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Copyright Valsir-Uneeq 2013
Valsir-Uneeq - 49 Brunton Circle, Foundersview South, Modderfontein - Gauteng - South Africa
PEX/AL/PEX piping system for water supply. It is an innovative system that was introduced on the market years ago and is used for the distribution of hot and  cold water distribution networks, such as heating and cooling reticulation, air-conditioning and compressed air. The  Multi-Layer pipe combines the characteristics  of plastic and those of metallic pipes. The polymer material used for  the internal and external layers is croslinked polyethylene  PE-X and the middle layer is aluminium. The pipe has  extreme advantages in terms of hygiene and corrosion resistance by using PE-X. The aluminium layer is formed  around the internal layer of PE-X and is welded with a continuous longitudinal weld. This characteristic makes the  pipe extremely easy to bend, once bent it will hold its shape. To guarantee excellent product quality and reliability, Valsir subjects the PEXAL pipe to severe, rigorous checks, in  accordance with the ISO 21003 regulation. In addition, the production process is constantly monitored using  sophisticated sensors and electronic systems. The PEXAL pipe is also available in an insulated version: as the pipe is contained inside an insulating sheath, heat  dispersion from the fluid transported towards the external environment is minimised. The Insulated PEXAL pipe can  be used in two different versions: one specific for hydrothermosanitary applications and another for air-conditioning  systems.    Crosslinked polyethylene (PEX)   Polyethylene is a thermoplastic polymeric material composed of numerous long molecules which, even at  moderately high temperatures (still under the melting point), starts to have a significant level of fluidity. Therefore,  the excellent qualities of this material are limited by the operating temperature. With the crosslinking process, the  polyethylene molecules are bound together to form a more complex three-dimensional structure: the chemical  reaction of crosslinking, in fact, transforms the product from thermoplastic to thermosetting. The material is  subjected to a structural modification which improves features such as abrasion, chemical resistance and  mechanical resistance over time. With crosslinking, the level of fluidity is considerably reduced and the performance  of the material is significantly increased. In addition to this increase in performance at high temperatures,  crosslinked polyethylene maintains the excellent properties of thermoplastic materials. There are various  technologies to obtain crosslinking of polyethylene but, as polyethylene does not have functional groups which have  the capacity to be crosslinked, it is necessary to add another component to the material. The internal and external  PEX layers of the PEXAL pipe are crosslinked with the silane method: crosslinking takes place with the creation of  chemical bonds due to the presence of silanes. This process takes place in part during the extrusion phase but  mainly in a second stage which consists of the positioning of the bars or rolls of piping in a tub of water at a  temperature of between 70°C and 95°C. The crosslinking process is activated by the humidity and the temperature  and is accelerated by the addition to the mixture of a suitable catalyst. Polyethylene crosslinked with the silane  method takes the name PEX-b.  Aluminium  The aluminium tape must respect high standards of quality:   the aluminium is degreased with a chemical treatment using acids  the surface of the tape is smooth and flat with edges which are free from burrs or waves  The alloy used has excellent mechanical features (high yield point) and good weld ability   Adhesive  The aluminium belt is secured to the internal and external PEX layers using two layers of glue.  The glue has been  specifically developed in order to maximise adhesion between the PEX and the aluminium and to make sure that  the gluing strength does not decline over time and with high temperatures (within the prescribed use temperature  interval for the pipe). Then, thanks to the adhesive, the two layers of PEX and the layer of aluminium go on to  constitute a whole with properties which are greater compared to the individual component.    Characteristics Combines the advantages typical of metal pipes with those of plastic pipes.  One pipe is used for numerous applications: systems for plumbing, heating and cooling at high and low  temperatures and for the distribution of compressed air.  Approved for drinking water and features an elevated degree of hygiene.  Maximum operating temperature of 95°C and 10 bar.  Extremely rapid and easy to install. Elevated chemical resistance to the main substances dissolved in water. Pexal Easy also guarantees  excellent resistance to chlorine.