| 137 / | HD | FLUID HANDLING |
| 455 | DF | LINE CONDITION CHANGE RESPONSIVE VALVES {11} |
| 493 | DF | .~ Bi-directional flow valves {4} |
| 493.1 | DF | .~.~ One head and seat carried by head of another {3} |
| 493.3 | | .~.~.~ Supporting valve spring carried by supporting valve {2} |
| 493.4 | DF | .~.~.~.~> Spring stop on supported valve stem |
| 493.5 | DF | .~.~.~.~> Spring abuts guide for supported valve stem |