head space

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Are there any rules of thumb or more precise formulas to determine how head
space affects the pressure of co2 when bottling beer?

I'm trying to figure out things like, hypothetically:

If I had a bottle with 12 ounces of beer and 1 ounce of head space what % of
the co2 would be in the beer and what % of the co2 would be in the head
space? If I bottle the beer and prime it with the same amount of sugar but
leave half the head space (1/2 oz)  how does the pressure in the bottle
change?

Ultimately I'm wondering, if I leave too little head space, how high can the
pressure in the bottle go to?

Thanks for any info or pointers.





Re: head space


If you leave too little head space in the bottle, the beer will not properly
carbonate.  I don't know why, but it won't.

 I use a bottle filler and find when it is withdrawn, there is just the
right amount of headspace.

Keep it simple, keep it home made, relax, have a home brew. . . or something
like that.
Jay
"beerburgerandfrieswithbeer"
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head
of
the



Re: head space



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That my be so. Never tried to find out because I use a filler wand too.
However, I know when filling 5L mini kegs, T-A-D, or Party Pigs, you need to
use about 1/3 less priming sugar to achieve the same results as bottles. I
know the percentage of head space on these containers is smaller than that
of a 12 oz bottle, but I couldn't say if the smaller amount of priming sugar
is due to the larger volume of brew, the smaller percentage of head space,
or a combination of the two.

Mark R



Re: head space


wrote:

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I also use a bottle filler & when filling bottles I try to leave about
as much headspace as in the bottles - whether they be
stubbies 375 ml or tallies 750 ml - as ( I estimate ) there is when i
buy them from the bottleshop.    That's worked for me for about
30 years.  

I've been kegging for about 15mths now, using 26 litre or 19 litre
soda syphon kegs.  When I fill the kegs i try to get as little
headroom as  possible as the kegs will be force carbonated [ ie no
priming sugar].  I assume this is the correct way to go.  

when bottling a brew i use 2 kegs and 20 to 40 stubbies ( varies due
to which kegs used).  Each stubby gets one carbonation drop ( sugar ?
dextrose glob made by the local home brew shop).  Tallies require 2
drops.  

Years ago i used to use a cafe-bar dispenser bottle to dispense sugar
teaspoon equivalents & i also used spend hours washing bottles

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I've had a few explosions over the years <grin>.
One probable cause would be by accidentally doubling the amount of
sugar / dextrose.  I think you would have to be in this order of error
to make much difference.  

Other causes of explosions ( i guess):  
-  crud on the bottle neck.
-  rust on the bottle cap   ( i re-use twist-tops )


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hth

Ian C



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I've read that this is because the pressure in the bottle builds up too
quickly and inhibits the yeast before they can finish carbonating the beer.

Re: head space


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MDixon (used to be a regular on here) did some experiments a while ago
along those lines.  IIRC, he found that yeast would remain active up until
around 45PSI or so, before they shut down and ceased activity.  Can a bottle
take that much pressure?  I don't know for sure, but it sounds high.  I
would guess that the bottle would blow before the yeast stopped?


John.

Re: head space


John 'Shaggy' Kolesar wrote:
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I know from an episode of Myth Busters that 3L plastic soda bottles blow
up around 90 PSI.  Is it reasonable to expect a glass bottle to hold
more or less?

I don't know.  Glass is thicker, but also more brittle.  IIRC, the
source for my original statement was one of the Charlie Papazian books.
  So he may have been speculating at that point.

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Yeah, those PET soda bottles can take a surprising amount of pressure.  IMO,
much more than a typical glass beer bottle.  Typically, glass becomes "iffy"
at anything higher than around 4 volumes of carbonation... whatever PSI that
works out to.

I could be entirely wrong here, but atmospheric is what... 14PSI?  So 4
volumes of carbonation should be something like 4X that, or 56PSI?  In that
case... maybe the bottles could take 45PSI and survive.

I've heard lots of theories over the years regarding how (or even if) the
amount of headspace effects carbonation.  I've never really seen anything
that has definitively answered the question though.  Lots of speculation,
but nothing really concrete.

It does make some sense that an initial burst of pressure build up would
halt yeast activity but... Does the pressure really build up that quickly?
Carbonation by the yeast is generally a relatively slow process.  Also, one
would assume that after the initial burst, as the CO2 dissolves into the
beer, that the yeast would resume when the pressure drops back down.


John.

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I've forgotten the names of all the laws and principles to do with the
relation between liquids gasses and pressure but I believe the reason for
"head space" in an enclosed container is two fold. The first is stability of
the contents of the container, the second is that zero head space can cause
serious problems with the container. Liquids don't compress and in a
container filled 100% even a slight temperature rise could cause a rupture.

With that reasoning if a little yeastie bug has munched on some sugar and
wants to fart out a little CO2 he will need some head space for his gas. If
there is 0 head space it might cause a compression problem and slow down or
stop the yeast from releasing its CO2.

As far as the amount of head space, as I pointed out earlier, there seems to
be a relation to the amount of sugar needed to the percentage of head space
and the size of the container. I've over filled bottles, and of course there
is always the last bottle which seems to get only about 8 oz, but they have
all come out with good carbonation. I have never tried a zero head space
test as I figured I would get the bottle bomb results.

Mark R



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