Half Filling Kegs?

[QldKev]

Hey Kevin, I was referring to the 'need 1x vol to dispense part'. I can't make head or tail of that.

I just used 3 vol as a simple number to illustrate the calculation, 2.5 is likely more appropriate, I don't measure any longer, if it feels right then it does

ahh, the 1x to dispense is because we normally only dispense at up to 1 bar (14.7psi = atmosphere) pressure. So at atmospheric pressure I only expect the CO2 to take the same volume as 1:1.

QldKev

 

[pk.sax]

Aha. Now you mention that, I had a look and it is at 1 bar that I dispense too. Well, usually. I do end up overcarbing by a bit and then topping up when req.
Still, if that is what you do leaving in hooked up all the time then there is something I'm missing. To me, partial pressure of dissolved gas had to match the partial pressure of the gas in the headspace so should keep constant to keep the beer from losing gas. Obviously, practical application isn't exactly reflecting the theory...

 

[devo]

Is it ok to half fill a 19lt keg?

Cheers

Yes but you will need to purge with C02 more so than you would with a full keg because there will still be a greater chance of residual Oxy still in your kegs head space.

 

[DUANNE]

Yes but you will need to purge with C02 more so than you would with a full keg because there will still be a greater chance of residual Oxy still in your kegs head space.

i half or 3/4 fill regularly because i like to bottle a few each batch. when i purge i do it by filling the keg brimming with starsan and hook a hose up to my tap and run the full keg into an empty keg. the starsan lasts forever this way and it means each keg fill i am obiged to clean and sanitise my beer line.

 

[adryargument]

Yes but you will need to purge with C02 more so than you would with a full keg because there will still be a greater chance of residual Oxy still in your kegs head space.

Does this really matter? If its sitting in a fridge then you only need a small layer of co2. It is heavier after all.

 

[wombil]

To keep it simple:
To carbonate and serve a full keg reouires 1 times v volume of gas.
To carbonate and serve a half full keg requires .5 times v to fill the headspace + .5 times v to serve the beer = 1 times v volume of gas.
Therefore it takes the same amount of gas to do a full keg as it does to do a half full keg.
Therefore your relation of gas used to beer served is twice as much for the half full keg.
As Bribie pointed out gas is cheap so who gives a stuff?
Einstein ,eat your heart out.
Maybe I am wrong but that's how it looks to me.
Just had to have a shot.

 

[Bizier]

Does this really matter? If its sitting in a fridge then you only need a small layer of co2. It is heavier after all.

These gases don't behave like water and immiscible oil. I would purge the keg more than normal (unless you use the starsan displacement method mentioned above) due to more O2 being there after transfer, and critically so if you are going to force carb with a rock and roll.

I guess if you don't plan on keeping the keg for long, it is refridgerated and should hold up OK.

I can tell you that if you measured the O2 in a half-full keg after rock and roll without a complete purge, your DO would be off the chart. BUT you might also never notice or care.

 

[Helles]

But your only getting half the beer for the same amount of gas
you could have got a full keg with the same amount of gas
I think this means you use more gas

 

[alcoadam]

I reakon I would of done 30+ half keg jobs and have oxidized more than i would like to admit too!


I would recommend burping the keg more than u think necessary, then burp it some more...fixed my probs.

 

[Wolfy]

Wouldn't logic suggest that it will use less CO2 when you have less beer to carbonate?

The more beer in the keg, the more CO2 that must be dissolved into the beer, in order to balance the pressure of the head-space/regulator. By the time the keg is empty (and full of CO2) the keg will be full of the same volume of CO2 in either case.

 

[alcoadam]

Hard to tell what uses more but i know that when i gas the (warm) half keg to 150-200, that's it.

 

[sim]

i half or 3/4 fill regularly because i like to bottle a few each batch. when i purge i do it by filling the keg brimming with starsan and hook a hose up to my tap and run the full keg into an empty keg. the starsan lasts forever this way and it means each keg fill i am obiged to clean and sanitise my beer line.

I used to do this, but i heard that starsan sitting in a keg can pit the stainless over time. If the particular beer warrants it I now clean and rinse the keg, fill with filtered water and push it out with co2 into the HLT, then dump in some sanitiser, swirl it around and push it out. Ive heard that this is less wastefull of co2 than a number of purges.

 

[Nick JD]

To remove the air from a half filled keg, place the gas QD on, wait till it's gassed, remove the QD and pull the ring.

Repeat 2 more times.

Burping the keg with the QD connected is burping your CO2 straight out the vent.

 

[crd0902]

To remove the air from a half filled keg, place the gas QD on, wait till it's gassed, remove the QD and pull the ring.

Repeat 2 more times.

Burping the keg with the QD connected is burping your CO2 straight out the vent.

Is that right. I hook gas up and wait till no gassing, pull ring and do this like three times or something. Am I supposed to disconnect or is that only half filled kegs please. Cheers
Chris

 

[raven19]

Am I supposed to disconnect or is that only half filled kegs please.

If you are carbing up slowly at serving pressure, then leave it hooked up.

If you are force carbonating the keg then dial up your pressure, get to your desired carb level, then remove the gas QD from the keg.

(I do the former, but its a personal choice).

 

[Nick JD]

We're taling about purguing keg headspace of air and replacing this with CO2.

 

[raven19]

I read the question based on the assumption the OP was now looking at the next step in the process after purging.

If I am incorrect, please disregard my post.

 

[hsb]

Burping the keg with the QD connected is burping your CO2 straight out the vent.

How so? Isn't Brownian Motion mixing up the fluids? Why should the CO2, rather than a mix of all the gases in there, work its way straight out of the Relief Valve?
Just curious. Can't say I have a personal handle on the behaviour of fluid mixes under pressure or anything.

 

[Nick JD]

Get a keg and fill it half full with water. Light a cigar.

Fill the headspace with smoke.

Attach QD and purge with QD connected.

Open keg and see if there's still smoke in there.

I have a feeling the CO2 will be doing a little loop between the QD and the vent and down in the middle of the keg will be a vortex of swirling cigar smoke (air).