How much pressure is in my keg? (noobie)

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Beer0clock

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Noobie kegger here.

How do I know how much pressure is in my keg?

For example suppose I force carbed by sending 30 PSI to the keg for 2 days. Now I want to turn the keg down to 10 PSI for serving. I'm told the proper way to do that is to disconnect the CO2, Hit the pressure release on the keg, and then re-attach the CO2 at 10 PSI. I'm told you need to release the pressure in the keg before turning the CO2 down to 10 otherwise the higher pressure in the keg will shoot beer into the regulator (is that true?).

But doesn't this method bring the PSI in the keg from 30 down to 0 then back up to 10? I assume that will create foam in the beer. Wouldn't a better method be to simply hit the release valve on the keg lightly until it goes from 30 down to 10? Therefore skipping the dip down to 0 PSI?

Of course you would need to know the PSI in the keg in order to do this. Does anyone attach a regulator temporarily to the keg to do this? Or is this just a dumb idea?
 
You're definitely over-thinking the process. If you have the keg at 30PSI, and then drop the pressure at the regulator to 10PSI, yes - there is a chance that you'll push beer back into your CO2 lines. This is mostly dependent on the level of the beer in the keg and the length of your gas-side dip tubes.

Now, if you have that same keg at 30PSI, purge the pressure to whatever atmospheric pressure is (you're never going to create a vacuum, or 0, in there!), then adjust your reg to 10PSI and reconnect, what happens is that for the 2 minutes or so it takes between purging, resetting, and reconnecting your reg, the pressure in the headspace will drop to atmospheric pressure, then immediately rise back to 10PSI once you've reconnected. This does not cause foaming - as long as you didn't overcarb the beer and your lines are an appropriate length. The amount of time at less-than-serving pressure is not nearly long enough for the CO2 to start escaping solution and causing foam.
 
Noobie kegger here.

How do I know how much pressure is in my keg?

For example suppose I force carbed by sending 30 PSI to the keg for 2 days. Now I want to turn the keg down to 10 PSI for serving. I'm told the proper way to do that is to disconnect the CO2, Hit the pressure release on the keg, and then re-attach the CO2 at 10 PSI. I'm told you need to release the pressure in the keg before turning the CO2 down to 10 otherwise the higher pressure in the keg will shoot beer into the regulator (is that true?).

But doesn't this method bring the PSI in the keg from 30 down to 0 then back up to 10? I assume that will create foam in the beer. Wouldn't a better method be to simply hit the release valve on the keg lightly until it goes from 30 down to 10? Therefore skipping the dip down to 0 PSI?

Of course you would need to know the PSI in the keg in order to do this. Does anyone attach a regulator temporarily to the keg to do this? Or is this just a dumb idea?

You can't think of the whole space in a full keg as an immediately reactive system. The liquid is one space and the space above the liquid is another system. The junction between the liquid and headspace is like a semi-permeable membrane where CO2 "pressure" will pass over time.

The moment you put 30psi of CO2 in the headspace, none of it is in the beer. Over time, the Co2 dissolves into the beer and eventually has the same amount of CO2 as the headspace. On the other side, if you drop the pressure in the headspace to zero, there is still 30 psi worth of CO2 in the beer unless time passes.
 
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