Theory and Method
IEC 60529 verifies numerals 5 and 6 with the same device in two configurations. Figure 6 defines a hose nozzle that projects a coherent stream at the enclosure, and the operator works around the specimen covering every practicable direction. Numeral 5 uses the 6.3 mm bore at 12.5 L/min, while numeral 6 uses the 12.5 mm bore at 100 L/min. Both apply at a standoff of 2.5 m to 3 m for one minute per square meter of exposed surface, with a three-minute floor.
Bore diameter is what sets severity. Doubling the bore roughly quadruples the cross-sectional area, and the standard raises flow eightfold across the step, so the numeral 6 stream carries far more mass and momentum onto the same seam. That gap explains why an enclosure passing IPX5 can still fail IPX6 despite the two ratings sitting one apart. Swapping nozzles rather than throttling a single nozzle keeps each bore at its designed geometry.
Delivery rate is the controlled variable, and pressure follows from it. The method asks the operator to set supply pressure until flow reaches the target rate, so the gauge at the handle serves as the feedback the operator watches while working. A 0 to 1.6 bar span covers the roughly 100 kPa that numeral 6 calls for, with headroom above it. Shutting off at the handle rather than at the supply lets the operator pause between faces without losing the setting.
