Hydrophobic membrane

Illustrated explanation

Gas exchange and condensation are different

2Hydrophobic membrane
Enclosure vent, membrane and internal condensationA vent crosses an enclosure wall between the outside and inside. Callout 1 marks the gas-exchange fitting, 2 the membrane that resists liquid water under declared conditions and 3 droplets forming on a cold internal surface. A vent does not eliminate internal condensation. Current term: Hydrophobic membrane, callout 2. 1 2 3 OutsideInside enclosureGas exchangeCold surfaceWater vapour
  1. Pressure-equalization vent

    The fitting provides a gas-exchange path that reduces pressure differences. Size it for the enclosure and operating conditions.

  2. Hydrophobic membraneThis term

    The membrane passes gas while resisting liquid water under defined conditions. Check water-entry pressure, contamination and orientation.

  3. Condensation

    Vapour can become liquid on a surface at or below the relevant dew point. Moisture and temperature conditions still need review.

A vent provides a controlled gas path through an enclosure wall. Its membrane resists liquid entry within declared conditions. Water vapour already inside can still condense on a sufficiently cold surface.

Conceptual enclosure section. Arrows do not specify airflow or pressure capacity, and a vent does not guarantee a dry enclosure.

ReferencesIEC 60529 — Degrees of protection provided by enclosures (IP Code)IEC 60670-1:2024 — Boxes and enclosures for electrical accessoriesISO 80000-5:2019 — Quantities and units — Thermodynamics