Chinese cars are generally used GB/T12480-1990 bus rainproof sealability test method, QC/T476-1999 bus rainproof sealability limit, after the integration of the revised standard for QC/T476-2007 bus rainproof sealability limit and test method.

According to the requirements of GB/T12480-1990, the rainfall intensity of the rain test chamber is 4~10mm/min, the spray pressure of the nozzle is 69~147kPa, and the rain time is 15min. in the actual operation process, the vehicle factory, in order to strengthen the inspection of the rain sealing performance of the vehicle, often increases the rain intensity by increasing the density of the nozzle to improve the spray pressure, etc., the rain intensity of the rain test chamber will be higher than that of the test chamber. The rainfall intensity of the test box will be several times higher than the recommended value, some manufacturers even super to 100mm/min, nozzle spray pressure will also reach 200kPa or more, so that the spray water atomization after sprinkling to the body.

In the different stages of vehicle production, the vehicle manufacturers on the vehicle test requirements are different.

Vehicle trial production period, the stage due to the vehicle production process, equipment parameters, etc. are in the test period, so the whole vehicle through a long period of rain test (between 4 ~ 8 hours), to find the possible leak parts, and then leak cause analysis and design or process improvement, the whole vehicle mass production, design and process defects are basically improved to complete, rain mainly for routine inspection, to prevent occasional non-conformity brought about by sealing defects.