| 165 / | HD | HEAT EXCHANGE |
| DIG 327 | DD | THERMOSYPHONIC HAVING VERTICAL AIR DRAFT PASSAGE {3} |
| DIG 331 | DD | .~ Air draft passage confined entirely by heat transfer surface {2} |
| DIG 335 | DD | .~.~ Plural air draft passages enclosed by casing {1} |
| DIG 336 | | .~.~.~ Angled air draft passage |