Euromag EUROSONIC 2000 HH, User Manual

Page: 21 / 80

EUROMAG | 21
MEASUREMENT
strength is lower than 700, relocate to a more
favourable location.
2) Try to polish the outer surface of the pipe, and
apply more couplant to increase the signal strength.
3) Tenderly adjust the position of the two transducers,
both vertically and horizontally, while checking the
signal strength. Stop at the position where the signal
strength reaches to maximum. Then, check the
transducer spacing to make sure it is the same as or
very close to what window M25 shows.
2.9.2 SIGNAL QUALITY
Signal quality is indicated as the Q value in the
instrument. A higher Q value would mean a higher
Signal to Noise Ratio (short for SNR), and accordingly
a higher degree of accuracy able to be achieved.
Under normal pipe condition, the Q value is in the
range of 60-90, the higher the better.
Causes for a lower Q value could be:
1. Interference from other instruments and devices
nearby, such as a power frequency inverter which
could cause strong interference. Try to relocate the
flow meter to a new place where the interference can
be reduced.
2. Bad sonic coupling between the transducers and
the pipe. Try to polish the pipe surface again, clean
the surface and apply more couplant, etc.
3. The selected pipe section is difficult to conduct the
measurement. Relocate to a more favourable pipe
line.
2.9.3 TOTAL TRANSIT TIME AND DELTA TIME
The total transit time (or travelling time) and the delta
time are displayed on menu window M93. They are
the primary data for the instrument to calculate the
flow rate. Therefore, the measured flow rate will vary
as the total transit time and delta time vary.
The total transit time should remain stable or vary in
a very small range.
The delta time normally varies less than 20%. If the
variation exceeds 20% in either positive or negative
direction, there could be certain kinds of problems
with the transducer installation. The user should
check the installation for sure.
2.9.4 TRANSIT TIME RATIO
This ratio is usually used to check whether the
transducer installation is good and whether the
entered pipe parameters are in consistency with their
actual values. If the pipe parameters are correct and
the transducers are installed properly, the transit
time ratio should be in the range of 100±3. If this
range is exceeded, the user should check:
1. Are the entered pipe parameters are correct?
2. Is the actual spacing of the transducers the same
as or very closed to what shown on window M25?
3. Are the transducers installed properly and in the
right direction?
4. Is the mounting location suitable and/or has the
pipe changed shape? Is the pipe too old (i.e., too
much corrosion or deposition inside)?
5. Is there any interference source inside the pipe?