Leakage Rate Chart

Nordfab’s Quick-Fit™ (QF) Ducting is designed for easy disassembly, reassembly, storage, or relocation. Completely eliminating the possibility for leakage jeopardizes the inherent benefits of QF® duct.
Still, standard QF ducting is designed to provide tight sealing and efficient airflow under negative pressures.
To that end, we are providing the following information for piping situations where fan sizing is of extreme importance. This data was obtained using standard components and was performed in accordance with the SMACNA, “HVAC AIR DUCT LEAKAGE TEST MANUAL.” The information gives the leakage rate per joint of duct at various pressures.
To use the chart, count the number of clamps, (this equals the number of pieces), per size and multiply by the number given beside the corresponding diameter and under the applicable pressure. These numbers assume that the product is correctly installed, free of dents in the joining ends, and that the gasket is in place.
Our special gasket material and sealants will increase the sealing capabilities.

Download our Nordfab General Engineering Specifications sheet which includes this chart as well as other helpful information.

Leakage Rate in CFM per QF Joint
Dia Inches 3 WG 5 WG 7.5 WG 10 WG 15 WG 20 WG 25 WG 30 WG
4 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
5 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
6 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
7 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
8 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
9 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
10 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
12 0.30 0.30 0.40 0.40 0.40 0.60 0.70 0.90
14 0.30 0.30 0.50 0.70 0.80 0.80 0.90 1.10
16 0.30 0.40 0.60 0.70 1.00 1.10 1.20 1.40
18 0.40 0.40 0.70 0.80 1.10 1.30 1.50 1.70
20 0.40 0.60 0.80 0.90 1.20 1.50 1.70 2.00
22 0.40 0.60 0.80 1.10 1.40 1.50 2.00 2.20