A refrigeration mechanic is conducting a full duct leakage test on a newly installed commercial duct system using a duct blaster device and manometer. The specifications call for a leakage rate of no more than 3% of the total system design airflow at 250 Pa (1 in. w.c.) static pressure. If the system's design airflow is 12,000 L/s (25,420 CFM) and the measured leakage rate is found to be 7 L/s/100m² (0.014 CFM/ft²) for 500 m² (5,382 ft²) of duct surface area, does the system meet the leakage requirement?

Question: A refrigeration mechanic is conducting a full duct leakage test on a newly installed commercial duct system using a duct blaster device and manometer. The specifications call for a leakage rate of no more than 3% of the total system design airflow at 250 Pa (1 in. w.c.) static pressure. If the system's design airflow is 12,000 L/s (25,420 CFM) and the measured leakage rate is found to be 7 L/s/100m² (0.014 CFM/ft²) for 500 m² (5,382 ft²) of duct surface area, does the system meet the leakage requirement?

Answer options:

• Yes, the system is within the acceptable leakage limits. ✅ No, the system leakage exceeds the maximum allowed percentage.
• The leakage rate cannot be determined without knowing the fan's RPM.
• The leakage rate cannot be determined without knowing the duct material.

Correct answer: No, the system leakage exceeds the maximum allowed percentage.

Explanation: First, calculate the maximum allowable leakage: 2% of 12,000 L/s = 240 L/s. Next, calculate the actual total measured leakage based on the specific leakage rate and total duct surface area: 0.025 L/s/m² * 12,500 m² = 312.5 L/s. Since 312.5 L/s is greater than the maximum allowed 240 L/s, the system does NOT meet the leakage requirement.