EPA 608 Type III (Low-Pressure) — practice test

EPA's test topics: Type III · Low-pressure appliances

EPA publishes the topics each Section 608 certification test covers. This is EPA's list for Type III · Low-pressure appliances, in EPA's words: its 7 areas and 27 topics. Every one of our 173 E608T3 questions ends with the regulation section or practice it rests on.

The real test, per 40 CFR 82 Subpart F, Appendix D: 25 questions from this part alongside the 25 Core questions; 70 percent passes; closed book.

From EPA's Section 608 test topics, read October 20, 2026. All four 608 topic lists, and the test format in the regulation's words →

High-yield EPA 608 Type III (Low-Pressure) topics

The material that shows up year after year. If you're short on time, start here.

• Before a low-pressure appliance is opened or disposed of, it is evacuated to 25 mm Hg absolute with certified recovery equipment. The one shortcut is a non-major repair with no evacuation to the atmosphere afterward, which only needs pressurizing to no higher than 0 psig. Table 1 has a single row for low-pressure appliances; the 200-pound split applies only to high- and medium-pressure appliances.
• A repair is major if you remove the compressor, condenser, evaporator or auxiliary heat exchange coil. It is also major if you uncover an opening of more than 4 square inches of flow area for more than 15 minutes. Major repairs do not get the 0 psig shortcut, so they need the full 25 mm Hg evacuation.
• For a non-major repair with no evacuation to the atmosphere afterward, a low-pressure chiller is pressurized to no higher than 0 psig before it is opened. Cover the openings when you cannot isolate the part. Refrigerants that boil at or below 85 degrees F at standard atmospheric pressure must not be pressurized with nitrogen, since that needs purging afterward.
• If the refrigerant boils above 85 degrees F at standard atmospheric pressure, use heat first to raise the pressure as far as it will go. Controlled hot water or a built-in heating device like a Prevac is the preferred heat, and nitrogen may then finish the climb to atmospheric pressure. Nitrogen is the fallback, never the first choice.
• These leak rules cover appliances with a full charge of 50 pounds or more of an ozone-depleting refrigerant such as R-123 (HFC appliances fall under 40 CFR 84.106, at 15 pounds). The allowed annual leak rate is 10 percent for comfort cooling and other appliances, 20 percent for commercial refrigeration and 30 percent for industrial process refrigeration, so a chiller cooling a building is held to 10 percent. Over the rate, you repair within 30 days of adding refrigerant (120 days for industrial process if a shutdown is needed), or you retrofit or retire.
• An appliance with 50 pounds or more that leaks 125 percent or more of its full charge in a calendar year is a chronic leaker. The report goes to EPA by March 1 of the next year and describes the efforts to find the leaks and repair the appliance. A 400-pound chiller that took 520 pounds in a year is at 130 percent, and you keep a copy of the report and any EPA response.

Where techs lose points on EPA 608 Type III (Low-Pressure)

Good technicians miss these — not from lack of skill, but because the question is built to catch them.

• Trap: a leak in a chiller lets refrigerant out. Because parts of it run below atmospheric pressure, a leak usually draws air and moisture in. The signs are a purge unit running more than normal and high condenser pressure.
• Trap: liquid goes in first because it is faster. On an evacuated chiller, add vapor first until the pressure is high enough that the refrigerant will not freeze the water in the tubes, and charge through the evaporator charging valve. Liquid into a deep vacuum can freeze and rupture tubes.
• Trap: once the liquid is out, recovery is done. You still recover the vapor down to the required level, 25 mm Hg absolute for a low-pressure appliance. Then wait a few minutes, and if the pressure creeps back up there is still liquid refrigerant in the system or in the oil, so keep recovering.
• Trap: the evacuation level depends on charge size and equipment age. For low-pressure appliances it does not: Table 1 gives 25 mm Hg absolute whether the recovery equipment was made before or after November 15, 1993. Only two things change it: a non-major repair with no evacuation to the atmosphere afterward (pressurize to no higher than 0 psig), and a leaking component that cannot reach 25 mm Hg (lowest level you can get without contaminating the refrigerant, never above 0 psig).

A study plan that works for EPA 608 Type III (Low-Pressure)

Roughly two weeks of real preparation, in the order that actually builds on itself.

1. Day 1: Leak detection. Learn the pressurization order (heat first, nitrogen only after heat and only above the 85 degree F boiling-point line), and why a chiller leaks air in. Know the 10 psig test limit under the rupture disc.
2. Day 2: Leak repair rules. Memorize 10, 20 and 30 percent, the 30 and 120 day repair clocks, the annual inspection rule, and the 125 percent chronic-leaker report due March 1.
3. Day 3: Recovery and evacuation. Work the Table 1 level, major versus non-major repairs, leaky components, heating oil to 130 degrees F, water in the tubes, and the 10 psig recovery cut-out.
4. Day 4: Recharging, the purge unit, and equipment room safety. Then take practice questions from every block and reread each one you miss.

Sample EPA 608 Type III (Low-Pressure) questions

Straight from the bank — answers highlighted, with the explanation underneath.

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