Beer Forum

NYNick · #1 (**permalink**) 10-24-2006, 08:24 AM

Our boat club installed a new 4-faucet Mini-Mushroom tap from Micromatic recently. We have a little too much foam on all taps, and the only difference I can see is that the beer lines are a smaller diameter (1/4" vs. 3/8") than the old tap. Temp is good, it's direct draw, same CO2 setup. Any ideas?

Thanks in advance for any advice,

-Nick

darck1 · #2 (**permalink**) 10-24-2006, 08:27 AM

Quote:

Originally Posted by NYNick

Our boat club installed a new 4-faucet Mini-Mushroom tap from Micromatic recently. We have a little too much foam on all taps, and the only difference I can see is that the beer lines are a smaller diameter (1/4" vs. 3/8") than the old tap. Temp is good, it's direct draw, same CO2 setup. Any ideas?

Thanks in advance for any advice,

-Nick

What's the distance from the keg to the tap? What's the "vertical lift" in the system (distance from center of keg to tap)? What beer are you dispensing?

NYNick · #3 (**permalink**) 10-24-2006, 08:36 AM

The distance is about 36", the beer is bud, bud light, Blue Point Toasted Lager and Blue Point Pale Ale. No trouble with old tap (it was an eyesore) same issue on all beers

darck1 · #4 (**permalink**) 10-24-2006, 08:52 AM

Quote:

Originally Posted by NYNick

The distance is about 36", the beer is bud, bud light, Blue Point Toasted Lager and Blue Point Pale Ale. No trouble with old tap (it was an eyesore) same issue on all beers

Sorry to hit you with math here Nick but this is the way I work it out...

I was told that the proper formula to use is this...

L=(P-(H x 0.5) -1) / R

L=Length (Are you saying 36 inches from keg to tap?)
P= CO2 Pressure (for the type of beer you're pouring I think it's around 14lbs if your temp is 38F)
H=Height (from the center of Keg to the faucet let's pretend its the three feet you're talking about since that's the only way I can see it - the taps being above the keg)
R=Resistance of the line

If the length is 3 feet like you say...

3=(14-(3 x 0.5) - 1) /R

3=9.5/R

3r=9.5 (This is the total resistance of the line)

We need to run line that has a total resistance of 9.5lbs. 3/16ID beer line has a resistance of 3lbs per foot... so if we run 3.17 feet of 3/16 you'll have the perfect resistance.

If (and this might be the case), you're really talking about 36 feet we'll have to change the numbers a little and use different diameter line. Let me know.

NYNick · #5 (**permalink**) 10-24-2006, 09:28 AM

Thanks for the info! The tap is direct draw, so it is about 36 inches in vertical height, but the line is longer, perhaps 6 feet. Would it make sense to have a larger diameter line and transition to the smaller line close to the tap?

darck1 · #6 (**permalink**) 10-24-2006, 09:44 AM

Quote:

Originally Posted by NYNick

Thanks for the info! The tap is direct draw, so it is about 36 inches in vertical height, but the line is longer, perhaps 6 feet. Would it make sense to have a larger diameter line and transition to the smaller line close to the tap?

Yes. So... your total line length is actually 9 feet? 3 feet to the tap and 6 feet beyond that?

That makes our equation...

9=(14-(3 x 0.5) -1) /R

9R=11.5

11.5 total resistance for 9 feet.

Let's say we use 3/16 diameter for 2 feet.

11.5 - 6 = 5.5

If we use 1/4" for the rest it would be 7' X 0.85 = 5.95

5.95 + 5.5 = 11.45 round it up and you get 11.5

So... 7 feet of 1/4"ID and then splice 2 feet of 3/16"ID for the final run to the faucet.

NYNick · #7 (**permalink**) 10-24-2006, 10:36 AM

The only thing that changed in our setup was the line size, is that a likely culprit? If so, why?

darck1 · #8 (**permalink**) 10-24-2006, 10:46 AM

Quote:

Originally Posted by NYNick

The only thing that changed in our setup was the line size, is that a likely culprit? If so, why?

The trick is to maintain the correct balance of carbonation to the beer but also have enough to push the beer out of the tap. Carbonation levels vary from beer to beer and the CO2 you have to apply also varies according to temperature. But, for most cases, with domestic beer, 14lb of CO2 pressure at 38F is usual.

Now to answer your question... If you're using, for instance 1/4" diameter line all the way to the tap... Resistance per foot of 1/4" ID line = 0.85

9 x 0.85 = 7.65lbs of resistance. We can add 3.5 pounds of resistance to this for the height above the keg = 11.15lbs. Add a pound to push the beer... 12.15lbs. It still falls short of the 14lbs of pressure that you have on your CO2. Therefore, you have too much carbonation and your beer will be coming out too fast also.

So... without all the math. The short answer is: Your system didn't have enough resistance in the line to offset the CO2 level.

Be careful of people who tell you to adjust the CO2 level to match your line length. CO2 level should only be modified to match your beer and/or your temperature.

ernestbud · #9 (**permalink**) 10-25-2006, 02:08 PM

if you are just running this out of a keg box just put 5' of 3/16 line on each tap on your bud products @12-14psi and it will pour great trust me I install them everyday with the 1/4" line you are not getting the correct resistence

darck1 · #10 (**permalink**) 10-25-2006, 04:16 PM

Quote:

Originally Posted by ernestbud

if you are just running this out of a keg box just put 5' of 3/16 line on each tap on your bud products @12-14psi and it will pour great trust me I install them everyday with the 1/4" line you are not getting the correct resistence

How's he going to make 5' of 3/16 line stretch 9 feet?

Beer Dr · #11 (**permalink**) 10-25-2006, 05:48 PM

Do you have an air duct blowing the cold air from the keg box up into the mini mushroom?

darck1 · #12 (**permalink**) 10-26-2006, 06:30 AM

Quote:

Originally Posted by Beer Dr

Do you have an air duct blowing the cold air from the keg box up into the mini mushroom?

Good question. I assumed he had something like that since he said "Temp is good". NEVER ASSUME! lol

Nick, when you say "Temp is good" do you mean the temperature of the beer? Or the temperature in the cooler? Use Scott's "chug test". Pour off a beer and chug it. Then pour another beer. Take the temperature of this beer. Is it 38? Or is it warmer?

ernestbud · #13 (**permalink**) 10-26-2006, 04:23 PM

he said in an earlier post it was 36" from keg to tap!!! so why do you want to go and slap a bunch of un-needed beer line in there 5' of 3/16 will get the job done @12psi no need for any3/8 or 1/4 just 3/16. I do this professionally everday I know what I am talking about

darck1 · #14 (**permalink**) 10-27-2006, 10:38 AM

Quote:

Originally Posted by ernestbud

he said in an earlier post it was 36" from keg to tap!!! so why do you want to go and slap a bunch of un-needed beer line in there 5' of 3/16 will get the job done @12psi no need for any3/8 or 1/4 just 3/16. I do this professionally everday I know what I am talking about

You are quite right and have my apologies. I didn't notice (or forgot) the 36" post earlier. I guess I was confused when he said it was for his club and I was thinking 36" was too short or something. Now that I think about it more I think that I thought the 36" was the vertical rise and he had 6 foot to run over that.

You're dead-on that 5' of 3/16 should do him fine and once again - my apologies.

Scott Zuhse · #15 (**permalink**) 10-28-2006, 01:16 PM

NYNICK,

When the tower arrived, did it have approx. five feet of 3/16" inside diameter line already installed? Normally this is what all air cooled Micro Matic towers are shipped with. If so, we will require exactly what temperature the beer is in the keg to determine what your keg PSIG should be.

If you can target 38F beer temperature, use 14 PSIG with the five feet of 3/16" line. Your flow rate will be approx. 120 oz/min. Be certain to place the flex tube into the tower to assure consistent temperature from the keg to the faucet.