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Copyright Valsir-Uneeq 2013
Valsir-Uneeq - 49 Brunton Circle, Foundersview South, Modderfontein - Gauteng - South Africa
PEX ADVANTAGES   The Valsir crosslinked polyethylene (PEX) pipes are designed for sanitary systems, traditional heating and  underfloor heating. They are easily and rapidly installed because of their lightness and flexibility. The PEX pipes  are produced using high quality raw materials, in sizes ranging from 16 to 32 mm, in conformity with national  and international standards (UNI 9338, UNE 53-381-89,). They are certificated by AENOR and CSTBAT and  meet the hygenic requirements of Italian, Spanish and France Ministry of Health. A wide range of brass fittings  completes the product offering.   All hydronic heating and cooling systems are susceptible to oxygen entering the system through different  sources such as threaded fittings, boiler, pumps, air vents and gas permeable materials. Oxygen permeation is  the ability of oxygen molecules to pass through a material; it's due to the material's molecular structure and to a  difference in the partial pressure of oxygen on each side. Oxygen can be introduced in significant enough  quantities that, when combined with other factor, might cause unacceptably high rates of corrosion on ferrous  metal components. Valsir PEX pipes which incorporate the oxygen diffusion barrier dramatically reduce the  measurable amount of oxygen permeation. The barrier pipes are used in close circuits such as radiant floor  heating systems and radiator heating systems; the non-barrier pipes are generally used in open circuits such as  sanitary water distribution system. Resistance to chemical and electrochemical corrosion  PEX is highly resistant to both acids and alkalines; as a result it can be used to convey such chemical  substances without reducing its physical and mechanical properties. Given that PEX is a bad conductor of  electricity, it is not prone to destruction by stray current, which perforates metal pipe systems. Resistance to abrasion  PEX pipes are highly resistant to abrasion. This feature makes them suitable for conveying solids in water or  relining operations where the outer wall of the pipe slides along the inner wall of the pipe to be relined.  Absence of scale and mould  Metal pipes are rough inside, this causing scaling which reduces the bore of the pipe. Plastic pipes on the other  hand are extremely smooth so that the risk of obstruction caused by the build-up of scale and mould is  considerably reduced.  Low head loss  The surface of plastics is extremely smooth as it is free from the cracks and microflows, typical of metal pipes  traditionally used for conveying water. This feature results in high flow rates and low head losses.  Low thermal conductivity  The low load conductivity of plastics with respect to metal is a very important factor in energy saving, the  thermal conductivity of PEX being a mere 0.38 W/m·°C, as against 45 W/m·°C for steel, 52 W/m·°C for cast  iron, and 348 W/m·°C for copper. Plastic pipes in fact reduce the formation of condensate on the outer surface,  which is not the case with metal pipes. Low noise One of the main features of PEX is its high coefficient of acoustic insulation, which considerably reduces the  noise level during operation, even in presence of water hammering.  Rheological memory This is a particular feature of PEX. When the pipe is heated to the softening temperature of around 130°C (i.e.  the temperature at which the material becomes transparent), it is possible for the pipe to return to its original  shape. This means that wrong bending or squashing can be easily corrected. However this operation must not  be done on piping with an oxygen diffusion barrier as this would affect the multi-layer structure of the pipe.  Excellent workability PEX pipes used in private dwellings usually come in coils. Since this material is extremely lightweight they can  be handled without any special equipment. The average specific weight of PEX is 0.95 g/cm3 as against 7.85  g/cm3 for steel and 8.9 g/cm3 for copper. A 100-metre coil of 2-mm pipe, diameter 16 mm, weighs around 9 kg.  Cold bending of PEX pipes can be done without any particular equipment. The radius of curvature can be up to  eight times the diameter of the pipe. Hot bending is necessary for very small curvatures or high-pipe diameters.  The pipe is heated by hot air to the softening temperature; when it becomes transparent it can be shaped as  required. Once the pipe cools, it keeps its new shape. Due to its rheological memory, wrong bending can be  corrected by reheating and repeating the operation. This must not be done on piping with an oxygen diffusion  barrier as this would affect the multi-layer structure of the pipe.  Long life Taking into account the normal pressure and temperature values in private dwellings and thanks to the excellent  properties of PEX, pipe systems made up using this material have a life expectancy comparable to that of  masonry. A pipe undergoes mechanical stress because of the inside pressure and thermal stress due to the  temperature. Considering the property of PEX, the working temperature can range from -100°C to +110°C. At  working temperature below 0°C the pipe does not become brittle, as metal pipes typically do. However this does  not mean that the pipe can withstand the huge stresses generated by the water freezing and expanding inside  the pipe. At temperatures above 0°C, the regression curve of PEX gives the working pressure values for  different temperatures for a working life of 50 years.  Non-toxicity  PEX pipes are hygienically and toxicologically suitable for conveying drinking water and meet the most rigorous  standards, such as the Spanish, French, Irish and Italian ones.    1. Thermoline PEX - Crosslinked polyethylene pipe monolayer (16mm to 32mm)  2. Thermoline PEX (EVOH) - Three layer crosslinked polyethylene pipe (16mm to 32mm)