| 55 / | HD | GAS SEPARATION |
| 315 | DF | PLURAL SERIAL BASICALLY DIVERSE SEPARATING MEDIA {3} |
| 318 | DF | .~ Plural stages in unitary casing {2} |
| 320 | DF | .~.~ Deflector and fibrous, filamentary, particulate solids, or cohesive sheet filter type {6} |
| 321 | DF | .~.~.~ Multiple of one type in series of parallel in flow path {3} |
| 323 | DF | .~.~.~.~ Filters {1} |
| 324 | ![]() | .~.~.~.~.~ In parallel |