Duotight is a range of push in fittings for gas and liquid connections often used in home brewing keg/draught system setups (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.
They are made using an engineering grade of plastic called polyoxymethylene (also known as POM or Acetal) and allow hoses for gas and liquid (usually beer) to be quickly and easily disconnected which is often a requirement in home brew setups - as systems are disassembled for cleaning, new components are added, rearranged, or other problems are troubleshooted. The fittings all include a small 'collar' that when pressed allows the beer/gas line connected into the fitting to be removed. They aim to be a much more convenient, faster, and reliable method of making connections when compared to the previous standard of hoses being fitted over barbs and then clamped with stepless clamps or other varieties of hose clamps. All the fittings are rated to 100psi of pressure, and use a special dual O-ring design to ensure a leak free seal.
There are a large variety of fittings and applications, 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/join two beer/gas lines together.
We've been using KegLand Duotight push in fittings for our home made kegerator setup for some time now and wanted to share and outline are experiences. 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.
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 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 |
Thankfully, 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.
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 cleaners like Starsan or Stellarsan, or other harsh acidic baced cleaners like bleach. Although at the recommended dilution of these products, 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.
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.
As it turns out, the problem 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 the collar of the fittings to be of a stronger plastic compound called POK (polyketone).
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.
Our experience and research has come across a few other tips and suggestions to ensure your seals are good and connections stay leak free;
- Make sure the beer/gas line is pushed in all the way. Duotights 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.
- Ensure the end of your line is cut perfectly straight/square. 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.
- 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.
- 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.
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.
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. 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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