Correct option is A
Surge Tank:
A surge tank is a water storage device used as a pressure neutralizer in hydropower water conveyance systems in order to dampen excess pressure variance.
A surge tank (or surge drum or surge pool) is a standpipe or storage reservoir at the downstream end of a closed aqueduct.
A feeder dam, barrage, or pipe to absorb sudden rises of pressure, as well as to quickly provide extra water during a brief drop in pressure.
In mining technology, ore pulp pumps use a relatively small surge tank to maintain a steady on the pump.
For hydroelectric power uses, a surge tank is additional storage space or reservoir fitted.
Surge tanks are usually provided in high or medium-head plants when there is a considerable distance between the water source and the power unit,
The main function of surge tanks are as follows:
When the load decreases, the water moves backward and gets stored in it.
when the load increases, an additional supply of water will be provided by the surge tank.
In short, the surge tank mitigates pressure variations due to rapid changes in the velocity of the water and protects the pipeline against water hammers.
Water Hammer
When a liquid flowing through a long pipe is suddenly brought to rest by closing the valve at the end of a pipe, then a pressure wave of high intensity is produced behind the valve. This pressure wave of high intensity has the effect of hammering action on the walls of the pipe. This phenomenon is known as a water hammer or hammer blow.
