Wear of Fuel Injection Equipment and Filtration of Fuel for Compression-ignition Engines

Abstract

The dependence of the wear of fuel injection equipment on abrasive-particle size has been determined using closely graded abrasive prepared by air elutriation. A mechanism of wear is proposed which accounts quantitatively for the wear observed. The particle transmission properties of filters in common use, and of possible alternative filter materials, have been measured using the same preparations of particles. Some information on the nature and particle sizes of solids in fuels is presented. Estimates of the effect of various filters in reducing abrasive wear are made for a particular particle-size distribution of abrasive. These estimates are compared with the results of a review of service experience with current filters, gauze, cloth, and felt, in Great Britain. The choking properties of filter materials have been compared using a waxy sludge obtained from marine Diesel fuel, and a hypothesis of the choking mechanism is proposed which makes it possible to predict choking behaviour from initial resistance and thickness, and to assess, by means of a “figure of merit”, filter materials of different particle-transmission properties and thicknesses. For some services improved filtration is necessary. Papers transmit fewer particles than cloth or felt but choke more readily, necessitating the use of a large filter area; but provided the paper and free volumes on the clean and dirty sides are suitably chosen, a paper filter appears to be practicable giving a greatly improved pump element life with adequate filter element life and reasonable bulk.