The classical Bernoulli phenomena for uniformed flow in a pipe forms the basis of the static regain method for HVAC duct design. The fact that a junction in a multipath duct system is different from a liquid stream in a single pipe is completely overlooked. Mass is ignored in the static regain equation.

The desire to have equal branch static pressure behind each register to result in equal flow branch at each tap cannot be achieved since equal static pressure at the junctions does not assure total pressure balancing. The paper shows that "R", the static regain factor, is unpredictable, and that the saving energy by converting "kinetic energy" into additional static pressure is an illusion.

Units: Dual