Condensation

Illustrated explanation

Gas exchange and condensation are different

3Condensation
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: Condensation, callout 3. 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 membrane

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

  3. CondensationThis term

    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