| 165 / | HD | HEAT EXCHANGE |
| DIG 92 | DD | WITH VALVE OR MOVABLE DEFLECTOR FOR HEAT EXCHANGE FLUID FLOW {6} |
| DIG 109 | DD | .~ With by-pass of heat exchanger or heat exchanger section {2} |
| DIG 110 | DD | .~.~ Bypass within or surrounds heat exchanger {4} |
| DIG 113 | DD | .~.~.~ Bypass centrally located in heat exchanger {3} |
| DIG 114 | | .~.~.~.~ Having perforated wall |