🔍 Key Concepts

• Single-element feed water regulator basic purpose and what it measures/controls • How a thermo-hydraulic (heat + fluid) closed system responds when temperature changes • Where the actuating force for the valve in this system actually comes from

💭 Think About

• Ask yourself: In a single-element system, is the regulator reacting mainly to water level, steam flow, or feed flow? How does that limit what it can keep constant? • Think about a sealed tube-and-bellows type device: when the fluid inside is heated, what expands or changes, and what part of the regulator would that motion act on? • Consider which option describes a built‑in fail-safe feature and whether that is a defining operating principle for this specific type of regulator, or just a possible design choice.

✅ Before You Answer

• Identify which choice describes the primary sensing/actuating action (how motion gets to the valve) rather than a secondary feature like cooling or safety. • Verify whether a single-element regulator can truly hold water level constant over the entire load range, or if its control is more limited than that. • Eliminate any option that describes something that is not typical of a closed thermo-hydraulic system (for example, ask if cooling fins are really needed to prevent steam formation in such a device).