EES-401 Series Ultrasonic Energy Meter
Revision: 3.0.1
Page 18 of 90
4.4.3
Total Time and Delta Time
"Total Time and Delta Time", which displays in Window M93, indicates the condition of the installation. The
measurement calculations in the Energy Meter 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.
4.4.4
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 in Window M91.
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 Window M25,
(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.
4.4.5
Warnings
(1)
Pipe parameters entered must be accurate; otherwise the Energy Meter will not work properly.
(2)
During the installation, apply enough coupling compounds in order to stick the transducers onto the
pipe wall. While checking the signal strength and Q value, move the transducers slowly around the
mounting site until the strongest signal and maximum Q value can be obtained. Make sure that the
larger the pipe diameter, the more the transducers should be moved.
(3)
Check to be sure the mounting spacing is accordance with the display in Window M25 and the
transducer is mounted at the pipe
’
s centerline on the same diameter.
(4)
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 indeed fluid in the pipe or
the transducer is not too close to a valve or elbow, and there are not too many air bubbles in the fluid,
etc. With the exception of these reasons, if there is still no signal detected, the measurement site has
to be changed.
(5)
Make sure that the Energy Meter is able to run properly with high reliability. The stronger the signal
strength displayed, the higher the Q value reached. The longer the Energy Meter runs accurately, the
higher the reliability of the flow rates displayed. If there is interference from ambient electromagnetic
waves or the signal detected is too poor, the flow value displayed is not reliable; consequently, the
capability for reliable operation is reduced.
(6)
After the installation is complete, power on the instrument and check the result accordingly.