Determination of the presence or absence of water in hydrocarbon fuels is quite important. The adverse effects of excessive water in a fuel system cannot be overstated as ranging from corrosion to poor engine performance, and accordingly over the past 30 years of prior art in the field there have been various methods described for detecting water in hydrocarbon fuels.
For example in U.S. Pat. No. 2,968,940 (1961), Feldman et. al. describes a method to detect 30 parts per million disbursed water in jet aircraft fuels (the “go-no go” limit) by adding one-half gram of a mixture of sodium o-cresolsulfonphthalein and barium carbonate to 100 cc's of jet fuel, shaking it, allowing the powder to settle and noting its color. In U.S. Pat. No. 3,505,020 (1970), Caldwell et. al. discloses an improved mixture of methylene violet or fuchsia (3-amino-7-(dimethylamino)-5-phenylphenazinium chloride) and an absorbent from the Group II metals, such as calcium carbonate, to detect 30 parts per million disbursed water in jet fuels but without reference to the presence or absence of alcohol therein. In U.S. Pat. No. 4,070,154 (1978), Mascher et. al. discloses a colorimetric test for as little as 0.1% alcohol in jet aircraft fuels (the ice formation inhibitors) by an emulsion reagent of sodium vanadiate, 8-hydroxyquinoline, water, acetic acid and an organic solvent. Because water is part of his reagent, it was not intended to detect water in the fuel. In U.S. Pat. No. 4,608,345 (1986), Feldman et. al. describes a colorimetric test for detecting small amounts (1%) of alcohol in gasoline using a variety of alcohol soluble-hydrocarbon insoluble dyes with an absorbent from the Group II metals, such as calcium carbonate; however since the absorbent is non-selective, water must first be removed from the fuel by treating with a drying agent. In U.S. Pat. No. 4,676,931 (1987), the formation of colored hydrates has been described to detect disbursed water in fuels by adding an anhydrous powder which, when shaken with the fuel, would remove only the water so that the presence of alcohol would not interfere with the test. The preferred anhydrous powder was cupric sulfate because it formed two colored hydrated crystals, light blue and dark blue, depending upon the amount of water present, however a few problems were found using this test under actual field conditions. Indian patent 127,617 (1971) provides a device for determining the presence of suspended free water in aviation turbine fuels in concentration as low as 30 ppm. According to this, a composition containing a mixture of ferrous ammonium sulfate and potassium ferricyanide was applied to a filter paper, which was then used for detection of water in hydrocarbon fuels. Presence of water gives green/blue color. Indian patent 127618, 1972 provides a method and device for determining the presence of suspended free water in aviation turbine fuels in concentration as low as 30 ppm. The aforementioned U.S. and Indian patents are hereby incorporated by reference herein.
According to this, a composition containing a mixture of cresol red and barium carbonate in the ratio of 1:100 was used for the detection of free water in the fuel samples. The prepared composition is grayish white in color and packed in the gelatin capsules. Presence of water gives pink color.
The detection methods as mentioned in the prior art are mainly uses the stoichiometric amounts of expensive metal salts, which may produce large excess of metallic waste and thereof are detrimental to the environment. In view of the above problems, it is needed to develop a method for the detection of suspended free water in the hydrocarbon fuels with relatively safe and inexpensive chemicals. The embodiments of the present invention address that need.