A WPP valve bag is a specialized packaging solution designed for the efficient handling and safe transport of powdered, granulated, or bulk materials. Unlike standard bags, the valve bag features a self-closing filling spout (valve) which allows for rapid filling with minimal dust release, while maintaining a secure seal once filled.

A WPP valve bag is a kind of packaging bag made from woven polypropylene (WPP) fabric, incorporating a valve opening (filling spout) at the top. During the filling process, dry powdered or granular material is pumped into the bag through that valve, and the internal pressure causes the valve to self-close, sealing the contents inside.