FREE-VALVE’s Pneumatic tungsten carbide seat double disc rotary swing valves are designed for pressurized and vacuum systems including dense and dilute phase pneumatic conveying systems, discharge and vent applications in steel plant and coal power. The double ceramic sealing faces of the valves are well ground and polished, which is ensure a reliable sealing performance of the valve,the valve is used to replace the dome valve in the pipe line of the ash system.