Companies that are using the DIN11864 fittings in their piping systems do require on occasion in-line filtration. (example pump protection @ stratup) We call these products Screens. A stainless steel mesh filter imbedded in the DN size O-ring.
Availbe in many different mesh sizes (filter retentions in µm).
Standards:
DIN11864 according to DIN
DIN11864 according to ISO
DIN11864 according to ASME BPE