3 General principles
3.2 Measurement arrangements
FLUXUS F501
2020-06-30, UMFLUXUS_F501V1-3EN
14
The average flow velocity of the fluid is calculated as follows:
v = k
Re
· k
a
·
where
3.2
Measurement arrangements
3.2.1
Terms
Sound path
The distance covered by the ultrasonic signal after crossing the pipe once. The number of the sound paths is:
• odd if the measurement is carried out in diagonal arrangement
• even if the measurement is carried out in reflection arrangement
Beam
The path covered by the ultrasonic signal between the transducers, i.e., the transducer emitting the ultrasonic signal and
the transducer receiving it. One beam consists of 1 or several sound paths.
v
– average flow velocity of the fluid
k
Re
– fluid mechanics calibration factor
k
a
– acoustic calibration factor
Δt
p
– time difference between 2 consecutive pulses
Δt
– transit time difference of ultrasonic signals S
1
and S
2
(Δt = t
2
- t
1
)
Diagonal arrangement
Reflection arrangement
The transducers are mounted on opposite sides of the pipe.
The transducers are mounted on the same side of the pipe.
Fig. 3.6:
Diagonal arrangement with 1 beam
and 3 sound paths
Fig. 3.7:
Reflection arrangement with 1
beam and 4 sound paths
t
2
t
p
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