Duotight is a range of push in fittings for gas and liquid connections often used in homebrewing keg/draught system setups such as kegerators for connecting beer and CO2 gas lines to and from regulators, kegs, taps and other bits of equipment. The range was first released by KegLand in 2018, with a design update/revision in 2020.
Benefits of Duotight Fittings
Construction
Duotight fittings are made using an engineering grade plastic called polyoxymethylene (also known as POM or Acetal) and allow gas and liquid hoses (usually beer) to be quickly and easily disconnected. This is a common requirement in homebrew setups as systems are disassembled for cleaning, new components are added, rearranged, or other problems are troubleshooted.
Locking Collar
All Duotight fittings include a small collar that, when pressed, allow the connected line to be removed. They aim to be a more convenient, fast and reliable method of making connections compared to fitting hoses over barbs and securing with clamps. All fittings are rated to 100psi and use a special dual O-ring design to ensure a leak free seal, which is where we suspect the "duo" part of the product name came from.
Large Range of Fittings & Applications
There are a large variety of fittings and applications for Duotight components, such as connecting gas and liquid lines to quick disconnects, but there are also options for one way check valves, in-line ball valves that can be turned on/off, T-pieces for splitting one connection into two, 90 degree elbows and double ended female connectors to combine or join two beer or gas lines together.
The product range seems to always be expanding, and KegLand are starting to integrate Duotight connections into some of their components like their spunding valves, and even quick disconnects.
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| Some KegLand products like the inline regulator above now feature integrated Duotight connections |
Our Experience with Duotight Fittings
We've been using KegLand Duotight push in fittings for our homebrewery setup for several years now. This setup includes a DIY Kegerator, as well as a Series X Kegerator.
In our setup we use the following Duotight connections;
- KL06880 - 8mm x FFL (to fit MFL disconnects) - screw on thread to fit gas and liquid disconnects as well as the gas outlet hose on our gas bottle regulator
KL06880 - 8mm x FFL (to fit MFL disconnects) - KL07481 - 6.5mm x 8mm reducer - used to connect liquid line to our Pluto Dispensing Gun
KL07481 - 6.5mm x 8mm reducer on our pluto gun - KL02387 - 8mm female x 8mm female double tee piece - used to "T" our gas line to connect multiple kegs
KL02387 - T Piece for splitting gas line - KL06903 - 8mm female x 5/8" female thread - screw on thread to fit liquid line to tap shanks
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| KL06903 - 8mm female x 5/8" female thread - screw on thread to fit liquid line to tap shanks |
Initial Setup & Leaks
When we were initially setting up and installing our Duotight fittings we did experience some issues with leaking, however we soon discovered the cause of the leaks was due to us not installing them correctly.
The leaks solely occurred on our push in fittings connected to MFL threads (ie. our liquid and gas disconnects) and turned out to be caused by the Duotight fittings not being tightened enough on the threads.
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| Comparison of old & new style Duotight disconnects |
We previously mentioned that KegLand now integrate Duotight connections into some of their products, and this is a great innovation since it removes a potential source of leaks by not having to attach separate Duotight fittings onto threads as we outlined just above.
In saying that, we have found that with the Duotight integrated disconnects (on the right in the picture above), we have had to manually tighten the red cap on the top of the fitting as they weren't fully tightened during manufacturing.
Duotight Instructions
KegLand have a document available with clear instructions on how the Duotight fittings should be fitted and tightened on MFL threads. The nature of the Duotight design means a small amount of compression is required for the fitting to seal properly. Tightening by hand is not sufficient as we discovered, and explains why the threaded side of the fitting has the hexagonal shape to allow a spanner/shifter to tighten it. In short, after hand tightening, a further turn of 180 degrees is required to reach the required amount of compression in the fitting.
After adjusting all of our threaded fittings accordingly, we've had no more leaks.
Brittle & Cracking Fittings
Another common complaint amongst customers is fittings becoming brittle, cracking, and developing a chalky surface. These issues are almost exclusively caused by the use of harsh cleaning chemicals on them such as phosphoric acid based sanitizers like Starsan or Stellarsan, or other harsh acidic products like bleach. Although if mixed/diluted at the recommended strength, such problems should not occur but if they are left to dry after being sprayed the water evaporates and as it does, the concentration of the residual phosphoric acid (or other active cleaning agent) increases which causes a rapid deterioration in the plastic.
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| An example of Duotight fittings cracking/splitting |
Such problems have never occurred with any of our Duotight fittings, but nor have we ever sprayed the outside of our fittings with any cleaning/sanitising products. This just isn't necessary. We've always connected our hoses and fittings together, and then ran a cleaning/sanitising solution through the lines and fittings to clean/sanitize them.
Duotight Design Revision
As it turns out, the problem above was prevalent enough to prompt KegLand to release a design revision for the Duotight fittings in September 2020. This design revision essentially changed the material of the collar to be of a stronger plastic compound called POK (polyketone).
EvaBarrier Line Compatibility
Duotight connectors are design to be compatible with KegLand's EvaBarrier range of beer/gas lines. Just make sure that you get the correct Duotight fitting width/diameter to match the Outer Diameter (OD) of your EvaBarrier line. The most common appears to be 8mm and is what we use exclusively for all our fittings.
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| EvaBarrier line is recommended for use with Duotight fittings |
Mixed Reviews Amongst Homebrewers
The Duotight range has mixed opinions on homebrew discussion groups as to their reliability and susceptibility to leaks with some swearing by them, and others vowing never to use them again after poor experiences.
Our Tips for Using Duotight Fittings
Our experience and research has come across a few other tips and suggestions to ensure your seals are good and connections stay leak free;
- Push the Line All the Way In: Duotight fittings use a double O-ring design so you need to make sure your line is pushed in all the way to ensure both O-rings seal correctly.
- Straight Cuts: Angled cuts will prevent the line from inserting all the way to the end of the fitting, so it won't sit flush and won't seal correctly within the fitting.
Pro Tip: Use a tube cutter like the one pictured below for straight and smooth cuts every timeA tube cutter helps to ensure clean cuts of beer/gas line every time
- Smooth Ends: Ensure there are no burrs or surface imperfections (from cutting or a previous connection) on the outside of the line before you push it into the fitting. Trim the line to remove any bits that aren't perfectly smooth.
- Pull Test: After pushing the hose into the fitting, give it a firm pull to try and pull the hose out - there should be next to no movement/give in the line when it is sealed/seated correctly.
- Use Locking Clips: As another level of protection, there are also 'locking clips' available that slide in between the collar and the fitting. These prevent the collar from being pressed in which is required to release the tube/line from within the fitting. Although we've never had a fitting come loose, we figured it's some cheap insurance and another layer of protection since a 10 pack of clips only costs AU$1.
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| Duotight connector on liquid disconnect (MFL thread) with blue locking clip in place |
Are Duotight Push In Fittings Any Good?
In a word, yes. There are a few tricks and things to be wary of if you're going to use Duotight fittings, but if you follow the instructions (or check out KegLand's YouTube videos) for details on how to setup and install the fittings correctly, you're almost guaranteed a trouble free experience. For extra peace of mind we'd recommend using the locking clips as well, especially considering how inexpensive they are to buy.
Using the aforementioned tube cutter is also strongly recommended to help ensure your cuts are straight and smooth, to give the fittings every chance of making a good, leak-free seal every time.
The convenience of push in fittings like Duotight makes them a really worthwhile investment. Sure, others swear by the tried and true method of hoses and clamps, though they can inevitably leak or cause lines to split if done up too tight as well. Being able to quickly disconnect hoses and fittings without the need for any tools at all is something we find very beneficial. We'll definitely be continuing to use Duotight fittings for all our hoses and connections on our kegerator setups.
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