🔍 Key Concepts

• Function of a steam pressure-reducing regulator (how outlet pressure is controlled by a spring and diaphragm/piston) • Which component is normally turned by hand or wrench to compress or relieve the control spring and thus change set pressure • Difference between parts that move automatically with pressure (valve, diaphragm, plug) and parts that are manually positioned (adjusting screw)

💭 Think About

• Trace the force path from the outlet pressure sensing element up to the control spring: which part’s compression would change the downstream pressure setting? • Look carefully at which labeled part is clearly threaded and designed to be rotated from outside the housing, rather than being fully enclosed inside the body. • Ask yourself: if you were the engineer on watch and needed to change the outlet set pressure, which labeled part could you realistically put a wrench on without disassembling the regulator?

✅ Before You Answer

• Identify the exposed threaded component that bears directly on a spring controlling the regulator. • Confirm that this part can be turned from outside the casing without breaking pressure containment (no covers or flanges need removal). • Verify that the part you choose is not a movable valve plug or linkage that responds automatically to pressure, but a manual adjustment screw acting on the spring.