Permeable membrane cap

The Schott Duran permeable membrane cap can release gases to relieve pressure in a sealed bottle.

The membrane screw cap is made of polypropylene with a welded-in PTFE membrane (0.2 µm) for pressure compensation. This cap system is temperature-resistant up to 140°C, suitable for autoclaving. The two-way membrane, with pressure equalisation from 0.1 bar, is suitable for storing gas-forming media and exothermic reactions.

Since pressure compensation takes place through the membrane, the cap can remain tightly screwed on during the autoclaving process, significantly reducing the risk of contamination. Since the membrane prevents the entry of liquids and solids, the contents of the bottle remain sterile.

The white PTFE membrane is limited to relieving pressure approximately twenty times in its lifetime. Once expended, the membrane changes to an off-white or grey colour to signal replacement.

The caps are available in the thread sizes GL28, 32, 45 and GLS80.