Duct Air Leakage Test Using Blower
- Select a test pressure not in excess of the pressure class rating of the duct.
- Calculate the allowable leakage using leakage factors related to the duct area of the
section to be tested. - Select limited section of duct for which the estimated leakage will not exceed the
capacity of the test apparatus. - Connect the blower and flowmeter to the duct section and provide temporary seals
at all open ends of the ductwork. - Inspect the connection between the test piece and the test blower.
- To prevent over pressurization of the duct, provide a volume damper on the inlet of
the blower to control the pressure, pressurized the duct section to the required level. - Read the differential pressure and determine the equivalent orifice flowrate using
table 5-2.
- Compare the leakage in cfm pre square foot with the allowable leakage
determined in step above. If it meets the allowable leakage rate, it’s Ok. If it does not meet the allowable rate, follow the steps below:
Inspect the connection between the test piece and the test blower for any
leakage.
Depressurized and repair all audible leakage.
Allow repaired seals to cure and retest until leakage rate is within acceptable
limit. - The duct under testing shall be pressurized for 30 minutes.
- Verify all pressure test results and acceptable tolerances within the mentioned
tables.
The leakage amount shall not exceed the permissible leakage rate in CFM per 100 square feet or 9.29 square meters of duct surface for the pressure and leakage classes shown in the table below. The permissible leakage rate shall be calculated as per the section 4 of SMACNA HVAC Leakage Test
Manual.
Duct Air Leakage Test Using Blower
