How long to force carb: The calculator

[pcqypcqy]

OK, got the stepwise stuff working. Prelim numbers suggest 30 psi for 48 hours puts you at 2.5 volumes, then you set to your serving/long term equilibrium pressure. I'll play with this a bit more before sharing to make it neater and double check it's working correctly, probably will be Monday when I'm back at my work desk before I can do that.

Been thinking about the data collection, I'll find a spare dial gauge and barb fitting to screw it into, attach it with a short length of hose to a gas disconnect, then put this on as soon as I take the carbonation gas off the keg. Hopefully the volume within the gauge is negligible with respect to the headspace, and in any case if I let the keg reach equilibrium while the gauge is connected, then it shouldn't matter anyway. I can then watch that gauge to determine when equilibrium for that carbonation step has been reached.

Initially I'll just use fullish corny's as I'll test it on beer that I plan to drink. After christmas parties and case swaps are out of the way, I'll have a bit of spare keg capacity to maybe keg some half batches and gather that data as well.

 

[pcqypcqy]

I don't know about the equation but that seems to work for my ales
the only time i'm interested in g/l is if i'm priming for bottling other than that if it's over carbed from forgetting about it or any over reason I just degas it too easy.

Just checking, Lyrebird is talking about g/L of dissolved CO2, I get the feeling you're talking about g/L of added priming sugar?

 

[Lyrebird_Cycles]

You'll need to make a correction for the headspace volume anyway, just add any extra volume for the gauge to that and you'll be good to go.

Edit: this is in reply to #41 above.

 

[pcqypcqy]

Another idea - would measuring the gas bottle weight with a set of scales do the trick? I'm thinking a set of commercial scales that could handle the weight of a full gas bottle, reg, etc, but still measure to the gram or less.

I've seen these online for reasonable prices and I was thinking of getting one to calibrate the volumes on my sight glasses anyway.

if the equilibrium volume for 2.5 volumes is about 5g/litre, this should be measurable at the gram level for a full corny keg?

 

[Lyrebird_Cycles]

As I see it measuring the gas bottle won't take account of the gas "blown off" when you equalise the pressure in the corny and any result could easily be thrown off by leaks.

If you can get reliable <1 g accuracy with a mass of around 30 kg, I *think* you could do it measuring the corny itself but you'd have to be very careful to exclude things like condensation.

 

[damoninja]

For Damo and / or pcqy:

I'm assuming all the data you've collected is for an almost full Corny keg or similar.

As I see it, carbonation time will be dependent on fluid column depth so you'll get different results for vessels of different heights. I can't see why the relationship wouldn't be linear but some data would be good.

Correct - that's in my list of assumptions

FTR - this thing is getting out of my depth / care care factor, I love excel to bits but usually use it for automation and data analysis using formulas for data manipulation opposed to equations. Some people get annoyed with people taking charge but I've got no issues with my sheet and calc becoming obsolete in the interest of better model.

 

[GibboQLD]

That's interesting, subscript on the superscript. ASCII Special? It handles like text. How did you do that LC?

OT: It'll be the forum's stylesheets -- you can stack super/subscript with CSS as many times as you like, theoretically, and you'll still be able to copy/paste it like normal text.

Using the code below in an online evaluator will give you this, for example:

test
<font style="vertical-align: super;">test
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<font style="vertical-align: super;">test
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<font style="vertical-align: super;">test
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</font></font></font></font></font></font></font>

And now, back to our regularly scheduled program...

 

[pcqypcqy]

Correct - that's in my list of assumptions

FTR - this thing is getting out of my depth / care care factor, I love excel to bits but usually use it for automation and data analysis using formulas for data manipulation opposed to equations. Some people get annoyed with people taking charge but I've got no issues with my sheet and calc becoming obsolete in the interest of better model.

Yeah, sorry about that You just happened to start the thread at the same time as I was looking into this myself AND had way too much spare time on my hands.

Here's the spreadsheet based on lyrebirds input.

It's not a pretty chart, but I'm guessing there are too many variables at play here to simplify it that much.

Maybe we can think of some simple cases that are representative of what people do, like 24 hours at 40 or 30 psi, that sort of thing.

Inputs are all highlighted yellow, the rest should all be calculations or constants.

View attachment carbonation over time2.xlsx

 

[pcqypcqy]

As I see it measuring the gas bottle won't take account of the gas "blown off" when you equalise the pressure in the corny and any result could easily be thrown off by leaks.

If you can get reliable <1 g accuracy with a mass of around 30 kg, I *think* you could do it measuring the corny itself but you'd have to be very careful to exclude things like condensation.

I might try a combination of methods. I want the scales anyway to calibrate my volumes, and I'm thinking about a kegmenter currently so if I get the spunding valve off that and pop it on the corny, should give me two methods to check without having bought anything specifically for it. If I adjust the spunding valve to have a high blow off pressure, theoretically it shouldn't blow off at all and the gauge will give me the headspace pressure.

The scales say they're precise to a gram, but at the price they're selling for I doubt it (around $50 from ebay).

To get scales that can reliably measure 40kg to 0.1g though you're talking a few thousand dollars, so it's a bit of a jump.

 

[damoninja]

Yeah, sorry about that You just happened to start the thread at the same time as I was looking into this myself AND had way too much spare time on my hands.

No sweat just throwing it out there so it's clear no toes being stepped on

 

[TheWiggman]

Any chance you could change the calculator so it deals with all SI units? (i.e. not PSI)

 

[pcqypcqy]

Any chance you could change the calculator so it deals with all SI units? (i.e. not PSI)

Try this.

I'm normally a stickler for SI as well, but I've found that with nearly all the references for brewing are in US Imperial units that sometimes it's just easier to go with the flow.

View attachment carbonation over time-si.xls

 

[pcqypcqy]

No sweat just throwing it out there so it's clear no toes being stepped on

If you want to give me an unlocked version of your sheet, I can use my model to update your charts with the curved increase over time (instead of linear as it is currently).

 

[Liam_snorkel]

in SI too? That would be super.

 

[pcqypcqy]

This fell by the wayside, but I'm thinking of doing some experiments soon.

I'll use my threaded pin lock gas disconnect and a closed spunding valve to measure, then I'll force carb at some temp/pressure for some time, and then disconnect the gas, put the spunding valve on and wait for the head pressure to reach equilibrium.

I'll then read the equilibrium pressure off the spunding valve gauge, and using the temperature read off a chart how many volumes were dissolved in that time step.

Not 100% accurate, but will give an indication of how the dissolved volumes changes with time.