Low-pressure chillers: EPA 608 Practice Questions

Question 1

Under Section 608, a low-pressure appliance uses a refrigerant with a saturation pressure at 104°F of what?

Accepted Answer

Below 45 psia

Answer

Between 170 and 355 psia

Answer

Above 355 psia

Answer

Between 45 and 170 psia

Question 2

Which refrigerant is commonly used in low-pressure centrifugal chillers?

Accepted Answer

R-123

Answer

R-404A

Answer

R-134a

Answer

R-410A

Question 3

Which low-GWP refrigerants are used in new low-pressure chillers in place of R-123?

Accepted Answer

R-1233zd(E) and R-514A

Answer

R-404A and R-507A

Answer

R-290 and R-600a

Answer

R-32 and R-454B

Question 4

In a low-pressure chiller, what pressure does the evaporator normally operate at?

Accepted Answer

Below atmospheric pressure (in a vacuum)

Answer

Around 100 psig

Answer

Exactly 0 psig

Answer

Higher than the condenser pressure

Question 5

Because much of a low-pressure chiller runs below atmospheric pressure, what usually happens at a leak?

Accepted Answer

Air and moisture are drawn into the chiller

Answer

Nothing enters or leaves, because the shell is under a vacuum seal

Answer

Refrigerant sprays out at high pressure

Answer

Oil is pushed out of the compressor

Question 6

What type of compressor do most low-pressure chillers use?

Accepted Answer

Centrifugal

Answer

Rotary vane

Answer

Scroll

Answer

Reciprocating

Question 7

R-123 is an HCFC. What is the status of its production in the United States?

Accepted Answer

Servicing only, until 2030

Answer

Banned since 1996

Answer

Unlimited, with no phaseout date

Answer

Allowed only in new chillers built after 2020 that have high-efficiency purges

Question 8

What are the ASHRAE 34 safety classes of R-1233zd(E) and R-514A?

Accepted Answer

A1 and B1

Answer

B2L and A3

Answer

A3 and A1

Answer

A2L and A2L

Question 9

At what pressure does the rupture disc on a typical low-pressure chiller evaporator relieve?

Accepted Answer

15 psig

Answer

20 psig

Answer

50 psig

Answer

5 psig

Question 10

Which appliances does Type III certification cover?

Accepted Answer

Low-pressure appliances

Answer

Motor vehicle air conditioners

Answer

Small appliances

Answer

High-pressure appliances

Question 11

Where do air and other non-condensables collect in an operating low-pressure chiller?

Accepted Answer

At the top of the condenser

Answer

At the bottom of the evaporator

Answer

In the compressor oil sump

Answer

In the chilled-water tubes

Question 12

Moisture shows up in the refrigerant of a low-pressure chiller. What is one likely source besides an air leak?

Accepted Answer

A leaking water tube in a heat exchanger

Answer

Too much compressor oil, which releases water as it breaks down

Answer

A dirty cooling tower fan

Answer

An overcharge of refrigerant

Low-pressure chillers: EPA 608 Practice Questions

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