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Building Products July 2017

DRAINAGE, PLUMBING AND WATER SUPPLY JULY 2017 | BUILDING PRODUCTS 67 can survive but are not active. At 60°C and above some 90% of bacteria will be killed within two minutes. The ‘optimal zone’ for bacteria to thrive is between 45°C and 60°C. Legionella pneumophila is naturally present in wholesome water and is similar to pneumonia. Its favourite habitat is biofilm, where microorganisms have gathered to produce a slimy substance that helps more nasty ‘gunk’ stick to it. At this stage the legionella is harder to kill. The infection is spread to humans via droplets of water that people breathe in. Potential sources, if not properly installed and maintained, include hot water tanks, cooling towers and evaporative condensers of large air conditioning systems, such as those commonly found in hospitals, hotels and large office buildings. Thankfully, there is a wealth of practical advice, legislation and literature available in print and online providing today’s designers, specifiers, installers and water suppliers with guidance and technical information on preventing and managing legionella and other contaminants. These range from the Health & Safety Executive’s Legionella’s Disease, the control of legionella bacteria in water systems to Water Safety in Buildings, published by the World Health Organisation. From a sustainability perspective, copper has one further advantage. It is 100% recyclable. In fact, some 80% of copper ever mined is still in use today. And while it takes 100 gigajoules of energy to refine one ton of copper, it takes only 10 gigajoules to reprocess it. So recycling is 90% better when environmental costs are taken into consideration. The supply network of medical gas in hospitals is as important as the gas compounds that are used; the successful delivery of one is not possible without the other. A fully functional medical gas system is integral to the inner workings of hospitals throughout the UK, including accident and emergency units, outpatient and inpatient wards, operating theatre suites and maternity units. The specialised pipe systems circulate a wide range of essential gas compounds around hospitals, including: oxygen, nitrous oxide, nitrogen, carbon dioxide and medical air. These gases are used to support an array of critical medical practices, such as pre-operation anaesthetics, the powering of pneumatic surgical equipment and the delivery of supplementary oxygen. For specifiers and contractors planning projects in such facilities it is important to note that in most cases, the medical gas piping used is almost exclusively copper. As discussed, this is due to its antimicrobial properties, which are proven to assist in the killing of pathogenic microbes, such as Legionella. The fittings and all component parts must be consistent with the piping material in this regard, to ensure that the best possible hygienic standards are met. In combination with this, brazing is the only type of jointing method allowed on piping for medical sites when connecting a copper-to-copper installation, and must always be used. The reason behind this is the brazing process ensures that the joint is as strong as the parent metal, and able to withstand highly demanding conditions. As with any brazing fitting, the jointing method uses the principle of capillary attraction to ensure a mechanically strong and leak-proof joint. Dan Wild is UK Business Unit Director for Conex Bänninger


Building Products July 2017
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