🔍 Key Concepts

• Expansion valve operation and what flows through the needle and seat • Conditions that cause high fluid velocity and flashing across a restriction • Effect of liquid vs. vapor refrigerant on metal erosion or washing of surfaces

💭 Think About

• Think about which choice would create a situation where liquid refrigerant suddenly changes to vapor right at a restriction point—what does that do to metal surfaces over time? • Which condition would most increase the speed and turbulence of refrigerant passing through the tiny opening of the expansion valve? • Look at each option and ask: does this primarily affect system pressure, system charge, compressor operation, or the condition of refrigerant arriving at the valve?

✅ Before You Answer

• Verify which option specifically promotes flashing of liquid to vapor at or before the expansion valve • Check which condition would cause high velocity flow and possible entrained particles at the needle and seat area • Eliminate options that mainly affect overall system pressure or compressor performance but not the local conditions at the expansion valve