Liquid Handling

Materials: GlassLaboratory GlassGeneral PropertiesGlass has very good chemical resistance against water, saline solutions, acids, alkalis andorganic solvents and in this respect surpasses the majority of plastics. It is only attackedby hydrofluoric acid, and – at elevated temperatures – by strong alkalis and concentratedphosphoric acid. Further advantages of glass are its dimensional stability, even at elevatedtemperatures, and its high transparency.Technical InformationSpecific properties of individual glassesFor the laboratory, various glasses with different technical properties are available.Soda-lime glassSoda-lime glass (e.g., AR-GLAS ® ) hasgood chemical and physical properties. Itis suitable for products which are usuallysubjected to short-term chemical exposure,and to limited thermal stress (e.g., pipettes,culture tubes).Borosilicate glass(Boro 3.3, Boro 5.4)Borosilicate glass has very good chemicaland physical properties. The abbreviationBoro 3.3 stands for a borosilicate glass type3.3 as specified in international standardDIN ISO 3585, for applications requiringvery good chemical and thermal resistance(including resistance to thermal shock), andhigh mechanical stability. Typical applicationsare components for chemical apparatus,round-bottom flasks, and beakers.Working with glassWhen working with glass, it is essential to consider its limitations regarding resistance tothermal shock and to mechanical stress. Strict safety measures must be observed:■ Do not heat volumetric instruments,measuring cylinders and flasks on hotplates.■ Exothermic reactions such as dilutingsulfuric acid or dissolving solid alkalinehydroxides must always be carried outwhile stirring and cooling the reagents,and in suitable vessels such as Erlenmeyerflasks – never in graduatedcylinders or volumetric flasks!■ Glass instruments must never be exposedto sudden temperature changes.When taking them out of a drying cabinetwhile hot, never place on a cold or wetlab bench.■ For compressive loads, only glass instrumentsintended for this purpose may beused. For example, filtering flasks anddesiccators may be evacuated only afterconfirming that they are in perfect condition.BRAND does not offer instrumentsfor pressure applications.www.brand.de331