Guide
EPA 608 leak rate calculator: the two methods, worked
Updated
An EPA 608 leak rate: the yearly share of full charge lost at the current rate. 40 CFR 82.152 gives two methods; a facility must use one for every appliance.
Talk to a specialist Five US HVAC platforms set against the EPA Section 608 duties, what each publishes, and the questions no vendor has answered in public.
Method one: the annualizing method
Take the pounds of refrigerant added to return the appliance to full charge and divide by its full charge. Take the shorter of the days since refrigerant was last added or 365, and divide by 365. Divide the first figure by the second and multiply by 100.
- Step 1: pounds added / pounds at full charge.
- Step 2: the shorter of days since the last addition or 365, divided by 365.
- Step 3: Step 1 divided by Step 2.
- Step 4: Step 3 multiplied by 100 gives the leak rate as a percentage.
Source: eCFR, 40 CFR 82.152, Definitions (leak rate, leak inspection)
Method two: the rolling average method
Add up the pounds of refrigerant added over the previous 365 days. If it is shorter, use the period since the last successful follow-up verification test showing every identified leak repaired. Divide by the full charge and multiply by 100.
Source: eCFR, 40 CFR 82.152, Definitions (leak rate, leak inspection)
A worked example
A comfort cooling chiller holds 200 pounds at full charge. A technician adds 8 pounds, and the last addition was 60 days ago.
By the annualizing method: 8 / 200 = 0.04. 60 / 365 = 0.164. 0.04 / 0.164 = 0.243, so the leak rate is 24.3%. That is above the 10% comfort cooling trigger, so the repair clock starts.
By the rolling average method, if those 8 pounds are the only addition in the last 365 days: 8 / 200 x 100 = 4%, under the trigger. The two methods answer differently for a recent leak, which is why the rule makes a facility pick one and use it everywhere.
What the result is compared against
The leak repair duties apply to an appliance with a full charge of 50 or more pounds. The trigger rates over a 12 month period are 30% for industrial process refrigeration, 20% for commercial refrigeration, and 10% for comfort cooling and all other appliances.
Above the trigger, a leak must be repaired within 30 days, or a retrofit or retirement plan made within 30 days and completed within a year.
Source: EPA, Stationary Refrigeration Leak Repair Requirements
Why the calculator belongs in the job system
Every input is a field a technician records: the full charge on the appliance, the pounds added, the date. If those live against the appliance, the software can compute the rate the moment a technician closes the visit, and open the 30 day task on its own.
If they live against jobs, someone is doing this arithmetic in a spreadsheet, and the 30 days are already running. Our EPA 608 compliance software guide covers what to test in a demo.