INF-TN1FSH-E
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1. PRODUCT OUTLINE
1.1. Outline
This high precision flowmeter is the world’s first clamp-on type ultrasonic flowmeter that adopts the pulse Doppler
method and the transit time method as its measurement principles. The ultrasonic flowmeter for industrial use
employs the pulse Doppler method, which directly measures flow distribution, thus easing straight pipe conditions and
allowing measurement of flows that have not grown into eddy or laminar flow. Combined use of the transit time
method allows the hybrid ultrasonic flowmeter to be used for measuring a significantly wide range of liquids. The
pulse Doppler method, which uses echoes coming from reflectors in a liquid to be measured, is ideal for the
measurement of liquids that contain air bubbles and particles. On the other hand, the transit time method, which
allows ultrasonic waves to pass through for measurement, is ideal for the measurement of clean liquids.
The new hybrid technique employing both the pulse Doppler and the transit time methods allows the flowmeter to be
used for wider range of applications. In addition, our self-developed switching algorithm ensures automatic switching
between the two methods depending on the conditions of a liquid to be measured (such as mixing status of air bubbles
or particles and flow rate), thus facilitating measurement.
1.1.1. Measurement principle
<Pulse Doppler method>
•
The pulse Doppler method measures flow distribution and flow rate based on the fact that Doppler frequency of the
echo coming from reflectors such as air bubbles and particles in liquids changes with fluctuation of flow rate.
Sensor 2
Sensor 1
Flow
Reflection
Air bubble
Flow rate
Pipe wall
Center
Pipe wall
Flow velocity
distribution 2
Flow velocity
distribution 1
<Transit time method>
•
Under the transit time method, ultrasonic pulses are propagated slanted from both upstream and downstream sides,
and time difference of flows are detected to measure the flow rate.
Sensor 1
!
2
Flow
Send
Receive
Sensor 2
!
1
Time difference
∆
T
Sensor 2
Sensor 1
