WASHROOM INFECTION CONTROL
With Securitouch technology, the mixer body remains at an ambient temperature.
a potential source of contamination, because some solenoid valves have a diaphragm that traps water, which then stagnates. Delabie’s electronic controls feature a piston-operated solenoid valve which expels and completely renews the water inside the valve every time it activates, preventing any stagnation. Another potential concern is stagnant water in the cold feed to a mixer when hot water is pre-blended by a centralised thermostatic mixing valve (TMV). A group TMV serving a run of showers and/or washbasins may result in a cold water deadleg downstream of the TMV, since there is no need to blend the hot water to a safer, more comfortable temperature. If the cold water draw-off is infrequent, biofilm has time to establish itself, and contamination is inevitable. Replacing a centralised TMV with thermostatic technology at the point-of-use will eliminate this potential source of infection.
Keeping safe
Hot water is the typical method for controlling Legionella bacteria in healthcare buildings. HSG 274 Part 2 states that hot water must be produced and stored at or above 60˚C, with a circulation temperature of 55˚C. At these temperatures, 90 per cent of the bacteria die within two minutes. However, at the point-of-use it is essential to keep staff, patients, and visitors, safe. Mechanical mixers feature a temperature limiter, but this is a simple mechanism, and although it carries a low risk level for bacterial contamination, it cannot offer complete anti-scalding safety. Pressure-balancing mixers provide an intermediate level of safety. The mechanism is also mechanical, but it adapts to variations in pressure at the hot and cold water inlets, providing a constant temperature at the outlet. If the cold water supply pressure drops suddenly, the mechanism shuts off the hot water to a trickle, significantly reducing the scalding risk. This also applies if the hot water pressure drops. Thermostatic mixers deliver safe blended water, and feature an anti- scalding failsafe mechanism (the hot water shuts off completely if the cold
58 Health Estate Journal June 2020
H9769 thermostatic showers reduce the risk of infection, and, Delabie says, ‘offer complete anti-scalding safety’.
water fails and vice versa). Due to such devices’ complexity, however, they carry a higher risk of contamination by waterborne pathogens in the absence of regular servicing and maintenance. For every point of use, HSG 274 guidelines task the Water Safety Groups with identifying the risk of scalding versus the risk of infection from Legionella. Each point of use therefore requires a solution that takes into account the relationship between infection control, anti-scalding safety, and the complexity of the mechanism.
Delabie’s technical solutions Conscious of this balancing act, Delabie’s engineers have developed solutions that can manage this complex set of needs – from mixers with simple ceramic mechanisms and maximum temperature limiters, through to pressure-balancing (EP) or thermostatic mixers with full anti- scalding failsafe. However, they have also designed additional safety features which are available on both types of mixers – Securitouch technology and sequential control.
Securitouch technology carries the hot water in narrow tubes to the mixing chamber. These tubes are insulated by an air gap inside the mixer body, so the exterior remains at an ambient temperature. The hot water is delivered directly to the mixing chamber, rather than running along the length of the mixer, minimising heat transfer. The wall connector for the hot inlet is also insulated, so any user inadvertently touching the body will not burn themselves. Sequential control is also available on Delabie’s mechanical, EP, and thermostatic mixers. The mixer opens with cold water, and hot water is
Carole Armstrong
Carole Armstrong is the Marketing and Communications manager for Delabie UK. Initially based at the head office in Picardy, France, she joined the company 11 years ago, and is responsible for technical translations, media relations, and events, in the UK market.
introduced only after the full flow rate is achieved. This provides the user with full temperature control up to the preset maximum temperature limit. However, the limiter can be overridden by maintenance staff if a thermal shock is required.
Flexibility is key
Now, more than ever, healthcare facilities are facing a rapidly changing environment. The ability to adapt relies on flexibility, and standardisation and ease of installation are essential to providing this flexibility. For example, Delabie’s Securitouch mixers have standard 150 mm centres, which can be easily mounted on IPS panels. Stopcocks in the connectors shut off the water supply in front of the panel if the mixer needs cleaning, decontaminating, or maintenance. Since the connectors for Delabie’s mechanical and thermostatic mixers are standardised, the Estates & Facilities team can easily switch between different types of technology at the point of use, especially if wards are re-purposed and the scalding/infection risk changes.
The importance of hygiene has long been high on the public health agenda. Maintaining hygiene in healthcare facilities poses specific challenges for system design. By understanding the risks, and installing products specifically designed to meet these challenges, the risk of contamination and scalding can be managed easily.
Further reading n Legionnaire’s disease. Technical guidance HSG 274. Part 2: The control of legionella bacteria in hot and cold water systems. Health & Safety Executive, 2014 [
https://tinyurl.com/ybsp9heo].
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