Where must gravity tanks be located in relation to the highest device?

Gravity tanks are designed to provide water for fire suppression systems by relying on gravitational force to create water pressure. The necessary height of the tank relative to the highest device—such as a sprinkler head or standpipe—is crucial because it directly influences the system's ability to deliver water with adequate pressure and flow rate.

The requirement to position gravity tanks at least 35 feet above the highest device ensures that there is sufficient hydrostatic pressure to enable effective operation of the fire protection system. When the tank is elevated, the weight of the water creates pressure, which helps to overcome friction losses in the piping and ensures that water can reach all areas of the system, especially those situated higher up.

Inadequate height would lead to pressure deficiencies, resulting in the risk of failure to deliver sufficient water during a fire emergency. Therefore, placing the gravity tanks at this specified height standard is critical for maintaining effective fire protection and ensuring compliance with the regulatory codes governing fire safety.