This Technical Specification gives guidelines for the selection and use of Doppler-based flowmeters for the measurement of liquid flow in small open channels and partly filled pipes. It is applicable to whole-channel flow measurements using a single meter at a fixed point in the cross-section.
It is not applicable to flow measurements made using Doppler-based current meters for point velocity measurement nor using mobile profiling systems.
A limitation of this technique is that measurement is made of the velocity of particles or other reflectors being transported by the liquid rather than that of the liquid itself.
NOTE Though the title refers to liquid flow in general, the main use of flowmeters which use the Doppler principle is for water or water-based liquid and particular reference is often made in the text to water.