Ductwork airtightness

This air leakage is driven by differential pressures across the ductwork envelope due to the combined effects of stack and fan operation (in case of a mechanical ventilation system).

The aim of this type of measurement is to relate the pressure differential across the ductwork to the air flow rate required to produce it.

Generally, the higher the air flow rate required to produce a given pressure difference, the less airtight the ductwork.

At construction stage, the airtightness of individual components depends on the design (rectangular or round ducts, pressed or segmented bends, etc.)

Components with factory-fitted sealing devices (e.g., gaskets, clips) meant to ease and accelerate the installation process are widely used in Scandinavian countries.

Typical reasons for poor ductwork air tightness include:[19][20][12] Sweden is often considered as a reference for airtight ducts: the requirements introduced in AMA (General material and workmanship specifications)[21] starting in 1950 have led to excellent ductwork airtightness on a regular basis in Sweden.