How Does It Work - Micronics Portaflow 222 User Manual

Portaflow 222 & 333 User Manual
Typical applications:
•
River water
•
Seawater
•
Potable water
•
Demineralised water
•
Treated water
1.2

How Does It Work?

Portaflow flow meters use a cross correlation transit time algorithm to provide accurate flow
measurements.
An ultrasonic beam of a given frequency is generated by applying a repetitive voltage pulse to the
transducer crystals. This transmission goes first from the downstream transducer to the upstream
transducer as shown in the upper half of Figure 1. The transmission is then made in the reverse
direction, being sent from the upstream transducer to the downstream transducer as shown in the
lower half of Figure 1. The speed at which the ultrasound is transmitted through the liquid is
accelerated or decelerated slightly by the velocity of the liquid through the pipe. The subsequent
time difference T1 – T2 is directly proportional to the liquid flow velocity.
Figure 1 Principle of operation
The Portaflow system can be set up to operate in one of five modes determined mainly by the pipe
diameter and the type of transducer set in use. Figure 2 illustrates the importance of applying the
correct separation distance between the transducers to obtain the strongest signal.
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Micronics
Issue 1.0 March 2021