LOW EXPANSION BOROSILICATE GLASS
From the 16th Century to today, chemical research teams have used glass containers for a very basic reason the glass containers is transparent, almost invisible. And so the contents and the reaction are clear visible, But because chemists music heat, cool and mix chemical substances, ordinary glass is not always adequate or laboratory works. Laboratory works requires apparatus made in a glass - which can readily be mould ed into any desired shape or from which offers maximum inertness when in contact with the widest range of chemical substances, which can withstand thermal shock with fracture and high temperature work without deforming, and which will be resilient enough to survive the everyday knocks to which it will be subjected in normal laboratory handling, washing and sterilizing processes.
Chemical Composition
Edutek Glassware is a low alkali borosilicate composition. Its typical chemical composition is given under. It is virtually free of magnesia-lime-Zinc group and contains only traces of heavy metals.
In general the 'Strain point' should be regarded as the maximum safe operating temperature of Edutek glassware. When heated above 500° C the glass may acquire permanent stresses on cooling. All Edutek lab ware is annealed in modern ovens under strictly controlled conditions to ensure minimal residual stress in the products.
Chemical Durability
Edutek Glassware in highly resistance water, neutral and acid solutions, concentrated acids and their mixtures as well as to chloride, bromine, iodine, and organic matters. Even during extended period of reaction and at temperatures above 100° C, its chemical resistance exceeds tha of mot metals and other materials. It can withstand repeated dry and wet sterilisation without surface deterioration and subsequent contamination.
Resistance to attack of various chemicals is shown under. Only hydroflioric acid, very hot phosphoric acid and alkaline solutions increasinglly attack the glass surface with rising concentration and temperature.
Contact Chemical |
Duration in hour |
Loss in Wt. mg/m |
Water distilled at 100°C |
6 |
10 |
Water Vapour |
|
|
130°C |
|
|
Alkali - 1N soln. of NA2Co3
boiling Infusion Fluids Isotonic |
6 |
4000 |
Nacl(0.85%) 121°C |
2.5 |
70 |
Glucose(5%)121°C |
2.5 |
50 |
Fabrication with Borosilicate Glass
Due to low expansion of glass and easy workability, this glass can be shaped, formed, joined into complicated apparatus. It can be done even by an analyst in his own laboratory. He can keep on changing till he gets what he needs. In case where annealing in a controlled oven is difficult he can do so b flame annealing which is also great advantage.
Optical Properties
Laboratory glassware made form Borosilicate Glass shows no noticeable absorption in the visible region of the spectrum. It appear consequently clear and colourless.
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