If the bellows in a thermo-hydraulic feed...

🔍 Key Concepts

• Thermo-hydraulic feed water regulator operation (how temperature and water level affect the bellows) • What the bellows actually does to the feedwater valve position when it expands or contracts • How a fail-safe design usually responds when a sensing element ruptures or loses pressure/charge

💭 Think About

• Think through what happens to the control signal to the valve if the bellows suddenly loses its fluid/pressure. • In normal operation, does bellows expansion tend to open the feed valve or close it as the water level rises? Now, imagine the bellows can no longer expand—what position will the valve move toward? • Consider the short-term effect on drum level just after the failure, and then the longer-term effect once the system stabilizes with the valve in that failed position.

✅ Before You Answer

• Identify whether the design is fail-open or fail-closed for the feedwater valve if the bellows fails. • Be clear on the relationship between feedwater flow and drum level: more feedwater vs. less feedwater over time. • Mentally trace the sequence over time: first few moments after rupture, then what happens as firing rate and steam demand continue unchanged.

If the bellows in a thermo-hydraulic feed water control valve ruptures, the boiler water level will __________.

increase only

decrease only

increase initially and then decrease

decrease initially and then increase

🔍 Key Concepts

💭 Think About

✅ Before You Answer