A more general theory for estimating collection efficiency is the contact power theory based on a series of experimental observations made by Lapple and Kamack (1955). The fundamental assumption of the theory is: “When compared at the same power consumption, all scrubbers give substantially the same degree of collection of a given dispersed dust, regardless of the mechanism involved and regardless of whether the pressure drop is obtained by high gas flow rates or high water flow rates” (Lapple and Kamack, 1955).
In other words, collection efficiency is a function of how much power the scrubber uses, not of how the scrubber is designed — an assumption with a number of implications in the evaluation and selection of wet collectors. Once we know the amount of power needed to attain certain collection efficiency, the claims about specially located nozzles, baffles, etc. can be evaluated more objectively. For example, the choice between two different scrubbers with the same power requirements may depend primarily on ease of maintenance (USEPA-81/10, p. 9-16; USEPA-84/03, p. 9-13).