When to use which type of glass?

Reflex level gauge glasses

Reflex level gauge glasses are installed in gauges that have a housing closed at the back. The incident light is refracted by the reflective grooves of the glass in the media-carrying area of the fitting. The area in which the liquid medium is located is thus shown as a dark bar – in contrast to the silvery gaseous area.

Diagram: Course of the light beams in the gaseous and liquid range


Transparent level gauge glasses

These glasses are mainly used in gauges open on both sides for high pressure applications. The incident light (daylight or that of a luminaire) passes through both sight glasses between which the medium is located. The level is visible as a line or through the medium itself. With aggressive media or when using saturated steam, the transparent level gauge glasses should also be provided with mica protection.

Diagram: Course of the beams