What is Equal Friction?

The Equal Friction design methodology sizes the supply duct system for a constant pressure loss per unit length such as 0.1″wg friction loss per 100 feet of duct. This is a low velocity industry standard.

Equal Friction is the most widely used method of sizing lower pressure, lower velocity duct systems. There is no equalization of pressure drops in duct branches unless the system has a symmetrical layout. Dampers are used for balancing.