What is the actual volume of a corny keg?

So I'm talking to this guy selling glass carboys and he tells me that they are 19L. I assume this means to be 5 gal, but he corrects me and tells me that a 5 gal carboy is actually 23 L.

And this is something I've noticed at the HBS for their 5 gal carboys. I have one at home, but when you fill it up its well over 20 L, probably 23 L like this guy says. So that makes it about 6.1 USgal and about 5 ImpGal. So is that how these things are classified, in Imperial Gallons? Or is that just for us up here in Canada?

None of this really matters, though. What has me concerned now is what the actual volume of a 5 gal corny keg is, because thats the system I plan on setting up soon. So what is the max fill volume on a 5 gal crony keg? Anyone know or can check?

And assuming I want it full in the end, what volume should I start with in primary?

when i fill a corny w/ 5 g of beer, i have about 3-4 inches of head space in the corny. i'd say they are 6 g capacity.

I have adjusted my brewing to 6 gallon batches. I sparge 7.5 gallons into the kettle and then boil down to 6 gallons over the course of an hour. The 6 gallons is the "hot" volume, then there is thermal shrinkage which is about 4%, then there is some stuff left behind (only about a quart). I end up with about 5.5 gallons in the primary. When you finally get to kegging, you will end up with just about as much as the keg will hold.

You have to be careful not to fill a corny keg too full. Don't submerge the short tube for the gas line which sticks down into the keg an inch or so from the gas port. If you do, you run the risk of back flowing wort into your regulator if you connect a pressurized keg to an unpressurized gas line (been there, done that, get check valves it's worth it).

So, the long and short of it is, make a little extra, like a 6 gallon batch, and you'll end up with a full keg by the time you get there. I've never actually measured the volume of a corny keg, but you've got my curiosity up now.

Prosit!

My pin lock corny keg has 640 uso stamped on the side . converts to 5 usg or 4.16 Imp. or 18.9 L. Hope this helps.

Wally

Wally said:

My pin lock corny keg has 640 uso stamped on the side . converts to 5 usg or 4.16 Imp. or 18.9 L. Hope this helps.

Wally

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Nobody is disputing that a 5 gallon cornie can hold five gallons. What is being asked is what is the actual capacity, bottom to top, NOT what is it supposed to hold, which is five gallons.

Sadly, I don't know the answer either.

Anyone ever figure out how much one can really hold and where exactly the 5g fill line would be?

Doing 10g batches and I always end up with the second keg a lot less full than the first.

Driftwood said:

So I'm talking to this guy selling glass carboys and he tells me that they are 19L. I assume this means to be 5 gal, but he corrects me and tells me that a 5 gal carboy is actually 23 L.

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He doesn't know what he's talking about. A liter is MORE than a quart. There are only 3.8 liters to a gal. X 5 = 19 L.

As far as cornies go, mine top out very close to 5 gallons. I had 6 gallons of BRR in the fermenter, left a quart of trub in the bottom and ended up putting 1.5L in a soda bottle. Most batches, hitting the fermenter with 5.25-5.5 gallons means a full cornie.

Don't forget, to force carbonate you have to have surface area for the CO2 to enter the ale. With a completely full cornie, the only surface would be the gas tube.

[By full, I mean you don't have to stick the lid in the ale while inserting it. So, 1-2 inches from the top.]

Hmm... I put 20L in one and still had 6 inches below the dip tupe.

I need a giant measuring cup to figure this out.

40L split into two cornies leaves one full and one a foot down. since 5g is 18.9 Liters.... They really are bigger than 5g.

I filled an Ale Pale with water o the 5 gal mark and dumped it into a ball lock corny. I took the picture below showing the water level below the dip tube. The 5 gal mark is indeed right at the weld line, 1 to 1.5 inches from the bottom of the gas dip tube.

Denny's Evil Concoctions said:

Hmm... I put 20L in one and still had 6 inches below the dip tupe.

I need a giant measuring cup to figure this out.

40L split into two cornies leaves one full and one a foot down. since 5g is 18.9 Liters.... They really are bigger than 5g.

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I guess it depends on the model of corny keg but 20 liters equals 21.14 quarts and 5 gallons equals 20 quarts. The instructions that came with my 2.5 and 3 gallon corny kegs said to fill them up even with the 'black line' visible on the inside of the kegs. It makes sense to me because keeping the head space volume consistent when carbonating, like filling to the black line 1.25 inches below the top of the keg, will give you more consistent carbonation. Its easier and uses a lot less less Co2 to carbonate a keg having an inch of headspace than one having 5 inches of headspace.

I am filling in a fairly complex spreadsheet to help out my brew day, and did a few measurements on my equipment. A lot of this equipment was gifted over the last couple years, so I'm not 100% sure of the sources/advertised sizes. One more caveat is that these measurements were made using hose water on an 80* day, and eyeballing the stamped volume markers inside my Brewer's BeAst 14+ gallon boil kettle (14 is the top measurement, with a couple extra inches above that...I believe it is a "16 gal" model...).

My carboy hits 5 gallons a couple inches below the point it tapers into the stem, and 6 gallons right at the base of the stem.

My corny keg hits 5 gallons with a few inches to spare -- the gas-in tube is [edit: 1/4"] submerged at 5 gallons. I have another keg that is slightly different (they were refurbished) that I plan to measure when it's floated.

Anyone know if the gas-in tube needs to be above the surface for proper functionality? (That is the question I was looking to answer when I found this thread...)

cookiemehnster said:

[...]Anyone know if the gas-in tube needs to be above the surface for proper functionality?[...]

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You'll be subject to fewer potential maladies if you don't submerge the gas dip tube.

But...you can also cut the gas tube down to 1/2" or even less. It only needs to be long enough to hold an O-ring. I've cut all of mine down to between 3/8-1/2"...

Cheers!

day_trippr said:

It only needs to be long enough to hold an O-ring.

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Ok thanks!