Spring in setting：

The spring is located at the inlet end of the pump.
When the spring in setting pump dispenses liquid, the liquid comes into contact with the in spring. A chemical reaction may occur, causing the spring to corrode and rust.

Spring out setting：

The spring is located at the top part of the pump.
When the pump dispenses liquid, the liquid does not come into contact with the spring. This prevents the liquid from contacting the spring, thus preventing the spring from rusting and polluting the liquid.