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Mini-Keg Tap - Simple Two Port Design FEB2012

I’ve followed the design and great info that SiouxerBrewer has shared here (, and I’ve posted my earlier alternate ‘rubber stopper’ design ( which has been working well for me. But I wanted to get away from the hold-down hardware, maintain the low profile, and keep it easy/cheap to build.

Sorry if these posts are long, I wanted to give as much detail as possible. The actual construction and use is really simple. The pictures tell the story. Basic steps are simply:

    CO2 side: Insert washer and hose onto hose barb splicer, cut end of hose barb off, slide on re-usable bung, and connect gas hardware to other end.

    Liquid side: same except instead of cutting the hose barb, you add ~ 6” of hose to form a dip tube, and connect the other end to a tap. That’s it. In the variation that I use, you pull 1/8” ID hose through the barb for the liquid side, and terminate the CO2 and liquid ends with a Luer connector for added flexibility.

Two things led to this design. One - I found it is easy to remove the built in tap that comes with the mini-keg, and that port is the same dimension as the top vent port. This simplifies everything, as we don’t need to get gas and beer through the same port, plus it makes it far easier to clean and dry, with no worries of that spigot trapping any nasties (see this POST for spigot removal tips - ). Second - I saw in this post ( ), that the thick-walled BevLex tubing fits fairly tight in the removable bung. I found that the 3/16” ID thick-walled BevLex tubing pushed over a 1/4” hose barb connector expands enough to seal very tightly in the bung (it is slightly larger than the plugs that come with the bungs), and can be bent over to keep the height to less than 1-1/2” above the mini-keg. The shoulder and washer will retain the assembly in the bung.

First I’ll show a design with 3/16” ID hose that can be connected to standard kegging hardware, then I’ll show the variation that I use on the tap side, which reduces the tap line length to ~ 2 feet for a good pour. I keep the lines closed/looped while conditioning/storing, and just add a tap and air stem (or other gas source connection) when I put them on for serving. This keeps total system costs very low if you keep multiple mini-kegs waiting to be put on tap.

This pic shows the low profile of the CO2 side (shown here with the Luer connectors, 1/4” barb-1/8” MPT, 1/8” FPT coupler, and 1/8” MPT air stem for the CO2 side, and Luer connectors to the Cobra Tap).


The key to the short line length is the line resistance provided by the 1/8” ID x 3/16” OD vinyl tubing I’m using - this tubing can be pulled through the PL200 hose barb splicer, and it seals tight. Two feet of 1/8” ID tubing takes up much less space, and saves about $5 over the usual ~ 10’ of 3/16” ID beverage tubing. I’ve been testing this to 45# with no issues at all.


If you want to try a SS hose barb (, note that it has a thinner wall with ~ 3/16” ID - so try 1/8” x 1/4” vinyl hose in place of the 1/8” x 3/16” - that should
provide a good seal. I have not tested this particular part, but I have tested and used 1/4” x 1/8” vinyl tubing pulled through 3/16” holes with no problems.

Optional, but I like to use these cheap Luer connectors for flexibility ( ~ $0.40 per piece). I buy Male and Female Luers with 1/4” barbs and some with 1/8” barbs so I can easily interconnect 3/16”, 1/4” and 1/8” ID tubing. I use these to go from the 1/8” ID tubing to the 3/16” tubing on the Cobra Tap, and I can easily pinch clamp the 1/8” tubing and remove the tap for cleaning/storage, or connect a longer line section if needed for highly carbonated beverages.

Assembly details next…


Here’s a detailed view of the assembly for the CO2 side. The individual components are shown in the top row, and then assembled in the middle row. Dip the 3/16” ID tubing in water just off the boil for 30 seconds to make it flexible enough to push over the barb (don’t forget to put the washer on first!). I like to keep a small gap so that the SS washer will move freely so it can be cleaned/dried/sanitized w/o trapping any gunk. Cut the barb as shown to keep it above the liquid level. Terminate the other end in whatever gas hardware you use in your system - slip the bung on before connecting that end.

The lowest row shows how to run the liquid side, if you are going with all 3/16” ID beverage tubing [NOTE: This is NOT what I’m using, I’m showing it here for reference - I use the 1/8” ID tubing assembly shown next]. Construction is about the same as the CO2 side, but don’t cut the barb off, and add ~ 6 1/2” of tubing to form a dip tube which will push right against the other side of the mini-keg. Trim the end at a little angle so it cannot end up flush against the inside wall and restrict the flow. A piece of 1/4” ID stiff poly tubing will work here as well. You will be able to get almost every last drop out by tilting the keg for the last pour.


Here’s how to construct the liquid port to use the 1/8” x 3/16” vinyl tubing. Cut a 1” length of the thick-walled beverage tubing, and push it over the SS washer and barb as for the CO2 side. Note that one end of the hose barb has a slightly larger ID than the other (I assume to help remove it from the mold during manufacturing). It might make it a little easier to pull the tubing through the larger side first, so put the 1” length of tubing on that larger end (you can tell which is larger by how far a pencil point will insert, or with some small drill bits). Next, slice some material away for ~ 2 to 3 inches of the 1/8” ID tubing and form a point so that it can be pushed/pulled through the hose barb. I find it easiest to slide an 1/8” dowel into the tube to hold it as I slice some material away, and then maybe lay it out flat to trim it up a bit to keep the edges smooth so it won’t catch on the way in the barb. If you are having problems, try some keg lube, and wipe it clean once it’s through.


Then pull the tubing through to that it can be trimmed to ~ 6-1/4” from the shoulder. Place a ~ 4-1/2” piece of 1/4” ID stiff poly tubing over the end, and push it onto the barb just enough to hold it in place. This keeps the small tubing from curling up away from the bottom, and can be pulled off for cleaning. Trim the other end to ~ 2’ past the barb, slide on the bung, and put on a 1/8” barbed Male Luer. The dip tube detail and complete liquid side assembly are shown here:


Parts List next…


PARTS LIST A (For Reference - Using all 3/16” beverage tubing, this is NOT what I do):

1 - Mini-Keg; emptied, cleaned, with spigot removed.
2 - Replaceable mini-keg Bung (Some kegs come with a re-usable type).
x feet - BevLex 3/16” thick walled tubing - length as needed for your system.
2 - PL200 1/4” x 1/4” Hose Barb Splicer (this has a shoulder in the middle)
2 - Retaining washers; 5/16” Stainless steel.
1 - Gas connection of your choice.
1 - Cobra Tap, or other connection for a tap.
tiny amount - Keg Lube

PARTS LIST B (My approach as shown with 1/8” ID liquid line):

1 - Mini-Keg; emptied, cleaned, with spigot removed.
2 - Replaceable mini-keg Bung (Some kegs come with a re-usable type).
2 inches - BevLex 3/16” thick walled tubing for bungs.
~ 3 feet - 1/8” x 3/16” Vinyl hose.
~ 4-1/2” - 1/4” ID stiff poly tubing, to form dip tube
2 - PL200 1/4” x 1/4” Hose Barb Splicer (this has a shoulder in the middle)
2 - Retaining washers; 5/16” Stainless steel.
1 - Female Luer - 1/4” Barb for gas side input.
1 - Male Luer - 1/8” Barb for liquid side.
1 - Pinch Clamp.
tiny amount - Keg Lube

I use the below parts only for the kegs in service:
1 - Cobra Tap.
~4 inches - BevLex 3/16” thick walled tubing for Cobra Tap.
1 - Female Luer - 1/4” Barb for Cobra Tap input.

CO2 side can be done any number of ways.

CO2 A) Schrader Valve Style - If you use a CO2 source with an air chuck - use an air stem connected only to kegs in service:

1 - Schrader style tank valve - 1/8” MPT
1 - 1/8” FPT to 1/8” barb nylon
a few wraps - Teflon Tape
6 inches - 1/8” ID vinyl hose
1 - Male Luer - 1/8” Barb from CO2 side to connect to Mini-Keg Female Luer.

CO2 B) I’m moving to this approach, with a Male Luer on the end of my CO2 source. Use ~ 6” of 1/8” ID vinyl hose with Luers on each end and a pinch clamp in the middle. Leave connected to keg in service, but pinched. Connect to CO2 source, and un-pinch to add CO2. Pinch before disconnecting CO2. Essentially, the pinch clamp makes a cheap ON/OFF valve.

6 inches - 1/8” ID vinyl hose.
1 - Male Luer - 1/8” Barb.
1 - Female Luer - 1/8” Barb.
1 - Pinch Clamp.

So for my “CO2 B” approach, we are looking at ~ $9 for everything you need to fill and put a mini-keg on the shelf (plus the mini-keg). This assumes you need to buy both bungs, but no shipping costs added. (see price/sources below).

The added cost to put a keg into service is ~ $5.50, including $3.50 for the Cobra Tap. You only need as many of these as you serve at one time. So I think this is a pretty cheap way to go, and I think it is pretty easy to construct, and quite robust - very few connections or opportunities for leaks.

Using the system next…



Clean and sanitize the mini-keg and bung/tubing.

Slide the Liquid Side bung down to bottom out against the retaining washer (I apply a bit of keg lube to the last 1/2” of tubing going into the bung, which might help to disassemble when empty).

Apply a bit of keg lube to the groove in the bung, and a little all around the shoulder.

Push the bung into the bottom port. I find it helps to get one small section of the groove in place, then move around from there. With the lube, it should seat pretty easily. I use a Popsicle stick or dowel to push around the center of the bung to help assure it is fully seated in the groove. Lift the flap around to double-check. After you do it once or twice, you will have the ‘feel’ for it.

You can add more sanitizer if you want, and can pull a little vacuum on the liquid out tube to suck out any excess sanitizer. It will get almost every drop. Close the tap if you keep a tap connected, and/or pinch clamp the hose.

Add priming sugar if you ‘naturally carbonate’. I’m finding that ~ 60% of the normal bottling rate works well, and I don’t know why it should be less, but I will get ~ 30 PSI at room temperature, which is in the ballpark on the CO2_volume/temperature charts. Fill with beer to ~ 1” from the top.

Insert the top bung/tube assembly the same as for the liquid side. Purge with CO2 if desired. Since I usually naturally carb, I just wait ~ 20 minutes to let the CO2 that escapes from racking push out the air.

For natural carb - close the gas side (see “Conditioning Options” below), keep in a warm (65F-75F) place for a few weeks. You can test the pressure with a gauge, expect ~ 30# at room temperature.

To serve, chill, connect a CO2 source at serving pressure (~ 10-12PSI), un-pinch and add a tap if you stored it w/o a tap. I generally just top off the pressure after pouring a pint. As the keg empties, the pressure will stay more steady with the extra head space, you can pour several w/o the pressure lowering much.

When emptied, release pressure, push the barbed portion of the tubing inside the keg using a dowel or Popsicle stick, so the tubing is looser in the bung. Then lift the lip of the bung, push in on the shoulder of the bung, work your way around and pull to remove the bung . If it is resisting, add a little keg lube as you work your way around, but this shouldn’t be needed - just go slow and easy to avoid tearing the bung. They come out pretty easy for me, a little practice helps.

“Conditioning Options”: Since I’m putting Luer connectors on my tubing (1/8” Male Luer on the Liquid tubing OUT, 1/4” Female Luer on the Gas tubing IN), I just pinch clamp the small diameter liquid tubing, then ‘close the loop’ by connecting this to the Luer on the CO2 tubing (twist the tubing CCW a few turns to keep the Luer from untwisting itself).

I also have a pressure gauge connected to a Male Luer, so I can pinch off the gas tubing on the keg (I slip a slit piece of 1/2” ID braided hose over the tubing, and pinch it with a small Vice-Grips), and connect the pressure gauge to check pressure. Or just leave a gauge connected, or an air-stem - it’s up to you. Or connect to CO2 to force carb. I’m using a paintball tank set-up.

Part Numbers, Sources, piece prices next…


Part Numbers, Sources, Cost - I’m not including shipping, many parts can be sourced locally, and shipping will vary with quantities and distance, but should be pretty minimal if you group your orders carefully. These are individual piece prices, I’ll repeat that for the way I set mine up, :

~$1.29 ea; Replaceable mini-keg Bung - Some kegs come with a re-usable type, scrounge, purchase from LHBS or:

~ $0.50/ft; BevLex 3/16” thick walled tubing - Any HBS, local or on-line.

~$1.99 ea; PL200 1/4” x 1/4” Hose Barb Splicer - I got at local Ace HW.
~$0.20 ea; Stainless Steel Washer 5/16” -
~$3.50 ea; Cobra/Picnic Tap,
~$0.21/ft; 1/8” x 3/16” Vinyl hose - I got at local TrueValue or Ace HW.
~$0.21/ft; 1/4” ID stiff poly tubing, to form dip tube - I got at local TrueValue or Ace HW.
~$0.40 ea; Female Luer - 1/4” Barb
~$0.40 ea; Male Luer - 1/8” Barb
~$0.40 ea; Female Luer - 1/8” Barb

Here are McMaster P/N for 1/4” and 1/8” barbed Luers, Male & Female - what you use depends on details of your system. I’ve also found these on Amazon with free shipping > $25:

~$0.45 ea; Pinch Clamp.
tiny amount - Keg Lube

If you use Schrader valve input, added P/Ns you might use:

~$3.57 ea; Schrader style tank valve - 1/8” MPT -
~$0.62 ea; 1/8” FPT to 1/8” barb nylon - $6.14 per pack/10 -

a few wraps - Teflon Tape

The system is working well for me, let me know if you find it useful or have any questions or suggestions for improvement.

Cheers - kenc

Looks awesome! Nice work thinking outside the box. Nice low profile and short tubing makes it ultra portable. Thank you for sharing.

This is awesome Knec.
Looks like I have a new project to start.
I can see a cooler full of these on the pontoon this summer.

I have everything except CO2 small tank dispenser and pinch clamps. Any suggestions for sources? Thanks for assisting…

Thanks for the feedback. Summer, pontoon, and some mini-kegs of home-brew sound great right now (we are getting a late year snow storm here in N IL this evening).

Sure thing. Pinch clamps are available at any home brew store. NB has them here ( I guess they call them ‘tubing clamps’): ... clamp.html

There are lots of options for the CO2. You can get a small ‘gun’ that takes the little cartridges (like the bikers use to fill bike tires). That can get expensive, but if you are only dispensing probably not too bad. Careful with those, they put out full pressure, so just a short shot at a time to bring i up to the pressure you need.

Or, use a 20 oz paintball tank, refills at sport places are ~ $4. But you need an adapter, and a regulator. I use a paintball ‘remote’ as the adapter, it has an on/off valve too.

I got my tank thru Action Village, ordered thru Amazon I think to save shipping. ... -tank.html

The remote is something like this: ... ranty.html

Or this: ... pling.html

No ON/OFF valve, but that might be better, my valve seems to leak, so I have to shut it off between charging kegs up.

And a regulator: ... tegory/41/

Or just get a ‘standard’ 5# CO2 tank and regulator.

Search the forums here for lots of options.

I also hope to get some added pics up - no big deal just a few more options for parts. In place of the 1/4" barb splicer and SS washer, a nylon 1/4" barb to 1/8" or 1/4" MPT adapter works as well. It has a large shoulder on it, so you don’t need the washer, that’s all.

I’ve also played around with ‘drilling’ a 3/16" OD SS tube through one of those nylon adapters. That seems to work, but I really don’t see any advantage, so I don’t plan to follow up. The whole inside of the keg is lined in plastic anyhow!

And I was also going to throw together a little variation to use to get the commercial beer out the first time you tap it. I find the built in spigot just foams too much. I just let the pressure off by pulling a few pints, then switch over to my ‘rubber stopper’ design. But if someone builds this style, they won’t have the rubber stopper hardware. The idea is simply a longer dip tube, and a tee for liquid and a check valve and hose to the CO2 supply to force CO2 right past the liquid. This would disturb yeast/sediment on a home-brew, but that shouldn’t be an issue for the packaged beer. Plus there would be some CO2 in the liquid line after charging, but I doubt this would be worse than the built in spigot. It just has to get you through those 5L.

I wish I had more mini- kegs - I finally got back to active brewing and will have 3 fermentors ready for bottling soon. I’d love to do about 3 mini-kegs of each, and bottle the remainder.


Here is my thought /idea for today! Why not prime the beer with CO2 from large tank via tire valve after filling from keg which is carbonated and then use an air pig that has been filled at tire garage with nitrogen? Use air valve to dispense beer when needed and not buy a small CO2 tank or play with throw away cartridges!! Just trying to “Get er done!!”

I think the garages around here charge for nitrogen.

I like having a regulator controlling the pressure going into the kegs.

Nice new design Ken. Much easier design than the fantastic work SiouxBrewer put forth.

Costco is free!

Why do the images not show?

Not all the old posts were carried over into the new format. Is a problem that some good information was not archived. @kenc_zymurgy most likely still has the pictures.

Looks like they are all links to external sites, and they have moved their site around. The links no longer link to those pics. I guess in the future I’ll need to save the images somewhere that is more permanent.

I think you can get the idea from the descriptions though. BTW, I gave up on these mini-kegs - I had a few that after several uses, developed a void in the plastic lining inside the can, and I got a metallic taste in the beer. It’s difficult/impossible to see, I didn’t know util I got bad beer.

I switched to this design, and have been very happy with it. Easy to clean, no problems at all:

ARGHHH! I see that the forum update here wiped out even the saved images. Let me know, I can look into updating it if you are interested.

Thank you for the information.

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