Balancing

[darck1]

Okay... I'm trying to "do the right thing". I guess my system is working pretty well right now but I don't understand why since I'm doing it all wrong. lol

My current system is a remote with about 9 feet of 3/16ID beer line. I keep it cooled using an air cooled system. Blower mounted in a chest-freezer blowing through 2inch rigid PVC to the tower (one elbow of 45 degrees to move the line toward the bar and one elbow of 90 degrees to move the line up to the tower). Air returns to the freezer via an insulated 4inch flexible aluminum duct that is around the 2inch PVC.

It works pretty good, keeps the beer nice and cold and the carbonation seems right. I just don't understand why since I'm serving Michelob Ultra Amber and Sierra Nevada at 14lbs CO2.

Using this formula...

L=(P-(H*.5)-1)/R

Where L=Length, P=Pressure used, H=Height of tap (above center of keg) and R=Resistance in the line (2.7 for 3/16)

To find the length I should be using I get these numbers...

L=(14-(3*.5)-1)/2.7 = 4.26 = About 4 and a quarter feet. Waaaaaay too short. I need 9 feet.

If I use 1/4ID line then I'll get a resistance of 0.7 which would work out to around 13 feet of line. I need only 9 feet so I obviously want maybe 6 feet of 1/4ID and 3 feet of 3/16

But this is where the math defeats me. How do I work out the exact lengths of 3/16th and 1/4 to equal 9 feet?

[darck1]

I don't know if this is right but I'll take a shot...

In the equation the only thing that I can really adjust is obviously the resistance of the line. My distance will always be 9 feet. The height above the keg will always be 3 feet and the pressure will always be 14 (that may not be perfect for both beers I'm serving but it's close enough I think).

So...

9=(14-(3x.5)-1)/R
9=11.5/R
9R=11.5
R=11.5/9
R=1.27777

So... if I can find line of total resistance 1.28 that would work.

Now I have to work out the combination of 1/4 and 3/16th that would equal that...

[darck1]

Let's try this (PLEASE! Somebody check my math!)

1.28(resistance per foot) x 9 (feet of line) = 20.52

I want 3 feet of 3/16th line to the tap 3x2.7 = 8.1 (total resistance for the 3ft)

20.52 - 8.1 = 12.42 (resistance left)

12.42 * 0.7 (resistance for 1/4 line) = 8.694ft of 1/4inch

So.....

If I use 8.69 feet of 1/4inch and 3 feet of 3/16th, that should give me the correct resistance...

Again... PLEASE TELL ME if this is totally bogus.

[Draught Prophet]

...is what I was once told by a very wise beer man.

What is the temperature of the beer in the keg and coming out of the faucet?

You start with your liquid temp and brewery co2 volumes and then determine your pressure. Your restriction = your pressure.

If your temp is 38 and your volumes are 2.5 (which I think they are), you are correct at 14 psig pressure to the keg. If your temp is anything other than 38, this 14# will change.

1/4 id line comes in different styles. Vinyl has a res of 0.85/ft and Brewmaster 2 barrier has a res of 0.3/ft. SS is 0.3#/ft and poly (hopefully your not using poly) has a res of 0.50#/ft Which one do you have?

Assuming that your temp is 38 and you have barrier line, you can create 14# resistance by using 4.25' of 3/16 (=12.75#) and then 4.75' of 1/4 Brewmaster (.3#/ft) for 1.4#. Total res = 14.15

Hope that helps.
Cheers,
Steve

[darck1]

Originally Posted by Draught Prophet

...is what I was once told by a very wise beer man.

What is the temperature of the beer in the keg and coming out of the faucet?

You start with your liquid temp and brewery co2 volumes and then determine your pressure. Your restriction = your pressure.

If your temp is 38 and your volumes are 2.5 (which I think they are), you are correct at 14 psig pressure to the keg. If your temp is anything other than 38, this 14# will change.

1/4 id line comes in different styles. Vinyl has a res of 0.85/ft and Brewmaster 2 barrier has a res of 0.3/ft. SS is 0.3#/ft and poly (hopefully your not using poly) has a res of 0.50#/ft Which one do you have?

Assuming that your temp is 38 and you have barrier line, you can create 14# resistance by using 4.25' of 3/16 (=12.75#) and then 4.75' of 1/4 Brewmaster (.3#/ft) for 1.4#. Total res = 14.15

Hope that helps.
Cheers,
Steve

Thank you Draught Prophet. My temp is 38 and I am using vinyl.

Unfortunately your post just missed my micromatic shopping cart... I already purchased line based on my calculations. I was basing my calculations on 1/4ID vinyl having a resistance of 0.7#.

I guess I'll substitute your 0.85 and see what numbers that gives me. At least, from what you tell me, my math is correct (even if one of my numbers is a little low).

[darck1]

Originally Posted by darck1

Thank you Draught Prophet. My temp is 38 and I am using vinyl.

Unfortunately your post just missed my micromatic shopping cart... I already purchased line based on my calculations. I was basing my calculations on 1/4ID vinyl having a resistance of 0.7#.

I guess I'll substitute your 0.85 and see what numbers that gives me. At least, from what you tell me, my math is correct (even if one of my numbers is a little low).

Crap. Substituting .85 as the resistance for the 1/4ID makes it much worse. I'd need 10ft of 1/4 to join to my 3ft of 3/16. I guess it's too late to call Micromatic and substitute the brewmaster. :-(

[Draught Prophet]

I'd call them, they usaully ship fast, but you might be able to get them. If they won't sell you Brewmaster by the foot, get 5/16 vinyl, it's got a 0.4 res.

[darck1]

Originally Posted by darck1

Crap. Substituting .85 as the resistance for the 1/4ID makes it much worse. I'd need 10ft of 1/4 to join to my 3ft of 3/16. I guess it's too late to call Micromatic and substitute the brewmaster. :-(

Alrighty... here's the final calculation.

Total resistance for my run is 11.5

I ordered 8.5ft of 1/4ID (Vinyl). TR = .85 * 8.5 = 7.23

11.5 - 7.23 = 4.27 remaining resistance

3/16" is 3.0 resistance

4.27 / 3 = 1.42

Soooo... if I splice my 8.5ft of 1/4" to 1.42ft of 3/16" I should have my total resistance of 11.5 with only 1 foot over my 9 foot run.