Pin Lock Keg Volume

[CGish]

I recently purchased four pin lock kegs. Their external dimensions are all the same. I was under the impression from my reading that most corny kegs are very similar in volume - around 5 to 5.2 gallons of usable space - in spite of slightly different exterior dimensions.



Part of the switch from bottling is altering my batch volume to end up with a full keg. The first three kegs just got filled with existing batches, and the excess in the fermentor was bottled. I got around to checking the volume of the final keg to adjust my batch sizes and I found something surprising.

The keg weighed 9 lbs 10.9 ozs empty.

When I filled it with water to about 1/8" below the gas inlet dip tube, the weight was 47 lbs 11.6 ozs.

Gas Dip Tube Length:


When I filled it with water right to the brim - so I could just slide the lid in - it weighed 50 lbs 15.6 ozs.

Using the weight of water as 8.33 pounds per gallon, this comes out to:

47.725 pounds full - 9.68125 pounds empty = 38.04375 pounds of water / 8.33 = 4.567 Gallons to the bottom of the gas inlet.

OR

50.975 pounds full - 9.68125 pounds empty = 41.29375 pounds of water / 8.33 = 4.957 Gallons stuffed completely full (impossible if one doesn't want their regulator ruined or a face full of beer if you need to depressurize the tank)

Question: Is 4.5 gallons of usable space a normal size for corny kegs OR do I have four odd ducks OR did I make a mistake in my math somewhere?

Thank You,
Cody

 

[eluterio]

Congrats on getting kegs and hope you enjoy them. Your math is probably correct maybe try one more experiment and fill a carboy up with 5 gallons of water and pour that into your keg. I honestly would be interested in seeing the difference. I have the pepsi kegs and ive added what I think is 5 gallons from my carboy. It came out short for reaching the top of my pepsi keg by a few inches. I would just start adjusting to make 5.5 gallons in your carboy lose about .5 from fermentation and the rest in your keg.

 

[Furore]

Your math looks pretty good to me. I cant say that i have ever weighed my kegs to check beforehand, but corny kegs should hold a standard volume.

You do have to consider that you will lose some of your volume to evaporation during fermentation, as well as the small amount from when you rack your beer off the trub. From when I used to bottle, I recall that I would typically get a yield of 48-50 bottles and I started with 5 gallons. 5 gallons is 640oz which is 53.3 12oz bottles. So say i lost 5 bottles worth of volume, thats 60oz, which is more or less a half gallon of liquid (64oz), bringing you right in line with your calculation for being right below the inlet tube at ~4.5gal

If you are really worried about them being smaller (unlikely), I would just have a couple 12/22oz bottles on hand for the residual amount. you could also put the extra into a sanitized growler and just top off the keg after you've pulled half a dozen pints that way you dont have to worry about bottlecarbing.

TL;DR: RDWHAHB, it'll be fine.

 

[CGish]

Thank you to those who replied.

I can easily modify my batch size to match the four kegs.

However, my original question still stands:

Is 4.5 gallons of usable space normal for a corny keg, or do I have an odd ball size?

 

[doug293cz]

I have ball locks that I recently measured (new rubber tops from AIH.) 5 gallons comes to just below the gas tube level, and full to overflowing (without lid) is 5.3 gal. So, if both of our measurements are correct, pin lock kegs hold slightly less than ball locks. I haven't seen this information reported elsewhere.

Brew on