WATER SYSTEMS
A Mixcal Careflo Plus TMV with thermal override, said by its manufacturer, Altecnic, to be the UK’s first of its kind.
systems, right up to the outlet, are also strongly recommended to prevent the growth of harmful bacteria in the deadleg between the TMV and the outlet. However, this can be costly, and take considerable time, in a facility with multiple outlets and TMVs. This is because each valve will need to be bypassed in order to successfully complete the thermal disinfection. A solution to this issue would be to use a TMV with built-in thermal override function.
Expansion vessels For elements of the water system up to the TMV, HTM 04-011
advises that
‘expansion vessels with a flow-through design provide less opportunity for water to stagnate and become contaminated’. This then helps to limit the flow of contaminated water throughout the system, with the expansion vessel being designed to keep the water flowing within the vessel. Flow-through expansion vessels
also come fitted with a ‘Flowjet’ valve (manufactured by Reflex), which assists in preventing Legionella growing in the system. The Flowjet valve has been designed to prevent stagnation or contamination in the expansion vessel. It does this by keeping the water flowing continuously through the bladder, and also allows isolation should the expansion vessel ever need to be removed. With this, it also allows for a drain facility, as well as a bypass.
Finding the complete solution To minimise the growth of Legionella pneumophila, healthcare estates managers and Water Safety Groups must seek out componentry designed to reduce the risk of Legionella. For example, there is a TMV that is WRAS-approved and TMV3 / D08 NHS regulatory certified that allows
A cut-out diagram of a TMV.
easy thermal disinfection right to the outlet – removing the time and cost of recommissioning the valve. The Mixcal Careflo Plus TMV, the first of its kind in the UK, removes the need to take off the TMV to ‘flush’ out the whole system, making the process quicker and more efficient. Using a special tool and the manual override function allows thermal disinfection to be performed through to the outlets, enabling a complete rather than a partial flush, thus preventing the growth of harmful bacteria. The Mixcal Careflo Plus TMV has been designed and made to meet the requirements of BS 7942:2000, and the NHS Model Engineering Specification D08, for use in hospitals and other healthcare settings, care homes, and schools. In addition, there are manufacturers that
offer a range of flow-through expansion vessels, varying from 8 to 1000 litres, which are suitable for a wide variety of system sizes. Vessels that also offer the benefit of all being nitrogen filled reduce the chance of internal corrosion, preventing the loss of pre-charge pressure. This then contributes to extending the life of the expansion vessel. Flowjet valves should also be supplied as an optional component.
Conclusions TMVs with a thermal disinfection function and flow-through expansion vessels are key components for any water system designed with Legionella prevention in mind, and enable healthcare estates managers and Water Safety Groups to protect those on their premises who are most vulnerable.
References 1 HTM 04-01: Safe water in healthcare premises. Department of Health, 20 May 2016.
https://www.england.nhs.uk/
publication/safe-water-in-healthcare- premises-htm-04-01/
2 HBN 00-10: Part C: Sanitary Assemblies. Department of Health, 20 March 2013.
https://www.england.nhs.uk/wp-content/ uploads/2021/05/HBN_00-10_Part_C_ Final.pdf
3 Legionnaire’s Disease: The control of legionella bacteria in water systems. L8 Approved Code of Practice and Guidance on Regulations. Health and Safety Executive, 2013.
https://www.hse.gov.uk/ pubns/priced/l8.pdf
Stephanie Allchurch
Stephanie Allchurch has been Product Development manager at Altecnic since February 2019, where she plays a key role in spearheading the development of the company’s product offering. She has nearly 20 years’ experience in the plumbing and heating industry, with specialist knowledge of water regulations and product specifications.
April 2022 Health Estate Journal 57
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