Technical data

3 Flow measurement
Topics covered in this chapter:
• Flow measurement principles
• Smoothing
• Acquisition mode
• Chord average flow and sound velocity measurements
• Volumetric flow rate values
• 3810 Series liquid flow meter diagnostics
3.1 Flow measurement principles
Daniel 3810 Liquid Ultrasonic Flow Meters measure the transit times of ultrasonic pulses
passing through the medium on two parallel planes. The measurement paths, referred to
as “chords”, are angled to the pipe axis, and each chord has two transducers acting
alternately as transmitter and receiver.
Figure 3-1 describes the flow measurement principle. This permits the transit times to be
measured both with and against the flow (upstream and downstream).
The transducers are mounted on the meter body at accurately known locations for each
pipe size so the distance L between opposing transducers and the angle are precisely
defined for the measurement path.
Transit-time measurement principleFigure 3-1:
Flow measurement
Operations 13