Calculating cu inch at PSI

[Vale71]

I was using the carbonation tables commonly referenced by homebreweres. I don't know if AJ's formulas are more accurate or not.
As for STP's it's a real quagmire, especially if you live in a metric country and try and use imperial units... It turns out in the metric world the standard temperature is 15°C and not 25°C as I erroneously used.
As for headspace pressure I was going on the assumption that the gas bottle would be at the same temperature as the keg so that there would be no cooling of the injected gas so as to maximize yield.

 

[doug293cz]

I was using the carbonation tables commonly referenced by homebreweres. I don't know if AJ's formulas are more accurate or not.
As for STP's it's a real quagmire, especially if you live in a metric country and try and use imperial units... It turns out in the metric world the standard temperature is 15°C and not 25°C as I erroneously used.
As for headspace pressure I was going on the assumption that the gas bottle would be at the same temperature as the keg so that there would be no cooling of the injected gas so as to maximize yield.

The best known table in the homebrew arena (the one linked by day_trippr above) is generated in a spreadsheet from an unknown equation. The equation I showed above was fitted to the ASBC table and has an RMS disagreement with the table of 0.01 volumes and a worst case error of -0.044 volumes, so it's pretty accurate.

STP (as I learned in freshman chemistry) is 0°C and 1 atm - looks pretty metric to me. Never heard of 15°C as a standard temp. It's critical in the definition of a volume of CO2.

Changes in the initial gas temp will shift the numbers somewhat, but the biggest error you made was doing calculations with gauge pressures rather than absolute pressures. The only legit math you can do with gauge pressures is subtraction. All other operations need to be done with absolute pressures.

Brew on

 

[Silver_Is_Money]

How many grams of CO2 are in a 5 gallon Keg of beer plus its headspace when at equilibrium at 2.4 volumes and at 36 degrees F?

What would be the carbonation level if one tossed the requisite grams of dry ice as calculated for the condition seen above (minus the grams already in solution from fermentation) into a keg that had 5 gallons of beer in it, and sealed up the keg and then waited 2-3 weeks? Lets say the keg is stored at 36 degrees F.

 

[Vale71]

The dry ice will quickly sublimate causing very high pressure to form in the keg. Either the PRV will release pressure or the keg will explode, so I guess after 2-3 weeks the beer will be quite flat. Or there won't be any beer if the keg exploded.

DO NOT TRY THIS AT HOME.

 

[Silver_Is_Money]

The dry ice will quickly sublimate causing very high pressure to form in the keg. Either the PRV will release pressure or the keg will explode, so I guess after 2-3 weeks the beer will be quite flat. Or there won't be any beer if the keg exploded.

DO NOT TRY THIS AT HOME.

Would this somehow be different as to danger level from attempting a "one shot" pressurization via a CO2 cylinder as has been discussed above?

 

[Silver_Is_Money]

Yes, I use "chart pressure" for the life of the keg. Refer to our favorite carbonation table to determine your "chart pressure". Then, use the only beer line length calculator worth using to determine the minimum tubing length give the chart pressure, tubing ID, and a few other user-specific parameters.

I use 12 psi indicated (which is roughly 11 psi at the keg once the two check valves in the gas paths are accounted for). When I was using standard 3/16" ID solid pvc tubing (ala Bevlex 200) I used 12 feet of it for most beers, which is roughly 1 foot per PSI, and always got great pours. When I switched to 4mm ID line, the lengths dropped to 6', with identical quality pours. So ID is important!

Cheers!

How would 5.5 ft. of 4mm ID and 10 PSI sound as to pours?

 

[day_trippr]

Perfecto!
I'm running 6 feet at the pressure related above...
[edit] Wait - I already said that

fwiw, @Bobby_M did some empirical testing and ended up at 5.5 foot lengths in his EVAbarrier kits...

Cheers!

 

[Vale71]

Would this somehow be different as to danger level from attempting a "one shot" pressurization via a CO2 cylinder as has been discussed above?

Definitely. You're adding a lot of CO2 all at once which is not possible when using a CO2 regulator as it has an upper limit and usually its own PRV as well.

 

[Pkrd]

I've always assumed STP to be 760mmHg, 20°C because thats what is used in my field.

Peeking into the rabbit hole I'm reminded that at 4°C water reaches it's maximum density, and thus I can fit the maximum amount of beer in my keg. That's some practical, useful physics.

 

[Vale71]

Wikipedia alone lists 21 different "standards" for STP.
It begs the question of whether it still makes sense at all to use the expression "standard"...

 

[Vale71]

STP (as I learned in freshman chemistry) is 0°C and 1 atm - looks pretty metric to me. Never heard of 15°C as a standard temp. It's critical in the definition of a volume of CO2.

15°C at 1 atm is ICAO's ISA standard model of the atmosphere. As a fellow pilot I assume you'll be familiar with it.

 

[Pkrd]

I want NIST traceable standards. How do I know I have quality beer otherwise?

 

[Silver_Is_Money]

Perfecto!
I'm running 6 feet at the pressure related above...
[edit] Wait - I already said that

fwiw, @Bobby_M did some empirical testing and ended up at 5.5 foot lengths in his EVAbarrier kits...

Cheers!

Does anyone make 4mm suitable barbs, or are EVAbarrier fittings and tubing the only way to go here?

 

[VikeMan]

Does anyone make 4mm suitable barbs, or are EVAbarrier fittings and tubing the only way to go here?

AFAIK, 4mm isn't very standard/common. I use 3/16" ID tubing, with 1/4" barb swivel nut connectors...
https://www.morebeer.com/products/flare-fitting-set-14-nut-barb.html I heat the end of the tubing in hot water to soften it slightly, then push the barb in. It makes a great interference fit that won't come loose. It's easiest to do this if you have the swivel nut connector already attached to a flare type QD...
https://www.morebeer.com/products/ball-lock-beverage-flare.html
With this arrangement, there's no need for any type of clamp to hold the tubing on the barb, and you can change out terminated lines without having to cut already installed tubing or remove clamps.

With 3/16", you would need a longer line length than with 4mm (assuming similar "roughness"), but standard tubing isn't expensive.

 

[day_trippr]

Does anyone make 4mm suitable barbs, or are EVAbarrier fittings and tubing the only way to go here?

You can stretch the 4mm over a 1/4" barb with the judicious use of heat, did so myself on a 6-way barbed manifold I wasn't about to replace for an MFL style just to replace the gas tubing. That said, the PTC fittings are a joy to use vs swivel nuts...

Cheers!

 

[Silver_Is_Money]

You can stretch the 4mm over a 1/4" barb with the judicious use of heat, did so myself on a 6-way barbed manifold I wasn't about to replace for an MFL style just to replace the gas tubing. That said, the PTC fittings are a joy to use vs swivel nuts...

Cheers!

Did you apply hose clamps?

 

[doug293cz]

Wikipedia alone lists 21 different "standards" for STP.
It begs the question of whether it still makes sense at all to use the expression "standard"...

Yeah, I saw that. However, whenever I see a detailed definition of a "volume" of CO2, it states 0°C (32°F.) The paper I included in may last post is one example, and here is another: Master the Action: Carbonation - Brew Your Own

Brew on

 

[doug293cz]

15°C at 1 atm is ICAO's ISA standard model of the atmosphere. As a fellow pilot I assume you'll be familiar with it.

The ISA "Standard Atmosphere" is a whole different animal than "STP" for chemistry/physics. Also, the standard atmosphere defines pressure and temp as a function of altitude. Something very important for aerodynamic performance.

Brew on

 

[doug293cz]

How many grams of CO2 are in a 5 gallon Keg of beer plus its headspace when at equilibrium at 2.4 volumes and at 36 degrees F?

What would be the carbonation level if one tossed the requisite grams of dry ice as calculated for the condition seen above (minus the grams already in solution from fermentation) into a keg that had 5 gallons of beer in it, and sealed up the keg and then waited 2-3 weeks? Lets say the keg is stored at 36 degrees F.

CO2 has a density of 1.977 g/L at 0°C (32°F) and 1 atm pressure. So, one volume of carbonation is 1.977 g/L of beer. Note that CO2 is not quite an ideal gas, and has a density a bit higher than what you would calculate from the ideal gas law (1.965 g/L.)

Brew on

 

[day_trippr]

Did you apply hose clamps?

Yes, I did. I now have a crapton of unused band clamps after switching literally every other gas and liquid connection to PTC fittings and just couldn't bring myself not to use them for that manifold and chance an issue down the road.

Anyway, after heating the ends up to go over the barbs I put ~1" long pieces of heat shrink tubing over the same ends and shrunk them tight before applying the clamps. That's one that you "probably don't need" but it keeps the worm clamp from digging into the line...

Cheers!

 

[Silver_Is_Money]

Very nice!!! The heat shrink tubing as a protection is a great idea.

 

[Bobby_M]

The Duotight fittings for EVAbarrier tubing make stretching over barbs a useless endeavor. You can hook up 5 kegs including liquid and gas runs in about 20 minutes without screwing around with heat, clamps, flare gaskets, etc.

 

[day_trippr]

Well...if you have a $70 barbed manifold I submit it does actually make sense

Cheers!

 

[Silver_Is_Money]

Duotight fittings do not seem to be currently available, and there is no guarantee that they will either become or remain available going forward. An alternative is currrently shipping, but it has only single 'O- Rings' (whereby double 'O -rings' put the 'Duo' in Doutight), and is thereby suspect of being at least potentially of lesser quality thereby.

 

[day_trippr]

John Guest has a lot of experience in ptc fittings. And there's also DMfit single o-ring fittings that seem well made to me. Both are readily available today.

I wouldn't be so quick to embrace the dual ring design anyway...

Cheers!

 

[Bobby_M]

Well...if you have a $70 barbed manifold I submit it does actually make sense

Cheers!

I like the EVA/DUO combo so much more that I would sell that $70 manifold for $50 and start over.

 

[Bobby_M]

Duotight fittings do not seem to be currently available, and there is no guarantee that they will either become or remain available going forward. An alternative is currrently shipping, but it has only single 'O- Rings' (whereby double 'O -rings' put the 'Duo' in Doutight), and is thereby suspect of being at least potentially of lesser quality thereby.

I don't know where you are shopping but I think you've been given bad information. I have them in stock and the vendor I buy them from has plenty. Daytripper is right though, if in the future DUO was unavailable, John Guest and DMfit have been doing pushfit for a very long time. Don't talk yourself into an inferior setup for invalid reasons.