| 210 / | HD | LIQUID PURIFICATION OR SEPARATION | 
| 321.6 | DF | CASING DIVIDED BY MEMBRANE INTO SECTIONS HAVING INLET(S) AND/OR OUTLET(S) {15} | 
| 321.72 | DF | .~ Each section having inlet(s) and outlet(s) {5} | 
| 321.75 |  | .~.~ Planar membrane {1} | 
| 321.76 | DF | .~.~.~> Spiral flow |