From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Analysis of water solubility and ice separation in various aviation fuel blends at different temperatures.
| Identifier | ExFiles\Box 150\1\ scan0210 | |
| Date | 29th September 1936 guessed | |
| - 4 - In this connection, the most practical consideration is not the amount of water dissolved in the gasoline at any given temperature but rather the amount of water that drops out of solution as ice at any given temperature below the freezing point of water. Accordingly, in comparing the water tolerance of Isopropyl Ether with that of other types of aviation fuel, two different methods of determination were used. In one set of tests, the total water content of the fuel, when saturated with water at 77°F or at 32°F was determined. In these tests, calcium hydride was added to the water saturated fuels and the hydrogen evolved by reaction with the water was accurately measured in a gas burette and calculated back to its equivalence in milliliters of water per 100 milliliters of fuel. The water contents of three types of fuel were as follows: Ml. of water/100 ml. Ml. of water/100 ml. Saturated at 77°F. {Mr Friese} Saturated at 32°F. {Mr Friese} 100% Regular Aviation Gasoline 0.007 0.006 Aviation Gasoline with 40% Benzol 0.022 0.019 Aviation Gasoline with 40% Isopropyl Ether 0.085 0.062 In the second series of tests, in which the actual water separation was measured, it was shown that although the Isopropyl Ether blends dissolve more water at 77°F. {Mr Friese} , they also retain more water in solution at temperatures as low as -20°F. {Mr Friese} Consequently, the tendency to separate is not as great as appears from the water content at 77°F. {Mr Friese} In the second series of tests, the ice separation at -20°F. {Mr Friese} was determined directly. The aviation fuels were saturated with water at 70°F. {Mr Friese} and then pumped first through a precooler at 32°F. {Mr Friese} and thence into an ice trap at -20°F. {Mr Friese} At the end of each test, the ice trap was disconnected and its water contents were distilled with air through a weighed drying tube. The weight of water was then obtained directly. The results on the same fuels as used in the previous tests were as follows: Ml. of water separated at -20°F. {Mr Friese} per 100 ml. of fuel saturated at 77°F. {Mr Friese} 100% Regular Aviation Gasoline 0.0005 Aviation Gasoline with 40% Benzol 0.0030 Aviation Gasoline with 40% Isopropyl Ether (2 Tests) 0.0050 and 0.0060 The above results show that the blend of Isopropyl ether deposited hardly twice as much water as the benzol blend and ten times as much as the regular aviation gasoline. Furthermore in two more tests at -10°F. {Mr Friese} on the blend, in one of which the fuel contained an additional 0.5% of methanol, it was found that, although the same volume of separation occurred in both cases (0.005%), the separation occurred as ice in the absence of methanol and as liquid in the presence of methanol. The melting-point of the ice was +25°F. {Mr Friese} and the freezing-point of the liquid, which was found to contain about 40% methanol, was -50°F. {Mr Friese} It appears, therefore, that the tendency for Isopropyl Ether to take up water, | ||