December, 1930
INDUSTRIAL AND ENGINEERING CHEMISTRY
1301
Progress toward a Uniform Method of Measuring Detonation' Synopsis of Report of Subcommittee on Methods of Measuring Detonation of the A. P. I. Cooperative Fuel Research Steering Committee T. A. Boyd, Chairman GEXERAL
MOTORS RESEARCH LABORSTORIES,
DETROIT,
MICH.
This paper gives an account of the work of the SubHERE are three things in the main the engine apcommittee on Methods of Measuring Detonation of the which are essential to a pears to be suitable for the Cooperative Fuel Research Steering Committee. It purpose, and it is believed uniform m e t h o d of was prepared by the chairman of the subcommittee that approval of a tentative measuring t h e a n t i k n o c k with the cooperation of the members. The complete apparatus can soon be made. qualities of fuels: (1)a standmembership of the subcommittee is as follows: D. P. ardized engine and accessoThe elements of cheapness, Barnard, Standard Oil Company (Indiana); T. A. ruggedness, and d e p e n d a ries, (2) a common reference Boyd (Chairman), General Motors Research Laborability have been kept upperfuel or scale of fuels, and (3) tories; H. K. Cummings, Bureau of Standards; H. C. most in the engine develop a uniform p r o c e d u r e . AlDickinson, Bureau of Standards; Graham Edgar, ment. though only the engine apEthyl Gasoline Corporation; J. Bennett Hill, Atlantic A great deal of experimentpears to have been specified Refining Company; H. L. Horning, Waukasha Motor ing has been done on the in the original assignment to Company; Neil MacCoull, Texas Company; C. B. Veal essential accessories for the the subcommittee on Meth(Secretary), Society of Automotive Engineers. engine, particularly on means ods of Measurine Detonation. all three items cave been re: of carburetion, on power-abwiving the attention of the group in the order named, since they sorbing media, and on indicating devices. The important are so intimately associated that they cannot be effectively matter of carburetion has been delegated to a special group separated from one another. composed of D. P. Barnard, D. B. Brooks, and the following The antiknock value of a fuel obtained in any given case is carburetor experts who have consented to assist in this work: determined not altogether by the properties of the fuel under 0. C. Berry, of the Marvel Carburetor Company; C. S. test. It may be, and often is, affected in large degree by the Kegerreis, of the Tillotson Manufacturing Company; and engine and by the conditions and method under which the F. C. Mock, of the Bendix Aviation Corporation. engine is operated, as well as by the composition or charOn account of especial suitability for controlling engines acteristics of the standard with which it is compared. Thus, during experimental work, electric dynamometers have thus the percentage of benzene in a given fuel that is equivalent far been used as power-absorbing media in this development. in knock rating to some given concentration of lead tetraethyl Although the ultimate power-absorbing device that is most in the same fuel in not a uniform quantity irrespective of the suitable cannot be definitely settled until the method has conditions of test. It is affected in large degree by the car- been selected, enough information and experience has alburetor setting, by the spark advance, and by the temperature ready been obtained to make it appear that, when the time at which the determination is made, as well as by other factors, comes to do so, the matter of agreeing upon a suitable means such as the composition of the basic fuel used in the tests. of absorbing the output of the engine will not be difficult Inasmuch as the measurement of detonation is thus not a t or time-consuming. The important matter of instrumentaall a simple matter, it has been the aim of the subcommittee tion is one on which much work is being done, for instrumentato arrive at a combination of apparatus, method, and refer- tion is so intimately tied up with method that the best method ence scale which will yield results approximating as closely of test to use may ultimately hinge in part upon the instruas possible those obtained in representative service. mentation that is available.
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Standardized Engine and Accessories
Uniform Scale of Fuels
The 6rst action of the subcommittee was to pool their experience in the measurement of detonation, and on the basis of the result to draw up specifications covering the essential features of a tentative engine. Both a variable-compression and a fixed-compression model were included. Engines conforming as closely as possible to these specifications were then designed by H. L. Horning, and a small number were built in his factory and distributed to the laboratories of the subcommittee members. Next, as a means of determining the suitability of the engine, a cooperative program of tests was carried out on a series of special fuels which had been circulated for the purpose, utilizing different methods under controlled conditions. As is usual with new mechanical equipment, the results of these tests pointed to certain changes that should be made in the apparatus, and these are now in process of being incorporated. However,
The second essential to a uniform method of knock rating, which is a common scale of reference fuels, has already been settled in a tentative way by the adoption of normal heptane and isooctane (2,2,4-trimethylpentane)as primary standards. Mixtures of these two hydrocarbons form a scale of antiknock quality, the use of which has been approved as recommended practice by the Cooperative Fuel Research Steering Committee. By the plan adopted, the antiknock values of fuels are to be expressed in terms of octane number. Octane number has been defined to mean the percentage of isooctane by volume in the mixture of isooctane and normal heptane required to match the antiknock value of any given fuel. An effort is also being made to provide secondary fuels of designated octane numbers, in order that uniform reference fuels may be available in amounts adequate for routine work. The thought is, not that those laboratories which already have a scale of antiknock quality should a t once abandon
Received October 18, 1930. From paper presented at the Meeting of the American Petroleum Institute, Chicago, Ill., November 10 to 13, 1930.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
1302
it in favor of this new octane number scale, but rather that everyone should establish the relationship between his own scale and this one which is expressed in terms of octane numbers, in order that all investigators may be enabled to get on a common basis of reference, or that all may begin to talk a common language. It is recognized that, since the method and the conditions of test have a considerable influence upon the results obtained, determinations in terms of octane number may be only approximate for the present. But when both a definite apparatus and a specific method of test shall have been chosen, it is expected that this difficulty will be largely or altogether overcome. Uniform Procedure
As a means of putting the matter of knock-testing on a sounder basis, the Bureau of Standards and the different cooperating laboratories have been investigating the effects of the outstanding variables that influence the measurement of detonation. These include such factors as speed, temperature, compression, spark timing, atmospheric conditions, mixture ratio, and the like. The results of some of this work have already appeared in the literature, and a symposium on it is scheduled for the next meeting of the Society of Automotive Engineers. Accomplishments of Subcommittee
On account of the considerable time necessarily involved in getting the engines and accessory equipment designed, built, and delivered to the respective laboratories, most of the testing work of the subcommittee has been done during the current year. The effectiveness of the experimental work at the Bureau of Standards during the period has been largely increased by the special contribution of $5000 for the support of this work by a number of interested oil companies. This endeavor differs from some of the previous work done under the auspices of the Cooperative Fuel Research Steering
Vol. 22, No. 12
Committee in that, although m usual the experimental work is centered primarily in the endeavor at the Bureau of Standards, it is also being actively participated in at the laboratory of each one of the subcommittee members. Once a tentative apparatus can be approved, it will probably be made generally available a t once without waiting for further developments. It is expected that thereafter the scope of experimentation within the two industries concerned on further phases of the problem will be greatly extended. As giving some indication of the amount of work that has already been done within the Subcommittee on Methods of Measuring Detonation, it may be said that since its organization (and up to September 15, 1930) the group has held twenty-two meetings. With very few exceptions these meetings have been held at the time and place of some other gathering, which has been attended by representatives of both of the two industries interested. Following custom, the meetings of the subcommittee have been opened to anyone who wished to attend, and they have been largely attended. At sixteen of these twenty-two meetings, there was a perfect attendance and a t none were more than two members of the subcommittee absent. Cooperation of British Group
The subcommittee is fortunate in having the cooperation in this endeavor of a similar group in England. The British group is composed of the following key members: A. E. Dunstan, of the Anglo-Persian Oil Company; F. H. Garner, of the Anglo-American Oil Company; and J. Kewley, of the Asiatic Petroleum Company. The importance of this international cooperation is twofold.' There is, first, the help that the British group will give in arriving at a sound method, and, second, the benefit of the comparability and interchangeability of data that will arise from the resulting universality of apparatus and method over a large portion of the world.
Preparation of Metal Powders b y Electrolysis of Fused Salts I I-T horiurn1 F. H. Driggs and W. C. Lilliendahl WBSTINGHOUSB L A M P C O M P A N Y , BLOOMBIBLD, Nb
HE successful application of the electrolytic method to the preparation of uranium (1) suggested the possibility of its use in the production of metallic thorium. The electrolysis of anhydrous thorium chloride in fused potassium and sodium chlorides was attempted by Moissan and Honigschmidt (3) in 1904. Graphite rods were used as electrodes and the salts were fused in a porcelain crucible. A spongy mass was obtained which consisted of a large amount of oxide. No analysis of other impurities such as carbon, silicon (from the crucible), etc., is given. Von Wartenberg (4) used practically the same method, but substituted a carbon crucible for the porcelain one used by Moissan and HonigSchmidt. The metal obtained analyzed 87 to 88 per cent thorium, with the remainder consisting of thorium oxide, iron, carbon, and silicon. The two chief difficulties which the above experimentera encountered were: (1) the introduction of carbon when a carbon cathode was used; (2) the difficulty in working with the unstable thorium salt (ThCl,), which is easily hydrolyzed
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1 Received
September 23, 1930.
Ja
in air and volatile a t high temperatures. I n the work to be described a more stable thorium salt was used and the carbon cathode eliminated by substituting molybdenum, which does not alloy with thorium at the operating temperature of the bath. Preparation of Potassium Thorium Fluoride
It was first necessary to obtain a thorium salt which would be more suitable than thorium chloride for electrolysis in fused baths. To fulfil this requirement it should be anhydrous, stable in air, easily prepared, and dissolve in fused baths without decomposition. The double salt potassium thorium fluoride (KThFa) seemed to meet this requirement in every respect. This salt was prepared by dissolving 1000 grams of thorium nitrate (48% Thoz) in 5 liters of water, and adding 640 grams of potassium fluoride dissolved in 1000 cc. of water with constant stirring. The precipitate (KThF6) was allowed to settle and was washed by decantation until the wash liquors gave no test for nitrate. It waB then filtered and dried a t
