Modern petroleum research and development programs us well as practical marketing considerations require a more suitable method of expression than the Viscosity IndeE (V. I.) and the Pole Height. None of the many other proposed s?jstems are wholly satisfactory. Thirty -two Systems previously suggested are listed. In response to resolution No. 10 passed by the Third World Petrokum Congress, expressing the need for an improved index for viscosilylteniperature relation, the authors propose a n index for which the name Viscosity-Temperature Index (VTI) is suggested. Two Viscosity - U Temperature Index Charts (A & B), illustrating two variants of the VTI scale are presented. The VTI scales retain the popular and .widely recognized numbers of the Viscosity Index from 0 to 100. and also retain the L -Series values, which represent 0 (with, the suggestion that L be modified to give a straightened L -series). The 100 calue or upper limit of the scale is represented by P, the perfPCt U)) or ideal oil, the viscosity of which is independent of lernperahre. For this unchanging viscosity, the new expression Perma.nent Viscosity was coined. It is shown, that:
anomalous values are avoided; i! D
the sensitivity of the scale remains the same;
non-hydrocarbon materials as well as synthetics and hydrocarbon oils are equally covered - the latter bcin.g subjected increasinqly to extensive process ing and synthesizing, thereby reaching high inclex figures; Diesel fuels, Lerosenes, gasolines and water c an be included;
the viscositllltemperature relation of all lubricants and fluids are expressed in per - cent of P, the perfect oil having Permanent Viscosity U)).
VTIc, the third and final variant of the VTI scales is presented in two cha, rts (C, & c$).
A straightened L' (VTIcO) is used. It is shown th.at:
parallel values to the accepted V .I. (0 - 1 0 0) are obtained, thereby making the V .I. - m, odifietl by n straightened L' - part of the VTIc, while extending its application to the greatest possible limits;
constant values are obtained for the diflerent fractions into which lubricating oil from any one source ma?4 be divided, therebij maintaining th, eir famil ?, characteristics;
constant valews are obtained for any two set tenapera.t?wes.
Chart C, - erected for 320 and 100°F - makes possible the stiidy of the viscositylteni, peratrire behavior of very light flliids in.- eluding water and gasolines; d. the VTIc sca.le maintains all the virtues enumerated /or the VTIA &B scales in Part I and also expresses the visco,~it?lltem.percrtlLre rela, tion of nll fltsids in. percent of P, the perfect oil having "Permaned Viscosity".
K & ~ ~ Les. programmes inodernrs de rccherches et les realisations pratiques et d'ordre Pconomique exigent la mise nu point d 'une methode
