There is currently no material that can meet all the ex […]
There is currently no material that can meet all the experimental requirements. The use of glass or plastic products depends on the application and the design of the instrument. It is necessary to consider the special materials of the materials, and of course the cost.
General properties of glass
Glass products have good chemical resistance to water, salt solutions, acids, alkalis and organic solvents. From this point of view, more than most plastic products, only hydrofluoric acid and strong alkali or concentrated phosphoric acid at elevated temperatures Attack the glass. Another feature of glassware is the stability of the shape (even under elevated temperatures) and its high degree of transparency.
Special properties of a particular glass
In laboratory applications, there are many different types of glass that can be selected.
Nano-calcium glass has good chemical and physical properties. Suitable for short-term exposure to chemical reagents and limited thermal shock applications.
Borosilicate glass has excellent chemical and physical properties. As described in the international standard DIN ISO 3585, the primary hydrolyzed glass has a linear expansion coefficient of 3.3 and is suitable for applications requiring excellent chemical and thermal resistance (including thermal shock resistance) and high mechanical stability. It is a typical glass for chemical instruments, such as round bottom flasks and beakers and metering products.
Use of glass products
When using glass, it is necessary to consider resistance to thermal shock and mechanical force. Strict safety measures must be followed:
Do not heat volumetric instruments, graduated cylinders, or reagent bottles on hot plates.
When performing an exothermic reaction, such as diluting sulfuric acid or dissolving sodium hydroxide, be sure to continue stirring and cooling the reagents, and select a suitable container, such as a conical flask, never use a graduated cylinder or volumetric flask.
Glass instruments must never be exposed to sudden, intense temperature changes. When removing the glass instrument from the hot drying oven, do not place it on a cold or wet surface immediately.
For pressure-bearing applications, only glass instruments designed for this purpose can be used. For example, the filter bottle and the dryer can only be used after vacuuming.