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FLOWSIC100 Flare · Operating Instructions · 8013344/11L2/V 2-5/2018-10 · © SICK Engineering GmbH
Product Description
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2.1
System basic information
2.1.1
Functional principle
The FLOWSIC100 Flare gas velocity measuring devices operate according to the principle of
difference measurement in ultrasonic transit times. On both sides of a pipeline, the
sender/receiver units are installed in a certain path angle to the gas flow (
).
The sender/receiver units contain piezoelectric ultrasonic transducers which operate
alternately as senders and receivers. The sonic pulses are beamed at angle
α
to the gas
flow direction. Depending on angle
α
and gas velocity v, different transit times for the
respective sound direction (formulas 2.1 and 2.2) result from "acceleration or brake
effects". The higher the gas velocity and the smaller the angle to the flow direction, the
more the transit times of the sound pulses differ.
Gas velocity v is determined from the difference of both transit times, irrespective of the
value of the sound velocity. With this measuring method, changes of the sound velocity due
to pressure or temperature variations therefore have no influence on the gas velocity
determined.
Fig. 2
Functional principle of FLOWSIC100 Flare
POWER
Meas
Sender/
receiver unit,
slave
(probe B)
v = gas velocity in m/s
L = active measuring path in m
α
= path angle in
°
t
AB
= transit time of the sound
in flow direction
t
BA
= transit time of the sound
against the flow
Sender/
receiver unit,
master
(probe A)
t
BA
v
α
t
AB
L