Search Results

FILTERS of various types were tested with nonadditive mineral and two heavy-duty oils containing additives similar to the extreme types commercially available. In many cases the efficiency of a filter varied considerably, depending on the oil used. For instance, the efficiency of some filters with one additive oil was about the same as with the straight mineral oil but was much lower with the other type of additive oil. One filter had about the same efficiency with the nonadditive oil and with both of the additive oils.

TEMPERATURE rise in the gasoline as it passes through the fuel system is the important factor in vapor lock that is within the control of the car designer. Gravity and vacuum-tank feed systems are considered briefly, including tests showing that weathering of the gasoline in the vacuum tank consists largely in removal of propane. Vapor lock in a pump system is most liable to occur on the suction side, because of the difference in pressure. Increasing the capacity of the pump for handling vapor offers little relief. Evidence is presented to show the gain made by locating the fuel line where it is protected from the heat. One example is cited to show the advantages of keeping a large flow of hot engine oil away from the pump. It is advantageous also to locate the pump where it will be cooled by the air entering the engine compartment of the car.

WIDESPREAD adoption of crude-oil cracking processes to provide an adequate supply of gasoline of high antiknock value has introduced the gum problem. The solution of this depends upon the development of a satisfactory method for determining the true gum-content of a fuel at the time of test and for predicting the content of a gasoline stored for a given time under specified conditions, and upon the correlation of data obtained by these methods with the results of engine tests. Several methods proposed and used for determining the gum content of gasolines are described and data obtained by means of them are compared.

IN a previous paper covering a comparison of several methods for determining gum in gasolines, the conclusion was reached that the air-jet method gave the lowest and most reproducible results. Since gum deposition in the engine occurs in the presence of air, a more extended study of that method was undertaken. By evaporation of different volumes of gasoline and of various blends with a gum-free gasoline in each case, the concentration of gum and of gum-forming constituents was found to be one of the most important factors in determining the gum content. The temperature of the gasoline and the oxygen concentration in the atmosphere surrounding it during evaporation appeared to have little effect on the results. Further work on methods for determining the gum content is contemplated.

PREVIOUS work on vapor lock at the Bureau of Standards under the auspices of the Cooperative Fuel Research Steering Committee has resulted in considerable information regarding the relation between the properties of gasolines and vapor lock and between fuel-line design and vapor lock. Satisfactory means have been developed for predicting the conditions under which vapor lock would occur with a given fuel, but no extensive information has been available on the gasoline temperatures existing in the fuel feed lines of automotive equipment. This has made it very difficult for the refiner to supply satisfactory fuels for current automotive equipment. The present report includes temperature data obtained at several points in the fuel feed systems of 27 automobiles and 8 buses under various operating conditions.

THE PRESENT PAPER covers the results obtained in a second survey of fuel-line temperatures. Road tests were made on a large number of 1931 cars operated under various specified conditions, and fuel temperatures were measured in each case at several points in the fuel-feed system. On the average, no material improvement over the 1930 models was found. Individual models had been improved considerably, while others had become worse. This unchanged situation may be due, in part, to the fact that the results of the 1930 survey were not available in time so that full advantage could be taken of the conclusions in designing the 1931 models. Reasonable protection for most of the 1931 cars as regards fuel cannot be obtained in hot weather if they are run on gasolines having a Reid vapor pressure higher than 7 lb. per sq. in.

WEATHERING of gasoline occurs in fuel tanks, carbureter float-bowls and vacuum tanks of automotive equipment, the extent being dependent upon conditions of temperature and pressure. If there is sufficient fuel loss due to weathering, the vapor-locking tendency of the gasoline is reduced. Experiments were made in laboratory equipment to determine the amount of loss and the decrease in vapor-locking tendency of a number of gasolines under various conditions. The factors varied were temperature, pressure, time and the size of opening to the gasoline container. In general it was found that there is very little loss until the vapor pressure of the gas-free gasoline exceeds the external pressure. When the vapor pressure of the gasoline exceeds the external pressure, loss occurs until the vapor pressure becomes equal to the external pressure if sufficient time is allowed for the vapors to escape through the opening.

The study of fuel flow in gravity-feed systems, which has hitherto been confined to flow through simple orifices, has been extended to include the measurement of flow through systems of various designs. The results of this study indicate that variations in the cross-sectional area of the feed lines from that at the tank outlet may have a marked effect on the vapor-locking tendency. Constrictions in the line and increases in cross-sectional area along the direction of flow are particularly liable to cause trouble from vapor lock. Experiments with commercial carbureters show that weathering of the gasoline in the carbureter float-bowl reduces the vapor-locking tendency of the fuel and, under certain conditions, may even cause an increase in the flow through the jet.

PREVIOUS reports on the investigation of vapor lock in airplane fuel-systems have indicated that the tendency of aviation gasolines to cause trouble from vapor lock could be predicted from the standard A.S.T.M. distillation-data on the gasolines. The present paper deals with experiments made for the purpose of comparing the predicted conditions for vapor lock with those actually found in typical fuel-feed systems to cause trouble from this source. In gravity-feed systems, the predicted and experimentally observed conditions for vapor lock are in good agreement. On the suction side of a fuel pump, vapor lock occurs in a number of cases at lower temperatures than those predicted, particularly under conditions representing high-altitude flying in a system employing a long suction-lift.

THE REPORT deals specifically with that part of the Bureau of Standards' program involving vapor-pressure measurements. A description is given of a method and apparatus for the removal of dissolved gases from dried gasolines, without appreciably affecting the propane content and without otherwise changing their composition. Vapor-pressure measurements with a small bubble of vapor present have been made on 10 motor gasolines over a considerable temperature range. Log p, 1/T plots of these data were found to be linear in the case of all the fuels within 1 to 2 mm. on the average, p representing the pressure and T the absolute temperature. The normal bubble-points (p = 760 mm.) of the 10 gasolines were shown to be equal to the 10-per cent A.S.T.M. temperatures, corrected for loss, within the accuracy of determining the latter.

THIS paper is a concluding report on that phase of the equilibrium-volatility work at the Bureau of Standards which is applicable to engine performance as affected by vaporization in the manifold. New data on bubble-points are presented and an improved method is outlined for obtaining temperatures on specific air-vapor mixtures from the experimental observations. By taking into consideration the slope of the A.S.T.M. distillation curve, the 16-1 temperature at any percentage evaporated from 0 to 100 per cent can be computed from the A.S.T.M. temperature with an average deviation of 1 deg. cent. (2 deg. fahr.) by means of simple relations which are applicable to pure hydrocarbons and hydrocarbon mixtures, of any degree of complexity, within the gasoline range. Values for other mixtures can be readily obtained from the 16-1 temperatures.

THE extension of the equilibrium-air-distillation work of the Bureau of Standards to more volatile fuels, requiring measurements at temperatures considerably below 0 deg. cent. (32 deg. fahr.) has shown that the general relations deduced from the previous work are equally applicable to natural gasoline and to straight-run aviation-fuels and to natural-gasoline motor-fuel blends. Data are presented on three ethylether blends with gasoline which give information on the amounts of ether to be added to gasoline for starting motor-vehicle or airplane engines at various temperatures. For comparison, data on two benzene-blends are reproduced from a previous report. A study of the entire mass of volatility data has indicated certain trends of the temperature ratios with the slope of the A.S.T.M. curve and with temperature.

FIRST referring to previous reports made on laboratory methods for measurement of volatility, the author states that data for a variety of gasolines, obtained by the equilibrium air-distillation method, have been analyzed recently in comparison with the distillation curves of these fuels as determined by the procedure practised by the American Society for Testing Materials. According to the author, this analysis appears to indicate a definite relationship between the results on volatility and those obtained by the standard A.S.T.M. distillation method, so that it seems possible to deduce from the latter with reasonable accuracy the information on volatility which is pertinent to satisfactory engine performance. It is stated also that volatility can be regarded as the tendency to escape into the vapor or gaseous state and this escaping tendency is determined by factors which must be precisely specified so that numerical values for volatility may have significance.