| 210 / | HD | LIQUID PURIFICATION OR SEPARATION |
| 513 | DF | GRAVITATIONAL SEPARATOR {6} |
| 532.1 | DF | .~ Heavier constituent trap, chamber, or recess {2} |
| 533 | DF | .~.~ Closure or valve controlled discharge {3} |
| 537 | | .~.~.~ With discharge means for two or more lighter constituents |