The float operated low water fuel cut-off functions based on which principle?

The float operated low water fuel cut-off operates based on the principle of buoyancy. This mechanism uses a float that rises and falls with the water level in the boiler or fuel tank. When the water level is adequate, the float remains buoyant, allowing the system to continue operating normally. However, if the water level falls below a certain point, the float loses its buoyancy and drops. This drop triggers a sensor that activates the low water cut-off, shutting off the fuel supply to avoid unsafe operating conditions, such as overheating or boiler damage.

This principle is crucial in ensuring safety within boiler systems since maintaining an adequate water level is vital for proper steam generation and prevention of equipment failure. Other choices such as pressure monitoring, thermal expansion, and flow rate do not effectuate the same mechanism of action as buoyancy in detecting and responding to the water level changes in this context.