Leak Detection
Scope
Type II covers high-pressure appliances, and the leak-detection rules that get tested attach to the 50-pound charge threshold: an appliance holding 50 lb or more of refrigerant must be repaired once it leaks above its rate limit.
Methods are not mandated
EPA does not require a specific leak-detection tool. Electronic detectors, ultrasonic listeners, UV dye with a black light, soap bubbles, and nitrogen pressure testing are all acceptable. Trap answers claim the regulation mandates one method, or that you must add refrigerant to a suspected-empty system just to search for a leak.
Rates and clocks
The leak-rate thresholds are comfort cooling 10%, commercial refrigeration 20%, and industrial process refrigeration 30%. When a leak exceeds the threshold, repair within 30 days of discovery. If repair is not technically feasible, a retrofit or retirement plan is due within 30 days and the work must be finished within one year. Verification is a two-step process: an initial verification test after the repair, then a follow-up verification test within 30 days of the initial test.
Chronic leakers
An appliance that loses 125% or more of its charge in a 12-month period is a chronic leaker and must be retrofitted or retired.
Rule of thumb
Memorize the ladder 10-20-30: comfort cooling 10%, commercial refrigeration 20%, industrial process 30%.