EPA III Flash

Question 1

When leak testing a low pressure refrigeration system with nitrogen, what is the maximum test pressure?

Answer 1

10 psig

Question 2

Continuous excessive moisture collection in the purge unit of a low pressure refrigeration system could indicate what condition?

Answer 2

The condenser or chiller barrel tubes are leaking

Question 3

Leak testing a low pressure refrigeration system with nitrogen in excess of 10 psig could cause which of the following to fail?

Answer 3

Rupture disc, set at 15 psig

Question 4

What is meant by the term “high efficiency purge unit?”

Answer 4

Purge units which discharge a low percentage of refrigerant with the air which they remove

Question 5

Where is the lowest access point on a low pressure centrifugal AC appliance?

Answer 5

Evaporator charging valve

Question 6

After system servicing, why is refrigerant vapor re-introduced to the refrigeration system before refrigerant liquid?

Answer 6

Liquid charged into a deep vacuum will boil and may lower temps enough to freeze water in the tubes

Question 7

When using recovery and recycling equipment manufactured AFTER 11/15/93, techs must evacuate low-pressure appliances to the following level before disposing of the appliance:

Answer 7

25mm Hg absolute

Question 8

Appliances need not be evacuated all the way to the prescribed level when:

Answer 8

Leaks in the appliance make evacuation to the prescribed level unattainable

Question 9

When using recovery and recycling equipment manufactured BEFORE 11/15/93, techs must evacuate low-pressure appliances to the following level before making a major repair:

Answer 9

25 inches Hg vacuum

Question 10

What repairs are ALWAYS considered “major” under EPA?

Answer 10

Replacement of compressor, condenser, evaporator, or auxillary heat transer coils

Question 11

Under EPA’s regulations, which of the following methods can be used to pressurize a CFC-11 or HCFC-123 system for the purpose of opening the system for a non-major repair?

Answer 11

Warming the refrigerant (controlled hot water, thermal wraps)

Question 12

When recharging a refrigeation system with CFC-11, what vapor pressure is necessary in the shells before charging with liquid?

Answer 12

16.9” Hg vacuum, increase temp over 36 degrees F

Question 13

During vapor removal from a low pressure refrigeration system what systems should be on?

Answer 13

The system water pumps, the recovery compressor, and the recovery condenser water should all be on

Question 14

According to ASHRAE Guideline 3-1996, if the pressure in a system rises from 1mm Hg to a level above ________ during a standing vacuum test, the system should be check for leaks

Answer 14

2.5mm Hg absolute

Question 15

CFC-11 or HCFC-123 system refrigerant removal starts with:

Answer 15

Liquid Removal

Question 16

A rupture disc on a recovery vessel for low pressure refrigerants relieves at:

Answer 16

15 psig

Question 17

What is the primary water source for a recovery unit condensing coil?

Answer 17

Local municipal water supply

Question 18

When removing oil from a low pressure system, the temp should be 130 degrees F because:

Answer 18

Less refrigerant will be contained in the oil at the higher temp

Question 19

Identify the pressure corresponding to 32 degrees F for HCFC-123:

Answer 19

20 inches of Hg vacuum

Question 20

When evacuating a system, the use of a large vacuum pump could:

Answer 20

cause trapped water to freeze

Question 21

The PRIMARY purpose of a purge unit on a CFC-11 chiller is to:

Answer 21

Remove non-condensibles from the system

Question 22

Where does refrigerant go after it leaves the purge unit of a low pressure centrifugal system?

Answer 22

The evaporator

Question 23

Refrigerant is added to a centrifugal machine through the:

Answer 23

Evaporator charging valve

Question 24

Which of the following safety precautions should be adhered to for low pressure systems?

Answer 24

Do not syphon refrig by mouth, avoid spilling refrig on skin, use gloves and goggles

Question 25

ASHRAE Standard 15-1994 requires that each machinery room shall activate an alarm and mechanical ventilation before refrigerant concentrations exceed:

Answer 25

The TLV-TWA (threshold Limit Value - Time Weighted Average)

Question 26

What can charging liquid into a low-pressure system under 29” Hg cause?

Answer 26

System water freezing.

Question 27

For low-pressure units which will be idle for some time, what should be done to prevent air from entering the system?

Answer 27

Maintain a pressure slightly above atmospheric.

Question 28

If a high capacity vacuum pump causes trapped water in the system to freeze, you must increase the system pressure to allow the ice to melt. What is the only substance that can be used to increase the pressure?

Answer 28

Dry Nitrogen.

Question 29

What is the most common B1 rated refrigerant in Type III systems?

Answer 29

HCFC-123.