Half Filling Kegs?

[BPH87]

Is it ok to half fill a 19lt keg?

Cheers

 

[pk.sax]

Yes

 

[crd0902]

Sure is

 

[BPH87]

Cheers for the speedy replies!

 

[Cocko]

No probs



EDIT: BTW you are bleeding the keg with C02 after half filling yeah?

 

[brettprevans]

Do u care how much u fill up a bottle? A keg is a big arse stainless bottle. Carb and ur away.

 

[adraine]

Would that mean your using more gas? Or the same as the gas is in solution if the keg is full?

 

[Nick JD]

They force carb way easier too if you don't fill them to the top. I usually put around 14-17L in kegs.

 

[Cocko]

They force carb way easier too if you don't fill them to the top. I usually put around 14-17L in kegs.

In particular with the 'Ross' method - more head space = less rocking.

:icon_cheers:

 

[Nick JD]

In particular with the 'Ross' method - more head space = less rocking.

:icon_cheers:

I roll them on the ground. You get a massive surface area that way. Getting gas to dissolve is all about area.

 

[Cocko]

I roll them on the ground. You get a massive surface area that way. Getting gas to dissolve is all about area.

Tru dat! Tho..

I no longer rock or roll, it is just overnight styles for me these days...

:icon_cheers:


HA - 'Rock or Roll' .... funny....

 

[brettprevans]

Would that mean your using more gas? Or the same as the gas is in solution if the keg is full?

What do u think? more vacant volume will be filled by gas. So yes initially. Obviously as any keg drains u get more more dead space filled by gas but in this case u start with more deadspace

 

[kymba]

no

 

[QldKev]

would it be half full or half empty

 

[adraine]

What do u think? more vacant volume will be filled by gas. So yes initially. Obviously as any keg drains u get more more dead space filled by gas but in this case u start with more deadspace

I understand that logic I'm not a complete fool. I however was asking about the amount of gas in solution rather than in the dead space. Do you know the ratio of gas in solution in a std draught beer for example vs the dead space i.e. 60% - 100%? So as to see the amount of gas wasted or to look at the workflow and see if there is a way to recover it.

 

[pk.sax]

It's called equal pressure. The pressure of the gas in solution and that of gas in the space above will be the same, occupy ye same volume etc. so, whatever pressure you've dialled in, the amount of gas from the cylinder that is required to carbonate the beer to that will be the same as what is in the headspace if you half fill the keg.

PS: that is what an ideal gas (something like helium) will behave like. CO2 is not ideal but it's still a good approximation.

In other words, if you are carbonating to 3 volumes of CO2, you need 3 volumes to dispense as well or 6 volumes for the whole keg. Volumes of full keg, of course. Start at half a keg and you are carbonating to 1.5 vol CO2, fillin the dead space with another 1.5 vol and going to need another 1.5 vol to empty the keg. That is 4.5 vol for half keg of beer vs 6 vol for full keg, obviously, it is wasteful.

 

[QldKev]

I understand that logic I'm not a complete fool. I however was asking about the amount of gas in solution rather than in the dead space. Do you know the ratio of gas in solution in a std draught beer for example vs the dead space i.e. 60% - 100%? So as to see the amount of gas wasted or to look at the workflow and see if there is a way to recover it.

I say no, it would not require more CO2. Beer has approx 2.5x (ie 250%) CO2 in solution. But the key here is you may be starting with 50% full of CO2, but with either a full or half keg of beer, when empty you still end up with a full keg of CO2. So a full keg would need a full keg worth of CO2 to dispense. A half keg will need half a keg up front to fill the empty space, but only draw another half a keg worth to dispense.

But to put your mind further at ease, even if you wasted half a keg vol of CO2, it would not cost that much. We know we use 2.5x to carb and 1x to dispense = 3.5x volume. Depending on where you get your CO2 from, it cost me $1.50 to carb and dispense a keg. So if I wasted say 1/2 a keg vol it works out to be 1/7 of $1.50 = 22c.

QldKev

 

[pk.sax]

We know we use 2.5x to carb and 1x to dispense = 3.5x volume.

hocus pocus?

 

[QldKev]

hocus pocus?

2.5x is a lot better number than 3x for most standard beer styles.

edit: updated to include carb levels of beers

American Amber Ale: 2.2-2.8
American Brown: 1.5-2.5
American Dark Lager: 2.5-2.7
American Lager: 2.6-2.7
American Light Lager: 2.6
American Pale Ale: 2.2-2.8
American Pilsener: 2.6-2.7
American Premium Lager: 2.6-2.7
American Wheat: 2.3-2.6

Bamberg Rauchbier: 2.2-2.6
Barley Wine: 1.3-2.3
Belgian Dubbel: 1.9-2.4
Belgian Fruit Lambic: 2.6-4.5
Belgian Gueuze Lambic: 3.0-4.5

Belgian Lambic: 3.0-4.5
Belgian Pale Ale: 1.9-2.5
Belgian Strong Ale: 1.9-2.4
Belgian Tripel: 1.9-2.4
Belgian White (Wit): 2.1-2.6
Berliner Weisse: 3.5
Bire de Garde:
Bock: 2.2-2.7
Bohemian Pilsener: 2.3-2.5
Brown Porter: 1.7-2.5

California Common: 2.4-2.8
Cream Ale: 2.6-2.7

Doppelbock: 2.3-2.6
Dortmunder/European Export: 2.6
Dunkelweizen: 3.6-4.5
Dsseldorf Altbier: 2.2-3.1

Eisbock: 2.4

English Best (Special) Bitter: 0.75-1.3
English Brown: 1.5-2.3
English Dark Mild: 1.3-2.0
English Light Mild: 1.3-2.0
English Old/Strong Ale: 1.5-2.3
English Ordinary Bitter: 0.75-1.3
English Pale Ale: 1.5-2.3
English Strong (Extra Special) Bitter: 0.75-1.3

Flanders Brown: 1.9-2.5
Foreign-Style Stout: 2.3-2.6

German Pilsener: 2.5

Helles Bock: 2.2-2.7

Imperial Stout: 1.5-2.3
India Pale Ale: 1.5-2.3
Irish Dry Stout: 1.6-2.0

Klsch: 2.4-2.7

Maibock: 2.2-2.7

Mrzen/Oktoberfest: 2.6-2.7
Mnchner Helles: 2.3-2.7
Munich Dunkel: 2.2-2.7

North German Altbier: 2.2-3.1

Oatmeal Stout:
Oud Bruin: 1.9-2.5

Robust Porter: 1.8-2.5

Schwarzbier: 2.2-2.6
Scottish Export Ale: 0.75-1.3
Scottish Heavy Ale: 0.75-1.3
Scottish Light Ale: 0.75-1.3
Strong Scotch Ale: 1.5-2.3
Sweet Stout: 2.0-2.4

Traditional Bock: 2.2-2.7

Vienna: 2.4-2.6

Weizen/Weissbier: 3.6-4.5
Weizenbock: 3.7-4.7

 

[pk.sax]

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

 

[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.