What is the primary function of a water gauge glass?

The primary function of a water gauge glass is to visually indicate the water level within a boiler. This is crucial for safe boiler operation, as maintaining the correct water level is vital to avoid both low water conditions, which can lead to overheating and potential damage to the boiler, and high water conditions, which can cause carryover of water into the steam system.

The gauge glass provides a direct visual representation of the water level, typically through a transparent tube that connects to the boiler. It allows operators to quickly and easily monitor the water level without needing to rely on gauges, which may malfunction or be subject to misinterpretation. By observing the gauge glass, operators can ensure the boiler is operating within safe parameters, leading to enhanced efficiency and safety.

The other options do not align with the primary function of the water gauge glass. While fuel levels, steam pressure, and water temperature are important factors in boiler operation, they are measured and indicated by different instruments specifically designed for those purposes.