The Effectiveness of Water Jet Sprays in Cleaning and the Mechanisms for Disintegration

High pressure water jets are increasingly being used for cleaning surfaces on an industrial basis. In many instances the use of high pressure water, in such applications as car cleaning, is carried out in combination with mechanical brushes. However, there are many instances, particularly in self service units and where large industrial vehicles, which do not fit into a standard carwash, are cleaned, where a hand held lance alone, is used for the cleaning task. Because of the maneuverability of the lance and the relatively slow speed at which it is traversed over the surface, it is common practice to use a fan shaped nozzle in order to cover as large a surface area as possible as the wand is moved. Because of the nature of the operation and the geometry of the surface being cleaned, widely varying standoff distances can quite frequently occur between the nozzle and the surface. This can be of considerable importance since, as will be shown in this paper, there is a relatively rapid decrease in jet cleaning effectiveness with standoff distance.