DIN 51524, part 2 and 3 (HLP, HVLP), AFNOR NF E 48-603 (HM, HV), SIS SS 155434, VDMA 24318, Hoesch HWN 2333, Thyssen TH N-256132, CETOP RP 91 H (HM, HV), U.S. Steel 126, 127 and 136, Sperry Vickers M-2950-S and I-286- S, Denison Filterability TP 02100