Fresh water

The fresh water is supplied to the system, by one of two pumps which are self-priming or situated at a lower level than the storage tanks. The pump starters are controlled by pressure switches which operate when pressure in the service tank varies within pre-determined limits as water is used. The pump discharges through filters to a rising main, branched to give cold and hot supplies, the latter through a calorifier. A circulating pump may be fitted in circuit with the steam or electrically heated calorifier. An ultra-violet light sterilizer is fitted adjacent to the Pneupress tank of some systems. Ultra-violet light acts in such an arrangement, as a point of use biocide. Although effective as a means of killing bacteria, it does not apparently provide protection in the long term. The Department of Transport requirement for protection of fresh

F.W pumps Sanitary pumps

Figure 3.7 Domestic fresh and sanitary water system

91 litre —i calorifier for aft.

accommodation Reducing valve sr. i

Pump B \ j Pump A \ J Pump B Starter 'A' /starter'B'yStarter W Starter 'B' Non-return valve Non-return valve Non-return valve

F.W pumps Sanitary pumps

Figure 3.7 Domestic fresh and sanitary water system water in storage tanks, is that chlorine dosing or the Electro-Katadyn method, be used. Guidance on the procedures to ensure that fresh water is safe for consumption is provided by M notices listed at the end of the chapter.

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