This International Standard specifies the equations and reference tables relating temperature to EMF (electro-motive force) for Gold versus Platinum and Platinum versus Palladium thermocouples. For information and convenience of use it also provides the approximate equations for temperature as functions of EMF. The tables and equations in this standard are intended for use with thermocouples made from elements of purity not less than 99.999 % for Platinum and Gold and of 99.99 % for Palladium, by weight. Tolerances on initial values of EMF versus temperature have not been established for the thermocouples in this standard. Where required, these tolerances should be agreed between the wire manufacturer and the user. Temperatures in this standard are based on the International Temperature Scale of 1990 (ITS-90). They are expressed in degrees Celsius, symbol t90. Values of EMF, symbol E/μV, are given in microvolts. This standard does not cover extension or compensating wires for use with the pure-element thermocouples. The questions of their use shall be agreed between the manufacturer and the user.