flowIQ® 3100 TECHNICAL DESCRIPTION
Kamstrup
A/S • Technical Description • 5512
-1242_N1
_GB •
10.2019
27
−
=
2
1
1
1
V
V
L
T
In connection with ultrasonic flow sensors the velocities
1
V
and
2
V
can be stated as:
F
C
V
−
=
1
and
F
C
V
+
=
2
respectively
where:
C
is velocity of sound in water.
Using the above formula you get:
F
C
F
C
L
T
+
−
−
=
1
1
which can also be written as:
2
2
2
)
(
)
(
)
(
)
(
F
C
F
L
T
F
C
F
C
F
C
F
C
L
T
−
=
+
−
−
−
+
=
As
F
C
,
2
F
can be omitted and the formula reduced as follows:
2
2
=
L
C
T
F
To minimize the influence from variations of the velocity of sound in water, the latter is measured via absolute
time measurements between the two transducers. These measurements are subsequently in the built-in ASIC
converted into the current velocity of sound, which is used in connection with flow calculations.