Below is a list of PVC Check Valve manufacturers from Clear Lake, Minnesota. PVC check valves are unidirectional flow regulators made of a particularly versatile thermoplastic resin and easily suited to the specific needs of industrial, commercial and even domestic check valve applications. An acronym for polyvinyl chloride, PVC is a highly diverse polymer that can be formulated to suit a number of check valve applications. As check valves handle corrosive, acidic, basic and abrasive materials, among others, it is important to have valves that are chemically and physically compatible with the process streams they encounter.