While not necessary or even particularly useful for the direct purpose of flow measurement, this
inference of the fluid’s speed of sound is nevertheless useful as a diagnostic tool. If the true speed
of sound for the fluid is known either by direct laboratory measurement of a sample or by chemical
analysis of a sample, this speed may be compared against the flowmeter’s reported speed of sound
to check the flowmeter’s absolute transit time measurement accuracy. Certain problems within the
sensors or within the sensor electronics may be detected in this way