What device is commonly used to indicate low water levels in a boiler?

A water gauge is specifically designed to visually display the water level within the boiler. It typically consists of a glass tube or a series of tubes connected to the boiler that allows operators to see the current water level directly. Maintaining the proper water level in a boiler is critical for safe operations, as both low and high water levels can lead to significant operational problems.

The importance of this device cannot be overstated; it allows for immediate awareness of the water conditions in the boiler, enabling timely interventions to prevent overheating or boiler damage. Other devices mentioned serve different functions: for instance, a blowdown valve is used to remove sludge and sediment from the boiler water, a safety valve is designed to relieve excess pressure to prevent explosions, and a feedwater control system regulates the water entering the boiler but does not provide direct visual feedback about the current water level.