last times force carbonating in fast way always take me to under or overcarbonated beer, or just to much foam when dispensing, and I want to avoid that. Just plug the things and pour delicious right carbed beer.
    – jards
    Nov 5, 2014 at 14:04
  • 1
    You'd have to purge the the regulator first to get an accurate reading right. Just shutting the tank off won't do it. There will still be what ever pressure you last dispensed in the system. But its a really good idea that I think I'll try next time too.
    – brewchez
    Nov 5, 2014 at 15:44

3 Answers 3


The regulator will give you a reading of the pressure inside the keg, but will not release the pressure the way a spunding valve would -- you'll have to do that manually.

  • Thanks for the answer, Tobias. So, it seems useful to you? Do you think I'll take a more acurate carbonation doing that? Don't know if it will work as expected.
    – jards
    Nov 5, 2014 at 15:00
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    I've never had any luck force carbonating. I just set the regulator for the target pressure, and wait a week. Good luck :) Nov 5, 2014 at 15:30
  • Hello, Tobias and brewchez. 12 or so kegs later I am returning to this question because I don't have any sucess on this method. But I don't know if this is my regulator that is old and not beer specific or if this don't work at all. Do you both have ever tryed the method? Thanks!
    – jards
    Dec 29, 2014 at 10:17

As far as I understand the operation of a pressure regulator it works basically the opposite way of a spunding valve. While the spunding valve opens when the preset pressure is exceeded the pressure regulator closes.

That is if the pressure in your keg is lower than the preset pressure the regulator will open, letting the CO2 from the cylinder into your keg. When the keg reaches the preset pressure it will close and no more CO2 will flow into your keg.

This mean that if there's nothing preventing the pressure to escape and your keg is below the preset pressure the regulator would evacuate CO2 from your keg.

To avoid this you should make sure that CO2 can't be evacuated from the keg by either:

  • Connect the regulator to the cylinder (but keep the cylinder closed)

  • Preset the regulator to a pressure lower than that of the keg

  • Have a double stage regulator (the first stage work as a spunding valve of the cylinder)

  • Have a regulator that has a built in counter flow valve*

Also note that after closing the cylinder there will still be CO2 in the high pressure part of the regulator. If your keg is full this gas can contribute significantly to the pressure of the keg (if the preset pressure is higher than that in the keg). In that case you would need to evacuate that part, either by using the relief valve or disconnecting the regulator from the cylinder and connect it again.

* This could work to or against your advantage. If the counter flow valve is placed between the keg and the gauge there would be no flow of CO2 from the keg to the gauge and the gauge would be able not measure the gauge of the keg. However I find this construct unlikely.


Go over to homebrew finds look up spunding valve, he has all of the parts needed to build one. 25 bucks or so.

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