A reflex level gauge is a type of level measurement device used to determine the level of liquids in a tank or vessel. It consists of a transparent glass or plastic tube, which is mounted on the outside of the tank or vessel and contains a series of prisms or grooves that reflect light. The upper portion of the tube is filled with a liquid, typically a high-quality optical-grade oil, which has a higher refractive index than the gas or vapor above it. When light is directed through the tube, it is refracted by the liquid and reflected by the prisms or grooves, creating a clear indication of the level of the liquid in the tank. The level of the liquid is indicated by the boundary between the dark and light areas in the tube, which is created by the reflection of the light. Reflex level gauges are highly accurate and reliable, and they are commonly used in applications where the level of liquids needs to be visually monitored and recorded, such as in the chemical processing, pharmaceuticals, and food and beverage industries. They are also suitable for use in hazardous environments, as they can be constructed with explosion-proof enclosures and are compatible with a wide range of liquids. Reflex level gauges are easy to install and require minimal maintenance, making them a popular choice for applications where simplicity and reliability are important factors.