Kromschroeder GFK 50R40-6 (81940200) gas filter

The Kromschroder GFK 50R40-6 (81940200) is a gas filter listed under catalogue article 624.880.031. Parts of this type are installed in the gas supply line upstream of the gas valve to trap solid particles — rust, weld slag, pipe dross — before they can reach the valve seat, servo regulator, burner nozzle or modulating actuator. Clean gas keeps the valve sealing surfaces tight and prevents drift in outlet pressure. Gas filters are selected primarily by connection size and pipe thread (Rp or flanged), filter element fineness and the pressure rating of the housing. The element may be a sintered bronze cartridge or a pleated paper insert that can be cleaned or replaced. The housing often has a drain plug for condensate and a pressure tapping point so a differential pressure gauge can be fitted to monitor when the element needs servicing. When replacing a gas filter, confirm the thread size matches the pipework; the flow direction arrow on the housing must point toward the gas valve. Ensure the gasket or O‑ring is intact and that the filter is not installed upside down. Some multiblock gas valves incorporate an integrated filter, but here the GFK series is a separate unit. Periodically check the pressure drop across the element; a high drop indicates a clogged filter that can reduce burner output or cause flame instability.