CMBecker Ball Lock Quick Disconnect (QD) | Built-In Check Valve | Gas In | Flared | High-Quality Plastic QD | NSF Registered | Made in Germany | Assembled in USA

CMBecker Ball Lock Quick Disconnect (QD) | Built-In Check Valve | Gas In | Flared | High-Quality Plastic QD | NSF Registered | Made in Germany | Assembled in USA

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  • The highest quality plastic ball lock quick disconnect available to homebrewers
  • Built-in check valve to prevent liquid from backflowing into your draft system
  • Smooth operation—clicks into place on keg posts and is easily removed
  • Built-in flare washer—no need for a separate nylon washer that is required with stainless steel QDs
  • CMBecker is an international manufacturer of beverage dispensing solutions for both home and professional draft equipment
  • Gray plastic clearly identifies the disconnect as the gas in QD

Sleep a little easier knowing this gas in ball lock with built-in check valve has your back. The internal check valve allows gas to flow out, but won't allow backflow of liquid into your gas system. Many manifolds and regulators already feature check valves, but this disconnect will keep liquid from ever entering your gas lines in the first place. Especially handy if you force carbonate your beer using the bev out dip tube!

Why we love it:  Because we've had beer shoot back into our gas line and that sucks. At some point you will have a keg that is pressurized more than the pressure in your gas system. This could be caused by different carbonation levels, a keg sitting at room temperature, etc. So for example if the pressure in your keg is at 20 psi and your regulator is set at 12 psi, when you connect your gas in quick-disconnect liquid shoots from the keg into the gas line. Eliminate that possibility with this ingenious fitting.     


  • Internal Check Valve protects your system from liquid back flow
  • Made in Germany and assembled in the USA by CMB.
  • Extremely high quality for years of service.
  • NSF Approved for Food Grade Service!
Item # KEG729
Shipping Eligible for Free Shipping Program
Availability California - In Stock
Pennsylvania - In Stock
Weight 0.11 LBS
Community Q&A

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Browse 3 questions Browse 3 questions and 7 answers
Why did you choose this?
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Beer in your gas line once and these are worth it. The SOUND is annoying, but worth it.
Adam Arndt on Feb 7, 2023
To protect my new mini 360 regulator
Pickering, Richard on Nov 4, 2022
Beer in your gas line once and these are worth it. The SOUND is annoying, but worth it.
Adam Arndt on Feb 7, 2023
tired of cold brew coffee into my gas line
Marnie M on Jan 16, 2023
To protect my new mini 360 regulator
Pickering, Richard on Nov 4, 2022
To prevent beer getting into my gas line.
Aaron Sams on Aug 16, 2022
To ensure we don't get flow back into the CO2 line
Valued C on Jul 4, 2022
tired of cleaning beer out of gas line when using carbonation stone
Stephen Goadhouse on Mar 16, 2022
Had an issue and want these on my active kegs.
Steven K on Mar 15, 2022
Just what I was looking for
Jason C on Jan 31, 2022
To prevent liquid from entering my gas line
Roger Muncy on May 29, 2021
If you have ever connected to a full keg that was higher pressure than your gas line....this is for you!
Caleb C on May 14, 2021
Setting up a water carbonation system
Alex L on Mar 10, 2021
I had beer back up the airline once. Never again!
Matt W on Nov 24, 2020
An ounce of liquid prevention over regulator/distributor rebuild.
Philip V on Oct 20, 2020
check k valve
Michael N on Oct 10, 2020
Prevent fluid flow into gas line
Jeffrey Hasterok on Oct 8, 2020
To keep beer out of gas lines and regulator.
William S on Sep 4, 2020
stop gas equalization between kegs
Terrence Q on Jun 22, 2020
Issues with beer flowing into gas lines
Ryan D on Jun 19, 2020
To protect my regulator.
Jay S on May 21, 2020
To prevent liquid from entering gas line
Nicolo on Jan 21, 2020
To keep beer out of my gas lines.
Sean E W on Nov 18, 2019
Thought it would be good, for my 4 way carbonating manifold, as liquid has a tendency to get in the gas lines making it hard to clean.
Michael D on Nov 6, 2019
Loved the idea of a check valve to protect by gas system.
Preston K on Oct 7, 2019
tired of cold brew coffee into my gas line
Marnie M on Jan 16, 2023
To prevent beer getting into my gas line.
Aaron Sams on Aug 16, 2022
Will this work with 5/16 gas line, or only 1/4 line?
Marc Mendelsohn on Mar 4, 2020
BEST ANSWER: The other answers are correct that this can be used with any size of tubing as long as you have the appropriate size flare and barb combo.
There seems to be a difference in pressure from supply to keg. I tested with an empty keg. I set regulator to 10psi and let it fill for an hour or so. It's rather loud when gas is flowing. After an hour, I removed the checked ball lock and put my spunding valve on the gas post to check pressure. It only read 4 psi. Is this normal to have a 6psi pressure differential? I bought multiple of these and they all perform similarly.
Ryan Shenk on Sep 3, 2021
BEST ANSWER: My experience with this has been the same. They’re great at keeping beer out of your hose and gages but they’re slow letting gas through and you’ll never get an accurate pressure.
Does it require a flare washer?
Lanz Van Beurden on Aug 16, 2019
BEST ANSWER: Hi Lanz - this disconnect features a built-in clear plastic washer and does not require an additional nylon flare washer to function properly.

3.7 / 5.0
7 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Rated 2 out of 5
Failed after about 10 months, near impossible to clean/reset
I have always associated CMB with quality fittings, but I wasn't impressed with this byzantine design. It's super noisy, which I could let go if it worked well. But the real issue was that is did not do it's one job, I got backflow into the gas dip tube when I connected it to my force-pressurized keg (keg was at about 30PSI, connect was at about 15 psi).

After that I make the brilliant decision to disassemble it with my yearly QD breakdown-soak-cleaning, and without some kind of exploding diagram and advanced degree in aeronautical design, there's no prayer I have of getting it back together. All sorts of springs and diaphragms and ball bearings.

Needless complex, failed to do it's job. It's lucky I gave it an extra star for the 8 months it worked.
April 22, 2022
over 3 years ago
Rated 2 out of 5
Difficult to use, leaky
We bought several of these so that we would never again get beer up our gas lines. But they performed poorly. Seemed like gas didn't flow very easily, they were very difficult to remove from the gas posts, and they leak if the gas line is a bit taut. The leaking is what eventually caused us to throw them all into a box and we went back to the old standards.
July 20, 2021
Rated 5 out of 5
Ball Lock with check valve
This is a quality product that should last for years. Provides an extra level to protect beer from backflowing into CO2 regulator
June 12, 2021
over 3 years ago
Rated 4 out of 5
Great design except for cleaning
The design entails a two stage check valve. Each stage is comprised of a spring loaded steel ball that ipresses into an o-ring orifice. Without pressure, the spring holds it closed. Positive pressure from the gas line pushes against the ball and spring allowing gas to enter the keg. When the pressure equalizes, the spring pushes the ball against the o-ring orifice. If the pressure in the keg is higher than the gas line, this pushes the ball even harder into the orifice to keep it closed. This a much better design than the check valves in most gas manifolds. In addition, unlike the check valves in the gas manifolds that I’ve seen, it actually works. I tested it with a keg a Star San. However, in the event that some beer makes its way to the first check valve, it will be harder to clean and sanitize. Be very careful if you decide to disassemble it. Make sure to take notes so that you understand how to reassemble it. I bought 8 and will buy three more in the future to replace all of my standard gas ball connectors.
December 30, 2020
over 3 years ago
Rated 5 out of 5
Works as it should
Perfect for what it does. No more beer getting into the gas lines.
May 3, 2020
over 4 years ago
Rated 5 out of 5
Worth it!
Not cheap, but replacing a regulator because of backed up fluid is MUCH more expensive! Just get this for every gas-line keg connection and enjoy having one less thing to worry about. It is cheap insurance.
January 29, 2020
over 4 years ago
Rated 3 out of 5
Interesting device
There has been many times when shaking to carbonate, the liquid would flow into the co2 line. This necessitated taking the co2 line apart and PBW and Star Sanning it. RPITA. I also have a small 5lb tank I use to carbonate 1 lt test batches. It too, upon occasion, would back up the gas line. In my 6 product line kegerator, when I connected a new corny keg, unequal pressure between keyg and co2 would cause the same thing. This hopefully would prevent that. So far so good. The 3 star rating is for the 9 kegs in my temp controlled freezer. After I depressurized the kegs and replaced the with this item on the kegs no beer was moved the 14' above to the faucets . 14 psi worked to get a good flow before but the gas wasn't going into the kegs at 14 psi. I gradually increased the gas till i heard in flowing into the kegs, 19 psi was the point that the gas flowed. I let it flow for a while, then reduced it back to 14. We'll see if I don't get enough pressure after I dispense and need to turn it back up. I hope this isn't the case.
January 13, 2020
over 4 years ago