TYPE 3.9

Question 1

When leak testing a low-pressure centrifugal with nitrogen, what is the maximum test pressure?
A. 0 psig
B. 10 psig
C. 25 psig
D. 50 psig

Answer 1

B. 10 psig

Question 2

Charged low-pressure refrigeration machines may be most efficiently leak checked by;
A. adding dry nitrogen to increase the pressure.
B. adding refrigerant leak detection tracer dye.
C. adding heat with circulated hot water or heating blankets.
D. operating the purge system to see how much air comes out.

Answer 2

C. adding heat with circulated hot water or heating blankets.

Question 3

What should be done to reduce refrigerant loss from a purge unit on a R-123 chiller?
A. Leak test and repair the chiller.
B. Seal the purge unit discharge line.
C. Pipe purge unit back into the low side.
D. Pipe purge unit back into recovery unit.

Answer 3

C. Pipe purge unit back into the low side

Question 4

According to ASHRAE Guideline 3, the system should be checked for leaks if during a standard vacuum
test the pressure in a system rises from 1 mm Hg to a level above;
A. 1.5 mm Hg.
B. 2.0 mm Hg.
C. 2.5 mm Hg.
D. 3.0 mm Hg.

Answer 4

C. 2.5 mm Hg.

Question 5

A chiller with a charge of 200 pounds has passed the initial verification leak test. When must a followup
verification test be conducted?
A. The same day.
B. The next day.
C. Within 10 days.
D. Within 30 days.

Answer 5

D. Within 30 days.

Question 6

How long must owners and operators of low-pressure chillers using HCFC refrigerant keep records of
leak inspections, initial verification, and follow-up verification tests?
A. 2 years
B. 3 years
C. 5 years
D. Life of the appliance

Answer 6

B. 3 years

Question 7

What is the best method to determine a chiller’s normal charge for leak rate calculations?
A. Determine from the maximum power consumption.
B. Determine from the compressor horsepower.
C. Determine from the dimensions of the chiller barrels.
D. Use the charge stated on the equipment nameplate.

Answer 7

D. Use the charge stated on the equipment nameplate.

Question 8

A typical setting for the high pressure cut-out control on a recovery unit used for evacuating the
refrigerant from a low-pressure chiller is;
A. 2 psig.
B. 5 psig.
C. 10 psig.
D. 15 psig.

Answer 8

C. 10 psig.

Question 9

Refrigerant removal from a low-pressure system starts with;
A. vapor removal.
B. liquid removal.
C. vapor and liquid removal.
D. oil separation.

Answer 9

B. liquid removal.

Question 10

What must be done after recovering the liquid refrigerant from a low-pressure chiller?
A. Recover the vapor refrigerant.
B. Pressurize the system with nitrogen.
C. Separate the oil from the system.
D. Solvent flush the entire system.

Answer 10

A. Recover the vapor refrigerant.

Question 11

What is the result of raising the temperature of the room in which a low-pressure chiller is located?
A. Lower pressure in the chiller.
B. Faster refrigerant recovery.
C. Delayed recovery.
D. Reduced oil flow.

Answer 11

B. Faster refrigerant recovery.

Question 12

What is a typical advantage of a water cooled recovery unit?
A. Higher pressure at the recovery compressor’s discharge.
B. Higher pressure in the recovery tank.
C. Faster recovery of large quantities of refrigerant.
D. Greater percentage of refrigerant recovered.

Answer 12

C. Faster recovery of large quantities of refrigerant.

Question 13

Charging liquid R-245fa into a low-pressure refrigeration system under a vacuum greater than 18 inches
Hg vacuum can cause the;
A. liquid to absorb excess moisture.
B. purge unit to operate.
C. system water to freeze.
D. system water to boil.

Answer 13

C. system water to freeze.

Question 14

What should you do after reaching the required recovery vacuum on a low-pressure appliance?
A. Immediately disconnect the recycling or recovery equipment, and open the syster:n for service.
B. Wait for at least a few minutes to see if the system pressure rises before charging.
C. Break the vacuum with nitrogen and open the system for service to begin charging liquid.
D. Pressurize the system with nitrogen and perform a leak check.

Answer 14

B. Wait for at least a few minutes to see if the system pressure rises before charging.

Question 15

Which of the following actions would always be considered "major" under EPA's regulations?
A. Replacement of an evaporator coil
B. Replacement of a filter-drier
C. Replacement of a switch
D. Replacement of a purge unit

Answer 15

A. Replacement of an evaporator coil

Question 16

Which of the following statements is true of recycling and recovery equipment?
A. It must be tested by an AHARI-approved third party.
B. It must be equipped with low-loss ball valves and flare fittings.
C. It must be able to handle more than one refrigerant.
D. It must be labeled as certified to meet EPA’s requirements.

Answer 16

D. It must be labeled as certified to meet EPA’s requirements.

Question 17

How long must a technician evacuating refrigerant from appliances with a full charge of more than 5
pounds and less than 50 pounds that are being disposed of keep records of the event?
A. 1 year
B. 3 years
C. 5 years
D. 10 years

Answer 17

B. 3 years

Question 18

What evacuation level must technicians recover refrigerant to before disposing a low-pressure
appliance?
A. 0 psig
B. 15 inches of Hg vacuum
C. 25 inches of Hg vacuum
D. 25 mm of Hg absolute

Answer 18

D. 25 mm of Hg absolute

Question 19

Which of the following always falls under the EPA definition for "major maintenance, service, or repair?"
A. Replacing an oil filter
B. Replacing an expansion valve
C. Replacing a compressor
D. Replacing an accumulator

Answer 19

C. Replacing a compressor

Question 20

Where does the purge unit on a centrifugal system take its suction?
A. Top of the condenser
B. Compressor oil sump
C. Top of the evaporator
D. Suction elbow

Answer 20

A. Top of the condenser

Question 21

Why do chillers using low-pressure refrigerants require purge units?
A. These systems require the removal of contaminated refrigerant
B. These systems operate below atmospheric pressure.
C. Purge units remove refrigerant from the oil sump.
D. These systems require the removal of condensables from the chiller.

Answer 21

D. These systems require the removal of condensables from the chiller.

Question 22

What steps may be taken to prevent air accumulation into an idle low-pressure refrigeration system?
A. Leave the purge unit on-line at all times.
B. Maintain system pressure slightly above atmospheric pressure.
C. Open the air vents on the condenser.
D. Intermittently operate the system with no load.

Answer 22

B. Maintain system pressure slightly above atmospheric pressure

Question 23

Which of the following indicates air in a low-pressure system?
A. High head pressure
B. High liquid level
C. Low head pressure
D. Low suction pressure

Answer 23

A. High head pressure

Question 24

ASHRAE Standard 15-2013 requires the use of room sensors and alarms to detect;
A. refrigerant leaks.
B. high levels of ozone.
C. refrigerant contamination.
D. excessive oxygen level

Answer 24

A. refrigerant leaks.

Question 25

Which of the following safety precautions should be adhered to for low-pressure systems?
A. Use gloves and safety goggles when working with liquid refrigerant.
B. Reset the water freezestat after recharging.
C. Shut down the compressor before removing the gauge from the low side of the system.
D. Use a refrigerant leak detector before entering the mechanical room.

Answer 25

A. Use gloves and safety goggles when working with liquid refrigerant.