Many applications within the laboratory environment require products to be subject to pressure or vacuum conditions. But not all products are designed to withstand this.
Only those whose design includes the appropriate geometry and wall thickness, and which are explicitly designated as such, are suitable for working under pressure and / or vacuum.
Examples of such products include filtering flasks, desiccators, or flat flange vessels, as well as products like the DURAN® pressure plus+ range of bottles, which provide guaranteed vacuum and pressure resistance from –1 bar to + 1.5 bar due to modified geometry and a greater wall thickness than standard DURAN® borosilicate 3.3 laboratory bottles.
When used under positive or negative pressure, and especially when also working with differential temperatures, additional care measures must also be taken. Glass apparatus that is under pressure or vacuum should only be subject to further stress, such as significant temperature changes, with extreme caution, as the individual resulting strains are additive and could readily result in failure.
To guarantee optimum user safety when working with pressure in the lab, the following points should also be kept in mind:
- To avoid stresses in the glass, evacuated vessels or vessels under pressure should not be heated on one side or heated with an open flame.
- When working under pressure the maximum figures indicated in the product literature should not be exceeded.
- Before using glass equipment under vacuum or pressure it must always be visually inspected to check that it is in perfect condition and does not contain any serious scratches, micro-cracks or abrasions. Damaged glassware should not be used for work under pressure or vacuum for safety reasons.
- Never subject glassware to sudden pressure changes. For example, always re-pressurize evacuated glass apparatus slowly.
- Laboratory glassware with a flat bottom (for example Erlenmeyer and flat bottom flasks) should not be used under pressure or vacuum.
- The plastic coating of laboratory bottles has no influence on pressure resistance. These products are not designed for use under pressure. For pressure applications using laboratory bottles, products such as the DURAN® pressure plus+ bottle should be used.