Sight glass

The sight glass is a device that is used to observe the flow and indicates level of fluids in pipes and pressure vessels and for monitoring of thermal processes in industrial furnaces.

To this end, the sight glass from temperature-and pressure-resistant glass must exist or be covered to prevent permanent radiation. The mechanical stresses from the adjacent tubes takes on a massive housing if that sight glass is not fixed with a simple block flange directly to the large pipe or system or to a pressure vessel. Because of their fragility sight glasses should always be protected with a primary shut-off.

To capture the level of oil containers eyes are used. For this purpose, single or multiple oil eyes in critical liquid levels, built about maximum and minimum in the vessel wall. In modified form, sight glasses are used to control the water level in steam generators.

A water meter is also designed as a sight glass.

Sometimes the sight glass also has a small turbine to indicate the direction of flow and the flow velocity of the fluid, such as gas pumps at service stations. In pipes with large diameter and large pressure vessels sight glasses are fitted with lights.