Questions about beer kegs in bars.

Factual Questions
1

I just got back from TGI Friday’s (yeah, I know, but it was open late and there isn’t much aound here where you can get anything decent at this hour) and along with my food I had a couple of beers. I was talking with the bartender about the different beers on tap, and he mentioned that the high volume beers (Bud, Lite, etc.) were kept in back. I asked how the beer stayed cold in the line if he hadn’t happened to pull say, a Bud in a while. He asserted that the CO2 in the line “pushed the cold” through the lines.

I was, like, “CO2?!?”

Because I had always understood that beer had it’s own carbonation. CO2 is injected into soda machines becuase they use municipal water and syrup concentrate, and need the CO2 to make the fizz, but beer? Well, apparently so. He even showed me the CO2 line into a handy keg. He insisted that this was only to carry the beer through the lines and the picture he painted was of cold C02 bubbles coursing through the beer as it passed along. My understanding is that the CO2 would be in solution in the beer, so there would be no bubbles, but my thought was that as the CO2 came out of solution as the beer was poured it would obey gas laws and cool the beer. This would jibe with the bartender’s empirical observation that the beer would come out warm if the CO2 was low.

Well, like any good doper confronted with new information, many other questions were raised, and my bartender friend was out of his depth, so I put my questions to the Dope Mind.

Is my theory about the CO2 coming out of solution and cooling the beer a valid concept? If not, how can beer stay cool for even a few minutes in a small diameter line with lots of surface area running maybe 25 feet from the back room? Is there another provision?

I can understand the logic of injecting CO2 to the tanks. Beer arrives from the brewery in a keg, mostly beer with a headspace made primarily of C02. As the beer is drawn out at the tap, CO2 is replaced. Fine and good. But here arises another problem. Different beers have different levels of natural carbonation depending on the type of beer, fermentation, blah blah blah. By hooking up a pressurized CO2 supply to all the kegs (lacking any kind of individual regulation, I am presuming) wouldn’t all the beers in the place evetually have an equal level of CO2 saturation after a short while? Wouldn’t that ruin some beers? I would think the subtle and divine bubbles of a Guiness would be ruined by the crass injection of a bunch of CO2 from a greasy steel tank that is also supplying the Diet Pepsi button.

So if not, why not? Or does it? I have always preferred tap beer, and now I am sorely dissillusioned. :eek:

2

Well if you think about it, without any extra CO2 the first pint out of a keg would be a lot more carbonated than the last over the span of the day. As the keg empties something has to be used to equalize the pressure, and if it’s not CO2 it will be air and this will not only oxidize your beer but it will lose carbonation to the air. Another possibility is nitrogen which solves the oxidation problem but not the carbonation problem.

Honestly I don’t know how bar keg systems work, but I would presume that part of the CO2 is released into the keg to push the beer out and the rest is released in the line to cool it.

3

Any good pub system has insulated and chilled lines from the kegs. They all use CO2 to push the beer out of the kegs. That is, all but Guinness. A good Guinness will use a nitrogen push. Quality bar systems can also regulate the amount of push given to any particular group of kegs. That way a quality beer won’t get the same treatment Coors Light does.

In a good pub, the barkeep will also run a bit from the tap before placing your glass under it, just to get the warm beer from the tapper out of the way. The lines may be cooled, but the tapper isn’t.

4

CO[sub]2[/sub] does get cold when it’s released to the atmosphere. If you open the valve on a cylinder of the stuff, the escaping gas is cold, and will probably also contain bits of solid - dry ice.

So, it is plausible that the CO[sub]2[/sub] chills the beer as it is dispensed through the tap.

Of course, another likely way to chill beer is with a jockey box - in its most simple form, nothing more than a picnic cooler full of ice with a spiral of tubing inside for the beer to run through to a tap on the side. Most bars have ice bins, so the beer lines can run through the bottom of the ice bin (the “cold plate cooler” on the above link) and chill the beer that way.

That’s why there’s a concept called “beer clean.” Not just clean, not just super-clean, but beer clean - not a trace of any contamination (dirt or cleaning products) allowed.

5

I have to say, though, that the idea (from the bartender mentioned in the OP) that the lines don’t have to be chilled because the CO2 can “push the cold” through beer that has been sitting for a while sounds like a load of BS. Sure, the CO2 is going to chill the beer near it, but the further you got from the keg, you’d just be pushing warm beer with cold beer. This is why the lines should be insulated and/or chilled.

6

CO[sub]2[/sub], or any pressurized gas, cools when you open the container because of the change of pressure. Unless there’s a pressure change, simply running CO[sub]2[/sub] through the beer will not cool it. In fact, warm CO[sub]2[/sub] will warm the beer. :slight_smile:

7

The pressure change happens at the tap as pressurized beer hits atmospheric pressure.

But, now that I think of it, there can’t be too much pressure in the line, or the tap will spray beer all over the room. (A quick and dirty way to tell your keg’s gone empty - the tap will splatter, rather than pour.)

I think that bartender’s been drinking too much of his wares with that “CO[sub]2[/sub] pushes the cold” line. I’ll wager he just doesn’t know his butt from a cooler plate in the ice bin.

8

I don’t know how/if the lines are kept cool at the bar where I work, but the kegs aren’t too far from the taps anyway. Also, I’m surprised no one has mentioned the super-chilled glasses. I never bothered to wonder before why we refrigerate the beer glasses, but maybe that is part of the reason - room temperature beer lines?

9

And to dull the taste of mass-produced crap. You’ll never catch a decent pub serving real beer in chilled glasses.

10

I can understand this if the beer is meant to be served at room temperature, but most beer in America, be it macrobrew or a local craft ale, is meant to be cold, and chilling the glasses is just one more little step to help keep it cold. I don’t think a cold glass is necessarily any indiction of the quality of the beer.

11

But not super-chilling, like samm mentioned. If I start seeing ice floes in my beer, I get a bit miffed. Very few craft beers, if any, are designed to be served at 33º F.

12

The Beer in the keg is kept under pressure by ( usualy ) CO2. The CO2 is at room temp wile in the pressure bottle, it drops Temp a little as it enters the keg but quickly returns to room temp.All of the gas is in a bubble at the top of the tank, very little disolves into the Beer as it is already carbonated. Now the room temp beer is pushed by the pressure of the bubble into a set of coils. The coils are either refridgerated or run under the ice bins to cool the Beer to about 35 F. The lines from here to the tap are insulated. As the Beer leaves the tap it loses a little pressure, not much just enough to push it through the lines, and drops a little in temp. Boiling CO2 helps slow the return to room temp, chilled glasses and mugs also help. Your job is to store all of the Beer at at body temp before all the CO2 evaporates. :slight_smile:

13

It’s been nearly twenty years since I was a cellarman, but here’s what I remember.

Most Australian pubs use a thing called a ‘Temprite’, which is a refrigerated coil immediately under the tap. The actual kegs down in the cellar may or may not be in a coolroom. I seem to recall the breweries actually recommending that kegs NOT be stored in the coolroom, and that the beer be pushed all the way upstairs to the bar at room temperature, and chilled by the Temprite at the last moment.

Beer lines (the pipes that come up to the bar) should be spotlessly clean, but beer glasses should not be. A good beer glass should be much cleaner than a household drinking glass, and it should be cleaned with proper industrial detergents that don’t contain ‘wetting agents’ which kill the froth, but it should never be surgically clean. A surgically clean glass will result in a flattish beer.

CO2 was used for full strength, mainstream beers, but often we’d substitute “Cellarmix” (which was fifty per cent nitrogen, from memory) for use in the light beers. Lower alcohol beers will pull much more ‘lively’ from the tap, and the nitrogen settles them a bit. Beer being a ‘living’ thing, it’s often different day to day, and if the full strength beer was playing up one day, we’d whack the Cellarmix on it, or if the light beer was pulling flat, we’d swap CO2 for it.

Mainstream Australian/US “lawnmower” beer should come out of the tap at about 3.5 degrees Celcius. This is a compromise point between the taste being deadened and the coldness that the average thirsty Joe likes.

If there is a bit too much gas pressure, the beer will pull FLATTER. If there is not enough, it will also pull flatter.

14

When i worked as a cellarman (at North Sydney Leagues Club), we used Temprites and a coolroom. The beer usually came out around 3[sup]o[/sup]C. We found that if the beer kegs weren’t refrigerated, at very busy times the Temprites sometimes couldn’t keep up with demand, and the beer would start to come out a little warmer than it should. The coolroom wasn’t freezing cold; just cold enough to ensure that the end prduct was always at the right temperature.

We fushed the lines with water every night, and twice a week all the lines were also flushed with a special cleaning solution.

15

Thanks for all the great responses. This makes more sense that what the guy was telling me. I knew I could get the answer here!

16

My experience was at a pizza place but our taps were litterally mounted to the outside of the wall of our walk in refrigerator. That walk in was at 34-36 degrees farenheit. The only part of the lines not exposed to that was about 6 inches going through the wall. Between the temp of the glass (kept in a cabinet door accessing the same walk in) and the temp of the lines I would be shocked if any beer we ever poured was served at more than 40 degrees F.

We had a CO2 system that kept pressure in the kegs but IIRC it was a pretty low pressure setup and used very little gas since unlike sodas which are carbonated on the fly from the dispensers, beer is already carbonated.

17

I have a home kegerator, in a refrigerator, with a 20lb CO2 bottle, in my garage. I have an outside kitchen, play area and an upstairs game room with a bar. I would like to use the same keg to supply upstairs, but do not know the limitations of running an insulated line 15’ up to supply a tap. Does anyone have any experience with this?

18

Unless you are tapping a few upstairs all day every day, I’d be leery of running a line there. Too much wastage from beer that has been sitting in the line between tappings.

19

Party at stewl’s place! :cool:

20

I think you’d have issues just using insulated lines, if you aren’t pulling beer regularly. Even insulated, the beer in the 15’ is going to be at room temp in a day, and you are going to get tons of foam on every pull until you are finally getting cold beer. You’d need actively refrigerated lines if you are going to do something like that.

I am a homebrewer with a home bar as well - the temp drop in just the base of the tap can cause foaming to the point where most people with home kegerators build in some kind of make shift fan system to blow cold air into the tab tree base to avoid foam.