I had read that the weight of a full keg at one point was 50 lbs, so that's the number I've been going with.
BYO Projects article is by Derrick Marlow.
I use a postal scale. I got it as a gift but if you look for something like that on Amazon, should get you thereSo, this discussion begs the question: What scales should I be using to weight my kegs?
Is this off final gravity or original gravity?It'll depend on temperature. At 70F, water is about 8.33 pounds per gallon. At 40F it's more like 8.35. There are calculators abound on the internet that can give you the weight of water (often in multiple formats, lb/gal, kg/l, etc) for a given temperature.
Once you have your water weight, multiply that by your specific gravity and you have your beer weight. So 1 gallon of beer at 70F and at 1.010 is 8.33*1.010 or 8.41 pounds.
to the max,
Old thread.pretty darned accurate
Is this off final gravity or original gravity?
Assuming it's final gravity
I prime my kegs with sugar nowadays , but like to leave a little headspace so I can fit up to 16oz of priming sugar solution. I inject it via the gas post and my gas diptubes are trimmed, but still like to leave a little extra to account for thermal expansion.Also, if you are force carbing, leaving a little room to maximize surface area will result in a quicker carbonation. This helps to get to drinking the beer a little quicker.
No, i don't think so. Mass and (I'm surmising) volume are lost as CO2 departs. Less dense, but almost certainly not, er, bigger. More mathy answers may be forthcoming. Doug?more volume after fermentation
I wonder whether either fermentation or carbonation significantly affect wort/beer volume or mass. I'm not sure what "significantly" means, of course. I haven't noted other conversation here about accounting for these (small, I think) effects in homebrewing tasks/decisions.will gain mass back through conditioning
These numbers look about right to me (where I did some similar calcs.)I don't think anyone was claiming truly profound changes to mass here
[edit] Although...found this on the Brewing Reddit. I can't vouch for it but there were other posts in the same thread that confirmed/amplified it...
"Turns out for five gallons/18.9 L of 1.060 wort at 75% apparent attenuation, 449.1 L/ 15.86 cubic feet/ 118.64 gal of CO2 is produced (standard temperature and pressure. This amounts to 0.88 kg/ 1.94 lb of CO2!"
For sure that's a lot more mass shed than would be gained if it's then brought up to 2.5 volumes of CO2...
Cheers!
Sounds like an interesting question to look at Sunday, when I will have some time.Wort will lose mass through fermentation, but will gain mass back through conditioning. It would take someone like our resident physics dude @doug293cz to calculate the net change but I suspect fermentation loss exceeds carbonation gain...especially as the OG increases...
Cheers!
Ok, let's give this a go. For simplicity, I will use a sucrose/water solution (after all that's what Plato and Brix used, and we pretend that beer behaves the same way.)Wort will lose mass through fermentation, but will gain mass back through conditioning. It would take someone like our resident physics dude @doug293cz to calculate the net change but I suspect fermentation loss exceeds carbonation gain...especially as the OG increases...
Cheers!
Give or take... Wow, there's a giraffe.. Thank you for doing the math.. clearly more sober than I, so I'm going to trust it.Ok, let's give this a go. For simplicity, I will use a sucrose/water solution (after all that's what Plato and Brix used, and we pretend that beer behaves the same way.)
Water has a density of 0.9982 g/cm^3 at 68°F (20°C), and sucrose has a density of 1.587 g/cm^3. Let's assume we start with 20 L of a 15°P solution (15% by weight of sucrose.) 15°P corresponds to an SG of 1.06111 (from NIST tables), so 20 L weighs 20 L* 998.2 g/L * 1.06111 = 21,184 g (21.184 kg.) The weight of the sucrose is 21,184 g * 0.15 = 3177.6 g, and the water weighs 21,184 g * 0.85 = 18,006.4 g.
Each 342.30 g of sucrose that is fermented creates 4 * 44.01 g = 176.04 g of CO2, 4 * 46.07 g = 184.28 g of ethanol (EtOH), and consumes 18.01 g of water. So, if we ferment all of the sucrose we create:
3177.6 * 176.04 / 342.30 = 1634.2 g of CO23177.6 * 184.28 / 342.30 = 1710.7 g of EtOH3177.6 * -18.01 / 342.30 = -167.2 g of water lostThus after fermentation we have a solution containing 1710.7 g of EtOH and 18,006.4 - 167.2 = 17,839.2 g of water (ignoring any water evaporation during fermentation.) The total weight of the solution will be 1710.7 + 17,839.2 = 19,549.9 g. This solution will be 100% * 1710.7 g / 19,549.9 g = 8.75% EtOH by weight (~10.9% ABV.) The solution has an SG of 0.9854, so the volume will be 19,549.9 g / (998.2 g/L * 0.9854) = 19.875 L.
So, we lost 20 - 19.875 = 0.125 L (125 ml or ~ 1/2 cup) of volume during fermentation (again ignoring any water or EtOH evaporation during fermentation.)
What about the CO2? A fermentation done at 68°F will have a residual carbonation level of 0.84 volumes. 1 volume is equal to 1.977 g/L of CO2, so we will have:
19.875 L * 0.84 * 1.977 g/L = 33.0 g of CO2 in solution1601.2 g of CO2 will have bubbled out of the solution during fermentation. The volume effect of 33 g of CO2 in solution is unknown at this point, but should be small compared to the total volume.
Brew on
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