Technical Communications

Republished from BrewingTechniques' May/June 1993.

Dispensing from Kegs

There is a solution to this paradox. If you use 3/16-in. i.d. PVC line, which has a pressure drop of 3 psi/ft, you can get a 12-psi pressure drop across the liquid line. Now you can dispense your beer and maintain it at 12 psi, and by using a 4-ft liquid line (3 psi X 4 ft = 12) you will get close to a 0-psi pressure at the tap. I switched all of my draft lines to 4 ft of 3/16-in. i.d. PVC line and now maintain and dispense all my beers at about 12 psi. I have never been happier with my draft system!

I know some of you release the pressure on your kegs before dispensing. This will work, but it is a real pain for multitap draft systems, and why do something you don't have to? Give this 3/16-in. line a try. You'll like it.

One important note: Your regulator gauge may not read the pressure your kegs are really at because of the pressure drop across check valves that may (should) be in your carbon dioxide lines. Installing a check valve at each carbon dioxide outlet prevents cross pressurization and contamination. I have seen about 2 psi pressure drop across each check valve. I have one at the regulator output and one at each output from my gas manifold (see Figure 1). This means that I must set my regulator to 16 psi to get 12 psi at my kegs (16 psi - 4 psi = 12 psi). Your systems may vary. Also, getting the 3/16-in. i.d. line onto the standard 1/4-in. barb is a bit difficult. I heated mine up in hot water and then quickly pushed them on.

Good luck and better dispensing!

--Bob Jones
Alamo, California

Reference
(1) Values obtained from gas saturation tables, Beer & Brewing,
Vol. 12 (Brewers Publications, Boulder, Colorado, 1992).

DRY HOPPING RECOMMENDATIONS

Why not dry hop at pitching time? Three reasons. First, if you use the blowoff method, either the hops will clog the blowoff tube or the kraeusen will pump hops out of the fermentor and into the blowoff vessel, which will give your blowoff a nice hop nose but which won't do your beer any good. Second, when carbon dioxide actively bubbles out of the green beer it takes with it dissolved gases (like excess oxygen) and other aromatics (like hop aromatics). (For this same reason, if you're adding fruit to your beer, I recommend that it not be added until the really ferocious fermentation is over.) Third, it's safer to wait until fermentation is almost finished to minimize sanitation worries.

Won't the dry hops introduce all kinds of nasties into my beer? Many brewers that I've talked with have been hesitant to try dry hopping because of fears of infection. It took me a long time to convince myself to dry hop (I, too, was afraid of contamination). Eventually, three things got me to try it. First, if you wait to dry hop (as I suggested above), the beer has very little sugar left, quite a bit of alcohol, and its pH has dropped, making the environment relatively inhospitable to unwelcome visitors. Second, the boiling and flavoring hops have some antibiotic effects. Third, what self-respecting yeast or bacterium would live on hops? Hops are completely different from grape skins or a cup of raspberry juice in that they have no nutritional value. I suspect that hops would carry no more microbiota than is present in the area in which they've been stored (the dust in the bottling area is just as likely to infect your beer as the dry hops).

Should I use whole hops or pellets or plugs for dry hopping? Since I've started adding dry hops only during the last 7-10 days before bottling, the question of hop form has become less of an issue, but in my experience whole hops tend to float for a long time, making it easier to rack (siphon) the beer out from under them. The one time that I used pellets to dry hop, they began to sink to the bottom of the fermentor after about a week. After about two weeks, virtually all of them were at the bottom of the fermentor and were being covered by dormant yeast (where I doubt they continued to contribute anything to the beer). I suggest using whole hops if you have the choice, simply because I've found that dry hopping with whole hops makes it easier to rack than does dry hopping with pellets. Plugs are simply compressed whole hops and are equivalent to whole hops in the context of this discussion. Because they tend to be fresher than regular whole hops or pellets as a result of their packaging, plugs would tend to contribute more bouquet by weight than either pellets or whole hops.

--Al Korzonas
Countryside, Illinois