Function And System Design; Measuring Principle - Endress+Hauser Proline Prosonic Flow 91W Technical Information

Proline Prosonic Flow 91W

Measuring principle

Endress+Hauser

Function and system design

The measuring system operates on the principle of transit time difference. In this measurement method,
acoustic (ultrasonic) signals are transmitted between two sensors. The signals are sent in both directions,
i.e. the sensor in question works as both a sound transmitter and a sound receiver.
As the propagation velocity of the waves is less when the waves travel against the direction of flow than along
the direction of flow, a transit time difference occurs. This transit time difference is directly proportional to the
flow velocity.
Principle of the transit time difference measurement method
Q = v · A
a Sensor
b Sensor
Q Volume flow
Flow velocity (v & t )
v
t
Transit time difference (t = t
A Pipe cross-sectional area
The measuring system calculates the volume flow of the fluid from the measured transit time difference and
the pipe cross-sectional area. In addition to measuring the transit time difference, the system simultaneously
measures the sound velocity of the fluid. This additional measured variable can be used to distinguish different
fluids or as a measure of product quality.
The measuring device can be configured onsite to suit the specific application using Quick Setup menus.
Q
t
b
– t )
a b
a
b
t
a
A0013117
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