Keg Volumes

[madeebrews]

Does anyone have information on actual keg volumes? A 1/2 bbl or 1/6 bbl are rated at 15.5 and 5.17, but what is the actual volume they hold? Is there a percentage of head space built in to the design such that you can 'overfill' a keg with more than 15.5 or 5.17?

[indyGold]

This will vary little between manufacturers. 1/2 bbls will overfill to ~15.75 gallons, 1/6 bbls will overfill to ~5.25 gallons. It's a good idea to FOB kegs when filling. If a brewery isn't filling by weight, manually filling a keg till FOB starts to become liquid isn't wasting a lot of beer. It's clearing the headspace of oxygen.

[Natrat]

Agree that fobbing is important, but there should be no air if your kegs have been properly purged after cleaning.

Typically, I have found that actual keg volumes are within +/- 2.5% of total volume if you take the volume that the spear takes up into account. In practical terms, 1/6ths are usually between 5.15 and 5.21 gal, and halfs are 15.3-15.6 gal. Also, I have encountered overpressurized kegs (usually from freezing) that hold a whopping 17.5 gal in use in breweries.

Best is to set your standard of fill by weight, though very few operations actually do this unless it's built into a racking machine.

[MatthewS]

Accuracy in keg filling is pretty important, especially as the brewery grows. Every ounces matters.

Sanke fittings were designed to be filled upside down. By filling upside down with a FOB, you will fill to 15.5gallons (+/- 1.5% or so) I know of a few breweries that have done this and weighed kegs to see the loss vs beer savings. It is substantial enough and I believe worth building a racking shelf for filling upside down.

If we consider that without FOB, filling till we see beer, we are putting about 15.75 gallons into each 1/2bbl (very possible)
2000 1/2 bbl kegs with 15.7 gallons = 31,400 gallons
2000 1/2bbls kegs with 15.5 gallons = 31,000 gallons
that's 25 1/2bbls in my world.

I have weighed kegs over the years and at a brewpub, we were averaging about 15.6-15.7 gallons into each keg. For a brewpub, though, so really it just meant less cleaning for me. If these kegs were sold, we are just giving away beer.