11 Basic Measurement
82
UMFLUXUS_G8V4-6-1EN, 2018-10-10
11.6.2
Consistency Check
If a wide range for the sound speed has been entered in the program branch
Parameter
or the exact parameters of the
fluid are unknown, a consistency check is recommended.
The transducer distance can be displayed during the measurement by scrolling the key
.
The optimum transducer distance is calculated on the basis of the measured sound speed. It is therefore a better approx-
imation than the first recommended value which had been calculated on the basis of the sound speed range entered in the
program branch
Parameter
.
If the difference between the optimum and the entered transducer distance is less than specified in Tab. 11.1, the mea-
surement is consistent and the measured values are valid. The measurement can be continued.
If the difference is greater, adjust the transducer distance to the displayed optimum value. Afterwards, check the signal
quality and the signal amplitude bar graph (see section 11.6.1). Press ENTER.
Repeat the steps for all channels on which a measurement is being made.
11.6.3
Value of the Sound Speed
The sound speed of the fluid can be displayed during the measurement by pressing key
.
If an approximate range for the sound speed has been entered in the program branch
Parameter
and the transducer dis-
tance has been optimized afterwards as described in section 11.6.2, it is recommended to write down the sound speed for
the next measurement. By doing this, it will not be necessary to repeat the fine adjustment.
Also write down the fluid temperature because the sound speed depends on the temperature. The value can be entered in
the program branch
Parameter
or a user defined fluid can be created for this sound speed (see section 15.2 and 15.3).
The optimum transducer distance is displayed in brackets (here: 50.0 mm) in the upper
line, followed by the entered transducer distance (here: 54.0 mm). The latter value has to
correspond to the adjusted transducer distance. Press ENTER to optimize the transducer
distance.
Tab. 11.1: Standard values for signal optimization
transducer frequency
(third character of the
technical type)
Difference between the optimum and the entered transducer distance [mm]
shear wave transducer
Lamb wave transducer
G
20
-45...+90
H
-
-30...+60
K
15
-20...+40
M
10
-10...+20
P
8
-5...+10
Q
6
-3...+5
Enter the new adjusted transducer distance. Press ENTER.
Press key
again to scroll until the transducer distance is displayed and check the dif-
ference between optimum and entered transducer distance. Repeat the steps, if neces-
sary.
Note!
If the transducer distance is changed during the measurement, the consistency check will have to be
repeated.
L=(50.0) 54.0 mm
54.5
m3/h
Transd. Distance?
50.0
mm
L=(51.1) 50.0 mm
54.5
m3/h
