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Date: 21 Jun 2006 20:04:24
From:
Subject: good technical kegging reference
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Brewers,
I am in the process of (finally!) kegging my beers. I seek a good all
around reference for kegging and carbonation matters for a technically
minded person (i.e. not just a set of tables, rules and precedures).
As I play with my new gizmos, tons of little questions come to mind
that are too small and numerous to go posting here. If I had a better
understanding of the hardware (particularly the regularor) I'd feel
better.
Thanks,
-Nick
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Date: 22 Jun 2006 09:04:45
From: yddraig
Subject: Re: good technical kegging reference
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naramsey@umich.edu wrote:
> Thanks for the responses. I've read these proceedures - I guess I'm
> looking for more a foundational understanding.
>
> OK, here are a couple of specific questions.
>
> 1) How does the regulator physically work. What does turning that
> little screw actually do behind the scenes in there?
>
> 2) Fix a volume and temperature of beer in a keg, as well as a
> carbonation level in volumes of CO2. Am I to understand that there is
> a PSI which, when applied to the keg, puts it in "equilibrium" in the
> sense that no more CO2 will dissolve and no CO2 will gas out (pretend
> there is no check valve or whatever so that gas is free to go either
> way). Is this moreover the PSI you find in that force carbonation
> table everywhere? If so, does it really not depend on the volume of
> beer in the keg?
>
> Thanks again!
>
> -Nick
>
>
> John 'Shaggy' Kolesar wrote:
> > On 21 Jun 2006 20:04:24 -0700, <naramsey@umich.edu> wrote:
> > > Brewers,
> > >
> > > I am in the process of (finally!) kegging my beers. I seek a good all
> > > around reference for kegging and carbonation matters for a technically
> > > minded person (i.e. not just a set of tables, rules and precedures).
> > >
> > > As I play with my new gizmos, tons of little questions come to mind
> > > that are too small and numerous to go posting here. If I had a better
> > > understanding of the hardware (particularly the regularor) I'd feel
> > > better.
> >
> > Ask away, that's what the group is here for.
> >
> >
> > John.
I'll try to keep it simple. The regulator reduces the high pressure
CO2 (1200 PSI) down to a useable level (0-60 PSI), it also maintians
the pressure at a constant (regulated) PSI. By turning the screw you
can raise/lower the regulated pressure. The regulator accomplishes
this task (warning technical content) by using a diaphram, a needle
valve and a spring. Thi spring is in the low pressure side and presses
the diaphram and the needle valve closed. The screw is used to
increase the tension on the spring. When the spring tension is
increased the needle valve is allowed to open, causing gas to flow
through. The back pressure of the keg then assists in keeping the
needle valve closed and thus keeping the pressure near the set point.
Hope this helps
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Date: 22 Jun 2006 08:09:46
From:
Subject: Re: good technical kegging reference
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Thanks for the responses. I've read these proceedures - I guess I'm
looking for more a foundational understanding.
OK, here are a couple of specific questions.
1) How does the regulator physically work. What does turning that
little screw actually do behind the scenes in there?
2) Fix a volume and temperature of beer in a keg, as well as a
carbonation level in volumes of CO2. Am I to understand that there is
a PSI which, when applied to the keg, puts it in "equilibrium" in the
sense that no more CO2 will dissolve and no CO2 will gas out (pretend
there is no check valve or whatever so that gas is free to go either
way). Is this moreover the PSI you find in that force carbonation
table everywhere? If so, does it really not depend on the volume of
beer in the keg?
Thanks again!
-Nick
John 'Shaggy' Kolesar wrote:
> On 21 Jun 2006 20:04:24 -0700, <naramsey@umich.edu> wrote:
> > Brewers,
> >
> > I am in the process of (finally!) kegging my beers. I seek a good all
> > around reference for kegging and carbonation matters for a technically
> > minded person (i.e. not just a set of tables, rules and precedures).
> >
> > As I play with my new gizmos, tons of little questions come to mind
> > that are too small and numerous to go posting here. If I had a better
> > understanding of the hardware (particularly the regularor) I'd feel
> > better.
>
> Ask away, that's what the group is here for.
>
>
> John.
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Date: 22 Jun 2006 18:00:14
From: John 'Shaggy' Kolesar
Subject: Re: good technical kegging reference
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On 22 Jun 2006 08:09:46 -0700, <naramsey@umich.edu > wrote:
> 1) How does the regulator physically work. What does turning that
> little screw actually do behind the scenes in there?
My understanding is that the screw pushes against a spring on the inside
which itself puts pressure against a diaphram. Changing the pressure on
the diaphram adjusts how much gas the regulator will allow to come through.
If you're *really* curious, there are rebuild kits for regulators that
replace the internal components. They probably have instructions sheets
with them that show you what everything looks like inside. You could
probably find a copy of the instructions online somewhere, or maybe
someone else has a copy they can scan for you?
> 2) Fix a volume and temperature of beer in a keg, as well as a
> carbonation level in volumes of CO2. Am I to understand that there is
> a PSI which, when applied to the keg, puts it in "equilibrium" in the
> sense that no more CO2 will dissolve and no CO2 will gas out (pretend
> there is no check valve or whatever so that gas is free to go either
> way). Is this moreover the PSI you find in that force carbonation
> table everywhere? If so, does it really not depend on the volume of
> beer in the keg?
Exactly. How much gas goes into solution depends on temp and pressure.
By looking up the temp your beer is at and the amount of carbonation
you want, there is a specific PSI that you set the regulator to. Then
the keg will slowly absorb gas (becomes carbonated) until an equilibrium
is reached. At that point, no gas will come out or go in. Think
of it as the pressure of the gas in the beer being the same as the
pressure of the gas outside the beer. The PSI you use has nothing to
do with the volume of the beer. Once you reach equilibrium, as far as
distribution of gas goes, I don't think the CO2 even cares that the beer
is there. For example, my understanding is that if you pressurized an
empty keg and a full keg to the same PSI and allowed the full keg to
come to equilibrium (beer fully carbonated), you would end up with the
exact same amount of CO2 in both kegs. Gas is funny that way. Common
sense says that a keg full of beer won't hold as much gas, but it
doesn't really work that way. The gas and beer don't even know each other
are there, as far as how much will fit.
The next step is serving the beer. IMO, the best way to do this is to
use the same PSI to serve the beer as you use for carbonation. That way
the level of carbonation will not change.
In order to get a smooth pour (no foaming), you also want the resistance
of your tubing to equal the PSI of your dispensing pressure. Different
kinds of tubing are rated at a certain PSI/foot depending on size of
the tubing and to a lesser extent the material it is made from. The
standard beverage tubing is 3/16" ID and has a resistance rating of
~2 PSI/foot.
So, if you look on the chart based on your temp and level of carbonation
preferences and find that you need 12 PSI to carbonate your beer, you would
also use 12 PSI to serve your beer and need to supply 12 PSI of resistance
in your tubing (6 feet of tubing rated at 2 PSI/foot). Using too much tubing
is better than using too little though, so generally it's a good idea to
start out with it being a little long and then trim back if you need to.
12 PSI carbonation = 12 PSI dispensing = 12 PSI resistance.
This is called having a "balanced" system, and all of the values are
constant over the life of the keg. None of them depend on the volume
of beer. So it's a truly "set and forget" system.
John.
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Date: 22 Jun 2006 14:25:56
From: Jim Stansell
Subject: Re: good technical kegging reference
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On 22 Jun 2006 18:00:14 GMT, John 'Shaggy' Kolesar <spam@shagg.net >
wrote:
>
>The next step is serving the beer. IMO, the best way to do this is to
>use the same PSI to serve the beer as you use for carbonation. That way
>the level of carbonation will not change.
>
>In order to get a smooth pour (no foaming), you also want the resistance
>of your tubing to equal the PSI of your dispensing pressure. Different
>kinds of tubing are rated at a certain PSI/foot depending on size of
>the tubing and to a lesser extent the material it is made from. The
>standard beverage tubing is 3/16" ID and has a resistance rating of
>~2 PSI/foot.
>
>So, if you look on the chart based on your temp and level of carbonation
>preferences and find that you need 12 PSI to carbonate your beer, you would
>also use 12 PSI to serve your beer and need to supply 12 PSI of resistance
>in your tubing (6 feet of tubing rated at 2 PSI/foot). Using too much tubing
>is better than using too little though, so generally it's a good idea to
>start out with it being a little long and then trim back if you need to.
>
>John.
There might be other factors that add to the resistance in the system
if you're dispensing from taps mounted on the outside of a fridge or
kegerator. The taps themselves can add about 1 PSI worth of
resistance, plus you'll increase the resistance about 1 PSI (I think)
for each foot above the keg (or beer level in the keg) to the tap. I
sometimes notice that my beer pours a little slower right at the end
of the keg, presumably because of the additional height it must
travel. Or, I might be imagining it!
However, if you're using the standard cobra tap to serve, John's
explanation is spot on. John, where were you five years ago when I was
balancing my own system? !!!!!
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Date: 22 Jun 2006 21:01:52
From: John 'Shaggy' Kolesar
Subject: Re: good technical kegging reference
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On Thu, 22 Jun 2006 14:25:56 -0400, <jim.stansell@comcast.net > wrote:
> There might be other factors that add to the resistance in the system
> if you're dispensing from taps mounted on the outside of a fridge or
> kegerator. The taps themselves can add about 1 PSI worth of
> resistance, plus you'll increase the resistance about 1 PSI (I think)
> for each foot above the keg (or beer level in the keg) to the tap. I
> sometimes notice that my beer pours a little slower right at the end
> of the keg, presumably because of the additional height it must
> travel. Or, I might be imagining it!
Yeah, the taps add additional resistance, also any height differential
technically does count since the gravity also adds to the resistance.
However, IMO, trying to calculate it down to that level is probably
overkill. It's not an exact science. I think that just going with the
resistance and length of tubing (leaving it a little long and trimming
if necessary) is as accurate as you need to get.
John.
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Date: 22 Jun 2006 14:18:33
From: John 'Shaggy' Kolesar
Subject: Re: good technical kegging reference
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On 21 Jun 2006 20:04:24 -0700, <naramsey@umich.edu > wrote:
> Brewers,
>
> I am in the process of (finally!) kegging my beers. I seek a good all
> around reference for kegging and carbonation matters for a technically
> minded person (i.e. not just a set of tables, rules and precedures).
>
> As I play with my new gizmos, tons of little questions come to mind
> that are too small and numerous to go posting here. If I had a better
> understanding of the hardware (particularly the regularor) I'd feel
> better.
Ask away, that's what the group is here for.
John.
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Date: 22 Jun 2006 05:25:53
From: yddraig
Subject: Re: good technical kegging reference
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naramsey@umich.edu wrote:
> Brewers,
>
> I am in the process of (finally!) kegging my beers. I seek a good all
> around reference for kegging and carbonation matters for a technically
> minded person (i.e. not just a set of tables, rules and precedures).
>
> As I play with my new gizmos, tons of little questions come to mind
> that are too small and numerous to go posting here. If I had a better
> understanding of the hardware (particularly the regularor) I'd feel
> better.
>
> Thanks,
>
> -Nick
Congrats, kegging is the *ONLY* way to go. Currently I'm in the
process of changing from Corny kegs to single entry Sankey kegs. The
only drawback to kegging is that there no *dead soldiers* to count to
tell you when you've had enough ;).
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Date: 22 Jun 2006 05:55:07
From: Dick Adams
Subject: Re: good technical kegging reference
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<naramsey@umich.edu > wrote:
> I am in the process of (finally!) kegging my beers. I seek a
> good all around reference for kegging and carbonation matters
> for a technically minded person (i.e. not just a set of tables,
> rules and precedures).
>
> As I play with my new gizmos, tons of little questions come to
> mind that are too small and numerous to go posting here. If I
> had a better understanding of the hardware (particularly the
> regularor) I'd feel better.
The regulator adjusts the CO2 pressure on the keg. For serving
beer the optimal psi is 8-10. For force carbonation, it's at
least 20 psi.
The underlying theory is to use the CO2 to evacuate any oxygen
in the keg amd to have the beer absorb the CO2.
This is done by filling with CO2 and then releasing all of the
gas. I do it twice. After the second release, I attach the CO2
to the "beer out" valve so the CO2 fills the tank from the bottom
up, i.e., more absorption. Then I disconnect the CO2 from the
"beer out" and and attach it to the "beer in". This requires
two different disconnects. I release the gas one more time and
let the keg fill with CO2. Then I roll the keg on my lap until
I get tired of rolling it. More absorption. Then it goes into
the refrigerator for 4 to 7 days with the CO2 tank attached.
There is a chart you should copy at http://tinyurl.com/qll94.
For a diatribe on the evils of forced carbonation, see
http://tinyurl.com/m5uny
Dick
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Date: 22 Jun 2006 14:16:44
From: John 'Shaggy' Kolesar
Subject: Re: good technical kegging reference
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On Thu, 22 Jun 2006 05:55:07 -0000, <rdadams@smart.net > wrote:
> The regulator adjusts the CO2 pressure on the keg. For serving
> beer the optimal psi is 8-10.
There are lots of variables. IMO, the best PSI is the one that gives you
a balanced system. Use the chart you included further below to look up
what PSI is needed at your desired temp in order to give your desired
amount of carbonation. That PSI is the optimal pressure for serving the
beer. It's going to be different depending on how warm/cold and
flat/carbonated the brewer wants their beer. One range won't work well
for everybody.
> For force carbonation, it's at least 20 psi.
That's one way to do it, however I personally like to set the regulator to
the PSI that you found as described in the previous paragraph and let it
sit with the tank connected and turned on for about a week. IMO, it gives
you much more predictable results.
> There is a chart you should copy at http://tinyurl.com/qll94.
This is where you get your carbonation/serving PSI from.
> For a diatribe on the evils of forced carbonation, see
Oh please. Talk about a totally clueless article with a major agenda
to push (typical CAMRA BS). IMO, giving someone a link like that to read
probably does their brewing education more harm than good. Sure, there are
definitely valid opinions on both sides as to what type of carbonation
an individual brewer prefers to use. But the amount of rediculous
(probably intentional) misinformation in articles like that doesn't do
anybody any good (except for the activist that is trying to force their
view on everyone).
John.
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Date: 22 Jun 2006 10:43:24
From: yddraig
Subject: Re: good technical kegging reference
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naramsey@umich.edu wrote:
> > I'll try to keep it simple. The regulator reduces the high pressure
>
> An odd choice, given that the word "technical" is in the title of my
> post and I keep asking for details! :)
>
> > CO2 (1200 PSI) down to a useable level (0-60 PSI), it also maintians
> > the pressure at a constant (regulated) PSI. By turning the screw you
> > can raise/lower the regulated pressure. The regulator accomplishes
> > this task (warning technical content) by using a diaphram, a needle
> > valve and a spring. Thi spring is in the low pressure side and presses
> > the diaphram and the needle valve closed. The screw is used to
> > increase the tension on the spring. When the spring tension is
> > increased the needle valve is allowed to open, causing gas to flow
> > through. The back pressure of the keg then assists in keeping the
> > needle valve closed and thus keeping the pressure near the set point.
>
> Now that's better...
>
> So then the gauge simply measures the ambient pressure on the "low
> pressure side", right?
Correct
>
> This raises another question. I have noticed the following behavior
> that I don't fully understand.
> Suppose I close the (output) valve on the regulator and open the co2
> tank. The gauge reads some pressure. If I then hook up some closed
> system to the valvue (e.g. an empty keg, or just the line with a
> disconnect on the end) and then open the valve, the pressure drops and
> stabilizes at some lower level. I would have expected it to drop
> momentarily while the gas was flowing and then to restabilize at the
> original PSI. Why is this?
I'm going to guess that it has to do with the amount of gas in the low
pressure side. When the regulator shuts off the diaphram expands
slightly (after closing the needle valve), because the volume of gas
is quite small it is possible compress the gas in the low pressure side
enough (due to diaphram movement) to actualy create an increase of
pressure (ideal gas law PV=nRT
http://www.7stones.com/Homepage/Publisher/Thermo1.html ). If you
operate in reverse, connect the closed system, let it equalize then
close the shutoff you should see no increase in pressure.
>
> On a related note, regarging "dialing in pressure" for force
> carbonation, I have heard people say that one should set the pressure
> by closing the valve and opening the co2 tank to take a pressure
> reading, and then adjusting the pin and repeating until you get the
> right pressure reading. Apropos my question above, this is not the
> pressure that will in fact be delivered to the keg when the valve is
> opened because the pressure will drop when you do this. Which pressure
> do you pay attention to when you are reading the PSI from some table
> for force carbonation?
>
> -Nick
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Date: 22 Jun 2006 10:23:11
From:
Subject: Re: good technical kegging reference
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> I'll try to keep it simple. The regulator reduces the high pressure
An odd choice, given that the word "technical" is in the title of my
post and I keep asking for details! :)
> CO2 (1200 PSI) down to a useable level (0-60 PSI), it also maintians
> the pressure at a constant (regulated) PSI. By turning the screw you
> can raise/lower the regulated pressure. The regulator accomplishes
> this task (warning technical content) by using a diaphram, a needle
> valve and a spring. Thi spring is in the low pressure side and presses
> the diaphram and the needle valve closed. The screw is used to
> increase the tension on the spring. When the spring tension is
> increased the needle valve is allowed to open, causing gas to flow
> through. The back pressure of the keg then assists in keeping the
> needle valve closed and thus keeping the pressure near the set point.
Now that's better...
So then the gauge simply measures the ambient pressure on the "low
pressure side", right?
This raises another question. I have noticed the following behavior
that I don't fully understand.
Suppose I close the (output) valve on the regulator and open the co2
tank. The gauge reads some pressure. If I then hook up some closed
system to the valvue (e.g. an empty keg, or just the line with a
disconnect on the end) and then open the valve, the pressure drops and
stabilizes at some lower level. I would have expected it to drop
momentarily while the gas was flowing and then to restabilize at the
original PSI. Why is this?
On a related note, regarging "dialing in pressure" for force
carbonation, I have heard people say that one should set the pressure
by closing the valve and opening the co2 tank to take a pressure
reading, and then adjusting the pin and repeating until you get the
right pressure reading. Apropos my question above, this is not the
pressure that will in fact be delivered to the keg when the valve is
opened because the pressure will drop when you do this. Which pressure
do you pay attention to when you are reading the PSI from some table
for force carbonation?
-Nick
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Date: 22 Jun 2006 18:39:48
From: John 'Shaggy' Kolesar
Subject: Re: good technical kegging reference
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On 22 Jun 2006 10:23:11 -0700, <naramsey@umich.edu > wrote:
> This raises another question. I have noticed the following behavior
> that I don't fully understand.
> Suppose I close the (output) valve on the regulator and open the co2
> tank. The gauge reads some pressure. If I then hook up some closed
> system to the valvue (e.g. an empty keg, or just the line with a
> disconnect on the end) and then open the valve, the pressure drops and
> stabilizes at some lower level. I would have expected it to drop
> momentarily while the gas was flowing and then to restabilize at the
> original PSI. Why is this?
Because consumer grade regulators are not very accurate. ;)
When you close the output side and open the tank you're hitting it with
a very quick burst and then the diaphram/spring is snapped shut. When you
connect the keg to it the diaphram/spring opens again and eventually closes
more slowly as pressure gradually equalizes. The diaphram/spring doesn't
shut at the same pressure both times. No, it's not really supposed to
do that, but it's a mechanical limitation in how they design these things
in order to make them relatively inexpensive.
Take a typical spring, stretch it fairly far and then suddenly let go and it
will spring back to one size. Take the same spring, stretch it open the
same amount, but this time keep your hands on the ends and gradually ease
off on how hard you're pulling the ends apart. Eventually the spring will
stop closing, but probably not to the same size as it did when you just
let go of it.
It would probably be more accurate to set the regulator screw with the keg
connected than it would with the output of the regulator closed. But it's
still not going to be 100% perfect. Also, over time these regulators can
drift in their ability to set a pressure. I haven't noticed it with mine,
but I've heard of some that after a couple of years don't register nearly as
accurately as they used to. IE, the gauge may say 10 PSI, but you've
really got 15 PSI coming through. It's probably due to the springs and/or
diaphrams getting worn out over time.
> On a related note, regarging "dialing in pressure" for force
> carbonation, I have heard people say that one should set the pressure
> by closing the valve and opening the co2 tank to take a pressure
> reading, and then adjusting the pin and repeating until you get the
> right pressure reading. Apropos my question above, this is not the
> pressure that will in fact be delivered to the keg when the valve is
> opened because the pressure will drop when you do this. Which pressure
> do you pay attention to when you are reading the PSI from some table
> for force carbonation?
As I mentioned above, the pressure on the gauge while the keg is connected
will probably be more accurate than the reading it shows when you close
the regulator valve and hit it with a quick burst of pressure from the
tank.. Also, keep in mind that when you first connect a new keg, gas will
continue slowly seeping into the keg over time as the beer absorbs CO2. The
gauge is only going to give you a meaningful reading when no gas is flowing.
IMO, you can close the regulator output valve and open the CO2 tank
to get your initial setting and then connect the keg (making the pressure
drop) until gas stops flowing. It may take awhile, but once the gas
stops and everything stabilizes, then you can "dial in" the pressure if
you want to fine tune it.
In a perfect world you wouldn't have to do that, but it should get you
close enough that it doesn't matter.
Also, you really should have a check valve between your keg and
the regulator. Some regulators come with a check valve built into the
output valve, but if yours doesn't you'll want to get one seperately and
put it inline. This prevents pressure from backing up the system into
your regulator. You'll be glad you did this the first time you over
carbonate a keg and the check valve prevents the keg from shooting beer
backwards through your gas line (which can ruin the regulator).
John.
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