Vicosity Index of Lubricating Oils - Industrial & Engineering Chemistry

E. W. Dean, A. D. Bauer, J. H. Berglund. Ind. Eng. Chem. , 1940, 32 (1), pp 102–107 ... Kyungseok Noh , Joohyun Shin , and Jay H. Lee. Industrial & ...
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PHENOLSOLVENT-EXTRACTION PLAKTFOR

THE

PRODUCTION OF LUBRICATING OILS

OF

HIGH VISCOSITYINDEX

H E viscosity index scale question. Hypothetical oil for petroleum oils, as proposed by Dean and has a viscosity index of 100. Davis (3) and subsequently revised by Davis, LapeyD is equal to L - H , and Equation 2 is simply a conrouse, and Dean (@, was based on Saybolt Universal of Equationusable veniently 1. equivalent viscosities. The constants used in making the calculaDerivation of Basic tions did not extend below 40 Constants seconds Saybolt Universal The general nature of the viscosity a t 210" F. basic constants for the visA need exists for basic cosity index scale is indiconstants in kinematic as well cated by Figure 1. The L as Saybolt units and for the E. W. DEAN, A. D. BAUER, APiD and H curves were originally extension of the scale to J. H. BERGLUND located by Dean and Davis lower values. The present (3) through actual tests of Standard Oil Development Company, paper reports the preparation and availability of a New York, N. Y. blends of finished lubricating table of kinematic constants oils derived, respectively, from the extreme types of covering the range of 2.0-75.0 commercial oils with which the senior author was familiar a t centistokes (equivalent to 32.8-349 Saybolt seconds) a t 210" F. the time. However, the use of these data as a basis for the The new table, except for a slight revision in the range scale was arbitrary, and we did not attempt to characterize corresponding to 40-50 seconds Saybolt a t 210" F., is equivalent to that previously published ( 2 ) according to the relathe numerical values in terms of specific types of crude oil. tion between kinematic and Saybolt viscosities that has been The two important considerations were, first, to establish a approved by the American Society for Testing Materials ( I , 4). scale which within reasonable limits would give the same The constants covering the range from 2.0-4.2 centistokes at viscosity indices for oils of similar origin but different viscosity and, secondly, t o define the scale precisely. 210" F. are new material (Table I). The two curves were defined in terms of the published equations (3) : Definition of Viscosity Index

T

of Lubricating

Oils

The viscosity index of an oil is a figure calculated from known viscosities a t 100" and 210" F. according t o one of the following equations:

- L7 v. I. = LL-H x v. I. = x

y

100

(1)

100

(*)

For 100 V. I.: Y = 0.0408X2 For 0 V. I . : Y = 0.2160X2

+ 12.568X - 475.4

+ 12.070X - 721.2

(3) (4)

where Y = Saybolt viscosity at 100" F. X = Saybolt viscosity at 210' F. The lowest experimentally determined points for the H and L curves were, respectively, 49.0 and 42.0 seconds Saybolt a t 210" F. The extrapolation of the equations below about 50 seconds proved to be unjustifiable although extensions in the other direction have yielded consistent results for viscosities much higher than those of the heaviest oils actually used by Dean and Davis in deriving their equations. The inconsist-

where U is the viscosity of the oil a t 100" F., and L and H a r e basic constants representing viscosities a t 100" F. of hypothetical oils having the same viscosity a t 210" F. as the oil in 102

INDLSTRIAL AAD ENGIhEERlhG CHEMISTRY

JANUARY; 1940

103

OF OILS FROV CRUDES(NOTREFINED BY TABLE I. VISCOSITYINDICES SOLVENT EXTRACTIOK)

No.

Source"

Centistokes 210' F. 100'

Description

Kinematic Viscosity Viscosity Index Index (Fenske)

F.

From Pennsylvania Crudes 4.686 99.2 1 300--~ii-dist[ll-ate Commrrc-ial 300 oil 1.592 1 -~~ 97.3 4.904 1.636 2 46.2 4.89 100.0 1.640 1 Commercial 300 oil 3 101,l 5.834 1.846 1 Lab. dist dewaxed, narrow c u t 4 ... 95.3 5.981 1.858 1 Lab. dist:: dewaxed, narrow cut 5 ... 5.917 99,s 1.859 1 Lab. dist., dewaxed, broad c u t 6 ... 5.80 107.6 1.86 3 Lab. dist., not dewaxed 7 ... 6.411 97.0 1.949 1 Lab. dist., dewaxed, broad cut 8 ... 98.3 7.068 2,080 1 Lab. dist., dewaxed, broad cut 9 7.420 91.5 2.121 1 L a b dist dewaxed narrow cut 10 93.4 7.904 2.215 1 Lab: dist:: dewaxed: broad cut 11 8.50 110.9 2.39 3 L a b dist. not dewaxed 12 8.930 95.0 2.398 1 Lab: dist.: dewaxed, broad cut 13 92.3 9.158 2.425 1 Lab. dist., dewaxed, narrow c u t 14 120: 5 10.03 87.2 2.544 2 Commercial spindle oil 15 10.19 94.3 2.600 1 Lab. dist dewaxed broad cut 16 ... 95,3 2.842 11.75 1 L a b dist" dewaxed' broad c u t 17 91.0 2,881 12.16 1 Lab: dist:: dewaxed: narrow cut 18 13s:9 12.02 104.0 2.926 1-4 Lab. blend, commercial oils 19 139.1 13.30 107.4 3.13 3 L a b dist not dewaxed 20 14.27 98.8 3.216 1 Lab: dist:: dewaxed, broad cut 21 ... 14.29 99.9 3.225 1 Pressed dist., filtered 22 14.74 96.6 3.267 1 Pressed dist., unfiltered 23 1iS:i 87.8 3.325 15.57 2 Commercial spindle oil 24 123.0 15.47 95.5 3.356 2-4 Lab. blend commercial oils 25 16.83 99.3 3.552 1 L a b dist 'dewaxed, broad c u t 26 92.1 1 Lab: dist" dewaxed, narrow cut 3,376 15.78 27 101.1 3.948 20.03 1 Lab. dist:: dewaxed, broad c u t 28 ... 21.38 95.1 4.060 1 Lab dist. dewaxed narrow c u t 29 122.1 21.59 108.1 4.186 1-4 Lab: blenh, commeikal oils 30 111.1 123.2 22.60 4.33 3 Lab. dist. not dewaxed 31 24.13 101.6 4.417 1 Lab. dist.: dewaxed, broad cut 32 102.1 ii2:2 24.58 4.470 2-4 Lab. blend, commercial oils 33 41.22 103.0 103.9 6.121 4 Commercial motor oil 34 From Texaa a n d Louisiana Crudes 126.6 2.613 10.343 91.9 1 Commercial spindle oil 35 95.0 128.1 2.951 12.51 5 Commercial spindle oil 36 111.8 3.745 18.927 89.9 1 Commercial spindle oil 37 114.7 96.0 3.933 20.21 5 Commercial spindle oil 38 91.1 109.9 3.970 20.84 5 Transformer oil 39 Sources of oils: 1,refinery KO.1; 2,refinery No. 2; 3,Pennsylvaniacrude fractionated by Dean and Lane, U. S . Bureau of Mines; 4,commercial motor oil, believed not t o be refined b y solvent extraction; 5 , refinery N o . 3.

... ... ...

...

...

TABLE 11. BASICCO~YSTAXTS IN THE RANGE4C-50 SECONDS SAYBOLT LNIVERS.4L AT 210" F. RETRACTABLE O L E O LASDING G E A R OF A M O D E R N AIRPLANE

This device must operate under Tvidely varying temperature conditions and requires an oil of high viscosity index.

Viscosity a t 210' F. Former Constants Say- KineH L D bolt mstic 7- Saybolt-40 4.20 107 138 31 120 161 41 41 4.51 42 4.82 133 185 52 43 5.13 147 210 63 161 237 76 44 5.43 176 265 89 45 5.75 191 293 102 46 6.06 47 6.37 206 322 116 48 6.68 222 353 131 239 386 147 49 6.99 257 422 165 50 7.29

S e w Constants

--HSaybolt 107.1 119.3 132.7 146.9 161.5 176.3 191.3 206.2 222.0 239 0 255,l

7 -

Kinematic 22.280 25.136 28.184 31.408 34 588 37.980 41.266 44,559 47.992 51.697 55.161

-L

Saybolt 137.9 l57,9 181.7 208,4 236.5 265.1 293.9 322.4 352.3 386,2 422.0

Kinematic 29.360 33.883 39.208 45.088 51,030 57.430 63.630 69.830 76.302 83,672 91.398

--DSaybolt 30.8 38.6 49.0 61.5 75.0 88.8 102.6

116.2 130.3 147.2 166.9

-

Kinematic 7.080 8.747 11.024 13.680 16.442 19,450 22.364 25.271 28.310 31.975 36.237

encies in the range of 40 to 50 seconds at 210" F. were rectified by Davis, Lapeyrouse, and Dean (a) who published some empirical constants that have been proved by subsequent experience to be reasonably satisfactory. Some further slight changes in this specific range have, however, been found necessary in the tables described in this report, as the empirical figures do not fall on a smooth curve. The low viscosity extension just adopted and covering the range below 4.20 centistokes (40 seconds Saybolt) at 210" F. is defined in terms of the following equations: For 100 V.I.: I' = 1.4825X + 0.91375X2 (5) For 0 V. I.: Y = 1.655X 1.2625X2 (6) where Y = kinematic viscosity at 100' F. X = kinematic viscosity at 210" F.

+

-0

50

H

L

100

L

150

centistolies at 1 0 0 " ~ .

FIGCRE 1.

GEiYERAL B.48IS O F T H E VISCOSITY I N D E X SCALE

Saybolt Universal viscosities are not desirable for this lorn range, and the extension is in centistokes only.

INDUSTRIAL AND ENGINEERING CHEMISTRY

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VOL. 32, NO. I

TABLE111. SPECIMEN PAGES FROM TABLES OF CONSTANTS FOR CALCULATING VISCOSITYIKDEX FROM KKOWN KINEMATIC OR SAYBOLT VISCOSITY(AT 210' F.)

-

Viscosity

H

4.00 4 01 4 02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28 4.29 4.30 4.31 4.32 4.33 4.34 4.35 4.36 4.37 4.38 4.39 4.40 4.41 4.42 4.43 4.44 4.45 4.46 4.47 4.48 4.49

20,550 20.635 20 720 20. E05 20.590 20,975 21.060 21.145 21.230 21.315 21.400 21.4E8 21.576 21,664 21.752 21.840 21.928 22.016 22.104 22.192 22,280 22.370 22.460 22.550 22,640 22.730 22.820 22.910 23,000 23.090 23.180 23.272 23.364 23.456 23.548 23.640 23.732 23.824 23.916 24.008 24.100 24.194 24.288 24,382 24.476 24.570 24.664 24.758 24.852 24.946

Ir

H

L

D

-Viscosity

25.040 25.136 25 232 25.328 25.424 25,520 25.616 25.712 25. E08 25.904 26. COO 26.C98 26.166 26.294 26.392 26.490 26.588 26,686 26.784 26.882 26.980 27.080 27 180 27.280 27.380 27.480 27.580 27.680 27.760 27.880 27.980 28.082 28.184 28.286 28.388 28.490 28.592 28,694 28.796 28.898 29.000 29.104 29.208 29.312 29,416 29.520 29.624 29.728 29.832 29.936

33,720 33.883 34 046 34 209 34,372 34.535 34,698 34.E61 35. ti24 35.187 35,350 35,521 35. E92 3 5 . E63 36. ti34 36.205 36.376 36.547 36.718 36.889 37.060 37.238 37.416 37.594 37.772 37.950 38.128 38.306 38.484 38.662 38.840 39.024 39.208 39.392 39.576 39,760 39.944 40.128 40.312 40.496 40,680 40.869 41.058 41.247 41.436 41.626 41.814 42,003 42.192 42.381

8 680 8.747 8.814 8 681 8 948 9 015 9.082 9.149 9.216 9 283 9.350 9.423 9.496 9.569 9.642 9.715 9.788 9.861 9.934 10.007 10,080 10.158 10.236 10.314 10.392 10.470 10,548 10.626 10.704 10.782 10.860 10.942 11.024 11.106 11.188 11.270 11.352 11.434 11.516 11.598 11.680 11.765 11.850 11.935 12,020 12.105 12.190 12.275 12.360 12.445

40.0 40.1 40 2 40 3 40.4 40.5 40 6 40.7 40.8 40.9 41 . O 41.1 41.2 41.3 41.4 41.5 41.6 41.7 41.8 41.9 42.0 42.1 42 2 42.3 42.4 42 5 42.6 42.7 42.8 42.9 43.0 43.1 43.2 43.3 43.4 43.5 43.6 43.7 43.8 43.9 44.0 44.1 44.2 44.3 44.4 44.5 44.6 44.7 44.8 44.9

Kinematic Viscosity D Viscosity

26.820 26,944 27.068 27.192 27.316 27.440 27.564 27,688 27.812 27.936 28. C60 28.160 28.320 28,460 28,560 28.710 28.840 28.970 29,100 29.230 29.360 29.497 29.634 29.771 29,908 30.045 30.182 30.319 30.456 30.593 30.730 30.875 31.020 31.165 31.310 31.455 31.600 31.745 31.890 32.035 32.180 32.334 32.488 32,642 32.796 32.950 33.104 33.258 33.412 33.566

6.270 6.309 6.348 6.387 6.426 6.465 6.604 6.543 6,562 6.621 6.660 6.i02 6.744 6.766 6.828 6.870 6.912 6.954 6.996 7.038 7.080 7.127 7.174 7.221 7.268 7.315 7.362 7.409 7.456 7.503 7.550 7.603 7.656 7.709 7.762 7.815 7.868 7.921 7.974 8.027 8.080 8.140 8,200 8.260 8.320 8.380 8.440 8.500 8.560 8.620

4.50 4.51 4.52 4.53 4.54 4.55 4.56 4.57 4.58 4.59 4.60 4.61 4.62 4.63 4.64 4.65 4.66 4.67 4.68 4.69 4.70 4.71 4.72 4.73 4.74 4.75 4.76 4.77 4.78 4.79 4.80 4.81 4.82 4.83 4.84 4.85 4.86 4.87 4.88 4.89 4.90 4.91 4.92 4.93 4.94 4.95 4.96 4.97 4.98 4.99

VISCOSITYINDEX TABLE IV. BASICVALUESFOR CALCULATINQ Visoosity H 107.1 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

66

67 68 69 70 71 72 73 74 75 76 77 78 79

119.3 132.7 146.9 161.5 176.3 191.3 206.2 222.0 239.0 255.1 271.7 288.4 305.3 322.2 339.2 356.4 373.5 390.8 408.2 425.6 443.1 460.6 478.4 496.1 514.0 531.8 549.8 567.8 586.1 604 623 641 660 678 697 716 734 753 772

L

D

Visoosity

137.9 157.9 181.7 208.4 236.5 265.1 293.9 322.4 352.3 386.2 422.0 456.1 490.5 525.2 560.5 596.0 632.3 668.6 705.5 742.8 780.6 818.9 857.4 896.5 936.2 976.1 1,016.3 1,057.1 1,098.3 1,140.1 1,182 1,225 1,268 1,311 1,355 1,399 1,444 1,489 1,534 1,580

30.8 38.6 49.0 61.5 75.0 88.8 102.6 116.2 130.3 147.2 166.9 184.4 202.1 219.9 238.3 256.8 275.9 295.1 314.7 334.6 355.0 375.8 396.8 418.1 440.1 462.1 484.5 507.3 530.5 554.0 578 602 627 651 677 702 728 755 781 808

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119

H 791 810 829 849 868 888 907 927 947 966 986 1,006 1,026 1,046 1,066 1,087 1,107 1,128 1,148 1,168 1,189 1,210 1.231 1,252 1.273 1,294 1,315 1.337 1,358 1,379 1,401 1,422 1,444 1,466 1,488 1,510 1.532 1,554 1,576 1,598

L 1,627 1,674 1,721 1,769 1,817 1,865 1,914 1,964 2,014 2,064 2,115 2,166 2.217 2,270 2,322 2,375 2,428 2,481 2,536 2,591 2,646 2,701 2,757 2,814 2,870 2,928 2.985 3,043 3,102 3,161 3,220 3,280 3,340 3,400 3,462 3,523 3,585 3,648 3,711 3,774

D 836 864 892 920 949 977 1,007 1,037 1,067 1,098 1,129 1,160 1,191 1,224 1,256 1,288 1,321 1,353 1,388 1,423 1,457 1,491 1,526 1.562 1,597 1,634 1,670 1,706 1,744 1,782 1,819 1,858 1,896 1,934 1,974 2,013 2,053 2,094 2,135 2,176

Visoosity 120 121 122 193 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 163 154 155 156 157 158 159

Saybolt Viscosity D Viscosity

H 107.1 108.3 109 4 110.6 111.9 113.1 114.3 115.6 116.8 118.0 119.3 120.7 122.0 123.3 124.6 125.9 127.2 128.6 129.9 131.3 132.7 134.1 135.5 136.8 138.2 139.7 141.1 142.5 144.0 145.4 146.9 148.4 149.8 151.3 152.7 154.2 155.7 157.1 158.6 160.0 161.5 163.1 164.6 166.0 167.5 168.9 170.5 172.0 173.5 175.0

FROM

137.9 139.7 141.5 143.4 145.4 147.3 149.3 151.4 153.5 155.7 157.9 160.1 162.6 164.8 167.1 169.4 171.7 174.3 176.7 179.1 181.7 184.2 186.8 189.4 191.9 194.7 197.3 199.9 202.8 205.5 208.4 211.3 213.9 216.8 219.7 222.4 225.2 227.9 230.9 233.7 236.5 239.6 242.3 245.2 248.1 250.9 253.9 256.7 259.3 261.5

30.8 31.4 32.1 32.8 33.5 34.2 35.0 35.8 36.7 37.7 38.6 39.4 40.6 41.5 42.5 43.5 44.5 45.7 46.8 47.8 49.0 50.1 51.3 52.6 53.7 55.0 56.2 57.4 58.8 60.1 61.5 62.9 64.1 65.5 67.0 68.2 69.5 70.8 72.3 73.7 75.0 76.5 77.7 79.2 80.6 82.0 83.4 84.7 85.8 86.5

45.0 45.1 45.2 45.3 45.4 46.5 45.6 45.7 45.8 45.9 46.0 46.1 46.2 46.3 46.4 46.5 46.6 46.7 46.8 46.9 47.0 47.1 47.2 47.3 47.4 47.5 47.6 47.7 47.8 47.9 48.0 48.1 48.2 48.3 48.4 48.5 48.6 48.7 48.8 48.9 49.0 49.1 49.2 49.3 49.4 49.5 49.6 49.7 49.8 49.9

U

L

D

176.3 177.9 179.3 180.7 182.4 183.8 185.2 186.8 188.2 189.8 191.3 192.7 194,2 105.7 197.2 198.7 200.1 201.6 203.1 204.6 206.2 207.7 209.2 210.9 212.3 214.0 215.6 217.1 218.9 220.5 222.0 223.7 225.4 227.0 228.6 230.3 232.1 233.7 235.5 237.4 239.0 240.7 242.4 244.0 245.7 247.2 248.9 250.5 252.0 253,6

2G5.1 268.1 270 9 273.6 276.6 279.4 282,2 285.2 288.0 290.9 293.9 296.6 299.6 302.4 305.2 308.2 311.0 313.7 316.5 319.3 322.4 325.1 328.0 331.0 333.8 337.0 339.9 342.8 346.1 349.2 362.3 355.6 358.8 362.0 365.2 368.5 372.2 375.5 379.1 382.8 386.2 389.8 393.6 397.1 400.6 404.2 407.8 411.4 415.0 418.6

88.8 90.2 91.6 92.9 94.2 95.6 97.0 98.4 99.8 101.1 102.6 104.9 105.4 106.7 108.0 109.5 110.9 112.1 113.4 114.7 116.2 117.4 118.8 120.1 121.5 123.0 124.3 125.7 127.2 128.7 130.3 131.9 133.4 135.0 136.6 138.2 140.1 141.8 143.6 145,4 147.2 149.1 151.2 153.1 154.9 157.0 158.9 160.9 163.0 165.0

SAYBOLT VISCOSITIES(AT 210" F.)

H

L

1.620 1,643 1,665 1,688 1,710 1,733 1,756 1,779 1,802 1.825 1.848 1,871 1.894 1,918 1,941 1,965 1,988 2,012 2,036 2,060 2,084 2,108 2,132 2,156 2.180 2,208 2,229 2.254 2.278 2,303 2,328 2,353 2.378 2.403 2,428 2,453 2,478 2,503 2,529 2,554

3,838 3,902 3,966 4,031 4,097 4,163 4.229 4,296 4.363 4,430 4,498 4,567 4,636 4,705 4,775 4,845 4,915 4,986 5,058 5,130 5,202 5,275 5,348 5.422 5,496 5,570 5,645 5,721 5.796 5,873 5,949 6,026 6,104 6.182 6,260 6,339 6.418 6,498 6,578 6.659

D 2,218 2,259 2,301 2,343 2,387 2,430 2,473 2,517 2.561 2,605 2,650 2.696 2,742 2,787 2,834 2,880 2,927 2,974 3,022 3,070 3,118 3,167 3,216 3,266 3,316 3,365 3,416 3,467 3,518 3,570 3,621 3,673 3,726 3,779 3,832 3,886 3,940 3,995 4,049 4,105

Visoosity 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200

H

L

D

2,580 2,606 2,631 2,657 2,683 2,709 2,735 2,761 2,788 2,814 2,840 2,867 2,893 2,920 2,947 2,974 3,000 3.027 3,054 3,082 3,109 3,136 3,163 3,191 3,218 3.246 3.274 3,302 3,329 3,357 3,385 3.414 3,442 3,470 3,498 3,527 3,555 3.584 3,613 3,641 3,670

6,740 6,821 6.903 6,985 7,068 7,151 7,234 7,318 7,403 7,488 7,573 7,659 7,745 7,832 7,919 8.006 8,094 8,182 8,271 8,360 8,450 8.540 8,630 8,721 8,813 8,904 8.997 9,089 9,182 9.276 9,370 9.464 9,559 9,654 9.750 9,846 9,942 10,039 10,137 10.235 10,333

4,160 4,215 4,272 4,328 4,385 4,442 4,499 4,557 4,615 4,674 4,733 4,792 4,852 4,912 4,972 5,032 5,094 5,155 5,217 5,278 5,341 5,404 5,467 5,530 5,595 5,658 5,723 5,787 5.853 5,919 5,985 6,050 6,117 6,184 6,252 6,319 6,387 6,455 6,524 6,594 6,663

INDUSTRIAL AND ENGINEERING CHEMISTRY

JANUARY, 1940

105

spond closely to those of more viscous products refined by the same processes from the same stocks. The constants in the range 40 to 50 seconds Saybolt (4.20 to 7.29 centistokes) at 210" F. are shown in Table I1 in comparison with those which they supersede (2). I n the majority of cases the differences are not more than 1second Saybolt. No change was made in the constants for the range above 50 seconds Saybolt (7.29 centistokes) a t 210" F. except that some of the tabulated values show fractional seconds instead of being rounded off to even seconds, Saybolt.

'? 74

721

4-

701

i

Computation of Tables The older published table shows values of L, H , and D for each even second Saybolt at 210' F. The relatively large magnitude of the increments made it necessary to interpolate when high accuracy was desired, or even moderate accuracy in the lower ranges of viscosity. The new tables were computed with the following increment>s:

4G t .

i

/ i

xt *t 28

4-

22

20

2.00 30.0 40.0 40.0 160.0

Range of Viscosity t o 29.99 centistokes to 39.9 t o 75.0 t o 159.9 seconds Saybolt t o 350.0

Increments in Viscosity 0.01 centistoke 0.1

0.5 0 . 1 second Saybolt 1.0

Each individual set of constants in the range 2.00 to 3.99 centistokes a t 210' F. was calculated from Equations 5 and 6. Throughout the range 4.00 to 7.29 centistokes the H and L values were obtained by a special method of calculation which was equivalent to graphic interpolation on a greatly magnified scale. I n this range of viscosity the constants are not defined by equations.

FIGURE 2. XOMOGRSPHIC CHART FOR ESTIMATION OF VISCOSITY INDEX

Although Equations 5 and 6 extend down to zero viscosity, they cannot be used in the range where the oils they represent have vapor pressures that are too high to permit accurate viscosity determinations at 210" F. The lower limit of the table that has been prepared is 2.0 centistokes at 210" F., which, according to the A. S. T. M. viscosity conversion table, is equivalent to 32.8 seconds Saybolt. With this extension, the viscosity index scale now covers all ordinary lubricating oils. We selected these constants for the low viscosity range after plotting available data for low-viscosity commercial oils produced by operating subsidiaries of the Standard Oil Company of New Jersey. Products refined by solvent extraction processes were excluded. The extension is admittedly arbitrary, as were the constants for the higher range, but it has been demonstrated that the use of the new values permits viscosity indices to be obtained for "light" oils which corre-

TESTISG HIGH-VISCOSITY-INDEX MOTOROILS WITH REFRIGER.4TED ROOM

A

CAR OPERATEDIK

A

ISDCSTRIAL AAD ENGIA-EEHlhG CHEIIISTRY

106

J-OL. 32, NO. 1

PAXEL BOARDOF

A

MODERS

TRSXSPORT PLANE

Control instruments in the center are for a Sperry Gyro-Pilot, the reliability of which is largely dependent on the use of an oil of high viscosity index

TABLE F7. BASICVALUESFOR H

L

u

Viscosity

2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8.0 8.1 8.2 8.3 8.4

6.620 7.143 7.684 8.243 8.821 9.417 10.031 10.664 11.315 11.984 12.671 13.377 14.101 14.843 15.603 16.382 17.179 17.994 18.828 19.680 20.550 21.400 22.280 23.180 24.100 25.040 26.000 26.980 27.980 29,000 30.040 31,090 32.150 33.210 34.270 35.330 36.390 37.450 38.510 39.570 40.630 41.690 42.750 43.810 44.880 45.970 47.080 48.220 49.390 50.590 51.820 52.980 54.150 55.273 56.473 57.699 58.873 60.063 61.305 62.513 63.723 64.969 66.251 07.501 68.753 70.041 71.286 72.542 73.793 75.089

8.360 9.043 9.752 10.485 11.244 12.028 12.838 13.672 14,532 15.417 16.328 17.263 18.224 19.210 20.222 21.258 22,320 23,407 24.520 25.657 26.820 28.060 29.360 30.730 32.180 33.720 35.350 37.060 38.840 40.680 42.670 44.500 46.460 48.440 50.430 52.430 54.430 56.430 58.430 60.430 62.430 64.430 66.430 68.430 70.430 72.460 74.550 76.740 79.040 81.440 83.920 86.460 89.040 91.660 94.095 96.528 98.958 101.398 103.925 106. 388 108.859 111.419 114.067 116.650 119.306 121.926 124.528 127.153 129.786 132.515

1.740 1.900 2.068 2.242 2.423 2.611 2.807 3.008 3.217 3.433 3.657 3.886 4.123 4.367 4.619 4.876 5.141 5.413 5.692 5.977 6.270 6.660 7.080 7.550 8.080 8.680 9.350 10.080 10.860 11.680 12.530 13.410 14.310 15.230 16.160 17,100 18.040 18.980 19.920 20.860 21.800 22.740 23.680 24.620 25.550 26.490 27.470 28.520 29.650

9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 11.0 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 12.0 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 13.0 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9 14.0 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 14.9 15.0 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 15.9

8. G

,

-

Viscosity

8.0 8.7 8.8 8.8

30.850

32.100 33.480 34.890 36.387 37.622 38.859 40.085 41.335 42.620 43.875 45.136 46.450 47.816 49.149 50.553 51.885 53.232 54.611 55.993 57.426

CALCULATING VISCOSITY INDEX FROM I