Machine components or fittings for silos to be used in the bulk solids handling industry, such as rotary valves, air locks, blowing seals/blow through valves, drop-through valves, plug-type diverters, flap-type diverters, ball-type diverters, tube-type diverters, rotary feeders, dosing equipment, dust collectors, fill vent valves, knife-gate valves, discharge units and pressure-relief valves