Below is a list of Diaphragm Control Valve manufacturers from Napa, California. Diaphragm control valves employ a membrane or elastomer film to regulate the process stream of various manufacturing operations. As the name would suggest, these process valves are used to control the flow of fluids, gases and semi-solids such as colloids and slurries. Everything from rate, pressure and temperature to liquid level can be regulated with the application of these valves.