How reflex level gauges work

Reflex level gauges are designed to detect the difference in refractive indices of vapor and liquid and level detection and can be used in a number of process applications.


Reflex level gauges are designed to detect the difference in refractive indices of vapor and liquid and level detection and can be used in a number of process applications. Courtesy: Dani KateReflex level gauges are commonly used for level detection within a specific vessel, and the primary principle is based on the difference in refractive indices of vapor and liquid.

Reflex gauges, also referred to as prismatic level gauges, offer a well-defined image of water levels. This reduces risks of distortions or reading areas. Because of this, a reflex level gauge can be installed in a tilt-view or vertical position to produce even greater accuracy in readings along with a much better degree of reliability. As imagined, this is highly beneficial for many industries.

Level gauges are also extremely flexible when it comes to combining more than one gauge section that allows for extended viewing areas. In addition, reflex level gauges may be applied in numerous applications to include feed water heaters, deaerators, boiler drums, and other types of tanks.

For a reflex level gauge, within the recess of a liquid chamber and behind a single piece of glass, is the liquid column that clamps down onto the gauge body. This glass is flat on the outside and on the inside has a series of prism grooves that face the vapor and liquid space. Based on whether light enters the vapor or liquid space, it is reflected or absorbed, respectively.

Once light encounters a groove's surface within the vapor space it reflects to the surface of the grooves on the opposite side, followed by reflecting completely back to the observation direction. During the liquid phase, light is absorbed, which creates one display for the area that is covered by liquid and another display for the area located above the liquid.

Using the prism glass, a reflex level gauge accurately measures liquid inside the vessel. When light hits the glass where there is no liquid, the prism reflects the light directly out of the gauge. Known as the "dry" area, a silver color is displayed while the "wet" part is displayed in black. The contrasting colors create a clear delineation line that makes it easy to view the measurement.

The composition and design of a transparent level gauge is unique. This gauge is nontubular and fitted with two plate transparent glasses with liquid in between. By different transparency of two media, the level of liquid is indicated. At the back of the transparent level gauge is a light source with rays reflecting down to the observer making it possible to read or estimate the measurement. For most installations, a transparent level gauge is appropriate.

Level gauges provide a number of benefits that are industry-specific. To ensure that your company takes full advantage of the benefits, it is important to consider only the highest quality gauges. By working with a manufacturer that has specialized expertise in producing level gauges you have full assurance of enjoying optimal performance and reliability.

Dani Kate is a content strategist and online blogger with knowledge of mechanical engineering. This article referenced case studies and data from McRae Engineering. Edited by Chris Vavra, production editor, Control Engineering, CFE Media,

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