What is a major risk of firing a boiler without visible water in the sight glass?

Firing a boiler without visible water in the sight glass poses a significant risk of a boiler explosion. The sight glass allows operators to monitor the water level within the boiler. If the water level is too low, it can lead to overheating of the boiler components, as there is insufficient water to absorb the heat generated during combustion. The metal of the boiler can overheat, weaken, and ultimately fail, which could result in a catastrophic explosion due to the rapid expansion of steam generated from the excessive heat.

Maintaining an appropriate water level is critical for the safe operation of a boiler. Regular checks of the sight glass ensure that operators are aware of the water level in real-time and can take necessary actions to prevent dangerous situations, including shutting down the boiler or adding water as needed. Proper maintenance and oversight are essential to avoid such hazardous conditions, underscoring the importance of operating within safe parameters.