The article below was one of many I wrote for many publications over several years, on behalf of a valve manufacturer. The publisher was ABC&D (Architect, Builder, Contractor & Developer) magazine.
Scalding: a totally preventable “accident”
The bill tabled by Mary Creagh MP in the Commons, calling for thermostatic mixing valves (TMVs) on all new baths to prevent scalding hot water from taps, has drawn much discussion on radio, TV and in the national press. Most authorities and members of the public agree that that bathroom scalding is a totally preventable “accident”.
Hot bath water is responsible for the highest number of fatal and severe scald injuries in the home. Every year around 20 people die as a result of scalds caused by hot bath water and a further 570 suffer serious scald injuries.
The degree of scalding depends on the temperature and volume of hot water, and the length of time the body is exposed to it. However, it can take only seconds for a severe scald to occur.
As adults we have all pulled back from water that was too hot at some time, but children and the elderly are at particular risk of life-threatening scald burns. The elderly are at increased risk because their skin tends to be less sensitive and they are less agile. For both reasons, they might not be able to pull away from hot water quickly enough to avoid scalding. People with a reduced ability to perceive risk or react to hazardous situations – for example those with mental or physical disabilities – are also at greater risk of injury.
About 500 UK children – the vast majority aged under five – are admitted annually to hospital with a severe scald caused by bath water. Tragically, some die. A further 2,000 suffer less severe scald injuries. A few seconds’ lapse can damage a child for life. Severe scalds can result in long-term disability and disfigurement, and can be among the most distressing and painful injuries a child can receive.
The problem of scalding water has become more acute in communal and public buildings because high temperature is the preferred method of controlling legionella bacteria: hot water is stored and distributed at a high temperature, so there must be thermostatic mixing valves at, or very close to outlets to prevent scalding.
In healthcare, thermostatic mixing valves certified to Buildcert TMV3, such as Honeywell TM200VP, must be fitted. BuildCert TMV3 approval is granted if a TMV complies with the requirements of NHS specification D 08.
Valves to the domestic TMV2 standard, such as Honeywell TM300, are acceptable for most other premises but a risk assessment should be carried out to determine if facilities are used by vulnerable people, such as young children, the elderly or mentally or physically disabled. If so, TMV3 valves should be installed to provide the maximum safety level.
Suggested best practice is for TMVs to be installed in all buildings even if there are no specific recommendations or requirements, unless a risk assessment has concluded that it is safe not to use TMV control; this assessment is based on the risk to the user and the capability, whether mental or physical, of the user to avoid being scalded. The relevant authority or controlling body should be consulted for the particular building.
Water Supply (Water Fittings) Regulations 1999 Guidance Document paragraph G18.5, issued by Defra, states: “Terminal fittings or communal showers in schools or public buildings, and in other facilities used by the public, should be supplied with water through thermostatic mixing valves so that the temperature of the water discharged at the outlets does not exceed 43 degrees C.”
Making a selection
TRVs employ a temperature sensitive element which controls the hot and cold water inlets to provide a safe uniform temperature. Choose valves that cut off the hot water inlet automatically if the cold supply fails and for WRAS approval for use with attended and unattended high pressure baths, as well as high and low pressure hand basins, bidets and showers.
Ensure the valve cap (which displays the temperature set point) is lockable to prevent unauthorised adjustment, as shown in the picture. Choose a valve designed for convenient “under-basin” and “under-bath” installation. To overcome any space restrictions there is a flexible connector and isolating filter valve for the valve (see illustration). There are models with tailpieces that incorporate isolation, strainer and test points.
BRE Information Paper IP14/03 includes a useful table showing, for various establishments and different types of appliance (bath, shower, or basin), whether a TMV is required by legislation or authoritative guidance, is a recommended option, or is suggested as “best practice”. It can be freely downloaded at www.capt.org.uk
Free advice on selection and installation of TMVs is available from the [company] Technical Support Line during office hours on xxxxx xxxxxx.
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