NT228B GB2
96 / 98
t (°C)
C (m/s)
t (°C)
C (m/s)
0
1 403
30
1 506.4
5
1 426.5
35
1 520.1
10
1 447.6
40
1 529.2
15
1 466.3
45
1 536.7
20
1 482.7
50
1 542.9
25
1 497
21.3
Sound Velocity in Fluids :
The speed of sound in a fluid is physical characteristic of this fluid which may be
linked to other characteristics, such as density (d), pressure (P), temperature (T)
or the % of two or several miscible products, or with another magnitude having
good analogy, like compressibility.
For most miscible products like refined petroleum products or petrochemical
bases, experience shows a reliable and accurate relationship between the speed of
sound and the density of the product for constant P and T or the concentration of
the mixture.
But, some other products show deviations of sound velocity depending mainly on
fluid compressibility.
Water has special and unique characteristics, but presents a very reliable relation
between this sound velocity and the temperature that allows a number of tests to
be run on the installation (see below).
Gases have lower speed of sound than liquids.
Refrigerating fluids are in the wide middle range, with high P & T coefficients.
21.4
Applications on Water :
Water has a very reliable “speed of sound < > temperature” relationship which will
be put to good use whenever possible for dimensional checking: from T, you can
predict this speed and compare it with the result obtained by UF 801-P on the
basis of the measured transit time and the set-up dimensions. A deviation may
require these values to be reexamined, like L for intrusive probes or the pipe
diameter and its thickness for external probes.
The following simple equation gives a good estimation of C between 10 and
100°C:
C
m/s
= 1557 – 0.0245 * (74 – T
°C
)
2
The following table defines the customary values more accurately.
