Technical Information : DURAN ® Glass
Properties of SCHOTT-DURAN® Borosilicate Glass, ISO/DIN Strain Points ℃ ............................................................................................................................................. 525 Softening Point ............................................................................................................................................. 820 Linear Coefficient of Expansion (0 ~ 300 ℃ ) × 10 -6 ........................................................................................................................ 3.3 Density g/cm 3 ............................................................................................................................................... 2.23 Hydrolytic Class (ISO / DIN) ............................................................................................................................ 1 Acid Class (ISO / DIN) ..................................................................................................................................... 1 Alkali Class (ISO / DIN) ................................................................................................................................... 2
Chemical Composition of SCHOTT-DURAN® Glass DURAN glass which is used in the laboratory and in industrial scale chemical plant, due to its excellent chemical and physical properties, has the following typical composition : 81% by weight SiO 2 13% by weight B 2 O 3 4% by weight Na 2 O/K 2 O 2% by weight Al 2 O 3
Optical Properties of SCHOTT-DURAN® Glass Spectral range in which the absorption of DURAN is negligibly small : approx. 310 to 2,200 nm absorptio of brown glass up to about 500 nm SCHOTT laboratory glasses do not show any significant absorption in the visible spectral range. Thus, DURAN appears transparent and colourless. Fairly large layer thicknesses (axial view through pipes) appear greenish. When working with light-sensitive substances, the surfaces can be coloured brown. The result is strong absorption in the short-wave region. In photochemical processes, light transmission of DURAN in the ultraviolet region is of particular importance. The degree of transmission in the UV region shows that photochemical reactions can be carried out, for example chlorinations and sulphochlorinations. The chlorine molecule absorbs in the range from 280 to 400 nm and thus serves as a carrier of the energy of radiation.
Transmission curves for DURAN
Important Notes for the user of SCHOTT-DURAN® Glass ! When working with glass, the limits of this material upon change in temperature and mechanical stress must be heeded and strict safety precautions must be observed : * Never subject glassware to abrupt changes in temperature. Thus, do not remove it from the drying oven while hot and place it on a * cold or, which is worse, a wet laboratory bench. This is true in particular of thickwalled glassware, such as suction flasks or desiccators. * Provide apparatuses with a support via a suitable stand and set up free of stress. Use, for example PTFE corrugated bellows to * compensate for stresses or vibrations. * Glass apparatus (e.g. filtering flasks, desiccators, etc.) must be handled with care when under pressure or vacuum. * To avoid setting up stresses in the glass, glass vessels under vacuum or pressure should not be heated from one side or with an * open flame. The maximum permissible pressures quoted in the catalogue should not be exceeded. * Before evacuating or pressurising glass vessels always check visually that they are not damaged in any way (heavy scratching or * other mechanical damage). Damaged items should not be used under vacuum or pressure. * Never subject glassware to abrupt changes in pressure, for example never aerate evacuated glassware abruptly. Flat-bottomed * glassware(for example Erlenmeyer or flat-bottomed flasks) must not be subjected to pressure or vacuum. The respective state-specific guidelines for the use of special glass in the laboratory must be heeded; for Germany, the guidelines for laboratory(“Richtlinienfur Laboratorien”), published by the Hauptverband der gewerblichen Berufsgenossenschaften, Zentralstelle fur Unfallverhutung und Arbeitsmedzin, Langwartweg 103, D-53129 Bonn, Fachausschuβ Chemie (Verlag Carl Heymanns KG, Gereonstrasse 18-32, D-50670 Koln) apply.
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