MORE ABOUT VERY HIGH CHEMICAL RESISTANCE
DWK Life Sciences GmbH
DURAN® glassware properties
Very high chemical resistance
DURAN® borosilicate glass is highly resistant to water, neutral and acid solutions, concentrated acids and acid mixtures, and to chlorine, bromine, iodine and organic substances. Its chemical resistance is superior to that of most metals and other materials, even during prolonged periods of exposure and at temperatures above 100 °C.
Only hydrofluoric acid, concentrated phosphoric acid and strong alkali cause appreciable surface removal of the glass (glass corrosion) at elevated temperatures (>100 °C).
Chemical composition
DURAN® has the following approximate composition (%):
| SiO2 | B2O3 | Na2O + K2O | AI2O3 |
| 81 | 13 | 4 | 2 |
Chemical resistance
| Hydrolytic resistance class (DIN ISO 719) | class 1 |
| Acid class (DIN 12 116) | class 1 |
| Alkali class (DIN ISO 695) | class 2 |
Due to its good hydrolytic resistance, DURAN® meets the requirements of the USP/ EP and is a neutral glass that corresponds to glass type 1. It can therefore be used in an almost unrestricted way in pharmaceutical applications and in contact with foodstuffs.
Inert behaviour
Due to the inert behaviour of DURAN® there is no contact or interaction (e. g. ion exchange) between medium and glass, which avoids interfering effects.
High usage temperature
The maximum permissible operating temperature for DURAN® is 500 °C. Above a temperature of 525 °C the glass begins to soften and above a temperature of 860 °C it changes to the liquid state.
DURAN® can be cooled down to the maximum possible negative temperature and is therefore suitable for use with liquid nitrogen (approx. – 196 °C). During such use/ freezing. In general DURAN® products are recommended for use down to – 70 °C. During thawing ensure that the temperature difference does not exceed 100 K.
DURAN® glassware is suitable for use in microwaves.
Minimal thermal expansion & high resistance to thermal shock
DURAN® glassware is characterised by high resistance to changes in temperature (?T=100 K). With its very low coefficient of linear expansion (3.3 x 10–6 K–1), literally no tension is built up in the article, when the temperature changes rapidly. Therefore, it does not crack or shatter, when boiling water is filled in.
Physical data
| Coefficient of mean linear thermal expansion ? (20 °C; 300 °C) | 3.3 x 10-6 K-1 |
| Transformation temperature T g | 525 °C |
| Temperature of the Glass at viscosity ? in dPa x s: |
|
| 107.6 (softening point) | 825 °C |
| 104 (working point) | 1260 °C |
| Maximum short-time working temperature | 500 °C |
| Density ? at 25 °C | 2,23 g x cm-3 |
| Modulus of elasticity E (Young´s modulus) | 64 x 103N x mm-2 |
| Poisson´s ratio µ | 0,20 |
| Thermal conductivity ?w at 90 °C | 1,2 W x m-1 x K-1 |
| Temperature for the specific electrical resistance of 108 ? x cm | 250 °C |
| Logarithm of the electrical volume resistance (? x cm) | at 250 °C 8/at 350 °C 6,5 |
| Dielectrical properties (I MHz, 25 °C) Dieletric constant ? | 4,6 |
| Dielectric loss factor tan ? | 37 x 10 -4 |
| Refractive index(? = 587.6 nm) nd | 1,473 |
| Stress-optical coefficient (DIN 52 314) K | 4,0 x 10-6 mm2 x N-1 |
Optical properties
In the spectral range from about 310 to 2200 nm the absorption of DURAN® is negligibly low. It is clear and colourless. Fairly large layer thicknesses (axial view through pipes) appear slightly yellow/greenish.
Cleaning of laboratory glassware
Special glass laboratory apparatus can be washed by hand in a soaking bath or by machine in a laboratory dishwasher. Laboratory dealers can supply a wide range of cleaners and cleaner-disinfectants for both methods. As contamination during the delivery of our laboratory glassware cannot be totally ruled out, we recommend washing laboratory glassware before it is used for the first time.
To care properly for laboratory glassware, it should be washed immediately after use at low temperature, on a short cycle and with low alkalinity.
Laboratory apparatus that has come into contact with infectious substances or microorganisms should be treated in accordance with the current guidelines. Dependent on the substance, autoclaving (e.g. to kill microorganisms) may be necessary prior to cleaning. It is generally recommended that cleaning or washing of glass products be carried out prior to autoclaving or hot-air sterilisation. This minimises dirt or impurities from adhering to the glassware surfaces and prevent damage caused by any possibly adhering chemicals.
For more details on the requirements of the new standard, you may contact us chingyee.tan@fleischhacker.biz or justina.tay@fleischhacker.biz
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Tel: +65 6356-7565 (Ext 221)
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