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Omega Engineering, Inc.
PO Box 4047
Stamford CT 06907-0047
Phone: 800 848-4286
Fax: 203 359-7700
Sounding Out the Flow: How Ultrasonic Flowmeters Work
In 1842, Christian Doppler discovered that a stationary observer perceives a sound to have shorter wavelengths as its source approaches, longer wavelengths as its source recedes. The Doppler effect explains why one hears rising pitch in the blowing horn of an approaching car. When the car zooms away, the pitch seems to drop. Ultrasonic Doppler flowmeters put this frequency shift to work in so-called dirty liquids containing acoustical discontinuities— suspended particles, entrained gas bubbles or turbulence vortexes.