Charlie Mind, Senior Marketing consultant and Authorising Engineer (Water) on the Water Hygiene Centre offers an replace on Scald Threat, trying on the points round thermostatic mixing valves and thermostatic mixing faucets.
One of many dangers related to water security that requires consideration is the danger of scalding.
The HSE Info Sheet HSIS6, states: “If sizzling water used for showering or bathing is above 44°C there’s elevated danger of significant harm or fatality” and {that a} “danger evaluation of the premises must be carried out to establish what controls are mandatory and the way the techniques shall be managed and maintained.”
This motion is regulated by the Well being and Security at Work and so on Act 1974 (HSWA), part 3.
The place susceptible persons are uncovered, or the place there’s potential for whole-body immersion, engineering controls must be offered to make sure that water hotter than 44°C is just not discharged from these retailers. Such engineering controls can embody thermostatic mixing valves (TMVs).
What’s a TMV?
A TMV mixes cold and warm water to ship water at a pre-set, secure temperature to scale back the danger of scalding.
Relying in your supply, variations of TMVs have been used on home water techniques for over 100 years, however protecting to the present century to keep away from debate, steering on the right use of TMVs might be present in HSE’s ACoP L8 again in 2000.
An instance piece of such steering was to make sure that the TMV must be sited as near the outlet as attainable (<2 metres), thus minimising the size of blended water that would give beneficial circumstances for micro organism to thrive, comparable to Legionella.
What’s a TMT?
A thermostatic mixing faucet (TMT) ensures that this size of blended water is stored as brief as attainable by constructing the TMV inside the outlet physique itself.
The Division of Well being’s (DoH), HTM04-01: Addendum Pseudomonas aeruginosa – recommendation for augmented care items again in 2013 acknowledged a, “TMV that’s integral to the physique of the faucet/bathe is most well-liked” because it reduces the size of blended water and ensures the chilly water is drawn by means of each time the outlet is used. It was changing into extensively recognized {that a} TMT was most well-liked to a standard TMV when it comes to bacterial danger.
Probably the most up-to-date steering from the HSE (2014) and DoH (2016) proceed to suggest that TMVs, the place practicable, must be “included immediately within the faucet becoming”, thus preferring a thermostatic mixing faucet.
The principle benefits of TMTs are:
– The size of blended water is minimised;
– The chilly water provide doesn’t signify a deadleg;
– Entry to take care of and restore is simpler as TMVs might be positioned behind panels/partitions/pipework;
– They’re in plain sight and fewer prone to be forgotten;
– Have a tendency be designed for healthcare premises, so supplies and design are chosen with bacterial danger in thoughts.
However what concerning the distinction in scald danger safety?
You will need to notice that not all mixing units constructed into the faucet head are thermostatically managed. Handbook mixer model faucets, as seen on a normal kitchen sink at residence, are thought of Sort 1 mixing valves, permitting the person to manually combine the water from chilly to full sizzling water temperature.
To extend scald safety, Sort 2 or Sort 3 mixing valves must be thought of, which each embody a set temperature restrict. Sort 3 mixing valves have enhanced efficiency specs, together with a failsafe function, which is able to shut off the new water if the chilly water provide fails.
Each TMVs and TMTs might be bought with various rated scald safety and each with TMV 3 certification, so a comparability of scald safety is “Sort” dependent.
Thermostatic mixing faucets have gotten more and more widespread in healthcare buildings because of the benefits listed above. Nevertheless, some disadvantages require consideration, these embody:
– Value
– Less familiarity – if put in in non-healthcare settings for customers not used to working them domestically;
– They sometimes are higher in measurement, so would require more room to put in;
– Potential to be broken or altered because the TMT is accessible;
– Entry to room the place TMT/outlet is put in is required, TMV’s might be cited in accessible service ducts like accommodations.
The choice to go for a standard distant TMV or a contemporary TMT will sometimes come right down to weighing up the steadiness of danger and price. Each choices might be licensed to Sort 3, thus guaranteeing the identical stage of scald safety.
TMTs provide a decrease inherent danger of bacterial development, however at a higher value. This is the reason TMTs are often present in healthcare buildings the place person susceptibility requires elevated safety towards micro organism and an infection. Ease of upkeep can be a critical consideration, as remote-style TMVs can grow to be tough to entry and/or isolate if isolation valves are lacking or ceased.
If scald danger is taken into account low and blended water is desired, a handbook mixer (TMV 1) sort faucet may very well be advisable, the place scald danger is deemed important, the choice of TMV versus TMT must be knowledgeable by contemplating the vary of things – Threat, Value and Problem.