Stainless Steel Membrane Housing Pressure Vessels enhance system appearance and allow you to take full advantage of the membrane capability. Safer and more reliable than the PVC membrane pressure vessels with similar ratings. This style is designed for direct connection to AMI/Applied Membranes and FilmTec/DOW male Style Elements.modle L L 1 A B (mm) (mm) (mm.in) (mm.out) 4021 600 540 Dg15, 1 / 2 " Dg15, 1 / 2 " 4040 1087 1027 Dg20, 3 / 4 " Dg15, 1 / 2 " 4080 2103 2043 Dg20, 3 / 4 " Dg15, 1/ 2 " 40120 3119 3059 Dg20, 3 / 4 " Dg20, 3 / 4 "