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Smacna duct pressure testing.
A comprehensive duct layout indicating sizes design airflows pressure class and routing of the duct system.
Table 4 1 is the basis of evaluating duct conforming to the smacna duct construction standards unless a specifier gives other limits.
Total leakage measured with a pressure differential of 0 1 inch w g.
Smacna first published a procedure for leakage testing of so called medium and high pressure ductwork since january 1965.
Commercial duct leakage pressure testing prospered for decades as a method of verifying one of many factors of hvac system performance.
Smacna 2012 hvac leakage test manual shows the recommended leakage class.
If at the specified test pressure the leakage factor f by test is lower than or equal to that associated with the specified leakage class the duct is in compliance.
Thus it is not worth the cost of testing the low pressure duct for leakage.
Testing duct leakage by pressurizing ducts can be traced back to smacna air duct leakage testing standards published in the 1960s.
Total leakage measured with a pressure differential of 0 1 inch w g.
Testing system designed for 2 in h 2o operation at 10 in h 2o ndt idneed to consider surface area of ductwork.
Smacna hvac air duct leakagg e test manual first edition 1985 ashrae 90 1 proposed.
Inches wg download the iphone app here.
Ducts shall be pressure tested to determine air leakage by either of the following.
Information required for duct construction 1.
It appeared in chapter 10 of the high velocity later high pressure construction standards and in chapter 8 of the balancing and adjustment of air distribution systems manual of 1967 vintage.
For our example with a seal class of c for the low pressure duc t the leakage would be about 2 cfm.
Duct liner metal nosing shall be used on leading edges of each piece of lined duct when the velocity exceeds 4000 fpm.
If field leak tests are required appr opriate test pressure and clear scope of testing must be specified.
Test pressure higher than duct design i e.
25 pa across the system including manufacturer s air handler enclosure all registers taped or otherwise sealed post construction test.
