Transparent Guage Glass

These work on the principle of difference in reflective indices of liquid in the tank and possible presence of gas with the liquid. The liquid will be black display while the gas or vapor will be white display.
These level gauges have glass etched with reflecting prisms at inner surface. This surface reflect the light falling on the surface and enable detection of surface of even colourless liquids. Operating Principal:
The Principall of the Transparent Guage Glass is based on the difference in the refractive indices of liquid and gas or in particular of water and steam. It has prismatic right angled grooves, on the side facing media.if a ray of light encounters the surface of one of the 450C slanted grooves in the gas or steam space it is reflected to the opposite surface of the groov and from there totally refiected back into the direction of observation The steam or gas space therefore appears as silver - whiteThe light ray which encounters the surface of a groove in the liquied space is almost totally absorbed.The liquid behind the reflex glass therefore apperars black. Light rays entering from outside the gauge are either absorbed or reflected depending opon whether they enter the water or steam space(Serveral sizes are available in both Transparent Gauge Glass & Reflex Gauge Glass)