Why must a broken mica on the gauge glass be replaced promptly?

Replacing a broken mica on the gauge glass promptly is essential primarily to prevent rapid fogging of the glass. The mica serves as a protective barrier that helps maintain the visibility of the water level in the gauge. When the mica is broken, steam and other gases can enter the gauge glass, leading to condensation and fogging. This fogging obscures the view of the water level, making it difficult for operators to accurately assess the boiler's water level, which is critical for safe and efficient operation.

Maintaining clear visibility through the gauge glass is crucial to avoid hazardous situations such as low water levels, which can lead to overheating or even catastrophic failures. Therefore, timely replacement of the broken mica ensures that operators can monitor the water level effectively and maintain boiler operations safely.