Type 3 prep

Question 1

What must a technician be certified in to maintain, service, repair, or dispose of low-pressure appliances?

Answer 1

Type 3 or Universal EPA certification.

Question 2

What are most low-pressure appliances subject to?

Answer 2

A lower allowable leak rate.

Question 3

Why will leaks in gaskets or fittings cause air and moisture to enter the sytem?

Answer 3

Low pressure systems operate in a vacuum.

Question 4

What do low pressure chillers that operate in a vacuum require?

Answer 4

Purge units.

Question 5

what is the purpose of a purge unit?

Answer 5

To remove non-condensables that leak into the system.

Question 6

What generally indicates a leaking system?

Answer 6

Excessive running of a purge system.

Question 7

What two things does high head pressure in a low-pressure system indicate?

Answer 7

Air in the system and the purge unit may not be operating properly.

Question 8

What type of purge units discharge a low percentage of refrigerant with the air they remove?

Answer 8

High-efficiency purge units.

Question 9

What is used to determine if a tube is leaky ?

Answer 9

Hydrostatic tube test kit.

Question 10

What can cause the rupture disc to fail when pressure testing a low-pressure refrigeration system with nitrogen?

Answer 10

Pressures greater than 10 psig.

Question 11

Where could the leak be in a low-pressure refrigeration system if excessive moisture continuously collects in the purge unit?

Answer 11

In the condenser or the chiller barrel tubes.

Question 12

How do you prevent air from accumulating into an idled low-pressure system?

Answer 12

Maintain system pressure slightly above atmospheric pressure.

Question 13

How do you check for a refrigerant leak to the water side of a chiller?

Answer 13

Place a leak detector probe in the drain valve opening of the water box with the water removed.

Question 14

What must you do prior to recovering refrigerant from a chiller suspected of having tube leaks?

Answer 14

Drain the water sides of the evaporator and condenser.

Question 15

What should be done if the pressure in a system rises from 1mm Hg to 2.5mm Hg during a standard vacuum test?

Answer 15

The system should be checked for leaks.

Question 16

What 3 things can the owner do when an appliance using regulated refrigerant exceeds the threshold leak rate?

Answer 16

Repair appliance to below the leak rate threshold, retrofit, or retire the appliance.

Question 17

What EPA leak repair category do chillers generally belong to?

Answer 17

Comfort cooling.

Question 18

What category would a chiller that diverts 55% of its cooling to manufacturing and 45% to cooling its office space be in?

Answer 18

Industrial process refrigeration leak rate category.

Question 19

How can you find a chiller’s normal charge for leak rate calcualtions?

Answer 19

The charge is stated on the equipment nameplate.

Question 20

When must the leak rate of an appliance using regulated refrigerant be calculated?

Answer 20

When topping off or recharging a system due to a loss of charge.

Question 21

How much time does an owner or operator have to retrofit or retire an appliance with 50 or more pounds of refrigerant that has exceeded the threshold leak rate?

Answer 21

18 months.

Question 22

What can not be used as an excuse to extend the appliance leak repair deadline?

Answer 22

Failure to have a certified service technician available.

Question 23

What does not require removing the appliance and storing it in a warehouse at the facility?

Answer 23

System mothballing.

Question 24

How much time does an owner or operator have to repair an appliance with 50 or more pounds of refrigerant so that it leaks below the threshold?

Answer 24

30 days.

Question 25

When must a follow up verification test be conducted within 10 days?

Answer 25

When a chiller with a charge of 200 pounds or more of ozone-depleting refrigerant has passed the initial verification leak test.

Question 26

What records is the owner or operator responsible for keeping?

Answer 26

All leak inspections, initial verification, and any completed leak repair follow-up verification tests for 3 years.

Question 27

What is the high-pressure cut out on a recovery unit used for low-pressure chillers?

Answer 27

Typically 10 psig.

Question 28

Why must you first remove the liquid refrigerant before the vapor refrigerant in a large low-pressure system?

Answer 28

Because of the high volume of liquid refrigerant.

Question 29

How much vapor refrigerant will an average 350-ton, R-123 chiller, at 0 psig have after all the liquid refrigerant has been removed?

Answer 29

Approximately 100 pounds.

Question 30

Why may it be necessary to break the vacuum using nitrogen during an evacuation of a system containing large amounts of moisture?

Answer 30

Increasing the pressure with nitrogen prevents the moisture from freezing and increases the speed of dehydration.

Question 31

What allows for faster recovery of large quantities of refrigerant?

Answer 31

A water-cooled recovery unit.

Question 32

What should be on during vapor or liquid removal from a low-pressure refrigeration system?

Answer 32

System's water pumps, recovery compressor, and recovery condenser water.

Question 33

What will also help achieve a faster refrigerant recovery?

Answer 33

Raising the temperature of the system or the room the chiller is located.

Question 34

Why should refrigerant oil be heated to 130F when being removed?

Answer 34

Less refrigerant will be contained in the oil at the higher temperature.

Question 35

What relieves at 15 psig for low-pressure refrigerants?

Answer 35

The rupture disc on a recovery vessel.

Question 36

What must recovery and recycling equipment be labeled as?

Answer 36

Certified to meet EPA's requirements.

Question 37

What kind of repairs allow you to warm the system's liquid refrigerant with hot water or warming blankets to bring it out of a vacuum?

Answer 37

When performing non-major repairs.

Question 38

What must be done before disposing of a low-pressure appliance?

Answer 38

The refrigerant must be recovered or evacuated to 25mm of Hg absolute.

Question 39

When must an oil sample be taken if the unit has had a compressor burn-out?

Answer 39

Before recovery/evacuation or dehydration.

Question 40

What should you do when evacuating/dehydrating a system that contains a large amount of moisture to break the vacuum?

Answer 40

Triple evacuate/dehydrate using dry-nitrogen.

Question 41

How is refrigerant vapor re-introduced into the chiller to prevent freezing the water in the heat exchanger tube bundle?

Answer 41

It is charged to a pressure which corresponds to its saturation temperature above freezing.

Question 42

What is the lowest access point on a low-pressure appliance?

Answer 42

The evaporator charging valve.

Question 43

How is absolute pressure (psia) converted to guage pressure (psig)?

Answer 43

Subract 14.7 from the absolute pressure (psia). ie 14.7 psia equals 0 psig.

Question 44

When does ASHRAE Standard 15-2013 require that each machinery room activate an alarm and a mechanical ventilation system?

Answer 44

When the TLV-TWA (Threshold Limit Value - Time Weighted Average) is exceeded.

Question 45

Why is the use of room sensors and alarms to detect refrigerant leaks of all refrigerant types required?

Answer 45

Not only because of refrigerant flammability and toxicity levels but because refrigerants are heavier than air and can displace oxygen.

Question 46

What should be worn when working with liquid refrigerant for low-pressure systems?

Answer 46

Gloves and safety goggles.

Question 47

What should be piped outdoors to prevent venting into the machine room?

Answer 47

The discharge from a rupture disc or pressure relief valves.

Question 48

How should all pressure relief valves be piped or installed?

Answer 48

In parallel, never in series.

Question 49

What is located on the evaporator of centrifugal chiller?

Answer 49

A 15 psig rated rupture disc.

Question 50

What do you use to remove ice from sight glasses?

Answer 50

Isopropyl alcohol.