What is the difference use between sight glass and gauge glass?

Sight glasses and gauge glasses, while similar, are designed for different purposes and are used in distinct applications.

Gauge Glass: A gauge glass is primarily used in boilers to visually display the boiler’s water level. The gauge glass is typically a level gauge that is connected to the boiler in two places: at the top and bottom. The water inside the boiler will settle at the same height as in the gauge glass, providing an accurate depiction of the water level. They are essential for safe boiler operation, allowing operators to add or reduce water when necessary. Gauge glasses can also be used in other types of equipment that require observing the level of liquid inside a vessel, like fuel tanks, chemical tanks, and other industrial vessels.

Sight Glass: A sight glass, also known as a sight window or sight port, allows an operator to monitor what’s happening inside a vessel or pipe in a process industry. Sight glasses offer a broader view into the interior of machinery, often used to observe processes, color changes, or the presence of particles. This can include everything from the mixing of ingredients in a large industrial food processor to the verification of flow in pipelines.

The main difference between the two lies in their application: gauge glasses are used to measure the level of a liquid in a vessel or tank, while sight glasses are used to visually inspect what’s happening inside a vessel or pipe.