2-21
1010ENFM-3B
Section 2
If the flowmeter reports [Use Ltn], you have to measure the distance between the upstream and down-
stream transducers. The flow computer issues the actual distance between the transducers in inches or
millimeters (See Ltn). Please consult Section 3 for details on how to use the Ltn measurement. Note that,
even though using Ltn does not call for the physical use of the Number Index, you can still change the
Spacing Offset to influence the strength of the transmit signal.
FUE1010EN uses a pair of precisely matched transducers. Therefore, you can select either one for the
Reference position. You must connect the Up transducer cable to the transducer mounted on the up-
stream side of the mounting track. This lets the meter display the flow direction correctly.
It is important that you note each transducer’s serial number and its Index position during the original
installation because to reinstall the flowmeter successfully, you must remount each transducer in its
original position. Transducer pairs have matching serial numbers except for the appended letters “A” and
“B”. This helps you to identify each transducer.
To select a different Spacing Offset
To access to Spacing Offset option list press
To move the cursor to the desired offset press
To store selection press
2.4.6 THE NUMBER INDEX MENU CELL
Selecting the Spacing Offset allows the flow computer to calculate the Number Index. The Number Index
establishes the spacing between a pair of transducers. You cannot override this recommendation. To
complete the transducer installation, you must accept the Number Index by mounting the transducer at
that point on your spacer bar or mounting track. Initially, the flow computer bases its Number Index
selection on the pipe diameter and estimated liquid sonic velocity (Vs) you entered in the Application
Data menu. When you invoke the [Install Completed?] routine, the flowmeter actually measures the
liquid sonic velocity (Vs). In some cases, it may prompt you to re-space the transducers to another
number index.
2.4.7 THE Ltn MENU CELL
This view only menu cell shows the distance in inches or millimeters between the front faces of the
transducers along the axis of the pipe. If you are mounting the transducers without a track or spacer bar,
you have to space them according to this value (see Section 3 for details). Note that Ltn may be a
negative number for direct mount on very small pipes where the transducer spacing overlaps.
2.4.8 HOW TO USE [INSTALL COMPLETED?]
Use the [Install Completed?] menu cell to inform the flow computer that you have mounted the transduc-
ers according to the selected mode and spacing requirements and are ready to start operation.
To start the [Install Completed?] routine for an original installation:
Select any transit-time mode (e.g., Clamp-On ) and press the <Right Arrow>.
Press the <Down Arrow> and scroll to the [Pick/Install Xdcr] menu cell. Press <Right Arrow>.
Install transducers as required (refer to Section 3).
ENT
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