Leak Detection, Evacuation and Charging

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Congratulations - you have completed Leak Detection, Evacuation and Charging.

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Question 1

Sniffer-type leak detectors have a(n) _____ that requires periodic maintenance.

A	headset
B	air filter
C	CO2 sensor
D	refrigerant reservoir

Question 2

When charging a system that uses a zeotrope refrigerant, the system should be charged using _____.

A	vapor refrigerant fed to the high side of the system
B	liquid refrigerant partially converted to vapor
C	liquid refrigerant
D	dry nitrogen

Question 3

To test for leaks using the electronic detector, the probe should be moved at a rate of about _____ per second.

A	3"
B	1"
C	2"
D	1/4"

Question 4

After a leak in a system using a zeotrope refrigerant is repaired and the system has been evacuated, the system should be charged with _____.

A	new refrigerant
B	recovered refrigerant
C	dry nitrogen
D	a blend of recovered and new refrigerant

Question 5

When pressurizing a system for leak testing, always charge with _____ first and remove the cylinder before charging with _____.

A	HCFC-22 refrigerant; dry nitrogen
B	HCFC-22 refrigerant; oxygen
C	dry nitrogen; HCFC-22 refrigerant
D	carbon dioxide; HFC-134a refrigerant

Question 6

When charging a system using pressure charts, if the measured discharge pressure is higher than the required discharge pressure, you should _____ the system.

A	add dry nitrogen to
B	remove excess refrigerant from
C	make no adjustment to
D	add refrigerant vapor to

Question 7

When pressurizing a system for leak testing, the safe maximum test pressure is approximately _____ psig.

A	25
B	10
C	125
D	150

Question 8

If a filter-drier is added, or if a long line set is used, the refrigerant charge must be _____.

A	decreased
B	transferred
C	increased
D	reclaimed

Question 9

When a system with a partial charge has insufficient pressure to support a leak test, _____.

A	the partial charge must be recovered, then the system is pressurized with an approved mixture of refrigerant and dry nitrogen
B	add dry nitrogen to the existing charge in the system to bring the test pressure up to 100-125 psig
C	vacuum leak-test the system
D	D) add refrigerant to the existing charge in the system to bring the test pressure up to 100-125 psig

Question 10

When moisture and acid are present in a system, the system must be _____.

A	steam cleaned
B	flushed
C	evacuated
D	destroyed

Question 11

Refrigerant that has been removed from a system and temporarily stored in approved containers is defined by the EPA as _____ refrigerant.

A	reclaimed
B	recycled
C	recovered
D	contaminated

Question 12

When charging a system that uses a zeotrope refrigerant, you should _____.

A	top off an existing charge if there was only a small leak
B	charge using liquid refrigerant
C	heat the refrigerant cylinder
D	charge using vapor refrigerant

Question 13

Refrigerant that has been remanufactured to bring it up to the standards required for new refrigerant is defined by the EPA as _____ refrigerant.

A	recycled
B	recovered
C	reclaimed
D	purified

Question 14

The best charging method used to charge an empty system is _____.

A	charging by superheat
B	liquid charging by weight
C	vapor charging by weight
D	charging by subcooling

Question 15

When a recovery unit is used to process a different refrigerant than was last processed, the recovery unit _____.

A	should be flushed with water
B	can be used without the need for maintenance
C	should be leak-tested
D	compressor oil should be drained and replaced with new oil

Question 16

Charging by superheat is performed on systems that use a _____.

A	fixed-orifice metering device
B	thermostatic expansion valve-type metering device
C	thermal-electric expansion valve
D	sight glass

Question 17

Moisture in a system reacts with refrigerant to form _____.

A	an azeotrope
B	nitrogen
C	hydrochloric and hydrofluoric acids
D	a noncondensible contaminant

Question 18

Charging a system by weight is performed when _____.

A	a complete charge is needed
B	the system uses a thermostatic expansion valve-type metering device
C	adjusting the charge in an operating system
D	the system uses a fixed-orifice metering device

Question 19

The oil in a vacuum pump should be changed _____.

A	about every five hours of pump operation
B	about every 15 hours of pump operation
C	immediately after pumping down a wet or contaminated system
D	before being used to evacuate a system that uses a different refrigerant than was last processed

Question 20

If a system uses a line set that exceeds the standard length, the refrigerant charge for the system must be _____.

A	transferred
B	decreased
C	reclaimed
D	increased

Question 21

Evacuating a system using a vacuum pump lowers the system pressure so moisture can _____.

A	condense
B	be drained
C	form
D	boil off or vaporize

Question 22

When vacuum leak testing a system, the vacuum gauge shows a pressure rise, but levels off between 1,000 and 2,000 microns. This indicates a _____.

A	leak-tight and dry system
B	leak-tight, but wet system
C	medium to large leak in the system
D	miniscule leak in the system

Question 23

A vacuum pump with a capacity of 6 cfm to 12 cfm should be adequate to evacuate systems with capacities up to _____ tons.

A	70
B	50
C	10
D	30

Question 24

The triple evacuation method requires that the system be evacuated three times to a level of about _____ microns.

A	50,000
B	2,000
C	500
D	1,000

Question 25

A reading of _____ microns displayed on a vacuum gauge is closest to a perfect vacuum.

A	500
B	1,300
C	50
D	25,000

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Leak Detection, Evacuation and Charging

Leak Detection, Evacuation and Charging

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