🔍 Key Concepts

• High-pressure fuel injection hazards to personnel • Correct behavior of needle valves and popping pressure in diesel injectors • Proper safety precautions when using a nozzle tester

💭 Think About

• Think about what happens if high-pressure diesel spray contacts your skin—how is this different from a surface burn? • Which statements describe normal injector operation, and which sound unsafe or mechanically incorrect? • What is the main reason we use a test stand/nozzle tester—are we trying to change spring settings, remove parts, or check something specific?

✅ Before You Answer

• Verify which option describes a safety risk to the operator, not a mechanical adjustment step • Check whether it would ever be correct practice to remove the spring before testing a nozzle on a tester • Consider whether a needle valve should open and then reseat sharply at popping pressure, or stay open afterward