Question 207Steam Plants - Assistant Engineer

The correct answer is A) bottom connection only. In a boiler water gage glass, a ball check valve is installed on the bottom connection to prevent the flow of hot water or steam into the gage glass in the event of a gage glass failure. This helps to prevent injury to the operator and potential damage to the equipment. The ball check valve is not installed on the top connection, as the top connection is used for the air supply that pushes the water level up into the gage glass. The drain valve (option D) is a separate component used to drain the gage glass, and is not related to the location of the ball check valve.