Often confused · Leak detection and repair
Leak-rate thresholds: 10%, 20% and 30%
Under Section 608, an appliance holding 50 lb or more of CFC or HCFC refrigerant must be repaired once its leak rate exceeds 20% for commercial refrigeration, 30% for industrial process refrigeration, or 10% for comfort cooling and every other appliance (40 CFR 82.157, eCFR as of October 5, 2026).
Part of Leak detection and repair in the Study guide
Where the points actually go
The three numbers aren't hard to memorize. Matching them is where it's easy to slip, because the stem hides the answer in two details: what the appliance cools, and which refrigerant class it holds. Cooling for people in a building points to comfort cooling. Cases and cold rooms in a store point to commercial refrigeration. Cooling inside a manufacturing process points to industrial process refrigeration.
35/35/15 retired in 2019
Older prep material still prints 35% for commercial and industrial process refrigeration and 15% for comfort cooling. Those were the thresholds before the 2016 rule's changes became applicable on January 1, 2019 (EPA regulatory updates, checked October 7, 2026). If a practice set gives you 35 and 15 as answers, it's grading you against a rule that ended in 2018.
HFC-only appliances left the leak-repair rule in 2020
Since April 10, 2020, the Section 608 leak-repair requirements don't apply to appliances charged only with HFCs (EPA regulatory updates, checked October 7, 2026). A separate rule under the AIM Act, 40 CFR 84.106, applies the same 20/30/10 thresholds to HFC appliances holding 15 lb or more from January 1, 2026, with residential and light-commercial air conditioning exempt. ESCO says AIM Act rules aren't tested on the 608 exam (ACHR News, September 19, 2026, checked October 7, 2026), so on the test, answer from Part 82. What else is changing with the question bank is on the new EPA 608 exam.
What crossing the line starts
Exceeding the threshold starts a clock: repair within 30 days of the refrigerant addition that revealed it, or 120 days when an industrial process shutdown is needed, followed by verification tests; otherwise a retrofit or retirement plan (40 CFR 82.157(d)–(h), eCFR as of October 5, 2026). The deadlines, inspections and extensions are laid out on leak repair requirements.
The thresholds, then and now
Leak-rate thresholds for appliances with 50 lb or more of CFC or HCFC refrigerant
| Appliance type | Repair when the leak rate exceeds | Before January 1, 2019 |
|---|---|---|
| Commercial refrigeration | 20% | 35% |
| Industrial process refrigeration | 30% | 35% |
| Comfort cooling and all other appliances | 10% | 15% |
Below 50 lb, or charged only with HFCs, these thresholds don't apply under Section 608. Sources: 40 CFR 82.157, eCFR as of October 5, 2026; EPA regulatory updates, checked October 7, 2026.
How the numbers moved
Through December 31, 2018
35 / 35 / 15
The thresholds before the 2016 rule took effect; still printed in older prep material.
January 1, 2019
20 / 30 / 10
The 2016 rule's thresholds become applicable (40 CFR 82.157).
April 10, 2020
HFC-only appliances drop out
Section 608 leak repair no longer applies to appliances charged only with HFCs (EPA regulatory updates).
January 1, 2026
A separate HFC rule
40 CFR 84.106 under the AIM Act applies 20/30/10 to HFC appliances of 15 lb or more. Not 608 exam content, per ESCO (ACHR News, September 19, 2026).
Match the percent to the appliance
Find the appliance type in each stem before you look for a percentage.
0 right · 0 of 7 answered
Commercial refrigeration holding 50 pounds or more of a CFC or HCFC refrigerant must be repaired when its annual leak rate exceeds:
Why each option is right or wrong
Answer: A. 20%
- ACorrect: for commercial refrigeration with 50 lb or more of an ozone-depleting refrigerant (CFC or HCFC), repair is required once the annual leak rate exceeds 20%.
- B25% is not a threshold in the current rule.
- C5% is not a threshold in the leak repair rule.
- D15% was the old comfort-cooling trigger; it does not apply to commercial refrigeration.
Commercial refrigeration holding 50 lb or more of a CFC or HCFC refrigerant must be repaired once the annual leak rate exceeds 20% (40 CFR 82.157, eCFR as of October 5, 2026).
What is the leak-rate threshold for comfort cooling equipment holding 50 pounds or more of an ozone-depleting refrigerant?
Why each option is right or wrong
Answer: B. 10% annually
- A5% is not a threshold in the leak repair rule.
- BCorrect: comfort cooling (and other) appliances with 50 lb or more of an ozone-depleting refrigerant must be repaired when the annual leak rate exceeds 10%.
- C20% is the trigger for commercial refrigeration, not comfort cooling.
- D15% was the comfort-cooling trigger before the 2016 rule took effect in 2019.
Comfort cooling appliances with 50 lb or more of an ozone-depleting refrigerant must be repaired once the annual leak rate exceeds 10% (40 CFR 82.157, eCFR as of October 5, 2026).
What is the maximum allowable annual leak rate for industrial process refrigeration equipment?
Why each option is right or wrong
Answer: B. 30%
- A10% is the trigger for comfort cooling, not industrial process refrigeration.
- BCorrect: industrial process refrigeration with 50 lb or more of an ozone-depleting refrigerant must be repaired when the annual leak rate exceeds 30%.
- C35% was the trigger for commercial and industrial process refrigeration before the 2016 rule took effect in 2019.
- D20% is the trigger for commercial refrigeration.
Industrial process refrigeration with 50 lb or more of an ozone-depleting refrigerant must be repaired once the annual leak rate exceeds 30%.
Under the Section 608 leak-repair rules, the owner must keep records of leak inspections and repairs for a high-pressure refrigeration system if its refrigerant charge is:
Why each option is right or wrong
Answer: B. 50 pounds or greater.
- A25 lb is below the threshold; leak repair and leak records apply from 50 lb.
- BCorrect: appliances holding 50 lb or more of an ozone-depleting refrigerant fall under leak repair rules, and the owner keeps the leak and repair records for 3 years.
- C100 lb is not a threshold in the leak repair rule.
- D150 lb is not a threshold in the leak repair rule.
Owners of appliances holding 50 lb or more of an ozone-depleting refrigerant keep records of leak inspections, repairs and verification tests for three years.
A 500-pound commercial refrigeration system leaked 160 pounds over 12 months. What is its annual leak rate?
Why each option is right or wrong
Answer: B. 32 percent
- A68% is not 160 divided by 500; it confuses the calculation.
- BCorrect: leak rate = pounds lost / full charge × 100, so 160 / 500 = 32%, above the 20% commercial refrigeration trigger.
- C20% is the trigger rate for commercial refrigeration, not the result of this calculation.
- D16% comes from dividing by 1,000 instead of the 500 lb charge.
The leak rate equals pounds lost divided by total charge, multiplied by 100. Here, 160 divided by 500 equals 0.32, or 32 percent, exceeding the commercial threshold.
A commercial refrigeration unit holding 200 lb of R-22 receives refrigerant additions of 12.0 lb, 16.5 lb and 13.5 lb over nine months. Using the rolling 12-month method, at what cumulative total does the leak rate first exceed the 20% threshold?
Why each option is right or wrong
Answer: D. 42.0 lbs
- AWrong: 28.5 lb (12.0 + 16.5) is 14.25% of the charge, still under the 40 lb (20%) threshold.
- BWrong: 40.0 lb is the 20% threshold itself, not a total these additions actually reach.
- CWrong: 45.5 lb is not a running total of these additions.
- DCorrect: the third addition brings the 12-month total to 42.0 lb (12.0 + 16.5 + 13.5), or 21% of 200 lb, past the 20% threshold.
Under the rolling 12-month method, the leak rate is the refrigerant added over the past 12 months divided by the full charge. The 20% threshold for a 200-lb unit is 40 lb. After the second addition the total is 28.5 lb (14.25%); after the third it is 42.0 lb (21%), past the threshold.
What determines if a leak repair is required under EPA regulations?
Why each option is right or wrong
Answer: D. Equipment leak rate exceeds trigger rate
- AA pressure drop can mean many things and is not the legal test for required repair.
- BA customer complaint does not trigger the EPA repair requirement.
- CLeaks should be fixed, but the legal repair requirement depends on the leak rate, not on any visible leak.
- DCorrect: repair is required when the appliance's leak rate exceeds the trigger for its type (20%, 30% or 10% for 50 lb or more of an ozone-depleting refrigerant).
Leak repair is required if the equipment's leak rate exceeds the trigger rate specified for that equipment type.
More practice across all four sections: Practice test · Timed mock
Before you divide
How is a refrigerant leak rate calculated?
At its simplest: refrigerant added to bring the appliance back to full charge, divided by the full charge, as a percentage over a 12-month period. 15 lb added to a 120-lb appliance a year after the last top-off is 12.5%. The rule's definition of leak rate sets the exact method (40 CFR 82.152, eCFR as of October 5, 2026).
Does a 40-lb R-22 system ever trigger leak repair under 608?
It doesn't under 40 CFR 82.157, which starts at 50 lb (eCFR as of October 5, 2026). The venting prohibition applies at every size, so a leak is never a license to vent during service.
Is the comfort-cooling threshold 10% or 15%?
10%, since January 1, 2019 (40 CFR 82.157, eCFR as of October 5, 2026). The 15% figure is the pre-2019 value.