🔍 Key Concepts

• Trace the steam flow path from the INLET through ports A, B, and C and see which components are directly exposed to high pressure steam. • Review how a pilot-operated (auxiliary) valve works in a spring-loaded pressure-reducing valve: the pilot usually controls pressure on a piston or diaphragm that moves the main valve. • Identify which side of the diaphragm E and piston H should see reduced (outlet) pressure versus inlet (high) pressure in order for the valve to regulate downstream pressure.

💭 Think About

• Looking at the cross‑section, which surfaces of the main valve K, piston H, diaphragm E, and auxiliary valve D are actually in communication with the high‑pressure inlet passage? • In normal operation, does high pressure steam tend to force the main valve more open or tend to shut it if the pilot were not venting/controlling anything? How does that help keep the outlet pressure constant? • Compare the purpose of the high pressure port C with the passage J that comes from the outlet side: which one is more likely to carry reduced pressure for feedback to the diaphragm?

✅ Before You Answer

• Verify which passage from the INLET actually leads to the area above or below the main piston H—do not assume it without tracing the drilled passages in the illustration. • Confirm whether the diaphragm E is connected to the outlet (low pressure) or inlet (high pressure) side; a pressure‑reducing valve usually senses downstream (reduced) pressure at the diaphragm. • Make sure that any option you pick matches the control function of the valve: high pressure should be used to move or load a part in a way that allows the spring and diaphragm feedback to regulate downstream pressure, not to bypass that control.