PVBs are manufactured by Watts, Febco, Zurn and other manufacturers. Backflow prevention devices such as PVBs are regulated by the International Plumbing Code, but may also be required by government regulations.
US Patent Issued to Franklin Fueling Systems on March 27 for "Liquid Filled Pressure/ vacuum Valve for Petroleum Underground Storage Tanks" (California, Connecticut Inventors)
Mar 28, 2012; ALEXANDRIA, Va., March 28 -- United States Patent no. 8,141,577, issued on March 27, was assigned to Franklin Fueling Systems...