Engineering Glassware
Tubular Sight Glasses:
Diameter and wall of glass tubing is expressed in millimetres and generally length is also although there is some tradition still of describing gauge glasses in inch dimensions.
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The common types are:
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SG-901 gauge glass, DURAN®, fire polished ends, annealed.
These are available in a range of sizes but the most common which replace the old inch sizes are:
12 x 2.2 (replacing 1/2”)
16 x 2.5 (replacing 5/8”)
19 x 2.2 (replacing 3/4”)
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SG-900 sight glass (tubular), DURAN, parallel ground ends (for compression between flanges).
Again available in a wide range of diameters, typically, these are relatively short for their diameter and are made from heavy-wall tubing. For instance, SG-900, 80 X 5.0 X120 which describes a parallel-ground sight glass 80 mm in diameter with a 5 mm wall and 120 mm overall length.
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Disc Sight Glasses:
Specified by diameter and thickness:
SD-920 sight glass disc, soda float glass, annealed
SD-921 sight glass disc, soda float glass, heat strengthened
SD-922 sight glass disc, SCHOTT Borofloat 33, annealed
SD-923 sight glass disc, SCHOTT Borofloat 33, heat strengthened
Discs can also be manufactured from other vitreous materials such as Schott Robax (glass ceramic) and clear fused quartz (silica).
