Below is a list of Ball Valves manufacturers from Palo Alto, California. A ball valve is a stop valve mechanism that is designed mostly for on or off service. These valves contain a ball with a hole bored through the middle that helps control the flow of materials being transported through a pipe. The hole can also be called a port. Ball valves can be used in virtually any industry that uses piping for the flow of liquids, gases, slurries or suspended solids.