EPA 608 Study Guide: Core, Type I, Type II and Type III

EPA's Q&A is direct: 'The EPA does not provide a study guide.' What it does publish is a test-topics page listing what each section covers. The questions come from a bank EPA developed and releases only to approved certifying programs (40 CFR 82.161(c)). Every test has 25 Core questions plus 25 for each type you take. You need 70 percent on each section to pass, or 84 percent on a mail-in Type I test.

This guide follows EPA's topic headings in order. Where a topic is regulation, the rule is cited. Where it is trade practice, such as gauge colors or recovery speed, the guide sticks to settled basics.

Core is on every test and covers the reasons behind the rules as well as the rules themselves.

• Environmental impacts: chlorine from CFCs and HCFCs reaches the stratosphere, where UV light frees it to destroy ozone. Ozone depletion lets more UV reach the ground, with health and environmental harm. CFCs have a higher ODP than HCFCs, which are higher than HFCs (zero). Know R-12 as a CFC, R-22 as an HCFC and R-134a as an HFC.
• Clean Air Act and Montreal Protocol: the Protocol is the international treaty phasing out ozone-depleting substances, and Title VI of the Clean Air Act carries it out in the U.S. EPA's topic list also includes the CFC and R-22 phaseout dates and the maximum Clean Air Act penalty, so check EPA's current figures for those. Venting is banned during service, at disposal, and for substitute refrigerants (40 CFR 82.154(a)). The ban took effect July 1, 1992, for CFCs and HCFCs, and November 15, 1995, for substitutes (Clean Air Act section 608(c)).
• Pressure classes (40 CFR 82.152): low under 45 psia at 104 °F (R-11, R-123), medium 45 to 170 psia (R-12, R-134a), high 170 to 355 psia (R-22, R-410A), very high above 355 psia or critical temperature under 104 °F (R-13, R-23).
• Covered equipment: all air-conditioning and refrigeration equipment with CFCs or HCFCs except MVACs. Substitutes such as HFCs are now covered as well.
• Self-contained recovery equipment works on its own. System-dependent equipment uses the appliance's own components (40 CFR 82.152). Recovery equipment needs third-party certification (40 CFR 82.158).
• Reclaimed refrigerant must meet AHRI Standard 700-2016 (40 CFR 82.152, 82.164).
• Sales restriction: only certified technicians, or employers of one, may buy refrigerant (40 CFR 82.154(c)).

This part of Core is the working knowledge behind every service call.

• Substitutes and oils: there are no true drop-in replacements. Many substitutes do not work with the oils used with CFCs and HCFCs, and the reverse is also true. Esters go with R-134a, and alkylbenzenes with HCFCs. Blends can fractionate: their components leak at different rates.
• Refrigeration: know whether the refrigerant is liquid or vapor, and at what pressure, at each point in the cycle, and where cooling happens (in the evaporator, as liquid boils). Gauges: blue for the low side, red for the high side, yellow for the center utility hose. Know their ranges and proper use.
• Three Rs (40 CFR 82.152): recover means remove and store without processing. Recycle means clean for reuse by the same owner. Reclaim means reprocess to AHRI 700 purity and verify by analysis.
• Recovery techniques: never mix refrigerants. Recovery speed depends on ambient temperature, the size of the recovery equipment, and hose length and diameter.
• Dehydration: evacuate the system at the end of service to remove air and moisture.

Safety questions are mostly common sense, but they are worded precisely.

• Exposure risks: oxygen deprivation, since refrigerant vapor is heavier than air and displaces it; cardiac effects; frostbite from liquid; and long-term hazards.
• PPE: gloves and goggles. Self-contained breathing apparatus (SCBA) is for extreme cases such as a large release in an enclosed space.
• Cylinders: reusable recovery cylinders must be DOT-approved and are painted yellow and gray. Never refill disposable cylinders. Never fill a cylinder more than 80 percent full, because liquid expands as it warms.
• Leak testing: pressurize with nitrogen, never oxygen or compressed air. Always use a pressure regulator and a relief valve.
• Shipping: label cylinders with the refrigerant identity and the DOT classification tag.

A small appliance is fully manufactured, charged and hermetically sealed in a factory with 5 pounds or less of refrigerant (40 CFR 82.152). Think refrigerators, freezers, window and room units, PTACs, dehumidifiers, vending machines, water coolers and under-counter ice makers.

• Recovery levels (40 CFR 82.156(b)): with equipment made before November 15, 1993, recover 80 percent. With equipment made on or after that date, recover 90 percent if the compressor works or 80 percent if it doesn't. Or evacuate to 4 inches of Hg vacuum.
• Use pressure and temperature to identify the refrigerant and to detect noncondensables.
• Passive (system-dependent) recovery with a dead compressor: install both high- and low-side access valves. Heat and sharply strike the compressor to free trapped refrigerant, or use a vacuum pump with a non-pressurized recovery container. With a working compressor, run it during passive recovery.
• Remove solderless access fittings at the end of service.
• R-134a is the likely substitute for R-12.
• Safety: refrigerants break down into harmful decomposition products at high temperatures, such as near an open flame.

Type II covers medium-, high- and very high-pressure appliances other than small appliances and MVACs (40 CFR 82.161(a)(1)(ii)). That includes residential splits, heat pumps, rooftop units, commercial refrigeration and many chillers.

• Leak detection: signs of leakage include excessive superheat and traces of oil on hermetic systems. Leak test before charging or recharging. For test gas, nitrogen alone is best; nitrogen with a trace of R-22 is better than pure refrigerant.
• Leak repair (40 CFR 82.157, appliances with 50 lb or more of an ozone-depleting refrigerant): trigger rates are 20 percent for commercial refrigeration, 30 percent for industrial process refrigeration and 10 percent for comfort cooling and others. The repair deadline is 30 days, or 120 with an industrial process shutdown. Know the recordkeeping and extension rules.
• Recovery techniques: recover liquid first to speed things up, chill the recovery vessel, heat the appliance. Reduce cross-contamination when switching a machine to a new refrigerant. After reaching the required vacuum, wait a few minutes to see whether the pressure rises.
• Recovery requirements: Table 1 levels (40 CFR 82.156(a)). For post-1993 equipment: high-pressure under 200 lb, 0 inches of Hg; high-pressure 200 lb or more, 10 inches; medium-pressure under 200 lb, 10 inches; medium-pressure 200 lb or more, 15 inches; very high-pressure, 0. Leaky appliances: as low as possible, never above 0 psig. Non-major repairs: 0 psig.
• A major repair means removing the compressor, condenser, evaporator or an auxiliary heat exchange coil, or opening more than 4 square inches of flow area for more than 15 minutes (40 CFR 82.152).
• System-dependent recovery is not allowed on systems over 15 lb (40 CFR 82.156(e)).
• Refrigeration: identify the refrigerant and read the P-T relationship, adding 14.7 to psig to get psia. Know the components (receiver, evaporator, accumulator and so on) and whether each holds liquid or vapor. Hydrocarbons are not approved for retrofits.
• Safety: never energize a hermetic compressor under vacuum. EPA's topic list also covers equipment-room requirements under ASHRAE Standard 15, which it describes as an oxygen deprivation sensor with all refrigerants. That is the answer the test expects, but the wording dates from the 1992 edition: current Standard 15 requires a refrigerant detector in every machinery room that alarms and starts ventilation at or below the refrigerant's occupational exposure limit.

Type III covers low-pressure appliances, mainly centrifugal chillers using refrigerants such as R-11 and R-123, which run with part of the system below atmospheric pressure.

• Leak detection: pressurize for a leak test, preferably with hot water or a built-in heating or pressurization device such as Prevac, otherwise with nitrogen. Excessive purging is a sign of leakage. Know the maximum leak test pressure for low-pressure centrifugal chillers (taught as 10 psig, below a rupture disc commonly set at 15 psig; some manufacturers specify less, such as Trane's 8 psig), the leak inspection requirements for appliances over the leak rate, and chronic-leaker reporting (125 percent of the full charge in a year, 40 CFR 82.157(j)).
• Leak repair: same 20/30/10 percent trigger rates for appliances of 50 lb or more.
• Recovery techniques: recover liquid first, then vapor. Heat oil to 130 °F before removing it. Circulate or drain the water in the chiller during evacuation so it doesn't freeze. Know the high-pressure cut-out level of recovery devices used on low-pressure systems, taught as 10 psig.
• Recharging: introduce vapor before liquid to prevent freezing the water in the tubes. Charge centrifugals through the evaporator charging valve.
• Recovery requirements: 25 mm Hg absolute for every low-pressure appliance, with pre- or post-1993 equipment (40 CFR 82.156(a)). For non-major repairs, pressurize to 0 psig with controlled hot water or a heating device such as Prevac. Wait a few minutes after reaching the vacuum to check for a pressure rise.
• Refrigeration: the purge unit removes noncondensables that leak into the vacuum side. Know the P-T behaviour of low-pressure refrigerants.
• Safety: equipment-room requirements under ASHRAE Standard 15. EPA's topic list describes these as an oxygen deprivation sensor with all refrigerants and a refrigerant sensor for R-123. Current editions of the standard require a refrigerant detector, set at or below the exposure limit, for every refrigerant (50 ppm for R-123).

These are the figures that turn up again and again. Each comes from the regulation or EPA's own pages.

Start with Core, since it is on every test and you must pass it. Learn the numbers in the table above until you can write them from memory, then work through the type sections you need. Universal candidates should give Type II the most time, as it carries the most regulation detail.

Use practice questions to find gaps, not to memorize answers. The practice tests on this site cover Core, Type I, II, III and a 100-question Universal mock. When you miss a question, go back to the topic and the rule behind it. Aim to score well above 70 percent on timed practice before you book the real test.