Effects of Fuel Corrosion Inhibitors on Filter-Separator Coalescence

The coalescence performance of fuel filter-water separators has been determined using JP-5 fuel containing a fuel system icing inhibitor and various fuel corrosion inhibitors. Using distilled water, the corrosion inhibitors degraded coalescence performance to a very slight degree. Using a very hard tap water, the corrosion inhibitors varied greatly in their effect upon coalescence, ranging from slight to severe. Of 10 corrosion inhibitors tested with hard tap water, only 3 permitted adequate coalescence performance. When tested with distilled water, all of the corrosion inhibitors performed satisfactorily. The effect of these fuel additives on the coalescence performance of the filter-separator was found to vary greatly, depending upon the type and quality of test water dispersed in the fuel. It is concluded that existing filter-separator test methods are deficient, in that the type and quality of test water is not controlled.