🔍 Key Concepts

• Needle valve design and purpose compared to gate, globe, and check valves • How flow rate is controlled in small lines or instrumentation systems • Relationship between valve type and pressure drop / backflow prevention

💭 Think About

• What feature of a needle valve’s internal shape (the long tapered stem and small seat) makes it useful for certain kinds of flow control? • In which situations would you need to make very fine, gradual adjustments to flow instead of simply turning flow fully on or fully off? • Which other specific valve types are normally used when the main concern is preventing backflow or minimizing pressure loss?

✅ Before You Answer

• Match the valve type to its primary function: isolation, throttling (regulation), backflow prevention, or minimal loss • Think about whether a very small flow passage in a valve would create more or less pressure drop • Recall which valve is typically dedicated to preventing reverse flow in a piping system