IPX4 摆管和喷嘴两种测试手法的不同用途是什么？

请教各位大侠，IPX4 摆管和喷嘴两种测试手法的不同用途是什么？是根据受测物大小来定义，还是不同产品类型来定义的？

14.2.4 Test for second characteristic numeral 4 with oscillating tube or spray nozzle
The test is made using one of the two test devices described in figure 4 and in figure 5 in
accordance with the relevant product standard.
a) Conditions when using the test device as in figure 4 (oscillating tube):
The oscillating tube has spray holes over the whole 180” of the semicircle. The total flow
rate is adjusted as specified in table 9 and is measured with a flow meter.
The tube is caused to oscillate through an angle of almost 360°, 180° on either side of the
vertical, the time for one complete oscillation (2 × 360°) being about 12 s.
The duration of the test is 10 min.
If not specified otherwise in the relevant product standard, the support for the enclosure
under test is perforated so as to avoid acting as a baffle and the enclosure is sprayed from
every direction by oscillating the tube to the limit of its travel in each direction.
b) Conditions when using the test device as in figure 5 (spray nozzle):
The counterbalanced shield is removed from the spray nozzle and the enclosure is
sprayed from all practicable directions.
The rate of water flow and the spraying time per unit area are as specified in 14.2.3.