Transparent glasses 

Glasses have smooth surfaces and are mainly used for high pressure (above 35 bars) and temperatures within the limits shown in the pressure and temperature table.

Owing to the rapid attack of the boiler water on the glass at high temperatures we in general recommend the use of mica protected glasses at temperatures above 243°C.

Reflex glasses 

Glasses are provided with moulded prismatic grooves on the side in contact with the medium. As a result of the difference in refractive index, light rays entering the gauge from outside are reflected or absorbed.

The light ray entering the steam or gas space strikes the groove face at an angle of 45°, being thereby refracted into the opposite groove face from which it is reflected back in direction of observation. The steam or gas space thereby appears silver-white. The liquid space behind the reflex glass appears black.

This eliminates any possibility of errors in reading the liquid level.

The reflex glasses are recommended for use within the limits shown in the pressure and temperature table.