There are several applications in the industry for which gauge glass is required. However, to measure the level of gas, air, or liquid in a tank, a working glass is required. However, you need to choose a glass that is best suited for your industry. There are different options that you have and we have mentioned them here.


The reflex variant is typically used in most traditional machinery. The microscopic light refraction principle is used in the working of the reflex gauge glass. The contrast in light between the liquid and the vapor is constantly measured. This in turn helps the readers in calculating the level of the liquid inside the container or vessel.

This type of level gauge glass doesn’t require the use of an external source of light. Additionally, reflex glass is one of the cheapest glasses in the market. This makes it very affordable for most industries and other companies. This is the main reason why this type of glass is used mostly throughout the world.

The process equipment manufacturers prefer to have the reflex variant of the level gauge glass. Several suppliers in the market can supply these glasses to you. However, you need to look for someone that supplies high-quality glass. Moreover, you need a glass specified to the process equipment that you are manufacturing.


This is the simplest type of gauge glass. It is made up of two transparent glass panels. These panels are inserted in opposite ends of the container or vessel. This allows the easy movement of light through the container. The light passes straight through the container as it enters from one end and then passes out from the other.

No prisms or mirrors are used in this type of sight glass. They are much easier to use as compared to reflex glass. It is suggested to use them where highly corrosive liquids are to be measured. Additionally, they work well in high-temperature conditions like in high temperatures. It is the simplicity of these glasses that have made them this popular and successful.


To measure the water level in the boiler the bicolor gauge is used. It is recommended that they must be used in all those boilers in which steam generation takes place. A set of LED lights is used inside the glass. This type of glass tells the reader about the temperature inside the chamber. It uses different colors and light behaviors to tell the reader about the temperature.

When the temperature inside the boiler starts increasing the green color starts deviating. In such cases, the green light ray deviates inside the bicolored glass. Due to this, the readers see a red color which shows the high temperature inside the chamber.

However, in the opposite case i.e. when there is more water than steam then red light deviates. At this point, the observers see a green light. The lights are transmitted by the medium. The mediums are the water and steam which determines which light color to pass.


The reflex, transparent and bi-color glasses are very good level gauge glass. However, they have certain limitations as well. For starters, they are susceptible to fractures that occur due to mishandling of the glass. Moreover, massive damage to the internal components of the glass is done by the fumes that arise from corrosive materials.

For such liquids, a special type of magnetic gauges is used. A float inside the chamber is linked to a magnetic indicator that is present outside the chamber. This way it shows an accurate reading of the liquid inside the chamber at all times.

Author's Bio: 

At Zight Glass, we specialize in the manufacturing equipment for the optical observation of fluids. Mainly this translates into the direct observation of level in tanks, the direct observation of a flow line, or the direct observation of the process inside a tank.