What is the purpose of a low water cutoff in a boiler system?

The purpose of a low water cutoff in a boiler system is to prevent low water levels from causing damage. This device is critical for safety because if the water level in the boiler drops too low, it can lead to overheating of the boiler components, resulting in potential damage or even catastrophic failures such as explosions. By monitoring the water level and shutting off the fuel supply if it falls below a set point, the low water cutoff ensures that the boiler operates safely and efficiently.

While managing water temperature, controlling flow rate, and facilitating air separation are important aspects of boiler operation, they are not the primary function of the low water cutoff. This device specifically protects against the hazards associated with low water levels, making option B the correct choice in this context.