Level Indicators in Boilers

Level Indicators are very important instruments in any boiler.  Level indicators tell the operator how much water is there in the boiler.  The Level indicator is a vertical tube made of glass which can withstand high temperature.  This glass is mounted on the boiler drum.  One end of the level indicator is placed below the water level, the other end is placed above the water level.  This is called the steam end.

As the level of water rises and falls in the boiler, the level in the indicator also changes.  The glass tube of the indicator is covered by another protective layer of toughened glass.
The indicator has a drain cock which can be opened to drain the water in the level indicator.  This is used to check the functioning of the level indicator. 

The level indicator has two safety balls at each of the inlets, the water inlet and the steam inlet.  If the glass of the level indicator gets broken, the balls seal the two outlets and prevent leakage.
The Level indicator is a simple device which provides a direct reading of the level inside the boiler.