084 HPM 1012

HPM October 2012

TUBES,VALVES,FITTINGS&PUMPS WWW.HPMMAG.COM Got a story? Ring us on 01732 748041 or e-mail twood@unity-media.com Plastic: a cost effective alternative Durapipe UK’s Des Dolan answers the most frequently asked questions regarding plastic pipework systems... Wprojects up and down the country system is approved. is smooth so there is nothing for the scale tosurface of copper can consist of tiny spikes ontowhich scale clings, further scale then clings tothat. In comparison, the surface of a plastic pipethorough in its testing and always includestesting of the solvent cement joints before aith rising copper prices and thesubsequent metal thefts that havebeen experienced on building over the last 12 months, an increasing number of Can trace heating be used with plastic piping? cling onto. contractors and installers are looking for cost Yes, plastic pipes can be equipped with trace effective alternatives to copper pipework. As a heating systems to prevent the pipes from Does plastic give off toxic gases when it burns? result, plastic pipework manufacturers, such as freezing. Reputable tape suppliers should be able Some plastic pipework systems can give off trace Durapipe UK, have experienced higher levels of to offer suitable tapes and installation advice amounts, but this would never be enough to be enquiries about the installation, performance such as putting an aluminium/foil barrier classed as hazardous in the event of a fire. As and effects of plastic pipework systems. between the pipe and the trace heating tape. The with many flammable materials the primary Here, are the most frequently asked questions surface temperature of the heating strips must hazard is smoke. received by Durapipe’s in-house technical not exceed 70°C. All trace heating systems support department relating to the use of plastic should comply with BS 6351 specification for How impact resistant is plastic pipework pipework systems for heating and ventilation electric surface heating devices. For more specific compared with metal pipework? applications in the building services industry. advice refer to the manufacturer. This will vary according to the material of construction but generally plastic solutions are How can we accommodate changes in length Does plastic pipework need insulating? very robust systems, particularly ABS, which is a due to thermal expansion? As a general rule, if you would insulate a copper very tough material, even at low temperatures of It is usually possible to accommodate thermal or steel pipe then you should also insulate a -40°C. movement utilising the natural flexibility of the plastic pipe. However, plastic has a lower rate of pipework at changes in direction. If there are thermal conductivity meaning that a reduced Is plastic pipework quicker to install than insufficient changes in direction, we would insulation thickness may be possible for plastic metal alternatives? advise the inclusion of expansion loops. pipework. However, as most insulation is Yes, it has been proven that installation time can Alternatively, it may be possible to utilise flexible purchased in a standard thickness, it means that be cut by up to 40% by utilising plastic pipework hoses or bellows. the overall result will be energy saving on hot systems. Plastic systems are approximately one water systems. sixth the weight of steel pipes so are much easier Can I joint ABS to PVC-U? to manually handle on-site and require no heavy This is not something that is recommended and Which plastic pipework systems are suitable lifting equipment. should be avoided if possible. However, it can be for chilled water applications? The other major area in which time is done but it is crucial that both systems are ABS is the ideal choice for such applications as it significantly reduced is the jointing process; suitable for the application. It is important that remains ductile and durable down to modern solvent cements, which are used with PVC-U cement is used and the joints are made temperatures as low as -40°C and is completely many plastic systems, have reduced the amount strictly in accordance with the manufacturer’s limescale and corrosion resistant due to its of pipe preparation required and offer quicker guidelines. smooth inner bore. drying times. For example, six-bar of pressure can be applied What is the lowest/highest ambient Why does copper pipe scale up, yet plastic within an hour of making joints on PVC-C temperature at which I can successfully make doesn’t? systems such as HTA for hot and cold water solvent weld joints? This is down to the surface roughness. The applications. Temperature is not critical to make solvent weld joints as long as the surfaces that need to be joined are kept clean and dry. However, for below zero temperatures additional curing time should always be allowed as the evaporation rate of the solvent will be slowed down. At higher ambient temperatures, cement should be applied briskly due to faster drying during application. Does solvent cement effect drinking water quality? No, the solvent cements and the plastic materials, whether that is ABS, PVC-C or PVC-U, do not have any detrimental effect on water quality. However, it is always advised to look for WRAS (Water Regulatory Advisory Scheme) testing and approval, particularly when dealing Durapipe plastic pipework with drinking water applications. WRAS is very 84 OCTOBER 2012 HEATING & PLUMBING MONTHLY enquiry number 170


HPM October 2012
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