Reflex glass level gauges working principle is based on the light refraction and reflection laws. Reflex glass level gauges use glasses having the face fitted towards the chamber shaped to have prismatic grooves with section angle of 90. When in operation, the chamber is filled with liquid in the lower zone and gases or vapors in the upper zone; the liquid level is distinguished by different brightness of the glass in the liquid and in the gas/vapor zone. The reflex level gauges do not need a specific illumination: the day environmental light is enough. Only during the night an artificial light must be provided.
- Reflex glass level gauges can be used in most of the cases and offer great advantages in terms of: low initial cost, low operating cost, easy level reading. Reflex level gauges cannot be used in certain cases as for example:
- when the separation level between two liquids has to be read (interface)
- when besides the level indication, the observation of the liquid colour is required
- when the process fluid is high-pressure water steam, since in this case the glass must be protected from the solvent action of the boiler water by using mica shields
- when the process fluid is such that can corrode the glass (e.g. high temperature alkaline solutions or hydrofluoric acid), since ica shields or Polytrifluorochloroethylene shields must be used to protect the glass