| 165 / | HD | HEAT EXCHANGE |
| DIG 327 | | THERMOSYPHONIC HAVING VERTICAL AIR DRAFT PASSAGE {3} |
| DIG 328 | DD | .~> Air draft passage confined entirely or in part by fin structure {2} |
| DIG 331 | DD | .~> Air draft passage confined entirely by heat transfer surface {2} |
| DIG 337 | DD | .~> Heating or cooling means entirely surrounded by air draft passage forming casing {3} |