December 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
theory does not account. Of course, both of these factors may be involved. However, the data, particularly in the lean limit work, leaves much to be desired. It is fairly certain that the values for the high molecular weight compounds are not entirely consistent. The use of a relatively small diameter tube accentuates the effects of heat loss to the wall. Convection effects may be exceedingly variable. The use of a spark to initiate combustion near the limiting composition raises many questions as to energy requirements for initiating a sustained flame front. I n short, it is believed that the determination of true lean limits offers a fruitful area for future study both in the development of improved experimental techniques and in the understanding of other combustion phenomena. ACKNOWLEDGMENT
The author appreciates the cooperative assistance of many of the staff of Experiment Inc. In particular, he is grateful to H. F. Calcote, Ruth Gilmer, and C. E. Setliff.
2869
LiTERATURE CITED
(1) Calcote, H. F., Gregory, C. A., Jr., Barnett, C. M., and Gilmer,
Ruth B.. “Spark Ignition I. Effect of Molecular Structure,” paper presented at the 119th Meeting of the AMERICAN CHEMICAL SOCIETY, Cleveland, Ohio. Calcote, H. F., Gregory, C. A,, Jr., and King, I. R., “Spark Ignition 11. Effect of Initial Temperature and Pressure,” paper presented a t the 119th Meeting of the AMERICANCHEMICAL SOCIETY, Cleveland, Ohio. Gaydon, A. G., and Wolfhard, H. G., Proc. Roy. Soc. (London), 196, 105 (1949). Jost, W. (Croft), “Explosions and Combustion Processes in Gases,” New York, McGraw-Hill Book Co., 1946. Lewis, B., and von Elbe, G., J. Chem. Phys., 15,803 (1947). Semenov, N. N., Uspekhi Fis. Nauk, 24 (1940), translated by NACA TM No. 1026 (September 1942). White, A. G., J.Chsm. Soc., 1925,672. Zeldovich, Ya. B., and Frank-Kamenetsky, D. A., Acta Phusiwchim. U.R.S.S., 9, 341 (1938). Zeldovich, Ya. B., and Frank-Kamenetsky, D. A., J. Phys. Chem. (U.S.S.R.), 12, 100 (1938). RECEIVED July 27, 1961. Presented before the Division of Gas and Fuel Chemistry at the 119th LIeeting of the . ~ X E R I C A NCHEMICAL SOCIETY, Cleveland, Ohio.
SPONTANEOUS IGNITION TEMPER ATU RES Commercial Fluids and Pure Hydrocarbons JOSEPH
L. JACKSON
Lewis Flight Propulsion La boratory, National Advisory Committee for Aeronautics, Cleveland, O h i o
Aitempts to understand the effect of molecular structure of hydrocarbons on spontaneous ignition temperature, and subsequent correlations of these temperatures with other combustion phenomena, require self-consistent data for a large number of pure hydrocarbons. Various compilations of spontaneous ignition temperature have been published, but as they were comprised of data obtained by many investigators, many inconsistencies exist. The data presented here are self-consistent because they were obtained in the same apparatus, by the same techniques, and by the same investigator. Tabulated values of
spontaneous ignition, and ignition delay, as determined in a crucible-type apparatus, are presented for 94 pure hydrocarbons and 15 commercial fluids. Although absolute values of ignition temperature depend on the apparatus and test procedure, it is believed that these self-consistent data will be useful to investigators who are concerned with thermal ignition processes, such as those encountered in internal-combustion engines. The data should also be helpful in establishing the relative fire hazard of the fluids investigated in the presence of a thermal ignition source under quiescent conditions.
N CONJUNCTION with the aircraft fire problem and as a
have been made (4-6). In general, the value obtained for the spontaneous ignition temperature of any substance will be dependent on the pressure, the nature of the igniting surface, the combustible to air or oxygen ratio, the movement of the mixture relative to the surface, and the time allowed for ignition to occur. Both individual and relative values of ignition temperature of different substances vary widely in the reported .data from different investigators. For example, the values quoted in the literature (3) for the spontaneous ignition temperature of benzene in air vary from370’ to 1062’ C. (690’ to 1944’ F.),
I
corollary t o the combustion research a t the Lewis Flight Propulsion Laboratory of the NACA, it was desirable to have self-consistent data on spontaneous ignition temperatures of hydrocarbons and aircraft fluids. Compilations of spontaneous ignition temperatures have been presented ( I , 4 ) but they are composed of data determined by many investigators using a variety of methods. Since different methods were used, there is no basis for comparing the ignition temperatures of the combustibles listed and it appeared desirable to redetermine the spontaneous ignition temperatures of a variety of pure hydrocarbons, fuels, and other liquids using a single procedure. I n this paper are reported the spontaneous ignition temperatures of 94 pure hydrocarbons and 15 commercial fluids as determined by one investigator using one method. 9 survey of the methods used for the determination of ignition temperatures is given in reference (3) and more rece,nt studies
APPARATUS AND PROCEDURE
The apparatus used in this work was the Scott, Jones, and Scott ( 4 ) modification of the ASTM crucible-type method ( 2 ) . Spontaneous ignition temperatures were determined by raising the temperature of the’ block and periodically dropping a few
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
2870
Table
I.
Spontaneous Ignition Temperatures of Pure Hydrocarbons SpontanPous Time Lag Ignition a t Last Estimated TemperaIgnition Purity, ture, ' F . Minutes' % Hydrocarbon
+
Propane Butane Pentane Hexane Heptane Octane Nonane Decane Hexadecane 2-Methylpropane 22-Dimethylpropane %Methylbutane 2,Z-Dimethylbutane 2,3-Dirnethylbutane 2 2 3-Trimethylbutane Zlkethylpentane 3-Blethylpentane 2,3-Dimethylpentane 2,2.3-Trimethylpentane 2,2,4-Trimethylpentane 2,3,3-Trimethylpentane 2,2,3,3-Tetramethylpentane 2,3,3,4-Tetramethglpentane 2 4-Dimethvl-3-ethylpentane 3:3-Dimethylheptane 2-Methyloctane 3-hiethyloctane 4-iVethy1octane 2 3-Dimethvlootane 4:Ethyloctske 2-Ai ethylnonane
940 807 544 50 1 477 464 4.53 449 446 890 853 800 824 790 849 585 580 640
468 418
0.3 0.05 0.1 0.2 0.2 0.3 0.1 0.2 0.1 0.4 0.2 0.2 0.7 0.4 0.2 0.06 1.1 1.0 0.1 1.2 0.9 1.7
1-Pentene 1-Hexene 1-Heptene 1-Octene 1-Decene 1-Tetradecene 1-Hexadecene 3-Nethvl-1-butene 2-Methyl-1-pentene 4-Methyl-1-pentene 2-Ethvl-1-butene 2,3-Dimetbyl-l-butene 2,3-Diinethyl-2-butene 2,3,3-Trimethyl-l-butene 2,4,4-Trimethyl-1-pentene 2,4,4-Trimethyl-2-pentene 2 3 4-Trimethyl-1-pentene 3:4:4-Trirnethyl-2-pentene
669 521 505 493 471 463 464 706 582 380 615 697 764 721 788 587 495 626
0.3 1.2 1.1 1.2 1.3 1.1 1.3 0.1 0.1 0.2 0.1 0.1 0.1 0.2 0.2 0 5 0.2 0.4
98 95 98 98 98 98+ 98t 95 t 98 -t
Cyclopentane blethylcyclopentane Cyclohexane Methylcyclohexane Ethylcyclohexane 1-Nethvl-2-tert-butylcyclohexane 1-AIeth~l-3-tert-butyloyclohexane (high boiling isomer) l-Methyl-3-te1%-butylcyclohexane (low boiling isomer) Alpha-pinene dl-Limonene
725 614 518 609 ,507 597
0.1 0.1 1.7 1.8 1.9 0.2
90 95 98 99 Q8t 99
580
0.2
99
556 506 505
0.4
99
1097 1054 1046 1048 934 1039 970 89 5 860 905 902 836 759 851 844 853 873 821 853 836 891 861 1017 1071 936
0.7 0.8 0.9 0.7 0.5 0.8 0.4 0.4 0.3 0.3 0.2 0.3 0.1 0.2 0.2 0.2 0.1 0.1 0.2 0.3 1.2 0.2 0.4 0.6 0.2 0.3 0.3 0.2 0.3 0.1 0.1 0.1 0.1 0.1 0.3
Benzene Toluene 1 3-Dimethylbenzene (m-xylene) 1'4-Dimethylbenzene (p-xylene) 1'2-Dimethylbenzene (o-xylene) 1~3,5-Trimethylhensene 1.2.4-Trimethvlbenzene 1,2,3-Tnmeth~lbenzene Ethylbenzene l-I\.lethyl-3-ethglbenzene I - X e t hyl-4-ethylhensene 1-Methyl-2-ethylbenzene 1 2-Diethylbenzene 1:3-Diethylhensene 1.4-Diethvlbenzene Propylbenzene Isopropylbensene Butylhenzene Isobutylhenzene see-Butylbenzene lert-Butvlbsnzene l-RIeth~l-3,5-diethylbenzene 1-Methylnapht halene Biphenyl 2-Methylhiphenyl 2-Ethylbiphenyl 2-Propylbipheny 2-Butylbiphenyl Diphenylmethane 1,l-Diphenylethane 1 1-Diphenylpropane 1:l-Dil;henylbutane 1-Eth lnaphthalene Tetraxydronaphthalene Decahydronaphthalene
816
837 806 845 818 734 626 440 112 450 447
840
845 811 962 909 870 863 898 794
521
0.1 0.1 0.4 0.5 0.5 0.9 1.1
0.9
1.1
1.0
0.5
98 98 98 98 98 98+ 98 98
++ + +
++ 98 f 98 + 98 + +
98 Q8+ 98+ 98 98 98 Q8+ 98 98
++ + ++ 98 + 98 + 98 + 98 +
;:$+ 98 98+ 98 98 98
++ +
98f 98498 98 98 Q8
++ ++
E I: 95+ ++
++ +
++ + +
+
+ + 98 + 98+ 99 + 99 + Q9 + 99 + 99 + 99 + 99 + 99 + 99 + 99 + 99 +
99 I 99 9Q 99 99 99 99 99 99 f
++ ++ ++ +
QQ
+
Wt
+ + + ++ + ++
99 99 99+ 99 99 99 99 99 89 99 95+ 96 f
+
Table
11.
Vol. 43, No. 1 2
Sponteaneous Ignition Temperatures of Fuels and Commercial Fluids
ala terial Aniline Chlorinated wax Diphenyloxide Hexachlorobutadiene Hexachlorodiphenyloxide n-Butyl alcohol Perfluorodimet hylc yclohexane Tricresylphosphate Tetraarylsilicate Aviation fuel 100/130 grade, 4 mi. tetraethyllead per gallon Gasoline Low volatility (49'7, aromatics) Low Yolatility (20% aromatics) Kerosene S.A.E. S o . 10 Lube oil S.A.E. No. 60 Lube oil
Spontaneous Ignition Temperature, F. 1100 770 1195 1144 1163 678 1204 1112 1070
Time Lag at Last Ignition Minutes' 0.1 0.1 0.2 0.1 0.01 0.3 0.1
844
0.1 0.1 0.2 1.1 0.02 0.1
943
900 480 720 770
o:i
drops of the combustible into the flask until ignition Tvas observcd. The temperahre of the block was then slowly lowered and the amoolnt of added combustible varied until the lowest temperature for ignition was found. If the substance is normally a gas a t room temperature, it was liquefied in dry ice. Biphenyl, which is a solid, was melted to obtain a liquid. Experiments indicated that the temperature of the liquid had Mtle or no effect on the ignition temperature. I t has been shown by Sortman, Beatty, and Heron (G) that zones of nonignition appear for some compounds a t temperatures above their minimum ignition temperatures. Since these zones may not appear for all fuel-air ratios the fuel-air ratio was varied in this study over wide limits, with repeated trials at lower temperatures, to eliminate the interference of such zones. Two minutee xere allowed for ignition to occur and t,he flask was purged with air betll-een each test. The t,irne required for ignition to occur was measured by a st,opwatch and varied from about 1 second to alniost 2 minutes. This time lag is not an independent variable in spontaneous ignition testing. For a given combustible, shorter time lags are observed for higher temperatures, hut the time lag at the minimum ignition temperature varies widely for various types of combustibles. Khile it is possible to select some relatively short time lag and determine the ignition temperatures of all combustibles a t this selected delay, the data presented herein are the minimum ignition temperatures and the time lags listed are at this minimum temperahre. DISCUSSION
The spontaneous ignit'ion temperatures and time lags of the pure hydrocarbons are given in Table I. Also listed in this table are the estimated purities of the compounds, most of which, Kith the except,ion of the butenes and cycloparaffins, were obtained from the Sational Bureau of Standards or the S A C A Lews Flight Propulsion Laboratory. The data for the commercial fluids are presented in Table 11. The ignition temperatures were reproducible to * s o F. Khile it is recognized that the absolute values may have doubtful meaning since the ignition temperature is dependent t o a great extent on the met'hod of its determination, it is believed that the relative order of the compounds is significant since the spontaneous ignition temperaturrr reported here were determined by one operator in one apparatus. LITERATURE CITED
(1) Associated F a c t o r y Mutual Life Insurarice Co., IND.ENG.CHEM., 32, 880 (1940). (2) "ASTRI S t a n d a r d s on Petroleum P r o d u c t s and L u h i i c a n t s , " pp. 199-200, Philadelphia, American S o c i e t y for Testing M a t e r i a l s , 1948.
(3) D u n s t a n , S a s h , Brooks, a n d Tizard, "Science of P e t r o l e u m , " vol. IV, pp. 2970-5, Oxford, E n g l a n d , Oxford University
Press, 1938. (4) S c o t t , G. S., Jones, G. W., and S c o t t , F. E., Anal. Chem., 20, 238 (1948). (5) S o r t m a n , C. IT-., Beatty, H. F., a n d Heron, S. D., IND.ENG. CHEM.,33, 357 (1941). (6) T a y l o r , C . F., S.A.E. @cart. Tiuns., 4, No. 2, 232 (April 1950).
RECEIYEDNovember 13, 1950.
END OF SYMPOSIUM
