Page 355 - Water Loss Control

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FIGURE 18.19 Sustaining valves can be used to protect supply.

FIGURE 18.20 Sustaining valve installation.

Flow-control valves and pressure-sustaining valves can be used to reduce the
impact of these situations and ensure a constant supply of water for all consumers.
These valves in conjunction with pressure-reducing valves in areas of excess pressure
help to ensure that an even supply pressure is given to all parts of the system.
Sustaining and flow control features can also be added to pressure-reducing valves,
see Fig. 18.19, and the photograph in Fig. 18.20, making the valve an efficient tool for
directing water around the system and ensuring a good turn over of reservoir water,
which in turn ensures good water quality. This type of control is often necessary when
considering protecting reservoir volumes during times of high demand, as hydrauli-
cally some reservoirs will empty quicker than others will. In this situation without con-
trol, some reservoirs can always be virtually empty, while others never empty.

18.17.4 Sectors with Large Industrial Customers
In sectors with very large consumers, care should be taken to make sure that flow and
pressure profiles used for sizing valves are representative of the highest and lowest