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UNIT 27 REVIEW QUESTIONS ANSWER KEY GO BACK TO INDEX
27-1) What is the purpose of the pressure regulator on the nitrogen cylinder?
27-2) A refrigeration system data plate states that the low side test pressure is 150 psig
and the high side test pressure is 450 psig. What does this mean?
27-3) What is the maximum pressure that should be used for leak testing a refrigeration
system with a hermetic compressor?
27-4) What is the difference between corona discharge and heated diode electronic leak
detectors?
27-5) How does an LED refrigerant leak detector work?
27-6) What refrigerants can be detected with a halide torch?
27-7) What is the advantage of an ultrasonic leak detector?
27-8) How can dye indicate system leaks?
27-9) Why does increased purge operation indicate a leak in the low side of a low-
pressure system?
27-10) What method is recommended for raising the pressure of the refrigerant in a low-
pressure chiller?
27-11) What is the maximum safe pressure to impose on any low-pressure system?
27-12) A system in a 90°F room is charged to 100 psig with nitrogen to perform a
standing pressure test. When the system pressure is checked later, the room
temperature is 70°F. What pressure would you expect to see in the system?
27-13) How do leaking refrigerant systems cost their owners money?
27-14) What items should be included in a preliminary visual inspection when looking
for refrigerant leaks?
27-15) What leak detection method does the EPA consider the best for pinpointing leaks?
27-16) Compare older UV lights used for fluoresecent dye and newer flashlight models.
27-18) Besides a leak, what can make the vacuum rise on a standing vacuum test?
27-19) How do soap bubble solutions indicate very small refrigerant leaks?
27-20) Why should technicians never use oxygen to pressurize refrigeration systems
when leak testing?
