RAC 40 quiz 8 review Questions Exam
Questions And Answers Solved 100%
Correct
After repairing a System that has had an electrical motor failure (compressor burnout) it
is good field practice to re-use the recovered refrigerant in that system - Answers -✔✔
False
Air entering a refrigerant system can eventually lead to compressor failure - Answers -
✔✔ True
The maximum recommended pressure for leak testing is 150 PSIG on the low pressure
side of the system - Answers -✔✔ True
While under a deep vacuum any liquid water under the oil in the motor compressor
assembly can be removed by operating the compressor motor for several seconds
without any adverse effect on the system - Answers -✔✔ False
Clearance tolerance are such that the ordinary clean refrigerant oil can be used
satisfactorily in a vacuum pump - Answers -✔✔ False
The oil in a vacuum pump should be changed after each time it is used - Answers -✔✔
True
When using a standing pressure test for leak checking _________________ should
never be used since an explosive mixture can be created - Answers -✔✔ Oxygen
Only two substances should be in the refrigeration system for proper operation they are
______________ and oil - Answers -✔✔ Refrigerant
____________ Microns is equal to 1mm Hg. - Answers -✔✔ 1000
The electronic vacuum gauge is attached to the system so it can measure the
pressure__________ the system - Answers -✔✔ inside
A deep vacuum involves reducing the pressure in a refrigeration system to a micron
gauge reading of ____________ or below - Answers -✔✔ 250
There are ___________ microns in 1 mm Hg. - Answers -✔✔ 1000
, Sludge is produced when moisture acid and ______________ are present in the system
- Answers -✔✔ oil
A(n) ___________ pressure could also mean refrigerant vapor is still seeping from the
refrigeration system - Answers -✔✔ increase
Explain why triple evacuations are not normally preformed on large systems - Answers -
✔✔ It takes a long time to evacuate a large system so to do multiple evacuations it will
take too long. Plus you would need a lot of nitrogen to purge into the system in between
evacuations.
A pressure of 100 microns has been reached with the vacuum pump operating. the
pump is turned off and the gage reading rises to 5000 microns and stays there. what
does this indicate? - Answers -✔✔ This indicates that a lot of refrigerant and moisture in
the system is still being boiled off but your system is tight
a pressure of 100 microns has been reached with the vacuum pump operating. the
pump is turned off and the gage reading rises to 500 microns and stays there. what
does this indicate? - Answers -✔✔ This indicates that there is still a little moisture in the
system being boiled off. other than that your system is tight and leak free
why is refrigerant not used for a system standing pressure test - Answers -✔✔
Refrigerant is bad for the ozone layer so it is much safer to use nitrogen because if
there is a leak, it would leak nitrogen instead of refrigerant
why is nitrogen considered a non-condencable gas - Answers -✔✔ Because it does not
have moisture and does not condense. (dry-gas)
a pressure of 100 microns has been reached with the vacuum pump operating. the
pump is turned off and the gage reading rises to 5000 microns and keeps rising what
does this indicate? - Answers -✔✔ This indicates that there is a leak in the system
why must all valves must be open when an evacuation is performed - Answers -✔✔ So
there aren't no restrictions in the system and all the moisture can be evacuated
smoothly.
why is it a good idea to removed Schrader stems from service valves prior to
evacuation? - Answers -✔✔ Shraders cause a big restriction when even accurate
reading so to remove a Schrader using a valve core removal tool will speed up the
process
a micron gage is used to measure_________ - Answers -✔✔ B. Absolute pressure
below 1 mm Hg
Questions And Answers Solved 100%
Correct
After repairing a System that has had an electrical motor failure (compressor burnout) it
is good field practice to re-use the recovered refrigerant in that system - Answers -✔✔
False
Air entering a refrigerant system can eventually lead to compressor failure - Answers -
✔✔ True
The maximum recommended pressure for leak testing is 150 PSIG on the low pressure
side of the system - Answers -✔✔ True
While under a deep vacuum any liquid water under the oil in the motor compressor
assembly can be removed by operating the compressor motor for several seconds
without any adverse effect on the system - Answers -✔✔ False
Clearance tolerance are such that the ordinary clean refrigerant oil can be used
satisfactorily in a vacuum pump - Answers -✔✔ False
The oil in a vacuum pump should be changed after each time it is used - Answers -✔✔
True
When using a standing pressure test for leak checking _________________ should
never be used since an explosive mixture can be created - Answers -✔✔ Oxygen
Only two substances should be in the refrigeration system for proper operation they are
______________ and oil - Answers -✔✔ Refrigerant
____________ Microns is equal to 1mm Hg. - Answers -✔✔ 1000
The electronic vacuum gauge is attached to the system so it can measure the
pressure__________ the system - Answers -✔✔ inside
A deep vacuum involves reducing the pressure in a refrigeration system to a micron
gauge reading of ____________ or below - Answers -✔✔ 250
There are ___________ microns in 1 mm Hg. - Answers -✔✔ 1000
, Sludge is produced when moisture acid and ______________ are present in the system
- Answers -✔✔ oil
A(n) ___________ pressure could also mean refrigerant vapor is still seeping from the
refrigeration system - Answers -✔✔ increase
Explain why triple evacuations are not normally preformed on large systems - Answers -
✔✔ It takes a long time to evacuate a large system so to do multiple evacuations it will
take too long. Plus you would need a lot of nitrogen to purge into the system in between
evacuations.
A pressure of 100 microns has been reached with the vacuum pump operating. the
pump is turned off and the gage reading rises to 5000 microns and stays there. what
does this indicate? - Answers -✔✔ This indicates that a lot of refrigerant and moisture in
the system is still being boiled off but your system is tight
a pressure of 100 microns has been reached with the vacuum pump operating. the
pump is turned off and the gage reading rises to 500 microns and stays there. what
does this indicate? - Answers -✔✔ This indicates that there is still a little moisture in the
system being boiled off. other than that your system is tight and leak free
why is refrigerant not used for a system standing pressure test - Answers -✔✔
Refrigerant is bad for the ozone layer so it is much safer to use nitrogen because if
there is a leak, it would leak nitrogen instead of refrigerant
why is nitrogen considered a non-condencable gas - Answers -✔✔ Because it does not
have moisture and does not condense. (dry-gas)
a pressure of 100 microns has been reached with the vacuum pump operating. the
pump is turned off and the gage reading rises to 5000 microns and keeps rising what
does this indicate? - Answers -✔✔ This indicates that there is a leak in the system
why must all valves must be open when an evacuation is performed - Answers -✔✔ So
there aren't no restrictions in the system and all the moisture can be evacuated
smoothly.
why is it a good idea to removed Schrader stems from service valves prior to
evacuation? - Answers -✔✔ Shraders cause a big restriction when even accurate
reading so to remove a Schrader using a valve core removal tool will speed up the
process
a micron gage is used to measure_________ - Answers -✔✔ B. Absolute pressure
below 1 mm Hg
