EPA 608 Practice Test

EPA 608 Type III: Low-Pressure Practice Questions

Type III: Low-Pressure makes up 9 of every 50 questions on a Tigertest EPA 608 practice test. Here are 10 of the 36 questions on it, each with the answer and the reason.

Updated 2026-11-10 by the Tigertest team. Based on 40 CFR Part 82 Subpart F and the EPA Section 608 test outline. Each real section is 25 questions, 18 to pass.

1. 1. Under EPA's Section 608 definitions, a low-pressure appliance uses a refrigerant with which property?

   • A.Critical temperature below normal indoor room temperature
   • B.Liquid saturation pressure below 45 psia at 104 F
   • C.Boiling point below minus 50 F at atmospheric pressure
   • D.Liquid saturation pressure above 170 psig at 104 F

   Answer: B. 40 CFR 82.152 defines a low-pressure appliance as one using a refrigerant with a liquid-phase saturation pressure below 45 psia at 104 F, such as R-11 or R-123.

2. 2. Which group lists only refrigerants used in low-pressure appliances?

   • A.R-404A, R-507A, R-407C, and R-448A
   • B.R-22, R-410A, and R-134a
   • C.R-12, R-500, and R-502
   • D.R-11, R-123, and R-1233zd(E)

   Answer: D. R-11, R-113, R-123, R-1233zd(E), and R-514A all boil above room temperature at atmospheric pressure, so they are low-pressure refrigerants used mainly in centrifugal chillers.

3. 3. At atmospheric pressure, low-pressure refrigerants such as R-123 have a boiling point above approximately what temperature?

   • A.50 F
   • B.Minus 40 F
   • C.Minus 15 F
   • D.0 F

   Answer: A. Low-pressure refrigerants boil above about 50 F at atmospheric pressure; R-123 boils near 82 F and R-11 near 75 F, so they are liquids at room temperature.

4. 4. What type of equipment most commonly uses low-pressure refrigerants like R-123 or R-514A?

   • A.Supermarket reach-in display cases
   • B.Household refrigerators and freezers
   • C.Centrifugal chillers
   • D.Window and through-the-wall air conditioners

   Answer: C. Low-pressure refrigerants are used mainly in large centrifugal chillers for comfort cooling in commercial buildings.

5. 5. A technician explains why an operating R-123 chiller loses performance over time. Because the low side runs in a vacuum, what usually happens at a leak?

   • A.Oil is forced out through the relief valve
   • B.The rupture disc opens again and again
   • C.Air and moisture get drawn in
   • D.Refrigerant sprays out at high velocity

   Answer: C. The evaporator of a low-pressure chiller operates below atmospheric pressure, so leaks pull air and moisture in rather than pushing refrigerant out.

6. 6. From which part of a low-pressure chiller does the purge unit draw noncondensable gases?

   • A.The top of the condenser
   • B.The liquid line ahead of the metering device
   • C.The bottom of the evaporator shell
   • D.The compressor oil sump and reservoir

   Answer: A. Noncondensables such as air collect at the top of the condenser, so the purge unit takes its suction from that point.

7. 7. What is the main job of the purge unit on a low-pressure chiller?

   • A.Pull the chiller into a deep vacuum
   • B.Recover the full charge before major repairs
   • C.Return lubricating oil to the compressor sump
   • D.Remove air and moisture from the refrigerant

   Answer: D. The purge unit separates noncondensables and moisture from refrigerant and returns the refrigerant to the system; high-efficiency purge units keep refrigerant loss very low.

8. 8. A building engineer notices the purge unit on an R-11 chiller is running far more often than it used to. What does this most likely indicate?

   • A.The refrigerant charge is too high
   • B.Air is leaking into the chiller
   • C.The condenser water is too cold
   • D.The compressor oil needs to be changed

   Answer: B. Excessive purge operation means noncondensables are entering the system, which in a low-pressure chiller points to a leak that should be found and repaired.

9. 9. A technician needs to leak test an idle R-123 chiller sitting at a slight vacuum. Which method safely raises its pressure for testing?

   • A.Pressurize the shell with oxygen to 25 psig
   • B.Circulate warm water through the tubes
   • C.Run the purge unit with its valves reversed
   • D.Add compressed air through the purge unit

   Answer: B. Controlled hot water in the tubes or heating blankets raise the refrigerant's pressure for leak checking; dry nitrogen may also be used, but never air or oxygen.

10. 10. A service crew is pressurizing a low-pressure chiller with dry nitrogen to look for leaks. What pressure must they not exceed?

    • A.15 psig
    • B.25 psig
    • C.150 psig
    • D.10 psig

    Answer: D. Low-pressure chillers should not be pressurized above 10 psig for leak testing, keeping a margin below the 15 psig rupture disc on the evaporator.