I.VDUSTRIdL A-VD ESGINEERISG CHEMISTRY
July, 1931
abilit'y. Acknowledgment is also gladly given to J. N. Street and s.A. shepard for their many suggestiolls andn.illing counsel throughout the course of this investigat'ion. Literature Cited Davey and Ohya, Trans. Insl. R u b b e r l n d . , 5, 27 (1929). Daynes. Proc. R o y . Sac. (London), 97A,286 (1920). Daynes, Trans. Insl. Rubber I n d . , 3, 428 (1928). Dew-ar, Proc. Roy. Inst. Gt. Britain, 21, 813 (1915). Edwards and Pickering, Bur. Standards, Tech. Bull. 387 (1920). ( 6 ) Grenquist. IND.ERG. CHEM?., 22, 759 (1930).
(1) (2) (3) (4) (5)
8-13
(7) Hauser, Trans. Inst. Rubber I n d . , 3, 451 (1928).
(8) Hauser, "Colloid Chemistry of the Rubber Industry," p. 33, Oxford University Press, 1928. (9) Kohman, J . Phys., Chem., 33, 226 (1929). (10) Lambourn, Trans. Insl. Rubber I n d . , 3, 452 (1928). (11) Morris and Street, IND.ENG.CHEH.,21, 1215 (1929); Indza Rubber J., 79, 25 (1930). (12) Schumacher and Ferguson, IND.ENG.CHEnf., 21, 158 (1929). (13) Steinitzer, Gummi-Zlg., 26, 1626 (1912). (14) Yenable and Fuwa, J. IRD.ESG. CHEx, 14, 139 (1922). (15) Winkelrnann and Croakman, private communication. (16) Wroblewski, Pogg. A n n . , 158, 639 (1876).
Alignment Chart for Estimation of Viscosity Index of Oils' I. Laird Newel1 T H E HENRYSOUTHER EXGINEERING Co., HARTFORD, CosK.
HE use of alignment charts or noniograms for the evaluation of engineering data is well known and many such charts have been constructed n hicli are in daily use. The accompanying a l i g n m e n t c h a r t is offered for the rapid evaluation of temperature-viscosity data of lubricants refined from petroleum oils. The viscositv index of p e t r o l e u m lubricants was first described and defined by Dean and Davis ( 2 ) as being a function of the Saybolt U n i v e r s a l viscosities of an oil a t 100" and 210" F. They found that the yiscosity relationships of oils a t these t e m p e r a t u r e s could be expressed by the general equation :
T
+
where
y = ax2 bx = c y = viscosity a t 100' F. x' = viscosity at 210' F
"4
VISCOSITY IOAdlF
ALIGNMENT CHART FOR ESTIMATION OF
3500
-
3000-
2500 -
VISCOSITY
-20007
3-
1500
Received February 263, 1931.
#OSITY AT
210°F
INDEX
'00
-
90
1000-
900
-
800
-
700
-
1;
VISC O S I T Y
--
The constants for this equation were 600 determined and reported for two series of oils having small and large changes 500 7 in viscosity TTith temperature. The viscosity index is found by comparison with these two series of oils, 400 and not only represents the degree of change of vi,wosity with changes of temperature of an oil, but also indicates 300 y the relative paraffinic or naphthenic character of the lubricant. A recent paper by Davis and McAllister (1) describes the use of the viscosity-index 200 constant in determining the structure of an oil. Although the 1-iscosity i n d e x has been developed by the use of viscosities a t 100" and 210°F., it is possible to use other temperatures, and since viscosity is often determined a t 130" F., as for 9. A. E. v i s c o s i t y numlier, IO0 the scales given on the chart include yiscositiec a t loo", 130°, and 210" F. I n using the chart, a straight line is drawn through points 1
INDEX
VISCOSITY
-I
representing the value of the oil viscosities a t two of the temperatures given, such as a t 100" and 210" F., or 130" and 210" F. The intersection of this line with the viscosity index scale will give directly the value for viscosity index of the oil. Literature Cited (1) Davis and ~IcAllister,ISD. E s G . CHEM., 22, 13?6 (1930). (2) Dean and Davis, Chem. M e t . En2 , 36. 618 (192%.
