SL1188P Ultrasonic transit-time flowmeter
Revision
：
2.0.0
Page
15
of
81
transducer mounting spacing should be re-adjusted and the pipe should be re-inspected. If necessary, change the
mounting to the Z method (Z has the highest signal strength).
4.2.2.
Signal Quality (Q value)
Q value is short for Signal Quality (displayed in menu 90). It indicates the level of the signal detected. Q value is
indicated by numbers from 00~99. 00 represents the minimum signal detected while 99 represent the maximum.
The transducer position may be adjusted and enough coupling used to get the signal quality detected as strong as
possible.
4.2.3.
Total Time and Delta Time
“
Total Time and Delta Time
”
are displayed in menu 93. The measurement calculations in the flowmeter are based
upon these two parameters. Therefore, when
“
Delta Time
”
fluctuates widely, the flow and velocities fluctuate
accordingly. This means that the signal quality detected is too poor. It may be the resulted of poor pipe-installation
conditions, inadequate transducer installation or incorrect parameter input.
Generally,
“
Delta Time
”
fluctuation should be less than
±
20%. Only when the pipe diameter is too small or
velocity is too low can the fluctuation be wider.
4.2.4.
Transit Time Ratio
Transit Time Ratio indicates if the transducer mounting spacing is accurate. The normal transit time ratio should
be 100
±
3 if the installation is proper. Check it menu 91.
ATTENTION
If the transit time ratio is over 100
±
3, it is necessary to check:
(1)
If the parameters (pipe outside diameter, wall thickness, pipe material, liner, etc.) have
been entered correctly,
(2)
If the transducer mounting spacing is accordance with the display in menu 25,
(3)
If the transducer is mounted at the pipe
’
s centerline on the same diameter,
(4)
If the scale is too thick or the pipe mounting is distorted in shape, etc.
Warnings
Pipe parameters entered must be accurate; otherwise the flowmeter will not work properly.
(1)
During the installation, apply enough coupling compound to stick the transducer onto the pipe wall.
While checking the signal strength and Q value, move the transducer slowly around the mounting site
until the strongest signal and maximum Q value are obtained. The larger the pipe diameter, the more
the transducer may have to be moved.
(2)
Check to be sure the mounting spacing is as calculated in menu 25 and the transducer is mounted at
the pipe
’
s centerline on the same diameter. Note that you can adjust the spacing slightly as described
above to fine tune the device.
(3)
Pay special attention to those pipes that formed by steel rolls (pipe with seams), since such pipe is
always irregular. If the signal strength is always displayed as 0.00, that means there is no signal
detected. Thus, it is necessary to check that the parameters (including all the pipe parameters) have
been entered accurately. Check to be sure the transducer mounting method has been selected properly,
the pipe is not worn-out, and the liner is not too thick. Make sure there is there is indeed fluid in the
pipe or the transducer is not very close to a valve or elbow, and there are not too many air bubbles in
the fluid, etc. Once you have ruled out all these reasons, if there is still no signal detected, the
measurement site has to be changed.
