Refrigeration System Pressure Testing and Evacuation

Auto audio on: the next questions will be read aloud when you click Continue.

1. 1

   What is the primary purpose of evacuating a sealed refrigeration system before charging it?

   A To circulate lubricant through the compressor B To remove air, moisture vapor, and other noncondensable gases C To raise the system pressure above atmospheric pressure
2. 2

   Which gas should normally be used to pressure-test refrigeration piping?

   A Dry nitrogen supplied through a pressure regulator B Compressed oxygen supplied directly from its cylinder C Water vapor supplied from a steam generator
3. 3

   The image shows an oxygen cylinder connected to refrigeration piping for a pressure test. Why is this practice prohibited?

   

   A Oxygen cannot produce enough pressure for testing B Oxygen always freezes inside copper tubing C Pressurized oxygen can react violently with oil and create a fire or explosion hazard
4. 4

   In the illustrated evacuation setup, the micron gauge is connected to the system at a service port far from the vacuum pump. What is the main benefit of this location?

   

   A It increases the vacuum pump's motor speed B It measures the vacuum within the system rather than mainly at the pump inlet C It automatically detects the refrigerant type
5. 5

   Why can removing Schrader valve cores significantly reduce evacuation time?

   A It removes a major flow restriction and improves evacuation conductance B It causes liquid refrigerant to absorb moisture C It increases the displacement rating of the vacuum pump
6. 6

   Which instrument is designed to verify that a refrigeration system has reached a deep vacuum?

   A A standard high-pressure manifold gauge B A clamp ammeter C An electronic micron gauge
7. 7

   After the vacuum pump is isolated, the graph shows pressure rising rapidly and continuing upward without leveling off. What does this most strongly indicate?

   

   A A stable, dry, and tightly sealed system B A leak or an incompletely isolated connection C Normal compressor lubrication
8. 8

   What is the role of dry nitrogen during a triple-evacuation procedure?

   A It breaks the vacuum and helps carry moisture vapor out during repeated evacuation B It permanently replaces the system's specified refrigerant C It chemically converts water into compressor oil
9. 9

   How does dirty or moisture-contaminated vacuum pump oil affect evacuation?

   A It increases hose diameter and improves conductance B It converts the vacuum pump into a recovery machine C It reduces the pump's ability to achieve a deep vacuum
10. 10

    During a nitrogen pressure test, soap solution applied to a brazed joint forms steadily growing bubbles as shown. What does this indicate?

    

    A The joint is properly dehydrated B Pressurized gas is leaking through the joint C The nitrogen has changed into a liquid