TF1100-EH transit-time handheld flowmeter manual
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checked frequently until the signal quality detected is as strong as possible.
5.4.3 Total Time and Delta Time
“Total Time and Delta Time”, which displays in Window No.93, indicates the condition of
the installation. The measurement calculations in the flow 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.
5.4.4 Transit Time Ratio (M91, Very important for transducer mounting spacing)
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.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 in accordance with the display in Window M25, (3) if the
transducer is mounted at the pipe’s centerline on the same diameter, or (4) if the scale is too
thick or the pipe mounting is distorted in shape, etc.
5.4.5 Warnings
1. Pipe parameters entered must be accurate; otherwise the flow meter will not work
properly.
2. During the installation, apply enough coupling compounds in order 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 can be
obtained. Make sure that the larger the pipe diameter, the more the transducer should be
moved. 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. 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. With the exception of these reasons, if
there is still no signal detected, the measurement site has to be changed.
3. Make sure that the flow meter is able to run properly with high reliability. The stronger the
signal strength displayed, the higher the Q value reached. The longer the flow 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.
4. After the installation is complete, power on the instrument and check the result
accordingly.
