20 free EPA 608 practice questions

Correct answer: B · R-12, R-22, R-410A: a CFC, then an HCFC, then an HFC with zero ODP

Ozone depletion comes from the chlorine a refrigerant carries to the stratosphere. EPA's Core test topics expect technicians to know that R-12 is a CFC and R-22 an HCFC, and that CFCs have a higher ozone-depletion potential than HCFCs, which in turn are higher than HFCs. EPA's glossary explains why: HCFCs contain chlorine but deplete much less ozone than CFCs, and HFCs such as R-410A contain no chlorine, so their ODP is zero. Putting R-410A first reverses the scale. Putting R-22 first ignores that CFCs deplete more ozone than HCFCs. Treating all three as equal confuses ozone depletion with the venting rules: releasing R-410A is still prohibited under 40 CFR 82.154(a), even though its ODP is zero.

Look for this next time: Ozone-depletion potential runs CFC, then HCFC, then HFC; HFCs such as R-410A have zero ODP but still may not be vented.

Correct answer: C · Recycled it: cleaned it for reuse in the same owner's equipment

40 CFR 82.152 defines the three R's. Recover means removing refrigerant in any condition and storing it in an external container without necessarily testing or processing it. Recycle means extracting refrigerant and cleaning it for reuse in equipment of the same owner, typically by oil separation and passes through filter-driers, without meeting all reclamation requirements. Reclaim means reprocessing it to the specifications in Appendix A, based on AHRI Standard 700-2016, and verifying that with the prescribed laboratory analysis. Cleaning the R-22 and charging it into the same owner's second unit is recycling: more than recovery, but without the analysis it is not reclaimed. Under 82.154(d), used refrigerant sold to a new owner generally must first be reclaimed by a certified reclaimer.

Look for this next time: Recover removes and stores, recycle cleans for the same owner's equipment, and reclaim meets AHRI 700 specifications verified by analysis.

Correct answer: A · Fill it to no more than 80% full, leaving room for the liquid to expand

EPA's Core test topics cover both points in this scenario. Reusable recovery cylinders must be DOT-approved and carry a yellow and gray color code, while disposable cylinders must never be refilled. And filling a cylinder more than 80% full is a named risk: liquid refrigerant expands as it warms, and a cylinder that becomes liquid-full has no vapor space left, so further warming drives the pressure up sharply and can rupture it. A hot afternoon makes that margin more important, not less. Filling to 100% or 95% removes or shrinks the vapor space that protects against expansion. A disposable cylinder is made for a single factory fill, so using it for recovery is the refilling EPA's topics rule out. A scale or an overfill shutoff helps keep the fill under the limit.

Look for this next time: Recover only into DOT-approved gray-and-yellow recovery cylinders, fill them no more than 80% full, and never refill disposable cylinders.

Correct answer: D · An ester (POE) oil, since HFCs are not compatible with mineral oil

EPA's Core test topics list lubricant compatibility as a substitute-refrigerant issue: many substitute refrigerants are incompatible with the lubricants used with CFCs and HCFCs, and the topics pair esters with R-134 and alkylbenzenes with HCFCs. R-134a is an HFC, so an ester (POE) oil is the match; the compressor maker's specification gives the exact grade. Mineral oil, used with CFC-12 systems, is the incompatibility the topics warn about. Alkylbenzene oil belongs with HCFCs such as R-22, not with every HFC. And refrigerant and oil do circulate together through the system, which is exactly why their compatibility matters. The same topics also remind technicians that there are no true drop-in replacements, so a refrigerant change means checking the oil too.

Look for this next time: Match the oil to the refrigerant: ester (POE) oils with HFCs such as R-134a, alkylbenzene with HCFCs, per the compressor maker.

Correct answer: C · Decline, since R-410A may be sold only to certified technicians or similar buyers

Under 40 CFR 82.154(c), refrigerant containing a class I or class II substance, and since January 1, 2018 any non-exempt substitute such as R-410A, may be sold only to listed buyers: for example, a buyer certified as a Type I, II, III, or Universal technician, a buyer who employs at least one certified technician and provides proof, or a buyer purchasing only for resale to certified persons. The small-can exception covers only MVAC refrigerant in containers of two pounds or less. A 25-pound cylinder for a home split system fits none of these, so the clerk declines. Thinking the rule covers only ozone-depleting refrigerants misses the 2018 extension to substitutes, which is also when HFCs came under the restriction, not when they left it. A signed promise is not a listed condition.

Look for this next time: Since 2018 the sales restriction covers non-exempt substitutes such as R-410A; sell only to certified technicians or other listed buyers.

Correct answer: A · A window air conditioner sealed at the factory with 1.5 lb of R-410A

40 CFR 82.152 defines a small appliance as one that is fully manufactured, charged, and hermetically sealed in a factory with five pounds or less of refrigerant, and it names room air conditioners, including window units, among the examples. Under 82.161(a)(1)(i), people who maintain, service, or repair small appliances need Type I certification. The split-system heat pump is charged and connected in the field, so it is not factory-sealed, and the walk-in cooler holds far more than five pounds; both are Type II work. The car's air conditioner is a motor vehicle air conditioner, which 82.161 sends to the separate program in 40 CFR Part 82, Subpart B, even though its charge is small. Factory sealing and the five-pound limit both have to fit.

Look for this next time: A small appliance is factory-made, factory-charged, and hermetically sealed with 5 lb or less; field-charged systems and car air conditioners are not.

Correct answer: D · 90% of the charge, or a vacuum of 4 inches of mercury

40 CFR 82.156(b) sets the recovery levels for small appliances, and 82.155(a) applies them to disposal. With recovery equipment manufactured on or after November 15, 1993, the technician must recover 90% of the refrigerant when the appliance's compressor is working, or 80% when it is not; with older recovery equipment, 80%. Evacuating the appliance to four inches of mercury vacuum also meets the rule. Here the compressor runs and the machine dates from 2018, so the target is 90%, or 4 inches of vacuum. The 80% figure applies only with an inoperative compressor or pre-1993 equipment. Zero psig is the level for a non-major repair on larger appliances, and 25 mm Hg absolute is the Table 1 level for low-pressure appliances.

Look for this next time: Small appliances: recover 90% with a working compressor and post-1993 equipment, 80% otherwise, or pull 4 inches of mercury vacuum.

Correct answer: B · Install access valves on both the high side and the low side

EPA's Type I test topics state that when a small appliance's compressor is inoperative, both high- and low-side access valves need to be installed: with no compressor to move it, refrigerant stays trapped on both sides of the system. The topics also list heating and sharply striking the compressor, to free refrigerant held in the oil, as a way to improve passive recovery. A single low-side connection leaves refrigerant on the high side. Venting the remainder breaks the venting prohibition in 40 CFR 82.154(a), whatever the size of the charge. Stopping at 0 psig falls short of 82.156(b): with an inoperative compressor and post-1993 recovery equipment, 80% of the charge must be recovered, or the appliance evacuated to 4 inches of mercury vacuum.

Look for this next time: With an inoperative compressor, install both high- and low-side access valves, and heat and tap the compressor to free trapped refrigerant.

Correct answer: C · Remove it at the end of service rather than leave it on the tube

EPA's Type I test topics state that solderless access fittings should be removed at the conclusion of service. A bolt-on piercing valve is a temporary way into a sealed system: it closes the hole it punched with a clamp and gasket, so leaving it on the tube, capped or not, leaves a possible leak point. Convenience for the next service call does not change that practice. The leak-rule option mixes up two things. The leak repair requirements in 40 CFR 82.157 apply only to appliances with 50 or more pounds of ozone-depleting refrigerant, while removing solderless fittings is a service practice on EPA's Type I topic list, and the venting prohibition in 82.154(a) applies to small appliances too.

Look for this next time: Remove solderless (piercing) access fittings at the end of service; they are temporary access, not a permanent part of a sealed system.

Correct answer: A · Air or other noncondensables, or a refrigerant other than the label says

When an idle appliance has settled at room temperature with liquid refrigerant inside, its pressure should match the saturation pressure for that refrigerant at that temperature, which is what a pressure-temperature chart lists. EPA's Type I test topics include using pressure and temperature to identify refrigerants and detect noncondensables. A reading clearly above the chart value points to air or other noncondensables in the system, or to a refrigerant different from the label, so the technician confirms what is inside before recovering it; the Core topics stress not mixing refrigerants. An undercharge with liquid still present reads at the chart value, and once only vapor is left the pressure falls below it. A higher reading is not normal, and a stopped compressor does not set standing pressure: temperature does.

Look for this next time: At rest with liquid present, pressure should match the PT chart; a higher reading suggests noncondensables or a different refrigerant.

Correct answer: D · 10 inches of mercury vacuum, the level for this size of high-pressure unit

R-22 is a high-pressure refrigerant: 40 CFR 82.152 defines high-pressure appliances as those using a refrigerant with a liquid-phase saturation pressure between 170 and 355 psia at 104°F and names R-22 as an example. Table 1 in 82.156(a) sets the level for evacuating before opening or disposal. For a high-pressure appliance with a full charge of 200 pounds or more, it is 4 inches of mercury vacuum with recovery equipment made before November 15, 1993, and 10 inches with equipment made on or after that date. This chiller holds 300 pounds and the machine dates from 2019, so the level is 10 inches. Zero inches applies to high-pressure appliances under 200 pounds, 15 inches to medium-pressure appliances of 200 pounds or more, and 25 mm Hg absolute to low-pressure appliances.

Look for this next time: High-pressure appliances of 200 lb or more: evacuate to 10 inches of mercury vacuum with post-1993 recovery equipment, 4 inches with older equipment.

Correct answer: B · It exceeds the 20% rate for commercial refrigeration; repair within 30 days

40 CFR 82.157 applies to appliances with a full charge of 50 or more pounds of an ozone-depleting refrigerant, and R-22 is an HCFC. Its trigger rates are 20% a year for commercial refrigeration, which includes supermarket systems, 30% for industrial process refrigeration, and 10% for comfort cooling and other appliances. At 25%, this rack is over its 20% rate, so the owner must have a certified technician find and repair the leaks within 30 days of the refrigerant addition, confirmed by initial and follow-up verification tests, or create a retrofit or retirement plan. The 30% rate belongs to industrial process refrigeration. The 35% rate was the older figure, before the revised rules took effect in 2019. Systems charged only with HFCs fall under separate rules in 40 CFR Part 84.

Look for this next time: For appliances with 50 lb or more of ODS refrigerant, the trigger rates are 20% commercial, 30% industrial process, and 10% comfort cooling and other.

Correct answer: A · Dry nitrogen alone, applied through a pressure regulator

EPA's Type II test topics give an order of preference for leak-test gases: nitrogen alone is best, and nitrogen with a trace quantity of HCFC-22 is better than pure refrigerant. The same topics call for leak-testing before charging or recharging, and the Core topics call for using nitrogen rather than oxygen or compressed air, with a pressure regulator and a relief valve. A trace of R-22 can help an electronic detector find a leak, but EPA ranks it below nitrogen alone, not above. Pressurizing with R-410A alone is the least preferred choice, because whatever escapes through the leak is refrigerant released to the air. Compressed shop air is not on EPA's list at all. Dry nitrogen through a regulator is the right first test.

Look for this next time: Leak-test with dry nitrogen through a regulator; nitrogen with a trace of R-22 comes next, and pure refrigerant last.

Correct answer: C · Refrigerant is still in the system, as liquid or dissolved in the oil

EPA's Type II test topics list the need to wait a few minutes after reaching the required recovery vacuum to see whether system pressure rises, because a rise indicates that liquid refrigerant is still in the system or in the oil. As that refrigerant boils off, the pressure climbs, so recovery is not finished; the technician resumes recovery until the vacuum holds. Treating the rise as normal would leave refrigerant behind to escape when the system is opened, and 40 CFR 82.156(a) requires evacuating all the refrigerant, including all the liquid, to the Table 1 level. A hose leak affects the hoses, but with the system isolated, a rising system pressure points to refrigerant still inside. The recovery machine's high-pressure cut-out protects the machine and does not explain the rise.

Look for this next time: After reaching the recovery vacuum, wait; a pressure rise means liquid refrigerant or refrigerant in the oil remains, so keep recovering.

Correct answer: D · High-pressure, since 160 psig is about 174.7 psia, within 170 to 355

The definitions in 40 CFR 82.152 use absolute pressure at 104°F: low-pressure is below 45 psia, medium-pressure 45 to 170 psia, high-pressure 170 to 355 psia, and very high-pressure above 355 psia or a critical temperature below 104°F. A gauge reads relative to the atmosphere, so EPA's Type II topics remind technicians to add 14.7 to convert psig to psia. Step by step: 160 psig + 14.7 = 174.7 psia, which falls in the high-pressure range. Comparing 160 with the psia limits without converting is what makes medium-pressure look right. Low-pressure would need less than 45 psia, and there is no 150 psig rule for very high-pressure. Medium- and high-pressure work both call for Type II certification under 82.161, but the category also changes the Table 1 evacuation level.

Look for this next time: Add 14.7 to a gauge reading to get psia before using the psia limits that define low-, medium-, high-, and very high-pressure.

Correct answer: B · 25 mm Hg absolute, the level for low-pressure appliances

R-123 is one of the refrigerants 40 CFR 82.152 names for low-pressure appliances, those using a refrigerant with a liquid-phase saturation pressure below 45 psia at 104°F. Table 1 in 82.156(a) sets the level for low-pressure appliances at 25 mm Hg absolute, whether the recovery equipment was made before or after November 15, 1993, before the appliance is opened or disposed of. That is a deep vacuum: 25 mm is about 0.98 inch, so against a 29.9-inch standard atmosphere it is roughly 29.9 − 0.98 = 28.9 inches of mercury vacuum. Zero psig is for a non-major repair after which the appliance will not be evacuated. Ten inches of vacuum is the level for high-pressure appliances of 200 pounds or more, and 4 inches is the small-appliance option.

Look for this next time: Low-pressure appliances such as R-123 chillers must be evacuated to 25 mm Hg absolute before they are opened or disposed of.

Correct answer: A · With controlled hot water or a built-in heating device such as Prevac

An R-123 chiller can sit below atmospheric pressure, so opening it as it is would pull in air and moisture. For a non-major repair with no later evacuation, 40 CFR 82.156(a)(1)(ii) requires pressurizing a low-pressure appliance to no higher than 0 psig before opening it, and for refrigerants that boil at or below 85°F at standard atmospheric pressure, it bars methods such as nitrogen that require later purging. R-123 boils below that line: NIST lists about 300 K, roughly 81°F. EPA's Type III topics name the allowed methods: controlled hot water or a system heating and pressurization device such as Prevac. Nitrogen is the method the rule excludes here, because purging it would carry refrigerant out with it. Compressed air adds air and moisture, and opening in a vacuum draws them in.

Look for this next time: For a non-major repair on an R-123 chiller, raise it to 0 psig with controlled hot water or a heating device, not nitrogen.

Correct answer: D · To keep the water in the tubes from freezing as the pressure drops

EPA's Type III test topics list the need to circulate or remove water from the chiller during refrigerant evacuation to prevent freezing. As recovery lowers the pressure inside the chiller, the remaining refrigerant boils at lower and lower temperatures and draws heat from the water in the tubes. Still water can freeze and rupture a tube, which could then leak water into the refrigerant circuit. Keeping the water moving, or draining it, prevents that. The step is not meant to keep the refrigerant liquid; recovery removes it as liquid and then as vapor. Water flow cannot push refrigerant out, because the water and the refrigerant run in separate circuits. And the purge unit removes noncondensables from the refrigerant side; it does not depend on the water pumps.

Look for this next time: Circulate or drain the water in a low-pressure chiller's tubes during evacuation so it cannot freeze as the pressure falls.

Correct answer: C · With vapor first through the evaporator charging valve, then liquid

EPA's Type III test topics give two recharging points: introduce vapor before liquid, to prevent freezing of the water in the tubes, and charge centrifugal chillers through the evaporator charging valve. In a deep vacuum, liquid refrigerant flashes to vapor at a very low temperature and can freeze the water in the tubes. Adding vapor first raises the pressure, and with it the refrigerant's boiling temperature, before any liquid goes in. Starting with liquid through the condenser or into the compressor ignores both points and risks frozen tubes and liquid reaching the compressor. Nitrogen is not part of the charging sequence: it would add a noncondensable gas that the purge unit would later have to remove, taking some refrigerant with it.

Look for this next time: Recharge a low-pressure centrifugal chiller with vapor first, through the evaporator charging valve, before adding liquid.

Correct answer: B · Air is leaking into the chiller; leak-test it and repair the leak

A low-pressure chiller's evaporator runs below atmospheric pressure, so a leak lets air and moisture in rather than letting refrigerant out. EPA's Type III test topics cover the purpose of the purge unit, which removes those noncondensables, and list excessive purging as a sign of leakage into a low-pressure system. A purge unit running far more than usual under a similar load points to a leak, so the next step is to find and repair it. A chiller holding 50 or more pounds of an ozone-depleting refrigerant such as R-123 is also subject to the leak-rate and repair rules in 40 CFR 82.157. An overcharge does not draw in air. Frequent purging is a warning sign, not normal aging. The purge unit handles noncondensable gases, not oil.

Look for this next time: Excessive purging on a low-pressure chiller signals air leaking in; find and repair the leak.