| 137 / | HD | FLUID HANDLING |
| 455 | DF | LINE CONDITION CHANGE RESPONSIVE VALVES {11} |
| 494 | DF | .~ With separate connected fluid reactor surface {8} |
| 505 | DF | .~.~ With opening bias (e.g., pressure regulator) {13} |
| 505.25 | | .~.~.~ Apertured reactor surface surrounds flow line |