| 210 / | HD | LIQUID PURIFICATION OR SEPARATION |
| 348 | DF | FILTER {25} |
| 500.1 | DF | .~ Material {6} |
| 500.21 | DF | .~.~ Semipermeable membrane {6} |
| 500.27 | DF | .~.~.~ Organic {7} |
| 500.28 | DF | .~.~.~.~ Cyclic {2} |
| 500.29 | DF | .~.~.~.~.~ Cellulosic {1} |
| 500.3 | | .~.~.~.~.~.~ Cellulose acetate {2} |
| 500.31 | DF | .~.~.~.~.~.~.~> Cellulose diacetate |
| 500.32 | DF | .~.~.~.~.~.~.~> Cellulose triacetate |