25' lines?

[betarhoalphadelta]

I have a 6-tap keezer that I'm doing maintenance on today. I can run 4 taps on a single pressure, and two taps on a second pressure. I was thinking of installing 25' lines on the two taps running alternate pressure to dispense higher-carbed beers as appropriate to style.

That said, I don't always have styles that need it... Will I get any flow through 25' lines at my typical 12-14 psi?

 

[mmonroe1050]

Hey bwarbiany,

That's a good question. I'm uncertain which type of lines you plan on running, and what the inner diameter will be, but the 3/16" ID beverage tubing that we offer provides two psi of restriction per 1' in length. This would be 50 psi of restriction in the 25' of lines, so while you will dispense beer, it will be at a very slow trickle.

For example, if you'd like to have one of your beers be carbonated and pushed at 18psi, then I would recommend using about 9-10' of 3/16" tubing. This will pour into the glass at around the same speed as the rest of your beers being carbonated and pushed at 10-12psi. Since the beer will have more CO2 in concentration, it might make more sense to start with 12-13' on the tubing, and then cut back if it's not pouring fast enough or is not foaming up as much as I'm guessing it will.

Hopefully this makes sense and helps. Let us know if you have any other questions!

 

[betarhoalphadelta]

Thanks mmonroe. All my current lines are 10' of 3/16" line, and dispense well at about the 12-14 psi range. I'm not sure I buy the 2 lb restriction per foot number, but I might start with the 25' lines as I have an apfelwein and a Belgian on now, so I might crank the pressure on those two. When I switch back to lower-carb beers I'll cut them back as necessary.

 

[grathan]

Elevation would have to play a role. Obviously gravity would flow without any psi..

 

[day_trippr]

Oft cited beer line resistance figures tend to relate to that obtained with maximum pressure/rate of flow - a condition that doesn't exist in our application. I believe the typical 3/16"id barrier beer line exhibits resistance closer to 1 psi/linear foot than 2, and the "glass lined" tubing is even lower.

Give this excel spreadsheet a try. The author did a great job on it - it's the only beer line length calculator I'd even bother using...

Cheers!

 

[erikpete18]

I had the same idea and put three 20ft lines into my keezer to go along with the 10ft lines I was using for the others. The 20ft work great for apfelwein, wheats/wits, and Belgians that I want highly carbed, but still work fairly well for standard 12psi beers as well. I ran out of normal tap room so I've got an IPA on one of the 20ft taps at 12psi, and while it does take a little longer to fill up a glass, its not a long wait by any means. I figured the IPA was a good candidate since I could theoretically up the carb level some and claim to myself that I was doing it to increase hop aroma release if it didn't pour at 12psi, but I haven't had to do that yet.

 

[betarhoalphadelta]

Thanks Erik...

I put the Belgian Patersbier on at my usual ~14 psi. I then proceeded to test it, and got a pint of total foam!

(Of course, I had forgotten than I left the kegs in my 80 degree garage all day and had just plugged the freezer back in, so everything was warm!)

 

[JuanMoore]

Thanks mmonroe. All my current lines are 10' of 3/16" line, and dispense well at about the 12-14 psi range. I'm not sure I buy the 2 lb restriction per foot number, but I might start with the 25' lines as I have an apfelwein and a Belgian on now, so I might crank the pressure on those two. When I switch back to lower-carb beers I'll cut them back as necessary.

Line resistance isn't a constant for a given line, it's variable, and highly dependent on flow rate. The 2psi/ft resistance figure is for beer flowing at ~1 gal/min, which IMO is too fast for just about any beer. It's also the flow rate most kegerators and many kegging kits are set up for with their 4-5' lines. Longer line will slow the beer slightly, which will also reduce the resistance. You can use the spreadsheet day_trippr posted to calculate exactly how long it will take to fill a pint with the pressure and line length you'll be using. I'd bet you'll be surprised how fast it will flow. I've used my 30' soda line for beer a few times, and the pour speed wasn't a whole lot slower than the 12' lines at the same pressure.

 

[betarhoalphadelta]

Line resistance isn't a constant for a given line, it's variable, and highly dependent on flow rate. The 2psi/ft resistance figure is for beer flowing at ~1 gal/min, which IMO is too fast for just about any beer. It's also the flow rate most kegerators and many kegging kits are set up for with their 4-5' lines. Longer line will slow the beer slightly, which will also reduce the resistance. You can use the spreadsheet day_trippr posted to calculate exactly how long it will take to fill a pint with the pressure and line length you'll be using. I'd bet you'll be surprised how fast it will flow. I've used my 30' soda line for beer a few times, and the pour speed wasn't a whole lot slower than the 12' lines at the same pressure.

Ah! That makes sense. It's like a coefficient of drag... I.e. F=kv where F is the resistance, and V is velocity... So as psi decreases, the resistance would decrease. And it should be able to flow regardless. Makes perfect sense when you put it that way.

Thanks!

 

[zachattack]

Ah! That makes sense. It's like a coefficient of drag... I.e. F=kv where F is the resistance, and V is velocity... So as psi decreases, the resistance would decrease. And it should be able to flow regardless. Makes perfect sense when you put it that way.

Thanks!

The drag coefficient is generally a function of the velocity squared! So it depends very highly on your flow rate. As the flow rate slows down, the pressure drop in the tubing goes way down. This is why for slower pours we need longer lines.

A good analogous situation to think about is wind resistance/drag on your car. The faster you go on the highway, the worse your MPG because of the significantly increased resistance. In the winter when the air is cold and denser, it's an even bigger difference.

 

[betarhoalphadelta]

The drag coefficient is generally a function of the velocity squared!

D'OH! Good thing I'm an electrical engineer, not a mechanical engineer, huh?

I think I was probably thinking of the spring equation F=kx, not sure why...