Speed of sound in pure water as a function of temperature

In view of the adoption of the International Temperature Scale of 1990 (ITS-90), which defines the International Celsius Temperatures, t90, the dependence on temperature of the speed of sound in pure water is examined. Drawing on the experimental data published previously [V. A. Del Grosso and C. W. Mader, ‘‘Speed of Sound in Pure Water,’’ J. Acoust. Soc. Am. 52, 1442–1446 (1972)], it is found that the change from the previous t68 scale is significant. At 100 °C, the difference between the two scales (t68−t90) is 0.026 °C, resulting in a difference of 0.022 m/s for the speed of sound. The speed of sound is fitted to a new fifth-order polynomial applicable over the t90 range 0–100 °C.