Water jet testing has a reputation for being subjective. It should not be. The variables are all measurable: nozzle bore, flow rate, distance from nozzle to enclosure, test duration, and the condition of the sample afterwards. When two labs disagree about an IPX5 result, one of those five numbers is usually the reason.
Two jets, two very different set-ups
IEC 60529 defines IPX5 with a 6.3 mm nozzle delivering about 12.5 L/min, and IPX6 with a 12.5 mm nozzle at about 100 L/min. Both are applied from roughly 2.5 to 3 m, with the sample on a turntable so the jet sweeps the whole surface. The minimum duration is normally around 3 minutes, often expressed as about 1 minute per square metre of surface with a 3-minute floor.
| Parameter | IPX5 | IPX6 |
|---|---|---|
| Nozzle internal diameter | 6.3 mm | 12.5 mm |
| Water flow | 12.5 L/min ±5% | 100 L/min ±5% |
| Distance nozzle to sample | 2.5 – 3 m | 2.5 – 3 m |
| Water pressure | Adjusted to achieve the specified flow | Adjusted to achieve the specified flow |
| Minimum duration | ~3 min (or 1 min/m²) | ~3 min (or 1 min/m²) |
Set the flow, not the pressure. Pump pressure is only the means to an end, and it changes with hose length, filter loading and the height of the tank. A flowmeter in the supply line, read and logged at the start of the test, removes most of the argument.
Sample preparation is half the test
Enclosures are tested in their normal service condition. That means cable glands fitted and torqued, covers screwed down to the specified value, drain plugs in place, and any doors latched as the manufacturer intends. Do not add tape, silicone or extra gaskets "just for the test", and do not remove the gasket to make the test easier. If a unit is normally mounted vertically, test it vertically; if it can be mounted in several orientations, the worst case should be covered.
For equipment that is powered during the test, decide beforehand what constitutes a functional failure and wire it so that it can be monitored safely. A lamp that flickers and recovers is a different finding from one that stays dark.
After the spray, the actual judgement
The standard does not require zero water inside every enclosure. It requires that any ingress does not interfere with normal operation or compromise safety. In practice that means inspecting for water on live parts, on insulation where tracking could occur, and in any quantity that could reach a terminal block. A few droplets on an internal wall below the cable entry may be acceptable; a pool under a PCB is not.
- Open the enclosure promptly after the test and photograph the inside before wiping anything.
- Check cable entries, gasket corners and display windows first — these are the usual paths.
- Note water on insulation separately from water on bare metal.
- Run the functional check before and after, and record both.
For IPX6, pay attention to mechanical effects as well. A 100 L/min jet carries enough momentum to flex a large thin panel or push a poorly retained gasket out of its groove. That is a genuine failure of the enclosure under the specified severity, not a test artefact.
Keeping the rig repeatable
Nozzles erode. A 6.3 mm bore that has grown by a few tenths of a millimetre will pass more water at the same pump setting, and the flowmeter will hide the change in jet shape. Check the bore with a plug gauge on a schedule, keep a spare reference nozzle, and replace rather than ream. Filters clog slowly, turntable speeds drift, and hoses kink: all of them belong on the same maintenance list as the flowmeter calibration.
If a result is close to the line, repeat with the sample dried and reassembled using new fasteners or a fresh gasket where the design permits. A marginal pass that depends on one particular gasket out of a batch of ten is worth investigating before the certificate is signed.
Sales Team