Sealed electronics in coastal areas, winter-road spray, and outdoor cabinets are not only exposed to rain. Salt fog can corrode housings, load the membrane with residue, and reduce airflow long before an IP rating looks failed on a datasheet.
That is why salt fog testing sits next to IP, temperature, humidity, and vibration when we check protective vents—not as a slogan, but as a way to see whether the part still does its job after salt exposure.
Watch the process:
The problem salt fog creates for vents
An ePTFE vent has two jobs at once:
- Keep liquid water, dust, and contaminants out
- Let air and vapor move so the enclosure can equalize pressure
Salt changes both sides of that balance. Fine salt aerosol can sit on the membrane surface, combine with humidity, and narrow the effective pore path. Metal or plated housings can corrode at threads, snap seats, or weld edges. If airflow drops, pressure stays trapped. Seals work harder. Condensation is more likely. In the field that often shows up as fogged lamps, corroded connectors, or housings that breathe poorly after a season of road salt or sea air.
A single splash or short immersion test does not reproduce that load. Salt fog is a longer, wetter, more corrosive condition.
What we look at after the chamber—not only pass/fail
A useful salt fog result is not only “no visible rust.” For a protective vent, the report should still answer:
- Does the membrane still block liquid water (water entry pressure / WEP after exposure)?
- Is airflow still in the specified range for pressure equalization?
- Is the adhesive, weld, thread, or snap-fit still sealed?
- Has salt residue clogged the face of the membrane?
- Did the housing or hardware corrode in a way that would leak or seize in service?
We run salt fog as one environmental check among several (IP ratings, temperature, humidity, flammability where required). The point is consistency: the same vent that leaves production should still vent and protect after salt exposure that matches coastal, road-salt, or outdoor duty.
Where this matters on real products
Salt fog is especially relevant when the enclosure lives outdoors or under the vehicle:
- Automotive lighting, ECU, radar, and camera modules
- Outdoor electronics: inverters, base-station boxes, cameras, sensors
- Energy and telecom cabinets near coasts or winter roads
- Any housing specified to IP67 / IP68 / IP69K that will also see salt
If your specification only lists IP and temperature, add salt fog method, duration, and post-test airflow + WEP. Those two numbers tell you whether the vent is still a vent.
What to request when you source vents
When you compare adhesive, weldable, snap-fit, or screw-in vents, ask for:
- Salt fog standard and duration used
- Sample orientation and whether the vent face was exposed
- Air permeability before and after test (@ stated pressure, e.g. 7 kPa)
- Water entry pressure after test
- Photos of membrane face and housing hardware
- How the result maps to your enclosure (coastal, chassis, wash-down, winter road)
That keeps the discussion on measured function, not on a single checkbox.
Related SST vent types
Need help matching salt-fog duty to membrane airflow and installation type? Send the enclosure volume, target IP, and environment (coastal / road salt / wash-down).
Email: apple@spider-amoy.com