IPX7 Immersion: Depth, Duration and the Trapped Air Problem

IPX7 is temporary immersion: the enclosure is immersed with its lowest point 1 metre below the surface and held for 30 minutes. The pass condition is that no water enters in a quantity that could cause harmful effects.

Trapped air

An enclosure with a large internal volume and a sealed design behaves like a diving bell. Water may not enter because the trapped air cannot escape, and the test passes without proving anything about the seal. The standard recognises this: where the enclosure is designed to breathe, the test should be done with the breathing path as installed, and the manufacturer may specify a pressure equalisation time.

Temperature difference

A warm enclosure immersed in cool water creates a partial vacuum as the trapped air contracts, which draws water in through paths that would otherwise stay dry. This is why products that pass a room-temperature immersion can fail in service after a hot day. Test at the temperature the product sees in use, and note it in the report.

After the test

Dry the outside, then open the enclosure and inspect. Water that has entered through a cable gland often appears at the lowest point rather than near the entry, so inspect the whole interior rather than the suspect area.

Related technical notes

• IPX8: Continuous Immersion by Agreement
• IPX9K: High Pressure, High Temperature Washdown
• IP5X and IP6X Dust Test: Talcum, Concentration and Duration