pressure calculations for cold plate box - Home Brew Forums

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04-26-2012, 04:07 PM   #1
rtockst
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Nov 2008
Benton, IL
Posts: 150

I'm working on getting a jockey box with a 6 pass cold plate built. I need to get it done asap, because I'm using it at a festival on May 5th. I want to serve 6 beers and I'm having trouble figuring out the line length I need to use and at what pressure.

I bought the plate used (10" x 15") w/ 6 passes. I'm assuming the ID of the lines on the inside is 1/4", but I don't know how long each pass is. I found a few different plates of the same size on the web and it says they have a line length of 18 feet. Does that mean each pass is 18 feet long?

So I want to know how to figure out what length of beer line to use if I want to serve 6 beers at about 2.5volumes. Here's what I figured up:

- line & height resistance - For the cold plate, if each pass is 18 feet, @ 0.3lbs/ft, that's a resistance of 5.4lbs for each pass in the cold plate. If I have 3lbs/ft of resistance with 3/6" ID beer line (which is what I think I should use), with 5 feet in between keg and cold plate, that's 15lbs resistance. I would use about 3 feet between cold plate and faucet, so that's 9lbs resistance. The height of the faucet above keg would be about 2 feet, so that's 1lb resistance. So in total, that's about 30lbs resistance for ONE line of beer. Does that mean I should have my regulator set at 30lbs, or do I need to multiply that by 6, since I want to serve 6 beers? Also, that would over carbonate my beer, right? See below:

- Beer temperature & regulator pressure- The kegs might not be iced down. Do I use the beer temp coming out of the faucet for figuring up the regulator pressure, or do I use the keg temp? I'm assuming the temp is 42F, I want 2.5 volumes (for each keg), and I have one gas regulator hooked up to a 6 outlet gas manifold. For 1 keg, I'd need 13.3psi to carbonate it to 2.5volumes. So does that mean my regulator pressure needs to be 13.3 x 6, since I want to do 6 beers?

Aside from the questions I have about multiplying my numbers by 6 because I want to serve 6 beers, I need to figure out how to balance the pressure. I can shorten up the 3/16" beer lines to reduce the resistance, but I can't change the 18' length through the cold plate. How can I balance this thing?

Thanks for any/all help!
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04-26-2012, 04:24 PM   #2
ebstauffer
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Nov 2011
Indianapolis, IN
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We have an annual block party where we regularly serve four beers, all running through a six circuit cold-plate (two are left empty). I'd guess there's about 6 to 8 ft' of beer line between the tavern head and the faucet, exclusive of the cold plate. I run my regulator at about 8 PSI (if I recall) adjusting it as necessary to increase flow / decrease foaming. Takes about two minutes to get it all dialed in. No fancy balancing, just high-pressure tubing from the regulator to each tavern head, using nylong "T" fittings where necessary. The box is sitting on a picnic height table and the kegs are sitting on the ground behind it.

Since we go through all four kegs in an evening we don't worry about keeping them on ice when they're being served as the CP does a fine job. Keep the cooler filled with ice and your temp will be fine.

I have never worried about about line length / back pressure / resistance / phase of the moon in the six years we've been doing this and have never had problems. The three main things you should concern yourself with are cleanliness, cleanliness, cleanliness. And then be sure to have enough CO2! I use a flow-jet pump to pump beer line cleaner through the entire system. I use beer line cleaner from Kegworks but your LHBS should have something that will work.

04-26-2012, 04:29 PM   #3
ebstauffer
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Indianapolis, IN
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04-26-2012, 04:47 PM   #4
kcolby
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May 2009
Houston, TX
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Quote:
 Originally Posted by rtockst For 1 keg, I'd need 13.3psi to carbonate it to 2.5volumes. So does that mean my regulator pressure needs to be 13.3 x 6, since I want to do 6 beers?
Pressure is Pressure. Don't put 78psi on the kegs!! Put the 13.3psi on the kegs for carbonating. Then serve as ebstauffer mentioned. The balancing can be worked out fairly easily unless you have a need for really high speed pouring (although with 6 kegs you'll probably be pouring more than one at a time which will help with getting beers out faster anyway). Be prepared to make little tweaks, and I would probably leave the extra line in since it'll give you the ability to run a little higher PSI (for faster pours).

Disclaimer: This is all back of the napkin, SWAG on my part. I cannot be held responsible for any spilled beer nor any perfect pours
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04-26-2012, 05:30 PM   #5
rtockst
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Nov 2008
Benton, IL
Posts: 150

Quote:
Quote:
 Originally Posted by kcolby Pressure is Pressure. Don't put 78psi on the kegs!! Put the 13.3psi on the kegs for carbonating. Then serve as ebstauffer mentioned. The balancing can be worked out fairly easily unless you have a need for really high speed pouring (although with 6 kegs you'll probably be pouring more than one at a time which will help with getting beers out faster anyway). Be prepared to make little tweaks, and I would probably leave the extra line in since it'll give you the ability to run a little higher PSI (for faster pours). Disclaimer: This is all back of the napkin, SWAG on my part. I cannot be held responsible for any spilled beer nor any perfect pours
Thanks for the input. I understand about the carbonation part... it's going to be 13.3lbs into each keg just having it set on 13.3.

But, does anyone at least know about how the 6 faucets being on there will affect the resistance? And yea, I guess it doesn't matter if I have to have the regulator set higher than the carbonating pressure to serve... we're only serving for one afternoon so that's not going to screw up the carbonation levels.
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04-26-2012, 06:53 PM   #6
camiller
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Apr 2007
Omaha, NE
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After rounding errors and stuff I would suggest starting at about 22-24 psi for serving pressure. For catering weddings and other events and such we have a total of 15 jocky boxes (admittedly serving commercial beer) and 22-24 PSI seems to be best.

On second thought, we run 7/16" from the kegs to the cold plate so 30 PSI might be better in your situation. We can usually hook everything up 4-5 hours before an event without a foaming problem.

Pro-tip after you clean and rinse the lines there will be water in the cold plate lines, make sure you get beer flowing through before you ice the plate. With just water in there it is possible to freeze it solid.

04-26-2012, 07:29 PM   #7
rtockst
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Nov 2008
Benton, IL
Posts: 150

Quote:
 Originally Posted by camiller After rounding errors and stuff I would suggest starting at about 22-24 psi for serving pressure. For catering weddings and other events and such we have a total of 15 jocky boxes (admittedly serving commercial beer) and 22-24 PSI seems to be best. On second thought, we run 7/16" from the kegs to the cold plate so 30 PSI might be better in your situation. We can usually hook everything up 4-5 hours before an event without a foaming problem. Pro-tip after you clean and rinse the lines there will be water in the cold plate lines, make sure you get beer flowing through before you ice the plate. With just water in there it is possible to freeze it solid.
Thanks for the example. Are all of those 15 boxes running off 1 regulator?? And yes, thanks for the tip.
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04-28-2012, 12:14 AM   #8
zman

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I am building a 4 tap jockey box with a 7 plate chiller and was wondering about some of the same things as rtockst. I plan on doing 8' lengths from the keg to the cold plate an 1' from the cold plate to the faucet. Sound like a good idea?
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04-29-2012, 02:40 AM   #9
rtockst
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Nov 2008
Benton, IL
Posts: 150

Quote:
 Originally Posted by zman I am building a 4 tap jockey box with a 7 plate chiller and was wondering about some of the same things as rtockst. I plan on doing 8' lengths from the keg to the cold plate an 1' from the cold plate to the faucet. Sound like a good idea?
That sounds good to me. I was planning on using 1/4" ID hose from the keg to the plate to reduce resistance a little, and then use the 3/16" ID hose from the plate to the faucet. Thoughts on that?
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04-30-2012, 03:51 AM   #10
zman

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I am using 3/16 all the way. I bought 50' of it from Micromatic, so too late to turn back now...lol. I have 8' in my kegerator for both taps and keep the psi @ 12-15 and it seems ok. From what I have read you want the hose from the plate to the tap to be about 1-1.5'. I should have mine finished this week plan to do a trial run with warm kegs and ice in the cooler only.
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