Four Kegs One Tap

I'm trying to think through the idea of running a four keg system through a single tap using a tablet interface. I have a good grasp on the electronics and would piece together parts of the KegBot project with my own modifications, but I'm not sure about the physics of things.

My initial through it to put an electric valve near each of the four keg lines. After going through their individual valve, I'd join all the lines into one, send it through a flow measurer (used to measure how much beer is left in each keg), and then have it go through a single faucet. You'd control which beer you want using a tablet computer.

I'm comfortable doing all the wiring and programming required to put this system together. The problem is I'm not sure if it would actually work. My main concern right now is the leftover beer that is in the line after the electronic valve is closed. I'm assuming that once you turn that line off, whatever is left in the lines will no longer dispense since it isn't being forced out by any CO2. This leftover beer would ultimately be dispensed in the next beer than is poured, but I may be switching between a porter and a wheat, and I don't want an ounce or two of porter in my wheat pour!

I was thinking installing some kind of a very small pump that would clear out the beer in the single line either through the main faucet or through a separate line.

Does anyone think that this would actually work as intended or am I missing something that would mess this situation up?

Based on your description of how you want this to work, I think you're looking at some serious engineering that would need to be involved in order to get this executed properly. It actually makes me think a lot about the growler filler at Victory Brewing Co. Guess that shows that essentially it's possible, although you're looking at slightly different ballgames in that they're dispensing under counter pressure and can easily blow out the lines (and I also presume that unlike us home brewers Victory doesn't mind losing a few ounces each time they fill a growler).

So, as far as clearing out the beer from the line goes, depending on how you set the system up you can have a valve that purges the line with CO2 to push the last bit out into your glass. I have a feeling that that will probably result in a ton of foaming and beer being sprayed everywhere though. Since you're thinking about only one serving line (albeit fed by 4 different lines), ideally it would be pretty short so you wouldn't have a lot of left over, in which case you could just drain it off by gravity into your glass after the bulk of the measure has been dispensed. The other option is to literally just drain it into the drain, but that would mean a lot of wasted beer when all is said and done. Lastly, and it's the craziest idea of them all, would be to run the "left overs" back into the original keg, but that would involve a lot of plumbing and you'd probably need some automated way to bleed pressure off the keg during the return.

You'll also probably need to think about how you might clean the serving line after different beers are poured, because as you said, getting porter in a summer wheat isn't cool. Depending on how you execute things it may not be a serious issue, but it's worth considering.

Anywho, your plans seem highly ambitious, butI'd love to see you pull it off so all the best with it.

i think your biggest issue would come with the beer left over between the tap and the valve.

If you figure it out we'd love to see it!

What if the beer is forced with CO2 from one of 4 kegs to a high point (higher than tap). That is where you put your 4 port manifold. From there run a single gravity line. If you are putting a flow meter on it anyways, you can measure an exact pint after the manifold and shut the flow at the manifold. Then it's gravity for the last 6 inches of beer line to the tap. You can then use a 90 degree shank (with elbow bending up instead of down) to get the last drops out of the shank.

^ that sounds good. The other "problem" you might have is a floppy tap handle if you don't have any pressure against it keeping it closed.

There is a bar in Portland ,OR that has a similar system. They have a Huge flat screen with all their beers on it, and how much is in each keg. The volume left is automatically tallied through a computer. It was featured in beer advocate a while ago. I apologize but I can't remember the name of the place, maybe a portlander can help out. If you had the name of the place you could email the owner, who designed the system and get some insight from a system already in place.

I figured it out. It's baileys tap room. I hope this helps.

For what it's worth, these are my thoughts:

1. Don't worry about "flappy tap handles," really not an issue.

2. Your biggest challenge, as you already noted, is any residual beer left over in the line before the tap. I'm no whiz on any brewing subject, but what it seems like you need to do is put the electronic line selector immediately before the valve. Make sure you have plenty of beer line going to each keg from the line selector to reduce foaming, but as long as there is little to no tubing from the line selector to the tap, you shouldn't have to worry about cross-contamination.

Hmmm. What if you had a fifth line that was a low pressure CO2. Your system pushes a standard pint, then switches to a 1 to 2 psi line that purges the remaining beer?

betzbrew said:

for what it's worth, these are my thoughts:

1. Don't worry about "flappy tap handles," really not an issue.

2. Your biggest challenge, as you already noted, is any residual beer left over in the line before the tap. I'm no whiz on any brewing subject, but what it seems like you need to do is put the electronic line selector immediately before the valve. Make sure you have plenty of beer line going to each keg from the line selector to reduce foaming, but as long as there is little to no tubing from the line selector to the tap, you shouldn't have to worry about cross-contamination.

Click to expand...

+1

I think the minimal manifold volume is the way to go and just accept that you will get a few ml of a different beer. The problem I see with purging is what happens when someone pours a 1/2 pint / sample? Of corse it could be set up that you pull a pint then release then pull again to purge. But that is a bit of an anoyance to just clear a couple of ml.
Basically get as short a shank as feasible then attach the 4 way splitter manifold directly to that, and the valves straight to the manifold.
The other issue is what solenoid valves are you going to use, as I read some have a very small orifice which could cause foaming issues, watch out for that.

Thanks for the info and suggestions!

2. Your biggest challenge, as you already noted, is any residual beer left over in the line before the tap. I'm no whiz on any brewing subject, but what it seems like you need to do is put the electronic line selector immediately before the valve. Make sure you have plenty of beer line going to each keg from the line selector to reduce foaming, but as long as there is little to no tubing from the line selector to the tap, you shouldn't have to worry about cross-contamination.

Click to expand...

I was thinking the same thing, however, I did read that the solenoid values that I need to electronically shut off each of the four liquid lines produce foam and that you should run additional line past the solenoids to mitigate that.

I suspect I have lots of experimenting ahead of me...

Apex bar, Portland????

Sorry didn't read close enough to the thread, one wine and two beer deep!

How about just run half an ounce into the drip tray before you fill up your pint? If the manifold is close enough to the faucet, its not going to be all that much.

Subscribed and watching, as well as maybe contributing. Im working on a custom Island Kegerator that will incorporate a Mixed Drink Dispenser as well as 4 taps, but this would be cool.

Have you sourced any parts for the manifold? Or valves depending on how you handle it?

sounds cool, but not worth it.

cheezydemon3 said:

sounds cool, but not worth it.

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Oh its worth it, about 70% of what I enjoy with brewing is all the little projects and DIY stuff. Also I love electronics and doing the coding. So in my opinion it is worth it.

What about putting 5 valves on it, and running a 1/4" water line to the fridge (if you can) to the fifth valve. Add a line to the program that monitors the flow on the beer lines. If there's no flow for 2 seconds, it closes the beer valve, opens the water, and you can purge quick. It would keep the water lines open until you selected the next beer.

The only issue I see is purging the water before you pour beer...

Adeering said:

Oh its worth it, about 70% of what I enjoy with brewing is all the little projects and DIY stuff. Also I love electronics and doing the coding. So in my opinion it is worth it.

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Right on!

My thought was that even a tiny bit of red wine in a pale ale will be noticeable. So you let it run a second in between. Maybe no big deal, but over time, how much beer gets dumped?

WAIT!!!! If this is all automated, why do a tap at all?

Have the four lines come in from above, not visible but separate.

Have a space below the lines where you place the glass. An x marks the spot kinda thing.

Push the button for wine, wine comes out of the wine line. STOP.

Want Stout? (hopefully the wine line doesn't drip) beer comes out of the stout line which is right next to the wine line, thepale ale line, and the Alt line (or whatever).

Kinda Star Trek like.

Or us the same idea with a spout thick enough to hide all 4 lines.

That way all lines are seperate, but distribute to the same spot!

cheezydemon3 said:

WAIT!!!! If this is all automated, why do a tap at all?

Have the four lines come in from above, not visible but separate.

Have a space below the lines where you place the glass. An x marks the spot kinda thing.

Push the button for wine, wine comes out of the wine line. STOP.

Want Stout? (hopefully the wine line doesn't drip) beer comes out of the stout line which is right next to the wine line, thepale ale line, and the Alt line (or whatever).

Kinda Star Trek like.

Or us the same idea with a spout thick enough to hide all 4 lines.

That way all lines are seperate, but distribute to the same spot!

Click to expand...

I do still like the idea of a having the beer handle / tap interface as the final exit for the beer.

I sadly haven't had much time to work on this project. I realized summer was creeping up and spent most of my free time actually making beer and cleaning up my current non-electronic keg rig.

I've done some testing with inline pumps and didn't come up with anything I liked. I may try seeing if I can purge the line with CO2 somehow, but my most likely beta version will either be having the beer manifold right next to the flow meter and shank to eliminate the amount of beer that can be left inline or to do what cheezydemon suggests.

If I go the line of not using a traditional tap and handle, I may still try and rig up an electronic handle with an accelerometer in it to actually signal the selected line to pour and close.

Heres what Im thinking:

Still have a tap handle but put a sensor on it to tell when it is opened (most likely a Hall effect sensor). The opening will act like a button and trigger a solenoid valve depending on which tap is selected on the tablet (or control interface).

Have the solenoid as close to a manifold as possible. Use a 5 port manifold and have the 5th port hooked up to the CO2 and on shutoff trigger another relay for a second to purge the manifold after each pull.

For the liquid relays im thinking something like these

Havent looked for a air valve or a manifold yet. But I think this could work

Adeering said:

...Still have a tap handle but put a sensor on it to tell when it is opened (most likely a Hall effect sensor). The opening will act like a button and trigger a solenoid valve depending on which tap is selected on the tablet (or control interface)...

Click to expand...

Or to be even more trick, modify the tap so it can ove back/forward/left/right = each direction = a different beverage!
Lots more work though

Have you looked into what the bars use to dispense sodas? http://www.wunderbar.com/products/beverage/soft-drink/soft-drink-soda-gun-pistol Perhaps the technology there can get you 4 beers out of one tap.

Or to be even more trick, modify the tap so it can ove back/forward/left/right = each direction = a different beverage!

Click to expand...

Beer joystick!

tommyonegun said:

How about just run half an ounce into the drip tray before you fill up your pint? If the manifold is close enough to the faucet, its not going to be all that much.

Click to expand...

+1 for KISS method.

I have my stuff ordered to test out this idea...

I'm going to attach my solenoids very close to the keg outlets. I'll run some extra line to help out with any foam the solenoids introduce and each of the four lines will run into check valves before entering a manifold that looks like this:

http://www.superiorgrowers.com/grow...nts/chrome-adjustable-air-pump-manifolds.html

I found these manifolds for running air in hydroponic systems, but they should work fine for my "beta testing" of this idea. The four 3/16 barbs will be for the beer lines coming from the kegs. The 1/4 barb will be the outlet. I think this set up will allow me the most control while mitigating foaming issues and keep the "leftover" beer to a minimum. Ideally, the manifold would be vertical (3/16 barbs on side, 1/4 barb on bottom) so gravity feeds it all down, but if I mount this so that the 3/16's are on top and the 1/4 is on the bottom, it should be close enough.

I'm hoping to build out a prototype over the next two weeks. If it works, I'll use the prototype for the next few months while I plan something prettier for the long-term.

Tech-wise, I'm basing the electronics mostly from the KegBot project. I've ordered that projects Kegboard system for the Arduino, along with all the components from SparkFun. I'm not using all the KegBoard features and will be hacking bits and pieces from the KegBot firmware to run it. I'll be using the Arduino's serial communications to talk with the Raspberry Pi. The Pi will maintain the database about what's on tap, how much is left, and provide controls for talking with the Arduino over serial to tell it to turn the solenoids on and off.

So I should be finishing my kegerator in the next week or so and gonna need to get the parts ordered shortly after.

What solenoids are you using?

So thinking outside the box on both your issues here...

What if, rather than using low pressure CO2 to push the left-over beer out of the tap, you use higher pressure CO2 to push the beer BACK into the keg through the same line. IE - select your beer, valve opens. Open tap handle, beer flows out tap. Close tap handle, and the HP CO2 back-purge line that's connected to your main trunk line close to the tap opens up. Because the solenoid valve for the original beer is still open, you push all the left over beer back into the line. A few second burst would take care of things, and then the valve closes and everything resets. Now you have mostly empty trunk line and no wasted beer.

As for figuring out what's left in the kegs - rather than flow sensors, which are quite costly (last I checked), throw a load-cell under each keg. Empty kegs should all be in the same weight range, and the average density / weight per pint of your various brews should be close enough for estimating. You'll at least be able to tell whether the keg is mostly empty or only half gone.

Good luck to you - keep us updated.
-Kevin

BadNewsBrewery said:

So thinking outside the box on both your issues here...

What if, rather than using low pressure CO2 to push the left-over beer out of the tap, you use higher pressure CO2 to push the beer BACK into the keg through the same line. IE - select your beer, valve opens. Open tap handle, beer flows out tap. Close tap handle, and the HP CO2 back-purge line that's connected to your main trunk line close to the tap opens up. Because the solenoid valve for the original beer is still open, you push all the left over beer back into the line. A few second burst would take care of things, and then the valve closes and everything resets. Now you have mostly empty trunk line and no wasted beer.

As for figuring out what's left in the kegs - rather than flow sensors, which are quite costly (last I checked), throw a load-cell under each keg. Empty kegs should all be in the same weight range, and the average density / weight per pint of your various brews should be close enough for estimating. You'll at least be able to tell whether the keg is mostly empty or only half gone.

Good luck to you - keep us updated.
-Kevin

Click to expand...

Like the idea, my only comment would be to make sure that the solenoid valves you use can handle flow in both directions.

Solenoid valve is open or closed. The check valve is s concern.

BadNewsBrewery said:

Solenoid valve is open or closed. The check valve is s concern.

Click to expand...

A lot of the solenoid valves I have seen are direction and will leak if pressurised in the oposite direction. Saying that it probably doesn't matter much are there will be pressure still against the other side of the shut valves on the other lines and the amount that did leak would not likely affect the other lines greatly.

mattd2 said:

A lot of the solenoid valves I have seen are direction and will leak if pressurised in the oposite direction.

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This I did not know. Well, if OP can find valves that work, my idea would still be viable. If you dispense your kegs at around 10-12PSI, you'd only need maybe 15-18PSI (guessing ) to push the beer back down the line into the keg.

Update:

I'll be putting this together this weekend. I have everything ready to go for the most part. All of the components are in, except for a few fittings that I'll be getting tomorrow and Saturday. My custom programming on the Arduino controller board is functional and I just have a few things to do on the Raspberry Pi to get it talking to the Arduino and serving web pages to the iPad. The iPad will be used to show the graphical interface of all the beers and will use the touchscreen to actually select a beer to pour.

I'll have to grab some picture of it operating and then begin the process of posting the all details on my blog. Very excited to finally see it in action!

Please post photos as you do this. SUBSCRIBED!

Also subbed for pictures. You brainy smarties.

Don't forget manual option. Suck if you forget to charge the tablet...

Dude, this is going to be amazing. Awaiting updates.

Don't forget manual option. Suck if you forget to charge the tablet...

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I had to create a fairly convoluted system to get the iPad to communicate with the other electronics. The drawback is it adds a bunch of bulky equipment. The good news is that I am able to use my iPhone or any other smart phone should the iPad not be charged!

An update on the system:

After hoping to have it put together last weekend, I ran into some unexpected software glitches that were causing intermittent errors. I also ran into some issues stemming from sloppy soldering. After hacking away an hour here and there in between family stuff over this holiday week, I've got things in pretty good working order. Once I figure out a way (good or otherwise) to actually organize all the cables that are running in the tap box and get it attached my keezer, I'll post some picks.

I've had to make a few sacrifices in order to get the basic system up and running and plan to make extensive revisions after summer homebrew season is over, but I'm still very happy with how it currently is.