Type III evacuation & charging: EPA 608 Practice Questions

Question 1

When charging an evacuated low-pressure chiller, why is vapor added before liquid?

Accepted Answer

Liquid would boil at a very low temperature and could freeze the tubes

Answer

Vapor fills the oil sump first

Answer

Liquid damages the purge unit if it is added while the purge is running

Answer

Vapor is cheaper

Question 2

During charging of a low-pressure chiller, what should the water in the evaporator and condenser tubes be doing?

Accepted Answer

Circulating

Answer

Frozen

Answer

Heated above 150°F

Answer

Drained and left empty with the system running

Question 3

Why should water be circulated through the tubes while a low-pressure chiller is evacuated?

Accepted Answer

To keep the tubes from freezing

Answer

It removes oil from the shell

Answer

It raises the rupture disc rating

Answer

It cools the vacuum pump, which shares the chiller's condenser water

Question 4

Moisture in an R-123 chiller can combine with the refrigerant and oil to form what?

Accepted Answer

Acids

Answer

A protective oil film

Answer

Ice crystals that clean the tubes

Answer

Additional refrigerant

Question 5

Where is liquid refrigerant normally charged into a low-pressure chiller?

Accepted Answer

Through the evaporator charging valve

Answer

Through the rupture disc fitting

Answer

Into the compressor suction line while it runs

Answer

Through the purge unit's drain connection

Question 6

Before a major repair, to what level is a low-pressure chiller evacuated using recovery equipment?

Accepted Answer

25 mm Hg absolute

Answer

25 in Hg vacuum

Answer

0 psig at the evaporator

Answer

4 in Hg vacuum at the recovery unit

Question 7

After a major repair, a low-pressure chiller is evacuated with a vacuum pump before charging. What is the purpose?

Accepted Answer

To remove air and moisture that entered while it was open

Answer

To raise the condenser pressure

Answer

To test the rupture disc

Answer

To recover the old refrigerant that is left in the chiller after the repair

Question 8

Recovered R-123 from a chiller is to be charged into a chiller owned by a different company. What must happen first?

Accepted Answer

Reclamation

Answer

It must be stored for 30 days so any moisture can settle out

Answer

It must be filtered once

Answer

Nothing, R-123 is an HCFC

Question 9

A technician starts charging liquid R-123 into a chiller that is still at 28 in Hg vacuum. What is the main risk?

Accepted Answer

Freezing and rupturing the water tubes

Answer

Contaminating the oil with air

Answer

Overheating the compressor motor if the chiller starts during charging

Answer

Overpressurizing the rupture disc and releasing the charge

Question 10

After evacuating a low-pressure chiller, the vacuum reading rises and then levels off. What is the likely cause?

Accepted Answer

Moisture still evaporating inside

Answer

A perfectly dry system

Answer

A failed rupture disc that is leaking air in

Answer

A leak to the atmosphere at the purge unit connection

Question 11

Why is it important to weigh or measure the refrigerant charged into a low-pressure chiller?

Accepted Answer

To match the full charge and support leak-rate records

Answer

To meet the DOT shipping rules for recovery cylinders being returned

Answer

To program the purge unit timer and the oil heater cycle

Answer

To raise the rupture disc rating

Question 12

When charging a low-pressure chiller, vapor is added until the pressure reaches what point before liquid is added?

Accepted Answer

The saturation pressure for 32°F

Answer

15 psig, the rupture disc setting

Answer

10 psig, the maximum leak-test pressure

Answer

0 psig, so air cannot enter the shell

Type III evacuation & charging: EPA 608 Practice Questions

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