This new EVA Double walled tubing is made with an EVA outer wall and also an inner proprietary polymer barrier.
Outer Barrier The outer barrier has accurately extruded tolerances and made from an EVA material. It also seals well when used with various DuoTight, John Guest or other push in fittings. The outer barrier gives the tubing excellent kink resistance so the line is able to bend around a tight radius without kinking.
Inner Barrier The inner barrier is made from a proprietary polymer that provides an excellent gas barrier. The significantly better barrier properties means your beer is better protected from oxygen and also has a better barrier to CO2 loss. So your beer will stay fresher for longer and not loose carbonation like other beer line types. In some beer line types you may notice that the beer sitting in the lines starts to taste flat and/or oxidised when sitting in the lines for an extended period. EVABarrier tubing is better in this regard and you will notice a significantly improved freshness of your beer especially if it's been sitting in the lines.
Due to the high density and smooth nature of the EVABarrier inner barrier the tubing internal surface is super smooth and almost completely impermeable. This makes it difficult for bacteria and other microbes to attach to the inside surface of the tubing.