1. It is well known by people that products can inordinately affect with all kinds of liquids,

 either they were in operative mode or storage mode.

It has varying effects on their raw materials and features

and even can damage the structrues when they are permeated, flowed, struck, and accumulated by liquids.

2. The aim of rain test is that it tests their operative stabilities and reliabilities

which their outside shells prevent the penetration and are corroded at the time or later when equipments are corroded by all kins of liquids.