Final answer:
A float valve is the device in an air accumulator designed to discharge water for flushing by using a buoyant ball that controls the water level.
Step-by-step explanation:
The device integrated within an air accumulator vessel designed to discharge a predetermined quantity of water to fixtures for flushing purposes is known as a float valve.
This type of valve uses a buoyant ball or a float that rises and falls with the water level in the tank. When the water reaches a certain level, the float actuates a mechanism to open or close the valve, thus controlling the flow of water into or out of the tank to maintain a consistent water level for efficient flushing.