The Kammerer sealing system "FD" is designed for gas tight shut-off-devices for granulates, dust, crystalline structured products, gasesand multipurpose use. The sealing system is achieved through a double- acting metallic pressure ring or PTFE slip-ring. This ring is pneumatically operated in a closed or open position from a control valve. The working pressure depends on the process pressure in the plant. For example a normal operating pressure of 6 bar can be sealed against a process pressure of 22 bar in the plant. During the operation the pressure ring is released pneumatically or by a spring, so that the wearoff will be minimized.