These valves are piston-type, gas powered, and normally open. They are heavy duty, semi-steel bodied valves that are built with control precision. The 32mm (1-1/4”) port size has a PTFE main seat, the 40mm (1-5/8”) port and larger have a metal to metal seat, the 100mm and 125mm (5” and 6”) port size versions of this unique suction stop valve utilize a larger capacity, remotely piped pilot operated solenoid, the R/S type S8F. In addition, the pilot regulator for these two larger sized valves is mounted on top of valve, with the strainer disc assembly piped into the side of the adapter.