Final answer:
The main reason a sprinkler system supplied by a gravity tank fails is due to inadequate pressure to distribute water effectively.
Step-by-step explanation:
The main reason a sprinkler system supplied by a gravity tank fails is due to inadequate pressure to distribute water effectively. In a gravity tank system, water is stored at an elevated height, and the pressure it exerts when flowing downwards is used to power the sprinkler system.
However, if the tank is located too low or the height difference between the tank and the sprinklers is not sufficient, the pressure may not be enough to reach all the sprinkler heads or provide adequate coverage.
For example, let's say the water tank is located on the ground floor of a building and the sprinklers are on the top floor. If the elevation difference between the tank and the top floor is not significant, the gravitational force acting on the water will be weak, resulting in low pressure at the sprinklers and limited water distribution.
Therefore, it is crucial to design a gravity tank system with careful consideration of the height and positioning of the tank, as well as the elevation differences between the tank and the sprinklers, to ensure sufficient pressure for effective sprinkler operation.