Elevated Storage Reservoirs ESR

These are generally provided in a plant to supply water by gravity to important points of use in case of power failures or when the water pumps are not working temporarily. They shall be conveniently located in a central place in the premises. 

The ESR exit line should be connected to the main water lines in the plant through solenoid valves which open automatically (with arrangement to open manually if it does not open) when power supply fails or when pressure in main line falls below a set pressure. This is to maintain supply of water to all important points of use till diesel generator set is started for resuming power supply to important pumps and other units. It will give the operators the vital 15-20 min to take necessary steps till these pumps are restarted (on power supply from the DG sets—which will be gradually loaded). 

Senior engineers shall decide in consultation with experienced plant operating personnel the order of importance of all critical water consuming units and the requirement at each of them for about half an hour. The ESR shall have a volume about 20 % more than the total of these individual requirements. Management shall invest an amount towards the cost of tank, its support structure, water piping for filling, automatically (opening) solenoid valves, etc. 

Provide a totally assured supply of water for safety showers, eyewash fountains, fire fighting, and cooling water for spray on certain storages of inflammable fluids by having dedicated storage tanks of appropriate capacity at a height. 

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The volume of elevated storage reservoir (ESR) can be calculated from these figures, and the cost of tank plus support structure, water piping for filling and pump cost can be estimated. A convenient location for the tank in the premises should be decided. It should be as near as the important user points as possible. 

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