PTFE FAQ

PTFE (Polytetrafluoroethylene) membrane filters are highly hydrophobic and offer exceptional chemical resistance, making them ideal for filtering aggressive solvents, acids, and bases. Their excellent liquid repellency, high purity, and broad chemical compatibility make PTFE membranes a preferred choice for vent filtration, gas filtration, solvent filtration, and other demanding laboratory and industrial applications.

For laminated PTFE membrane filters, the smooth PTFE membrane side should always face the feed solution (upstream) or the direction of liquid ingress. This orientation ensures optimal filtration performance, particle retention, and membrane support during operation.

Sterlitech Aspire™ ePTFE membranes are assigned a reference pore size based on bubble point test data. However, ePTFE membranes can also be characterized using several other methods, including: Absolute Pore Size – The largest pore in the membrane. Bubble Point – Measures pore size and verifies membrane integrity. Mean Flow Pore Size – The membrane's average effective pore size. Nominal Pore Size – A general pore size classification. Retention Rating – The membrane's ability to retain particles of a specified size.

No. Advantec unlaminated hydrophilic PTFE membrane filters are not permanently hydrophilic. After wetting, the membrane may revert to its naturally hydrophobic state if allowed to dry. Hydrophilicity may also be lost after autoclave sterilization or exposure to temperatures above 100 °C.

Laminated PTFE membrane filters should be installed with the laminated backing (shiny side) facing downstream and the dull PTFE membrane side facing the feed (upstream). This orientation provides the membrane with optimal mechanical support during filtration. If the filter is accidentally installed in the opposite direction, the 0.2 µm particle retention will not be affected—particles larger than the membrane's pore size will still be retained. However, the membrane may have reduced structural support, which can impact durability or performance under demanding operating conditions.