Determining Proper hose length for your kegerator

[LAGERFRENZY]

I was directed to this calculator by my LHBS which is quite a quantum leap up from the advice normally offered by the like - hope that it helps some people.

http://www.mikesoltys.com/2012/09/17/determining-proper-hose-length-for-your-kegerator/

 

[peteru]

It's all in gibberish! No metric option :-(

 

[LAGERFRENZY]

the guy is a world renowned fluids engineer ffs

there are imperial to metric calculators on the interweb

 

[damoninja]

I used this calc a while ago, I have my setup so that I can carb and dispense at the same time so have quite a long line to counter the ~14 PSI my reg's permanently set at. Figured it out before I came across this but was reassuring to know what I was doing matched what a calc said to do.

First go perfect serving pressure, nice speed of pour, little foam on first pour every few hours but honestly I like how it does that as it's usually just me and the brewery boss (I'm also the brewery boss) drinking the stuff and who doesn't enjot a decent head.

 

[pcqypcqy]

I spent a day converting this to metric in a spreadsheet. Best tool I've seen yet because it's actually a fluid mechanics analysis, doesn't use any rules of thumb.

I'll post it when I get home.

Roughly I use about 12psi pressure, aiming for around 2 to 2.2 volumes for all my beers. I end up with about 5m of 6mm ID line I think.

 

[pcmfisher]

I spent a day converting this to metric in a spreadsheet. Best tool I've seen yet because it's actually a fluid mechanics analysis, doesn't use any rules of thumb.

I'll post it when I get home.

Roughly I use about 12psi pressure, aiming for around 2 to 2.2 volumes for all my beers. I end up with about 5m of 6mm ID line I think.

You drink your beers on the warm side?
At 12psi 2 volumes is at 10 deg C
At 12psi 2.2 volumes is at nearly 8 deg C.

 

[damoninja]

:icon_offtopic:

A while back I made a calculator to tell you what your carb levels will be over time based on your set PSI and temperature, this thread reminded me I should post it here.

http://aussiehomebrewer.com/topic/92668-how-long-to-force-carb-the-calculator/

 

[pcqypcqy]

You drink your beers on the warm side?
At 12psi 2 volumes is at 10 deg C
At 12psi 2.2 volumes is at nearly 8 deg C.

I don't, no. I'll have to dig out the spreadsheet to remember exactly what I'm doing, but the keezer is set to 4, the line length is about 5 metres, and regulator is about 12psi, and I get good carbonation levels and a nice steady pour.

This is all from memory though. Will post tonight.

 

[peteru]

Thanks, looking at the spreadsheet now...

Maybe there's a bug there in there, involving pressure. Cell B14 seems to have a hard coded value, it should probably be a reference to contents of cell B4. Right?

EDIT: Similar case with the FG of beer.

 

[pcqypcqy]

Thanks, looking at the spreadsheet now...

Maybe there's a bug there in there, involving pressure. Cell B14 seems to have a hard coded value, it should probably be a reference to contents of cell B4. Right?

EDIT: Similar case with the FG of beer.

Good pick up, thanks.

 

[pcqypcqy]

Updated version attached

There's a few more little bugs in there, not quite giving the same results as the online calculator as follows:

• I've used an Imperial Pint at 568mL, which will obviously change the flow rate and flow through the calculations. I think the calculator used a US pint which is 473 mL. You can edit this though if you want to, all it does is uses the volume and the time to calculate a flow rate. It's the flow rate that's important to the calculation.
• Also, he used an approximation of the friction factor, and I've gone a little further and iterated to get a bit more precision
• switching between units a few times introduces some errors

All in all, I think it gives pretty similar results.

View attachment Beer Line Length Calculator - Metric and Imperial.xlsx

 

[damoninja]

Updated version attached

There's a few more little bugs in there, not quite giving the same results as the online calculator as follows:

• I've used an Imperial Pint at 568mL, which will obviously change the flow rate and flow through the calculations. I think the calculator used a US pint which is 473 mL. You can edit this though if you want to, all it does is uses the volume and the time to calculate a flow rate. It's the flow rate that's important to the calculation.
• Also, he used an approximation of the friction factor, and I've gone a little further and iterated to get a bit more precision
• switching between units a few times introduces some errors

All in all, I think it gives pretty similar results.

Awesome stuff again

Initially it feels a little off from my line length but I rarely pour pints usually I'm only pulling 350mL or so a time... And quite slow I might add, when I punched in 350mL it worked out to more or less give me my line length.

I ought to pull 500mL, time it. get an actual accurate vertical distance of travel, punch it in and see how close it is! I'm reckoning pretty damn close.

 

[BKBrews]

Now I'm super confused - most of the things I'd read said I would need about 2.5m of line for 4mm ID line. This puts it down around 1m? I input 11psi serving pressure and 200mm from keg to tap.

 

[pcqypcqy]

Now I'm super confused - most of the things I'd read said I would need about 2.5m of line for 4mm ID line. This puts it down around 1m? I input 11psi serving pressure and 200mm from keg to tap.

What flow rate are you getting? i.e. what size glass are you pouring and how long does it take to pour?

Keep in mind also that this guy approached from a proper fluid mechanics / first principles calculation. A lot of the other recommendations are rules of thumb with lots of approximations. Not to say they're wrong, just different.

If you're getting good pours, then it doesn't matter what this calculator tells you.

 

[pcqypcqy]

Awesome stuff again

Initially it feels a little off from my line length but I rarely pour pints usually I'm only pulling 350mL or so a time... And quite slow I might add, when I punched in 350mL it worked out to more or less give me my line length.

I ought to pull 500mL, time it. get an actual accurate vertical distance of travel, punch it in and see how close it is! I'm reckoning pretty damn close.

You can change the value of the volume you're pouring in the spreadsheet - set cell B7 to your glass size then just measure the time. The text says 'pint' but the spreadsheet doesn't care about that, it only wants the flow rate (volume/time)

 

[moonhead]

Updated version attached

There's a few more little bugs in there, not quite giving the same results as the online calculator as follows:

• I've used an Imperial Pint at 568mL, which will obviously change the flow rate and flow through the calculations. I think the calculator used a US pint which is 473 mL. You can edit this though if you want to, all it does is uses the volume and the time to calculate a flow rate. It's the flow rate that's important to the calculation.
• Also, he used an approximation of the friction factor, and I've gone a little further and iterated to get a bit more precision
• switching between units a few times introduces some errors

All in all, I think it gives pretty similar results.

Awesome tool. What I take away from it is, with 5mm line, about 3 meters seems to be a sweet spot, for various options...

 

[pcqypcqy]

Awesome tool. What I take away from it is, with 5mm line, about 3 meters seems to be a sweet spot, for various options...

That's the problem with a tool like this, is that once you have it you want to adjust everything each time. Unless you're going to have a dedicated tap/line for each pressure/carb volume you're targeting, it'll always be a compromise.

 

[peteru]

If there is a restriction at any point between bottom of dip tube and the tip of your tap, you will get slower pour rate. So, if your line is shorter, but slower than what is predicted, you might want to investigate.

On the other hand, if you are happy with your pours, it's probably not a good idea to change things.

 

[moonhead]

That's the problem with a tool like this, is that once you have it you want to adjust everything each time. Unless you're going to have a dedicated tap/line for each pressure/carb volume you're targeting, it'll always be a compromise.

I was thinking of making up a couple of lines with MFL connections on each end, to easily swap them out based on the beer style being poured. Not sure if that's really necessary anymore.... Though a short one for sparkling water would be good, no need to restrict that at all.

 

[waggastew]

....or just get one of these. Saw it in action today at Garage Projects in Wellington NZ