When handling glass vessels, pay attention to: • Only use glass vessels with a plastic coating for splinter protection. • Only use vessels which are suitable for use with vacuums (e.g. round-bottomed flasks). We recommend that only glass components supplied by the manufacturer are used. Do not use Erlenmeyer flasks. • Before each evacuation, check glass vessels for damage which might impair their strength, replace them if any such damage is found. • Do not heat glass vessels on one side only. • Retardation of the boiling of the gases to be pumped can lead to a sudden pressure increase. Prevent retardation of boiling by means of suitable measures (e.g. turbulent agitation).