MAXOS® safety sight and level gauge glasses have proved themselves universally where visual process control is essential. This includes pressure vessels subjected to thermal and chemical stresses and liquid level gauge application.

A high safety level is ensured by the use of special borosilicate glass of high chemical durability, exceptional purity and homogeneity. Combined with thermal pre-stressing (tempering), high precision processing Auer Lighting guarantees sight and level gauge glasses of highest quality.

Auer Lighting sells MAXOS® in more than 50 countries all over the world. Our special tempered reflex and transparent level gauge glasses and disc sight glasses can be supplied in a wide variety of sizes to fulfill our customers' requests.

MAXOS® - a registered trademark of Auer Lighting GmbH

Technical characteristics of MAXOS® Long form

Bending strength is determined by the surface compressive stress and the inherent resistance of the glass. The inherent resistance is heavily dependent upon the surface quality.

For safety reasons, the stress to the glasses caused by internal forces, thermal stress and vessel pressure have to be totally absorbed by the surface compressive stress so that a tensile stress of the glass surface is prevented.

Bending strength (typical values)

Standard level gauge glasses
≥ 150 N/mm2 21.000 psi
Average 170 N/mm2 25.000 psi
High pressure level gauge glasses
≥ 180 N/mm2 26.000 psi
Average 200 N/mm2 29.000 psi

Surface compressive stress

Standard level gauge glasses
≥ 90 N/mm2 13.000 psi
Average 100 N/mm2 14.500 psi
High pressure level gauge glasses
≥ 100 N/mm2 14.500 psi
Average 110 N/mm2 16.000 psi


Thermal shock resistance Δ T 265 K
Max. permissible temperature 300 °C (572 °F)
Protected with mica 320 °C (608 °F)


Standard level gauge glasses
≤ 0,08 mm 0,003 inches
High pressure level gauge glasses
≤ 0,05 mm 0,002 inches