🔍 Key Concepts

• Trace the refrigerant flow around valve 23 and identify which box (chill or freeze) that branch serves. • Relate a higher pressure setting at valve 23 to the corresponding saturation/evaporating temperature of the refrigerant. • Distinguish carefully between space temperature and evaporator coil minimum temperature in a refrigeration system.

💭 Think About

• Look at valve 23 in the illustration: is it located on the chill-box circuit or the freeze-box circuit, and is it a pressure-regulating valve on the suction or liquid side? • If you increase the set pressure of that valve, does the evaporator downstream operate at a higher or lower pressure, and what does that do to the refrigerant’s boiling (evaporating) temperature? • Once you know which evaporator is affected and how its minimum coil temperature changes, how will that influence the lowest space temperature that can be reached?

✅ Before You Answer

• Confirm from the diagram which coil or box is controlled by valve 23 (follow the piping to unit K or J). • Verify whether valve 23 is a pressure regulating valve on the suction line controlling evaporator pressure (and thus evaporator temperature). • Make sure you distinguish between a change in evaporator coil minimum temperature and the resulting space temperature, and choose the option that directly states the first effect.