Effective Storage Temperatures of Gasoline DESERT STORAGE TESTS ON MOTOR AND AVIATION GASOLINE DANIEL B. LUTEN, JR., AND KENNETH HEDBERG' Shell Development Co., Emeryville, Calif.
D
URING the early stages of World War 11,when intense desert warfare was foreseen, i t was realized that gasoline used in such operations would require a degree of stabilization against oxidative deterioration far in excess of the normal peacetime requirements for most of the United States. Obvious factors contributing to such high requirements are high summer temperatures, the exponential effect of temperature on rate of deterioration, and the necessity for prolonged storage of gasoline in theaters of military operations. The subject of specifications for Army all-purpose motor fuel (Specifications 2-103A and 2-103B) was considered a t a meeting of refiners called in December 1942 by the Ordnance Department; the problem of oxidation stability was referred to the Coordinating Research Council and, in turn, to the Gasoline Additives Group of the CFR Motor Fuels Division for study and recommendation. At a subsequent meeting of Ordnance representatives and the Gasoline Additives Group, it was agreed that the all-purpose gasoline should contain not more than 7 mg of ASTM gum ( D 381-42) and be free of lead precipitation after 6 months' storage. This storage was t o be in 5-gallon blitz cans or in 55-gallon black iron or galvanized drums in the open air without protection from the sun anywhere on earth, Based on this information, i t was the problem of the group to determine the most severe temperatures likely to be encountered, to determine the degree of stability required to withstand such conditions, and to recommend an accelerated test suitable for predicting storage stability under these conditions. A coordinated investigation of field storage deterioration and laboratory storage and accelerated deterioration was begun in the spring of 1943 and continued through 1946. Some of the results of this and derivative investigations have been published (1, 8, 19). Preliminary consideration of available temperature records by Keyser and Kuhn (8) indicated that summer temperatures in the Imperial Valley, California, would equal those to be encountered in any possible theater of operations (more detailed examination of climatological data indicates a few slightly hotter localities: Khartoum, Massaua, Iraq, Drath Valley). They also concluded that drum storage in the Imperial Valley during the 6 summer months would be equivalent to laboratory storage a t 110' F. for the same length of time. On the basis of these conclusions Camp Seeley of the Ordnance Test Command was chosen as the site for the 1943 storage program. Camp Seeley is in the Imperial Valley 8 miles west of El Centro and the same distance southwest of Imperial a t about 32.5" north latitude and 115.3" west longitude. The nrarest permanent cooperative observers for the U. S. Weather Bureau are a t Imperial and El Centro. Camp Seeley proved to be somewhat hotter than either of these stations, probably because the prevailing winds are westerly and Camp Seeley lies to the west of the irrigated area surrounding the towns. In 1944, Camp Seeley was closed, and the program was continued a t Blythe Air Base ("Blythe Air Port"), about 5 miles west of Blythe, Calif., at 33.6' north latitude and 114.6' west longi1 Present address, Crellin Laboratory, California Institute of Teohnology, Pasadena, Calif.
tude. The air base is about 5 miles west of Blythe, above the irrigated bottomlands of the Colorado River, and is hotter than the town. Climatological data have been obtained a t Blythe for many years and a t the air base for the few years since its establishment (18). OBJECTIVES OF STUDY
Control of the storage program obviously required detailed temperature records. These were obtained; their analysis has been described by Shepherd (18). I n addition, a quantitative relationship between atmospheric temperatures and gasoline storage stability was sought. This article summarizes the search for a means of predicting the storage stability of any gasoline of known stability characteristics and temperature sensitivity in any location for which standard meteorological data are available. This problem has been attacked in the following steps: Development of a means of interpreting the observed shortperiod fluctuating temperature experience of gasoline in a small container in terms of a single effective gasoline temperature. Correlation of effective gasoline temperature with coexisting air temperatures. Extension of this relationship to long periods by the use of available climatological data. Comparison of the long-period effective gasoline temperature thus derived from temperature observations with the effect'ive temperature of gasoline calculated from its observed rate of gum formation. A prerequisite to a solution of this problem is a knowledge of the effect of temperature on the oxidative degradation of gasoline in the presence of limited amounts of air. This has been shown (20) to be affected by temperature in the same manner as most chemical reactions. The relationship may be expressed by the Arrhenius equation in the form log,, t = A
+ BIT
(1)
where t is the time required for a specified degree of degradation to occur-e.g., formation of 7 mg. of gum--T is the absolute temperature, A is a constant characteristic of the gasoline and the specified degree of degradation ( A is of no concern in this investigation), and B is a constant characteristic of the gasoline which is determined by the magnitude of the effect of temperature. The value of B varies for different gasolines, but is ordinarily in the neighborhood of 5500" K. (9900' Rankine) and rarely is less than 5000" or greater than 6000" K. Gasolines containing significant amounts of xylidines must be considered exceptions; the value of B in such cases is markedly less than 5500". While it is certain that the value of B varies, it is doubtful in any individual case, in view of the experimental difficulties in determining B, whether the difference between the actual value and 5500' is real or experimental error, The authors have used 5500' in all calculations requiring the use of Equation 1 in this investigation. MATERIALS AND EQUIPMENT
Examination of the earlier data summarized by Keyser and Kuhn (8) suggested that it is important to know the temperature of the gasoline in all parts of the container over the entire period of the daily cycle, if effective temperature is t o be determined.
2098
INDUSTRIAL AND ENGINEERING CHEMISTRY
September 1953
Accordingly, a drum was equipped with 20 thermocouples distributed throughout its volume and arrangements were made for army personnel to obtain the necessary data. This drum was set up a t Camp Seeley in late July 1943, and work with it was commenced immediately.
c
a
The drum was a reconditioned ICC 17C Trisure flanged 55gallon steel drum. Six thermowells were placed in it. The thermocouples were iron-constantan and were welded t o the thermowells to provide better contact and to prevent change in their positions within the wells. The construction of the thermowells, their positions in the drum, and the location of the couples in the wells are detailed in Figure 1. Two thermometers were placed in the drum head; the bulb of one was in the vapor and the other was just immersed in the gasoline. The drum was filled with 50.0 gallons (at 68" F.) of depentanized 190" F. end-point straight-run gasoline (calculated by weight). The entire group of thermocouple leads was gathered into one cable leading t o the selector switch box. The switch box was connected by copper leads to the potentiometer; the reference junction was, therefore, in the switch box. Two potentiometers were used during the investigation, a Leeds and Northrup and a Lewis. Each of these was sensitive to 1" F. and had automatic reference junction temperature compensation. All instruments were kept in a louvered cabinet to shield them from the sun and the hot ground. Determinations made at the time of installation showed that temperature gradients and lags within the switch box and the potentiometer would give rise to serious errors. Accordingly, one thermocouple (No. 10) was disconnected a t the switch box and replaced by another one which was placed in contact with the bulb of the thermometer used a s the primary air temperature reference. This couple was then used to calibrate the entire system a t each inspection. I n 1944, the drum was set up a t Blythe, but only seven carefully chosen thermocouples of the 20 were used. A blitz can equipped with 12 thermocouples was constructed (see 1.3 for details), and the leads were connected to the selector switch in place of the unused drum couples. Construction methods were the same as for the drum. The reference junction, No. 10, was taped to a thermometer, which was then placed in a Dewar flask full of oil. This procedure eliminated small temperature drifts due to ground radiation which were observed during the previous year when-
~4"O.D.*20 90Steel Tubing
?-
0
Thermocouple
I
..
a
Figure 1. Thermocouple Arrangement in Drum for 1943 Measurements of Gasoline Temperature Use of switch point for No. 10 thermocouple was modified (see text). Encircled thermocouple numbers give loaatipns and numbers used in 1944
2099
ever the cabinet door was opened. Another thermometer was employed for air temperatures. A11 thermometers were compared to standard thermometers and were found to be accurate to within 1' F. GENERAL OBSERVATIONS
The 1943 test program covered the six hottest months of the year-May through October. In 1944 the program was started a month later; this, combined with the fact that the summer of 1944 was cooler than that of 1943, resulted in substantially less severe tests in 1944 than in 1943. During this portion of the year there is ordinarily very little rain in this region, but partly cloudy weather is common. In addition to the deviation from a regular daily pattern of temperature caused by such cloudiness, there is a considerable fluctuation of temperature at longer intervals, which results from variations in the flow of air eastward from the coast. I n general, however, the daily air-temperature cycle follows a uniform pattern. Minimum temperatures are reached usually just before sunrise.
A rapid and sustained increase in temperature starts a t 8
A.M.
and lasts until 2 P.M. during the summer months, with the maximum temperature a t about 4 P.M. After sunset there is a sharp decline in temperature until the middle of the night and a slower and, commonly, irregular decline from then on until sunrise. The mean daily temperature range is of the order of 30' F.
So far as the gasoline in an upright drum is concerned, the daily cycle is as follows (All times quoted in tables are Pacific War Time. To obtain mean sun time, subtract 45 minutes for Camp Seeley and 40 minutes for the Blythe test site.): Starting on a summer morning a t 5 :30 A.M. when atmospheric temperature has just begun t o increase, the temperature within the drum is a t its minimum for the 24-hour period and is fairly uniform throughout the gasoline, except for a few erratically distributed regions where there are small temperature variations. These appear to be the residual effects of the previous day's convection currents. The difference between the coolest and the hottest portion of the drum is not likely to exceed 2"F., and the mean temperature is only about 3" F. above atmospheric temperature. The vapor space has begun to warm up even before sunrise and is perhaps '5 F. above the gasoline temperature. At 7:30 A.M. the increase in temperature is small, but temperature stratification is present. The isotherms are horizontal planes through the gasoline. The vapor temperature is climbing more rapidly than that of the liquid surface. At 9: 30 tem erature is increasing rapidly, and the temperature gradient from gottom to top of the drum is much increased, particularly on the south and east sides-Le., the isotherms are tilted downward to the southeast-where it may exceed 15" F. [There appear t o be no sharp temperature gradients a t the wall of thp drum. Some of the measurements summarized by Keyser and Kuhn (8) showed t h a t wall temperatures were little if any higher than temperatures in the center of the drum.] The vapor temperature is increasing by 10' F. per hour, or more. By 11:30 the maximum gradient is at the south side of the drum and the magnitude of the gradient throughout the drum has begun t o diminish. At 1:30 P.M. the isotherms are again virtually horizontal surfaces and remain so for the rest of the day. The vapor temperature has reached its maximum of 15" t o 20' F. above the liquid surface. The total temperature gradient in the gasoline is about the same a t 1 :30 as at 11:30, but all the temperatures are much higher. At 3:30 P.M. the air temperature reaches its maximum, while the vapor temperature is already dropping rapidly. At 5 :30 P.M. the maximum gasoline temperature is encountered. The gasoline temperature has increased steadily during these 4 hours, but usually least at the top of the drum. The cooling off process which now sets in is most rapid from 5:30 t o 9:30 P.M. The temperature gradient diminishes steadily throughout the night and has almost disappeared by dawn. There appears to be no accumulation of heat over longer than daily periods. Even though the drum never quite cools off to air temperature (the blitz can does), the difference between minimum drum temperature and minimum air temperature does not increase through the summer. Larson has reported a seasonal retention t o occur in tanks as large as 50,000 barrels ( d ) . The
2100
INDUSTRIAL AND ENGINEERING CHEMISTRY
Yoi. 45, No. 9
a t an arbitrary reference temDAT-4 SHEET DURING 1943 S E A S 0 3 AT CaMP S E E L E Y FOR DRUM TEMPERATCRE perature, for degradation equal TABLE I. TYPICAL XEASUREMENTS~ COXTAISERIS UPRIGHTPO~ITIOX to that occurring in the interval July 2 5 , 1943 July 26, 1943 is calculated from Equation 2 Cb C PC PC PC PC PC PC c c c PC or Table 11. These values are Xoa-ind 1 0 N E 10 N E 3 PjE 5 P;E 5 NE 10 W 1 O W 5 W Nowind 5 S W summed to give the total time, Time Begun and Finished a t the reference temperature, 7:35A.M. 9:35 11:16 1 : 4 0 ~ . M . 3:30 5:25 7:30 9:25 11:31 1 : 2 5 A . ~ . 3:25 5 : 2 0 7 : 4 1 ~ . ~9:47 . 11:31 1 : 4 6 ~ . 1 1 .3:36 6:40 7:40 9:37 11:45 1:37a.x. 3335 5:32 required for the degradation ThermoDrum couple X o . Temperature, F. ___ __ experienced in the original in1 89 104 122 130 113 127 121 108 99 95 89 83 91 108 terval, and this sum, when 125 131 2 115 111 136 126 101 85 96 9a 92 110 3 127 117 138 128 133 112 101 86 96 90 divided by the original time 95 118 134 122 141 130 4 138 114 103 87 91 98 89 104 121 131 122 127 112 109 5 98 94 89 8-1 interval, givea the relative 91 109 131 6 123 137 127 116 111 100 86 96 90 severity of storage. Then, 93 132 117 7 111 126 139 129 112 101 91 96 86 96 120 137 134 8 125 141 130 101 114 97 91 87 from Equation 2 or Table 11, 91 108 130 124 9 114 136 126 110 99 84 84 94 92 110 116 109 10 115 121 106 92 98 82 88 80 the single temperature which 134 125 96 11 118 138 142 128 111 89 98 85 95 112 gives the same relative severity 12 90 106 135 123 123 129 108 100 89 86 97 115 132 92 110 R 137 125 127 13 110 101 86 I.7 of exposure, compared to the 134 123 137 96 122 14 141 127 112 101 87 98 129 90 306 123 111 133 122 108 99 15 83 93 reference temperature, is 127 116 131 93 108 111 138 126 16 100 85 95 found. This is the effective 122 96 116 133 I36 112 17 141 129 102 86 96 112 91 104 123 128 134 123 18 108 99 86 93 temperature for the prriod in 94 110 127 116 131 112 138 127 19 101 87 95 96 117 133 137 20 122 113 142 101 129 96 88 question. 152 Vapor 105 134 144 155 145 126 111 101 95 96 96 The relative severity of Liquid 118 97 127 143 surface 138 108 147 134 118 101 91 90 n, is due to the temstorage, 119 Air 106 90 114 116 96 120 111 104 86 89 93 perature difference of t x o sama Primary data for 1913 are given in full in ( 6 , pp, 212 ff.). ples over the same time interC = clear, PC = partly cloudy, CL = cloudy, 0 = overcast. Wind velocity in miles per hour and wind direction are indicated b y figures only and dircction-cg., 5 K E = 5 miles per hour northeast wind. val; it can also be expressed as All thermocouples but 10, 10 are for drum: No. 10 is reference thermocouple, and is to be compared t o "air temperature." the ratio of times of storage of the two samples a t the reference temperature. I t is calculated from authois do not know a t TT hat size such seasonal letention u ould begin, but suspect that a 250-barrel tank mould show it. When the drum is lying on its side, the situation dlffers apprcwhere T,is the reference temperature, 1 is the actual time of ciably only in that the temperature gradientP ma?; be as high a$ storage a t temperature T, and t' is the equivaleut time of storage 20" F. or more, and that the top of the gasoline reaches a masia t the reference temperature, T,. Such calculations are vastly mum temperature by about noon and iemains there until 5 P.x., facilitated by the tabulation of equivalent t,inies in Table 11. while the lower layers continue to heat up. IVhen T is some function of time, y(l), the relative severity of PROCEDURE storage over a period of time, iz - t l , is 0
~
The drum was painted a somewhat glossy black R hen first set up. Observations mere made a t intervals of 2 hours for 4 consecutive days while it was in this condition. I t was then painted olive drab (not infrared-reflecting) and 4 more days' readings n-ere taken without interruption. Then it was laid on its side with the anis pointing north and south. Four days' readings were taken in this position without interruption. Following this series it was again placed on end and readings taken one day cach week until the end of October. In 1944 both the drum and blitz can, painted olive drab, were used. During July, readings were taken two days out of each week, a t 2-hour intervals, with the drum and can alternatelv standing and on their sides. From August until November the same alternating Grocedure was employed but readings were taken only one day each week. A sample data sheet is given in Table I. EFFECTIVE TEMPER4TURES
The effective temperature may be defined, as follows: If a body of gasoline is stored for a given period of time a t fluctuating temperatures, a specific amount of degradation (gum formation) will occur. If the gasoline is stored a t a uniform temperature for the same length of time, other things being equal, there is some one temperature where the same amount of degradation r i l l occur. That is the effective temperature. The effective temperature may be determined by direct observation of gasoline deterioration, or estimated from temperature determinations, as follows: After the time interval of interest is broken into small portions having essentially constant temperatures, the time for each of these portions which is required.
n =
10"iTr
I;$
(3)
loalscod! (t2-td
The effective temperatmure. E ( T , B):;,is the T,for which n whence
=
1,
Since y ( t ) cannot ordinarily be defined, this equation is of little value here. Sherman (14) has evaluated the integral for certain simple cases. Use of Table I may be illustrated by a simple example: Suppose a sample of gasoline is stored for 1 hour a t each of the following temperatures: go", 110", and 130" F. The mean temperature of storage is 110" F., but the effective temperature is higher and is calculated as follows: 1 hour a t 90" F. is given in the table as equal to 0.48 hour at 100" F., 1 hour a t 110' F. equals 2.04 hours a t 100" F., and 1 how a t 130" F. equals 7.95 hours a t 100' F.; the 3-hour storage peiiod is equivalent t o 0.48 2.04 7.95 = 10.47 hours at 100" F. I t is, then, 10.47/3 = 3.49 times as severe as storage a t 100" F. The temperature at which storage is 3.49 times as seveie as a t 100' F. is, from the table, 117.7' F. This is the effective temperature. (The effective temperature is never less than the true average temperature, hut may be less than a n approximate average, as, for example, the mean of the maximum and minimum temperature for a 1day period,) The severity of storage is calculated to be greater by a factor of 1.7 than if the mean temperature were taken as the criterion of storage severity. If the three temperatures had been 105", 110°, and 115' F., the mean temperature mould be 110' F. and the effective tem-
+
-+
INDUSTRIAL AND ENGINEERING CHEMISTRY
September 1953
perature 110.8" F. I n this case the severity of storage is 1.05 times greater than indicated by the mean temperature ahd the difference is not significant. on the basis that if a In general, the authors have group of temperatures lice within a range of 100F. there is no significant difference between the effective and arithmetic averages. They have tried to avoid repetition of this sort of averaging, because it might lead t o significant errors; thus, a find result might include data covering a range much greater than 10" F. REDUCl'ION O F DATA TO EFFECTIVE TEMPERATURE
-
The reduction of data from the drum started with the correction of the observed temperatures for the difference between the No. 10 thermocouple and the observed air temperature (or refer-
BETWEEN TABLE 11. RELATIOXSHIP
REQL-IREDFOR
TEMPERATURE A N D
GIVENDEGREEO F DETERIORATION GASOLINE FROM EQUATION: A
TIME OF
~ 0 9 Q O O/668.8 n = (1 hour at
T.
F. 150
28.27
149
26.60
148
25.00
147
23,48
146
22,09
145
20.73
144
19.48
?L
An
1 67
1
T
=
T. ' F.
n 2 35 *
111
2 19
1 39
143
18.30
142
17.20
1 36 1 25 1 18
141
16.14
140
15.16
110
2 04
109
1 91
108
1 78
139
14.22
138
13.34
137
12.52
136
11.74
135
11.01
134
10.31
133
9 67
632
9,06
131
8.49
630
7.95
129
7.44
128
6.97
127
6.52
626
6.11
125
5.72
0 98
0 88 0 82
107
1 65
106
1 54
10:
1 44
104
1 34
103
1 24
102
1 16
101
1 08
100
1 000
99
0 929
98
0 864
97
0 803
96
0 746
95
0 692
0 70 0 64
0 61 0 57 0 53
94
0 643
93
0 597
92
D
0 51
124
5.35
123
5.00
122
4.67
121
4.37
120
4.08
119
3.81
118
3.56
117
3.32
116
3.10
515
2.90
114
2.70
113
2.52
0 47
0 45
0 41 0 39 0 37
0 35 0 33 0 30
91
0 25 0 24 0 22 0 20
0 20 0 18 0 17
554
0 614
90
0 476
89
0 442
88
0 410
87
0 380
86
0 352
85
0 325
84
0 302
83
0 279
82
0 258
81
0 239
80
0 221
79
0 204
78
0 189
77
0 174
76
0 161
0 29 0 27
0 16
0 13
0 13
T, OF.
n
75
0.149
74
0.137
73
0.127
72
0.117
71
0.108
70
0.0996
69
0.0918
68
0.0846
67
0.0778
66
0.0717
65
0.0659
An 0.012
0.010 0.010
0.009 0,0084
0 11
0 11
0.0078 0.0078
0 10
0 78
0 73
An
0 13
1 10
0 94
+ 469.81
0 15
1 60 1 52
)
n hours a t 100' F.)
112
1 06
n.
1089W/[T('F
0 10 0 08
0.0068 0.0061 0,0058
0.0051
0 08 0 08 0 071
0 065 0 061 0 057 0 054
64
0.0608
63
0.0559
62
0.0514
61
0.0476
60
0.0435
59
0.0400
58
0.0367
57
0.0337
56
0.0309
55
0.0284
54
0.0261
0.0049 0.0045 0.0038 0.0041 0.0035 0.0033
0 049 0 046
0 043 0 040 0 038
0.0030 0.0028 0,0025
53
0.0239
52
0.0219
51
0,0201
50
0.0184
0.0023 0,0022
0 034
0 032 0 030 0 028
0 027 0 023
0 023 0 021 0 019 0 018 0 017
0 015 0 015
0 013 0 012
49
0.0168
48
0.0154
47
0.0141
46
0.0129
45
0.0118
0.0020 0.0018 0.0017 0.0016 0.0014
44
'
0,0098
42
0.0090
41
0,0082
40
0.0074
ence temperature). The next step was to evaluate the effective temperature over the volume of the gasoline for each set of temperature observations. While effective temperature has been discussed as a function of time, its evaluation over space involves no new principles. It was anticipated that this operation would require averaging a large numbrr of small portions of the total volume, but circumstances were favorable and i t was found that, since the tilt of the isotherms did not exceed 10" F.. the effective temperatures of small horizontal sections of the drum did not differ materially from the mean temperatures of the same sections. Accordingly, i t was possible to determine the effective temperature simply by employing the mean temperatures of horizontal sections of the drum in the above procedure. T o obtain these mean temperatures, graphs were constructed in which the temperature of each thermocouple was plotted against its distance from the bottom of the drum. Values taken a t equal intrrvals from this curve were accepted as the effective temperatures of the sections in which they lay. They were effectively averaged. Examination of the results disclosed that, as a consequence of particular interest in events at the top of the drum, the greater concentration of thermocouples in that region was such that an arithmetic average of all nineteen temperatures would give the same results as those obtained by the more laborious procedure. The arithmetical average was used throughout for final results. I n a comparison of 29 sets of observations, the average difference between the average of the nineteen temperatures and the effective average from the curve was 0.05' F. and the probable error, assuming this difference t o be negligible, of the shorter method was 0.15' F. Four other short cuts tried in the same way gave average differences from the curve of 0.01" t o 0.30"F., with corresponding probable errors ranging from 0.24"t o 0.42" F. None of them was a s simple a s the one employed. The same procedure was tested with the data obtained from the drum on its side, with equally satisfactory results. Observations with the blitz can quickly showed t h a t temperature gradients were small enough to permit arithmetic averaging. Actually, the only thing gained by the use of a number of thermocouples in the blitz can was the assurance that a good average temperature was obtained. The results obtained with the multithermocouple-equipped blitz can were compared with those from the cans equipped with single thermoelements ( 1 2 )which were used in the drsert storage program. The comparison showed that the positions of the single thermoelements were such as substantially to give the effective temperatures. It appears, however, that the reliability of effective temperatures obtained with the cans equipped with single thermoelements was somewhat less than for the multithermocouple-equipped can. Accordingly, the authors have depended on them only when necessary. All the conclusions arrived a t in regard to the cans were valid both when the cans were upright and when they were lying flat. After the effective temperatures for the entire vessel had been calculated for each set of readings, the effective temperatures for daily periods were calculatpd. The results are summarized in Tables I11 and IV.
0.0013
CORRELATION O F RESULTS
0.0012 0.0011 '
0.0010
0.0108
43
2101
0.0009 0.0008 0.0008 0 . oooa
In the work described above effective gasoline temperatures were obtained for a number of individual days. These are, however, few compared to the total storage period, and it cannot be assumed t h a t they are in all ways representative. The uninterrupted 6-months series of readings (roughly 45,000) necessary t o cover the entire period of interest would have required an entirely unreasonable effort. Accordingly, a t this point the authors examined climatological data with the joint objective of establishing relationships to permit the extension of the available results to the entire summer period a t Camp Seeley and, more generally, of medieting effective temDeratures a t other locations for which more or less detailed climatological data were available.
-
INDUSTRIAL AND ENGINEERING CHEMISTRY
2102
TABLE 111. Daw. July 24c
1943 OBSERVED EFFECTIVE GASOLINE TEMPERATURES I N DRUM
-4ir Temp., F. hlax. hlin. Xean 87 102 117
Effeotive Effective Air Gasoline T:mpd, Temp., F. F.b 119.1 105.3
614
13.8
25c
120
85
102.5
108.0
121.0
26
114
89
101.5
102.1
115.9
13.8
27
111
85
98
100.4
114.6
14.2
114
86
100
101.8
115.2
13.7 13.4
115 118 104
85 86 85
100 102 94.5
103.9 106.8 96.0
117.6 121.7 107.8
13.7 14.9 11.8
103.0
13.5 11.1
Bv. for 24-27 July 28 29 30 31 Av. for 28-31 AUK. 2 d
.
SUM.IM-4RY O F
101
81
91
91.9
13.0
Weather Conditions Clear, light N.W. wind till midafternoon Partly cloudy from 11 A.M. on, light winds most of the day Generally partly cloudy, light easterly winds Partly c!oudy, clearing, after 2 P.M., light easterly winds Morning partly cloudy afternoon clear, light west'winds Clear, gentle winds Clear, calm Cloudy by noon, light ,rain the following early morning
Vol. 45, No. 9 best values available. The magnitude of a1 varies with the container and also with its position. I n Table V are summarized the experimental values of 81, as well as some estimates of its magnitude under more diversified conditions. As a1 does not appear t o vary with daily temperature range, nor with the temperature itself, it appears that the approximate equation
my,,
= 61
+ E v a , BE
Clear morning and evening cloudy in afternoon, moderat: winds Generally clear, light winds, clouding up in evening Partly cloudy, clearing in even ing Clear, light winds
(6)
may be properly used in such 102 80 91 92.3 106.5 14.2 3d calculations. I t s use reduces the calculation of effective 91 102 92.7 110.9 80 18.2 4d gasoline temperatures to the 82 93 114.2 104 9 5 6~ 18.6 5d problem of calculating effective -4v. for 2-5 15.5 16.4 109 80 94.5 98.7 115.1 Clear, light winds Aug. 11 air temperatures. 92 96.2 76 108 1 1 0 . 3 Clear, light winds 1 4 . 1 18 88.5 93.0 72 U n f o r t u n a t e l y , available 105 110.7 Clear, light winds 17.7 25 91.5 109.0 Clear, light winds 96.1 75 108 12.9 Sept. 1 data on air temperature are 16.3 Av. for August mostly too condensed to be of 103 78 90.5 93.4 109.0 15.6 Clear, moderately strong wind Sept. 9 in morning value in Equation 6. Further 108 71 89.5 16.2 94.4 110.6 Clear light winds in afternoon 15 74 88 91.1 approximations are necessary. 102 106.6 Clear' light winds in morning 22 15.5 72 88.1 98 85 1u7.8 Clear: light winds in morning 29 19.7 Examination of air tempera.4v. for September 16.7 ture data a t Imperial, Camp 69 84.5 88.1 13.2 100 101.3 Clear, moderate winds until Oct. 6 3 : O O P.M. Seeley, and Blythe reveals a 95 58 76.5 81.5 18.9 100.4 Clear, calm 13 relation between daily air tem56 68.5 16.7 86.3 81 70.1 Clear, calm 20 64 76 86.4 77.1 Clear, strong winds all day 9.3 88 27 perature range and the differ14.5 Av. for October ence between effective and 14.7 Av. for drum on end 15.5 -4v. for drum on side mean air temperature (this Drum on end, painted black. a This quantity is discussed below. difference is designated as &) Drum on side, painted olive drab. Drum on end, painted olive drab except for dates noted. for the same day. Values of 62 are plotted in Figure 2 against daily air temperature range for all of the dam. Published climatological temperatures (15-18) are almost al_ . , both a t Blythe and Camp Seecey, on which drum readings xere taken. The best valuis n-ays condensations of the original data. rlnd these are usually avrrages M here all temperatures, the high and the low, are given equal weight. They are, therefore, not immediately useful, because the essence of the effective temperature concept is that it gives the unequal weights to different temperatures which are dictated by chemical experience-that is, when temperature fluctuations are given equal weight by arithmetic averaging, it is not possible to recover an effective average from the condensed result without additional information. Approximatc procedures for U bridging this gap are outlined here. 0 0 The first approximation arises from an examination of Tables I11 and IV. There it is seen that the values for daily effective gasoline temperatures exceed the corresponding air temperatures by a relatiyely constant amount. The difference ( a ) between effective gasoline temperatures and mean air temperatures increases as the daily air temperature range-i.e., maximum minus = 2 minimum temperature-increases On the other hand, the difW > ference ( b ) between effective gasoline temperature and effective F I air temperature is apparently independent of daily air temperature range. (This quantity is calculated in essentially the same manner as effective gasoline temperature,) This latter difference, I I I I ( b ) , called a,, is more attractive for that reason and, in addition, IO 20 30 40 50 its use is more profitable later on than (a).It may be rcprescnted DAILY AIR TEMPERATURE RANGE (MAX.- MIN 1, "E as Figure 2. Relation between Effective and Mean Air (5) Temperatures at Camp Seeley and Blythe Test Sites where subscripts g and a refer to gasoline and air and the limits indicate that the difference is for daily perio'ds. Values of 61 for each day when readings were made are given in Tables I11 and IV, and the averages of these separate values are to be taken as the
Effective air temperatures, E(Ta,B), f r o m hourly or bihourly t h e r m o m e t e r or corrected t h e r m o g r a p h readings. M e a n air temperatures, ,?$(Tu), f r o m mean of daily maximum and minimum air temperatures b 1943 Camp Seeley data 3 1944 Blythe t e s t s i t e data
INDUSTRIAL AND ENGINEERING CHEMISTRY
September 1953
OF 1944 OBSERVED EFFECTIVE GASOLINETE~PERATURES TABLE IV. SUMMARY
Drum Effective Effective Air gasoline Air T e m p e r a t u r e a Temp,., ttmz., Max. Min. Mean F. 6i0
Date July
5 12 19 26 Aug. 2 30 Sept. 1 3 27
71 68 78 71 76 73 78 73 70 64 44 52
90.5 87.5 94.0 88.0 92.0 92.0 91.5 85.0 84.0 76.5 59.B 62.0
98.0 95.6 99.8 94.1 96.3 98.5 95.5 88.0 87.1 78.9 64.0 61.8
110.5 110.5 111.2 107.2 111.4 113.1 103.4 110.7 100.9 86.7 75.8 81.3
8 102 73 15 103 70 107 80 22 29 111 74 80 Aug. 9 101 23 110 73 73 Sept. 6 107 20 100 64 Oct. 4 95 57 56 18 92 Nov. 1 84 57 49 15 60 30 70 43 Av. Discussed below. b Long axis N-S.
87.5 56.5 93.5 92.5 90,5 91.5 90.0 82.0 76.0 74.0 70.5 54.5 56.5
91.9 93.0 97.4 100.0 90.7 96.4 96.8 88.8 82.2 74.2 73.4 54.3 58.3
108.5 110.4 112.3 116.8 103.5 111.7 110.0 103.9 95.0 89.8 86.5 62.1 68.2
'Oct.11 27 Nov. 8 24
110 107 110 105 108 111 105 97 98 89 75 72
Av. July (.
Blitz Can (MulvBlitz C a n b thermocouple) (Recorder) Effective Effective gasoline gasoline temp., F. 8ia tyy., 8ia
Vessels Upright 12.5 115.1 17.1 14.9 116.6 21.0 11.4 113.7 13.9 13.1 111.6 17.5 15.1 115.5 19.2 14.6 118.6 20.1 7.9 104.7 10.2 22.7 111.0 23.0 13.8 103.5 16.4 7.8 83.0 4.1 11.8 79.6 15.6 19.5 83.6 21.8 13.8 16.7 Vessels on Side 16.6' 109.5 17.6 17.4 110.7 17.7 14.9 113.7 16.3 16.8 120.3 20.3 12.8 108.4 17.7 15.3 116.2 19.E 13.2 114.6 17.8 15.1 108.7 19.9 12.8 99.8 17.6 10.6 95.5 16.3 13.1 92.4 19.0 7.8 62.3 8.0 9.9 75.1 16.8 13.6 17.3
TABLE v. VALUES OF 61 FOP DRUMSAND CANS Position of Vessel and Shieldinga
81,
14.3
Drum, isolated, on side, ong axis
14.5
N-S
N
F.
Drum, isolated, upright
Source of Value Unweighted average of mean IV from 'I* and Unweighted average of mean 'I1 and IV Estimated
Drum isolated, on side, long axis (14.5) in ahy direction Mean value from Table I V 16.7 Blitz can, isolated, upright, long axis N-S Blitz, can, isolated, upright, long 14.3 (11) axis E-W Blits can, isolated, lying flat, top 17.3 &fean value from Table I V pointing west Blitz. can, isolated, !ying flat, top (17.3) Estimated pointing In any direction 3 Blitz can, upright, in center of top (9,p. 14) layer of several close packed rows. all covered by olive drab tarphin All vessels painted dull olive drab. Same values apply for black and other dark oolors. Vessels painted hght aolors, particularly white, would have slightly lower values. Q
for the relationship between the two quantities are given in Table VI. We may define 62 =
E(??., B)lgdSY - M(Tu);d"Y
+
or the corresponding approximation
+ + E [M(Ta)LdsyjBIg 82
16.7 19.9 15.6 17.1 19.9 23.8 18.1 19.8 18.7 13.5 19.7 9.7 17.7 Upright 15.4 18.2 16.6 20.1 16.5 18.1 21.2 22.0 21.4 19.4 20.3 0.7 16.7 17.4
way, as can be designated as the effect of weather fluctuations and b4 as the effect of seasonal fluctuations The former has been evaluated in terms of monthly intervals and the latter in terms of the entire period in question, or of the six hot months of the year, or of the entire year. If both these terms are incorporated, the entire approximation becomes
E(T,, B):
=
61
+ + 63 + + M(T,): 62
64
(10)
If the 6's can be determined, only the
most condensed air temperature data are required-that is, the mean temperature for an extended period of time. Vessels 107.3 The preceding paragraphs suggest that 111.2 a variety of approximation paths are 114.0 120.1 possible and t h a t the nature of the data 107.2 114.5 available might dictate choice of the path. 118.0 This is certainly true and, in some in110.8 103.6 stances, i t is difficult to choose the best 98.6 93.7 procedure. I n general, i t seems obvious 55.0 that the most precise result will be ob75.0 tained by a procedure that makes maximum use of experimental data for the particular location and minimum use of approximation factors. It is equally obvious t h a t the highest precision is commonly not worth the effort required. Before this problem is considered in more detail, effective gasoline temperatures at the test site may be evaluated. EFFECTIVE AIR AND GASOLINE TEMPERATURES AT DESERT T E S T SITES
At Camp Seeley in 1943 air temperatures were recorded continuously by thermographs which were corrected periodically to agree with mercury thermometer readings' Discrepancies between the thermographs and the bihourly air temperature readings taken in conjunction with the drum readings were such t h a t the thermographs gave good average temperatures over intervals as long as a week but were not in good agreement with thermometer readings on a specific day. Accordingly, instead of a fully detailed Calculation Of effective air temperature, air temperature data were averaged by weeks and combined with the relation in Table V (using the average value for the daily temperature range indicated by the thermograph for the same week), These weekly effective air temperatures were then effectively averaged in one operation for the entire 6-month period. A value for the first 3 months was calculated in the same manner.
(7)
and extension to longer periods and substitution in Equation 6 give E(T0, B); = 61 f E { [SZ M(Tu);"'I, BJ: (8)
E(T0, B): = 61
114.7 115.5 115.3 111.2 116.2 122.3 113.6 107.8 105.8 92.4 83.7 71.5
2103
(9)
The information required is now reduced to a knowledge of the daily air temperature range and the mean temperature, by days, over the period in question. The operation required is to average the latter data effectively. The necessity of taking into account the temperature fluctuations of the daily cycle has been eliminated. Two further sorts of temperature fluctuations appear to be large enough to justify similar treatment-namely, those resulting from changes in weather, and the seasonal variations. If i t is postulated that these effects can be accounted for in the same
TABLE VI. RELATION BETWEEN AIR TEM~ERATURE Daily Air Temp. Range, F. 15 20 25 30 35 40
RANGE AND
82
62$
' F.
0.1
0.9 2 2 3 9 6 0 8.3
At Blythe Air Base in 1944,maximum and minimum air temperatures were taken with thermometers essentially according t o U. S. Weather Bureau specifications. Thermograph records were also maintained. The authors chose t o calculate mean daily temperatures as the average of the maximum and the minimum temperature, as is Weather Bureau practice. The mean temperature for each day was combined with the relation in Table V to obtain a value for the effective air temperature for each day of the
INDUSTRIAL AND ENGINEERING CHEMISTRY
2104
Vol. 45, No. 9
T o make this comparison it is necessary to interpret the differeiices in gum formation in field storage as opposed to laboratory storage a t 110" F as being due solely to temperature of field storage. On this assumption, and on the asPeriod slimption that the value of B is always 9900" It , the effec110.9 14.3 115.8 1.1 tive temperature of fifteen [Vented bare can, axis E-W 1.5 (6) 98.5 14.3 109.8 97.3 1.0 0.4 (6) [Drum, upright gasoline samples was calcuSealed bare ran axis E-JTr 14.3 109.8 108.4 1.0 0.9 (1) lated. These are compared, 14.3 109.8 97.3 1.0 0.4 (0 May-Oct. 1943 /Sealed lacquergd can, axis in Table VII, with the effec\Ve%i bare pan, axis E-W 14.3 109.8 111.3 1.0 1.1 (7) tive temperatures calculated 9 5 . 1 14 3 109.4 113.7 1 . 0 1 . 3 ( I O ) Drum, upright 111.8 120.0 1.1 Sealed bare can axis N-S 16.7 2.0 (f0) solely from temperature data. 111.8 120.0 1 . 1 Vented bare car;, axis N-S 16.7 2.0 (9, 10) T h e c o m p a r i s o n s are also 90.1 14.3 104.4 106.8 0.7 0.8 (9,10) Drum, upright 16.7 106.8 111.3 0.8 1.1 (9, 10) Sealed bare can axis N-S made in terms of relative June-Nov, 1944 Vented bare ea;, axis N-S 16.7 106.8 112.6 0.8 1.2 (9, IO) severity of storage, in ordei to Drum, upright 14.3 104.4 104.9 0.7 0.7 (4) or vented bare can, 16.7 106.8 110.0 0.8 1.0 (4) provide a linear rather than ,Sealed axis pi-S an exponential measure of the 109.3 111.7 0.95 1.13 Av. differences. The two methods are entirely independent, with the trivial exception that the value of B used in both has a single origin. 6-month period. These valueci were then effectively averaged as I n view of the independence of the-two methods, the variety of a single group t o obtain a value for the effective air temperature uncontrollable factors, and the magnitude of random errors, it is at the site for the 6-month period. A value for the first 3 months gratifying that the difference, on the average, between the efwas also calculated. Effective gasoline temperatures were calfective temperatures calculated by the two methods is only culated by Equation 6 using the values for 61 given in Table V. 2.4"F., which corresponds to an 18% difference in relative severVALIDITY O F EFFECTIVE GASOLINE TEMPERATURES ity. I t is concluded that this agreement confirms the propriety of the method of calculating effective temperatures from tempcraThe validity of the method which has been outlined can he turr data. It indicates, in addition, a high probability that syschecked by comparing the effective temperatures calrulated from tematic differences, other than temperature, between laboratory temperature data alone with those calculated from gum foimation and field storage are minor. data alone. Such a comparison cannot be expected to be very TABLE
EFFECTIVE 'rE11PERATVRES
VII.
FRO11 TEXPERATdRE >1EASURE1lEXTS COblPARED T O EFFECTIT-E TEhlPER.4TURCS FROX FORMATION Relative Severity of Storage in Fielri Rffnn. Effective Gasoline Comvared t o Temp., Laboratory tive E ( T a , B ) ,O F . a t l l O o F. Air Temp. Temp. Gum Temp. Gum E(Ta,B ) measforma- measformaa. F. 61, F. urements tion uremenls tion Reference Container and Position 110.9 115.8 Sealed bare can, axis E-W 96.6 14.3 1.1 1.5 (6) 14.3 110.9 110.0 1.1 1.0 (6) 1 . . . _ ~
I
precise, because there appear to be many uncontrolled factors which lead to a wide scattering in the rates of gum formation with different gasolines and in different containeis. Hon.ever, the Gasoline h d d i t i v e ~Group did obtain enough data so that, for a sizable group of samples, the extent of gum formation iii the desert can be compared with gum formation in the same time interval in laboratory storage a t 110" F.
TABLEVIII.
Period Long term annual mean Mean for 1943 May 1943 June July August September October May-July (3 mo.) May-October (6 mo.)
Mean for 1944 June 1944 July August September October November June-August 1944 June-November 1944
71.1 80.0 88.0 91.4 85.5
75.8 61.0 86.5 80.3
The calculation of effvctive temperatures has been summarized from rather detailed data a t the test sites and a method has been outlined to be used when only routine climatological data are available. The application of the latter method involved a reconsideration of the calculations for the test sites as well as of
MEANAND EFFECTIVE AIR TEMPERATURES AT AND NEAR TESTSITES
Mean Temperatures, F. CamD Seeley Imperial E l Centro test site Blythe 72.3 72.9 79.1 82.2 89.9 88.8 87.8 74.8 83.7 83 8
EXTENSION O F METHOD TO OTHER LOCPlLITIES
73.1 73.8 79.7 83.8 92.8 91.4 89.4 76.0 8 6 ,4
85 5
Blythe Bir Base 73.1 83.8 93.2 95.2 88.6 78.3 61.6 90.7 83.4
.. 83: 4 88.1 97.3 94.0 91.9 78.7 89.6 88.9
70 2 72.8 78.9 81.6 91.0 90.3 87.4 74.1 83.8 83.9
Blythe test site
si ,'5
90.5 93.1 86.2
76.0 59.5 88.4 81.1
a Calculated from monthly means, a t Imperial and Blythe, respectively, of daily temperature ranges by use of relationship of Table VII. b Calculated f r o m daily mean temperatures a t Imperial and Blythe.
1943 Test Program, Camp Seeley Values for Imperial Region 62"
&b
0.2 1.6 0.8 0.4 0.7 1.7 0.9 0.9
6.8 6.5 6.9 3.8 4.5 4.8
G.!
5.3
640
...
... ... ... .. .. ..
0.8 1.0
Values for Blythe Region 6za
636
6.2 7.0 6.4
0.9 0.3 0.4 0.5 0.5 1.1 0.5 0.6
6.0
6.9 3.2 6.5 6.0
d e
6rC
... ,..
...
... ...
,._
0.6 3.0
Effective Temp., E ( T a , B ) , ' F Camp Camp Seeley test Seeley calcd. directly from E l Centro Imperial test site Camp Seeley datad 86.7 86.1 90.4 91.9 90.3 96.2 .... 100.5 97.6 106.0 .... 95.6 93.0 98.2 .... 94.6 93 0 97.1 .... 82.5 81 3 Xi 2 .... 93.8 92.1 98.06 96.6 92.9 91.2 96.30 95.5 1944 Test Program, Blythe TBst Site Effective Temp., E ( T a , B ) , F. Blythe test site Blythe Air Blythe test calcd. directly from Blythe Base site Blythe test site dataa 87.4 90.9 88.6 .... 95.8 100.5 97.8 .... 97.2 102.0 99.9 .... 90.7 95.1 92.7 .... 82.8 85.7 83.4 .... 64.3 65.8 63.8 , . . . 94.0 98.3 96.0: 95.1 89.4 93.0 90.7 90.1
Calculated from monthly mean temperatures a t Imperial and Blythe Details of these calculations are given in text, Values derived from mean temperatures for periods plus sum of 6's.
September 1953
INDUSTRIAL AND ENGINEERING CHEMISTRY
climatological data and has led to a number of detailed conclusions. 1. The effective gasoline temperatures given by the sum of mean air temperatures and the 6's are properly applicable t o the immediate localities where the air temperatures were determined. Experience suggests that gasoline storage dumps will be in hotter, dustier areas than meteorological stations and that air temperatures will be higher at the dumps than in the nearby towns t o which the climatological data apply. The comparison, in Table VIII, of mean air temperatures a t the test sites and the neighboring towns supports this conclusion. The methods employed for computing values of t h e 6's employ condensed data and must therefore to some extent underestimate their values.
TABLE IX. APPROXIMATIOX PATHS FOR EFFECTIVE GASOLINE TEMPERATURE IN UPRIGHTDRUMS AT CAMPSEELEY AND BLYTHE TESTSITE Effective Gasoline Temp., F. Camp Blythe test Seeley site May-Oct. June-Nov. 1943 1944 112.2a 106. Sa 1. Guin formation 109,s 104.4 2. Detailed calculation a t test site 105.0 3. Mean temperature a t test site plus 6's for 110,6 Imperiai region 4. Mean monthly temperature a t test site 111 0 105 9 plus 62 6a t o give monthly effective air temperatures then effectively averaged and added t o 61 5 . lMean temperature a t nearby town plus 112.26 108 7d 6's 5' F. 110.5C a While the wide variation of the individual values derived from gum formation (Table VII, column 6) raises doubt whether even the mean is more reliable than the temperature-derived values, we have no alternative b u t to take the mean as the point of departure. However, the differences between the various containers are judged t o be given best by temperature differences. accordingly, the figure of 112.2 is the sum of 111.7 (Table VII, column 6, iast item), less 109.3 (column 5, last item), plus 109.8 (column 5, fourth item). b El Centro. C Imperial. d Blythe.
+
+
TABLE X.
Place Asia
Arlen
Trincomalee, Ceylon Hong Kong Calcutta, India Hyderabad. Pakistan M-adras, India Nagpur, India Port Blair, Andaman Is. Rangoon, Burma Saigon. Indo-China Jask Iran Bagdad, Iraq Verkhoyansk, U.S.S.R. Africa Accra, Gold Coast Entebbe, Uganda Freetown Sierra Leone KhartouA, Ang. Eg. Sudan Zanzibar E Africa, North Ame& Imperial, Calif. Ke West Fla. InAanapdis, Ind. Boston, Mass. Havre, Mont. Amarillo, Tex. Houston, Tex. Corpus Christi, Tex. Merida, Mexico Colon Canal Zone North -4;lantic Bermuda
2 105
As a result of these and some other intangible considerations, it seems advisable t o add 5 O F. t o effective gasoline temperatures calculated from climatological data. This quantity may be regarded as a safety factor for the inevitable summers that are more severe than the ones on which the data are based. 2. Several choices may exist for the reduction of available data to a single effective temperature. I n exploration of extension of the method to other localities the authors have re-examined the procedures employed a t the test sites. Table VI11 includes, in addition to monthly mean air temperatures, values by months of 62 and 63 and, by quarters and half-years, of 64 for towns near the sites. These are combined in several ways for which some logic exists and the resulting effective gasoline temperatures for the test sites are compared in Table IX. Tacitly, the temperatures derived from gum formation have been accepted as the best values (Table V I I ) and the detaiked temperature measurements a t the sites have been shown to give slightly lower results (2.4O F.). The three additional alternatives included in Table I X result from progressively less use of temperature measurements a t the test sites and more of routine climatological data. There does not seem to be much choice among them, and any of several paths will lead to essentially the same conclusion. 3. Effective gasoline temperatures were calculated from Weather Bureau data for a number of representative locations in the United States. The routine temperature data obtained by the Weather Bureau are daily maximum and minimum temperatures; these are given as such or are condensed to monthly mean maximum and minimum temperatures (18). (A condensation of climatological data has been published b y the Department of Agriculture, 1 7 . ) The values of 62 for the chosen locations were estimated by Table VI from the 1944 data for the monthly means of the daily temperature range (this gives a slightly low value because the curve in Figure 2 is concave upward rather than linear,
MEANTEMPERATURES A N D EFFECTIVE TEMPERATURE INCREMENTS FOR VARIOUS LOCALITIES Elevation above Sea Level, Feet 94 99 108 21 96 22 1017
Hottest month
Mean Temperature, F. Coldest 6 Hottest Year month months
64, O F.
Year
6 Hottest Months
88,
F.
6 Hottest LMonths
69,
F.
6 Hottest Months
E(l'o,B)' for 6 Hottest Months in Upright Drums
18 36 13 125 1883
89.4 86.4 82.0 86.1 93.1 90.0 95.0 85.3 87.1 85.8 90.7 94.4 60.0
76.3 78.7 58.7 66.5 63.5 76.2 68.1 80.5 76.7 78.8 87.4 48.9 -58.6
82.9 82.9 71.8 78.8 80.8 83.1 80.3 81.8 81.1 81.7 79.9 72.0 -3.8
8 7 . 1b 85.3d 79.76 84.5d 89.5d 87.34 86.5 82.88 83.28 83.26 87.5b 87.6b 40.6d
0.8 0.3 2.6 1.5 3.3 0.8 2.4 0.1 0.1 0.2 2.5 8.4 45.
0.1 0.0 0.1 0.1 0.2 0.2 1.0 0.1 0.2 0.1 0 2 1.3 4.9
108.5 104.6 100.6 103.9 110.5 106.8 108.8 102.2 102.7 102.6 109.0 115.2 67.8
60 3842 224 1280 56
81.3 70.2 82.4 93.4 83.4
74.7 68.6 77.9 72.5 76.7
78.7 70.0 80.7 84.5 80.2
80.4f 70.70 81.9f 90.3 b 82.30
0.3 0.1 0.1 1.5 0.6
0.0 0.1 0.0 0.1 0.0
101.2 95.1 103.2 115.7 103.6
5 718 15 2488 3590 41 20 72 36
91.8 83.6 74.3 71.7 68.3 75.9 83.7 82.2 83.1 80.9
53.8 69.2 27.3 27.9 12.9 33.1 52.7 56.4 72.3 79.3
72.4 76.8 51.4 49.6 41.6 54.6 69.1 70.4 78.2 80.2
84. O b 81.58 66.2b 63.7b 58.3b 67.9b 78.8b 78.86 81,4: 80.5
6.3 1.0 9.1 8.4 11.6 7.9 4.3 3.0 0.5 0.0
1.4 0.2 1.7 1.5 2.3 1.8 0.9 0.3 0.0 0.0
151 65
80.7 82.4
62.6 71.6
70.6 77.4
76.66 80.9b
1.7 0 5
0.5
0.0
96.4 100.2
680
83.3
79.5
81.3
82.6h
0.1
0.1
104.0
59
- 69
5.0 0 1.5 1 3.5 2.5 1 0.5 (0) (0)
110.3 101.2 90.4 87.7 85.1 92.8 100.5 99.4 100.7 99.8
77.4 106.5 82.6 84.7i 0.0 0 3 99.3 78.0 79.0 79.51' 0.0 0.0 101.1 77.7 80.3 81.80 0.1 0.0 104.3 84.2 84.8 85. O k 0.0 0.0 7 77.1 98.6 78.4 Apia, Samoa 79.30 0.0 0.0 38 96.5 74.6 Honolulu, T. H. 70.7 0.1 77.16 0.3 102.0 47 76.6 79.9 81.2d Manila. Philiuuine Reu. 0.0 0.0 -. a Sum of mean temperature 61, 62, 6a, 6r plus 5' F b May-October. 0 Values in parentheses estimated from general considerations. d April-September March-August. f Decemb$r-May. 0 'NovemberlApril. September-February. i October-March. i April-June and September-November. k JuneNovember. 97 23 126 21
85.8 79.8 82.5 85.2 79.3 78.4 83.1
0.6 0.2 1.7 2.2 1.7 1.3 0.5 (0.5) (0) (0)
2106
INDUSTRIAL AND ENGINEERING CHEMISTRY
but the difference does not appear to be material), while the so values were calculated for each month of 1944 by taking the difference between the effective average of mean daily temperatures over monthly periods and the corresponding mean monthly temperatures. The twelve values of 63 thus obtained for each place were averaged to obtain a best value. Values of 64 were obtained by taking the difference between the effective average of mean monthly temperatures over the desired interval, usually 6 or 12 months, and the mean temperatures for the same periods. The consequences of these calculations were studied to establish some rather rough rules for estimating the values of the 6’s for other places where data are unavailable or where detailed calculations are not warranted. The values of 61 in Table V are not universally reliable. They were obtained in low latitude, low altitude desert, and might not apply at all well to summer arctic conditions or under continual cloudiness. It appears that they are reasonable for partly cloudy weather. High winds will reduce the value of &. Gasoline stored on ground covered by green vegetation should give a lower value than gasoline stored on bare ground; the latter is certainly the more common condition. The values of 82 given in Table V I should be generally applicable simply because the form of the daily air temperature cycle cannot vary widely. When data on daily air temperature range are not available, 62 may be estimated as follows: At coastal locations the daily air temperature range is only 10’ t o 15” F.; accordingly 82 is so small that it is not worth while to calculate it for such places, even given the data. A good value for humid low altitude “Continental” locations away from the moderating influence of the sea, such a s the Mississippi Valley, is 20” F. Continental locations having considerable altitude (say, 3000 feet) or low humidity will have a daily range of roughly 30” F., while values as high as 40” F. or, rarely, 50” F. will be found only when most or all of the factors of continental location, high altitude, low humidity, and special local terrain are present. Very hot places, which are rarely found outside of continental regions, may have a daily temperature range 5’ F. higher than would be otherwise expected. Values of & are small and rarely worth evaluating. Values of 64 are small for tropical stations, but mag be considerable in the temperate zone, particularly a t continental locations. Values of 64 are easily calculated, the data are available (16,16), and the operation is worth while in specific cases if there is any doubt as to its magnitude. 4. On the basis of all these considerations, values of the 6’s have been calculated or estimated for a number of representative stations outside of the United States. with emphasis on the hot places. Values for 6 2 and 6 3 were estimated on the basis of geographical and climatological considerations and in the light of the values obtained for domestic stations. There are a few exceptions, in the case of where eetimates were made directly from data on daily temperature range obtained by private communication with the Weather Bureau. Values of 64 were calculated in all cases from mean monthly temperatures by averaging the values for each of several individual years (the value resulting from effectively averaging long-term monthly means would have been slightly, possibly not significantly, smaller). These data, together with the effective gasoline temperatures derived from them for both domestic and foreign points, are summarized in Table X. Table X speaks for itself. Two places are shown which are hotter than Imperial-namely, Bagdad and Khartoum. A few locations omitted for lack of data may be even hotter. Massaua in Eritrea is a conspicuous example. By and large, though, there are few places on earth where effective gasoline temperatures will exceed those found in the Imperial Valley. Contrasted t o this, there are many places where effective gasoline temperatures will exceed 100”F. during the hot months and it appears that values below 90” F. are rather exceptional in the warmer half of the temperate zone. One notable exception was included in the table t o show the extreme effects of continental location: Verkhoyansk, Siberia, is known as having the coldest winters on earth, b u t its summers are moderate and this great seasonal contrast gives rise t o an extraordinary value for 84 for the year. Expressed in another way, this simply means that effective temperature in such a
Vol. 45, No, 9
location is determined almost entirely by the summer temperatures. I n contrast to this extreme continental site, there is a marine location, on South Georgia Island (latitude 54”13’S, longitude 36 “33’W), where mean monthly temperatures never fall below 28” F. and yet effective gasoline temperatures are less than 60” F. This results, of course, from its equable climate: a mean summer temperature of 38” F., winter temperature of 30” F., ahd a daily temperature range which is probably less than 10’ F. SUMMARY
Intensive data on air and gasoline temperature a t a field test site have been used t o predict gasoline degradation at the same place. The results have been found in agreement with the observed degradation. The procedure has been extended by the use of approximations based on condensed data on air temperature to predict the rate of gasoline degradation a t any place for which routine climatological data are available. LITERATURE CITED
(1) Alspaugh, >X. L., S . A . E . Journal, 54, 289 (1946). (2) Am. Inst. Physics, “Temperature, Its Measurement and Control in Science and Industry,” chapter by Larsen, D. E., p. 1099 ff., Kew York, Reinhold Publishing Corp., 1941. (3) Bolt, J. A., S.A.E. Journal, 56, 89-90 (October 1948). (4) Coordinating Research Council, Xew York, “Report on 1944 Desert Storage Tests on Aviation Gasolines with and without CS,” pp. 66, 67, June 1945. (5) Coordinating Research Council, New York, “Report on 1943 Desert Storage Tests on 80 Octane Number All-Purpose Gasoline Stability,” p. 84, September 1944. (6) Ibid., p. 89. (7) Ibid., p. 90. ( 8 ) Ibid., Appendix by Keyser, P. V., and Kuhn, W. E., pp. 154-97. (9) Coordinating Research Council, New York, “Report on 1944 Desert Storage Tests on Stability of 80 Octane Kumber AllPurpose Gasoline,” p. 98, March 1945. (10) Ibid., p. 100. (11) Luten, D. B., Jr., and Hedberg, Kenneth, “Temperature of
(12) (13)
(14) (15)
Stored Gasoline. 1943-1945 CRC Desert Storage Tests on Motor and Aviation Gasoline. Part 11. Effective Storage Temperatures of Gasoline,” New York, Coordinating Research Council, July 1952. Shepherd, C. C., Ibid., “Part 111. Actual Air and Gasoline Temperatures,” New York, Coordinating Research Council, July 1952. Shepherd, C. C., and Luten, D. B., J r . , Ibid., “Part I. Introduction.” Sherman, J., IXD. EKG.CHEM.,28, 1027 (1936). Smithsonian M i s c . Collections 79 (1927).
(16) Ibid., 90 (1934).
(17) U. S. Dept. Agriculture, “Climate and Man,” Year Book of Agriculture, p. 664, 1941. (18) U. S. Dept. Commerce, Weather Bureau, “Climatological Data.” (19) Walters, E. L., Proc. Am. Petroleum Inst., 27 (III),116 (1947). (20) Yabroff, D. L., and Walters, E. L., IND.EXG.CHEM.,32, 83 (1940). RECEIVED for review July 22, 1952. ACCEPTED June 5 , 1953. Based on experimental work and calculations done in conjunction with the wartime desert storage testing of gasoline, carried out under the direction of the Gasoline Additives Group, Motor Fuela Division, Coordinating Fuel Research Committee, Coordinating Research Council, Inc. The full report of temperature investigations (11-18) has recently been issued and is obtainable from the American Petroleum Institute.
Correction I n the article, “Basic Factors in Pilot Plant Work’’ [A. L. Conn, IND.ENG.CHEM., 45, 1625 (1953)], the figure captions are reversed.
Correctly, these should read:
Figure 1.
Steps in Commercializing a Research Idea
Figure 2. Pilot Plant Functions
