🔍 Key Concepts

• Throttling vs. on/off (isolation) service in valve design • How flow across a partially open valve seat affects wear and vibration • Which valve types (plug, globe, gate, needle) are specifically designed for flow regulation

💭 Think About

• Ask yourself: Which of these valves is normally recommended for fully open or fully closed service only, not partially open? • Think about the internal shape of each valve: Which one has a flat or wedge-like disk that, if left partly open, would have high velocity flow eroding the seat? • Which valves give you fine, precise control of flow (good for throttling), and which are more like simple shutoff devices?

✅ Before You Answer

• Identify which valves (from the list) are commonly used as throttling/regulating valves in engineering practice. • Identify which common valve type is designed mainly as an isolation (on/off) valve and is not recommended for throttling because of potential seat and disk damage. • Before choosing, rule out all valves that are specifically intended for regulating flow, then look at the one that is not.