Sight glass tubes

We supply round glass tubes made of SCHOTT DURAN® as standard. These glass tubes made of ‘borosilicate glass 3.3’ are resistant to many mediums, high temperatures (continuous temperature 525°C) and pressure. SCHOTT borosilicate glass tubes are used, among other things, as gauge glass tubes and in a flow-through sight glass.

SCHOTT 3.3 Borosilicate glass tubes are available as standard in:

Outside diameter of Ø 3 ± 0.13 mm up to Ø 465 ± 6 mm.

Wall thickness of 0.7 ± 0.03 mm to 10 ± 1.4 mm.

Click on this PDF-file for all possible glasstube dimensions, wall thicknesses and tolerances.

For glass tubes with narrower tolerances see precision glass tubes

Cutting, beveling, grinding, sizing, flame polishing, drilling, reel off, printing, matting etc.

Other glass tubes sizes and materials (such as, quarzglas, acrylic glass, plexiglas) we provide on request, for example, higher pressure, temperature and specific requirements for optical measurements. See Technical glass.
Many people prefer to use a plexiglass tube, because they think that a glass tube breaks quickly. However borosilicate glass, is a hard type of glass that does not break soon.
Plexiglas tubes have the disadvantage that they are not resistant to all mediums and the maximum temperature is up to 70/90°C, plexiglass obsolete eventually (crackle), therefore we recommend borosilicate glass.

Borosilicate glass tubes are high resistant to water, neutral and acid solutions, concentrated acids and acid mixtures, as well as chlorine, bromine, iodine and organic substances. The following mediums damage the glass surface (depending on the concentration and temperature): hydrofluoric acid, hot phosphoric acid and alkaline solutions. Therefore, with these chemicals the use of borosilicate glass needs to be checked in each individual case.