ISO/TR TECHNICAL REPORT 3666 Second edition 1998-12-15 Viscosity of water Viscosite de I'eau Reference number ISO/TR 3666:1998(E) ISO/TR 3666:1998(E) Foreword ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(iSC committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with IsO, also take part in the work. isO collaborates closely with the International Electrotechnical Commission(lEC)onallmattersofelectrotechnicalstandardization. The main task of technical committees is to prepare International Standards, but in exceptional circumstances a technical committee may propose the publication of a Technical Report of one of the following types: repeated efforts; type 2, when the subject is still under technical development or where for any other reason there is the future but not immediate possibility of an agreement on an International Standard; type 3, when a technical committee has collected data of a different kind from that which is normally published as an International Standard ("state of the art", for example). Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether they can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to be reviewed until the data they provide are considered to be no longer valid or useful. products and lubricants. This second edition cancels and replaces the first edition (ISO/TR 3666:1977), which has been technically revised. Annexes A and B of this Technical Report are for information only. @ISO1998 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. InternationalOrganizationforStandardizatio Casepostale56·CH-1211Geneve20·Switzerland Internet [email protected] Printed in Switzerland ISO/TR3666:1998(E) TECHNICAL REPORT @ISO Viscosity of water 1 Scope This Technical Report gives values for the viscosity of water at several reference temperatures. The viscosity of wateriscommonlyusedthroughouttheworldasthebasisforthecalibrationofrelativeviscometers. 2 Values forthe viscosity of water The dynamic viscosity, n, and the kinematic viscosity, v, of water at 2o 'C and normal atmospheric pressure (0,101 325 MPa) are given by: n= 1,001 6 mPa-s V= 1,003 4 mm²/s The estimated relative uncertainty associated with both values is 0,17 %, as detailed in annex A. NOTE1 The viscosity values stated above are based on the value of 1,001 9 mPa-s reported by Swindells et al. in 1952 (see annex B) which was also the basis of ISO/TR 3666:1977 and corresponds to the IPTS-48 temperature scale. The change of this value by 0,000 3 mPa-s is due to the difference of 12 mK between the IPTS-48 and the ITS-90 temperature scale at 20 °C. Based on a critical evaluation of the results of water viscosity measurements published between 1949 and 1994 (see annex A), the temperature dependence of the viscosity of water, expressed by the viscosity ratio V, = n(T)/n(20 °C) for temperatures Tbetween 15 °C and 40 °C, is given by the values listed in table 1. Table 1 - Recommended values for the (dynamic) viscosity ratio V,= n(T)/n(2o °C) of water at various reference temperatures; density p, temperature coefficients U, U, and pressure coefficient Temperature, T Dynamic viscosity Density, p Temperature Temperature Pressure ratio, V, coefficient,U, coefficient,U coefficient, °℃ kg/m3 K1 Ki1 10 MPa' 15 1,136 0 ± 0,000 6 999,10 0,026 5 0,026 4 -6,14 20 1,000 00 998,20 0,024 5 0,024 3 -4,28 23 0,930 6 ±0,000 4 997,54 0,023 5 0,023 2 -3,28 25 0,888 5 ± 0,000 3 997,04 0,022 8 0,022 5 -2,65 30 0,795 8 ± 0,000 3 995,65 0,021 3 0,021 0 -1,22