Siemens SITRANS FUH1010PVX, Operating Instructions Manual, Page: 91 / 226

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1010BXFM-3
Section 2
2.4.6 LETTER INDEX (1011 Transducer) - LETTER and NUMBER INDEX (990
Transducer)
The 1011 transducers utilize a different spacing method then the 990 transducers.
The 1011 Transducer
After selecting the mounting method, the computer checks entries for pipe size, transducer
type, etc., and then recommends a Number Index. Use this Number Index to position the
transducers at the proper distance apart when using a track or spacer bar. One transducer is
positioned at the REF point and the other is positioned at the given Number Index. While this
positioning provides the best signal strength in most cases, there are situations where either
more signal quality or more amplitude is desired. This can be accomplished by moving the
cursor to [Spacing Offset] and selecting either ”Min” for a better signal quality, or “Max” for
greater amplitude. After selecting “Min” or “Max”, the computer will recompute a different
Number Index. Move the transducer to that new position.
The 990 Transducer
This menu provides both a Letter Index and a Number Index. The Number Index (like the
1011) provides the spacing between transducers while Letter Index provides for changes, if
necessary, for signal strength and amplitude. Higher letter indices provide greater signal
levels but, in some cases, slightly decreased signal quality.
For transducers mounted independently and where manual measurements of the distance
between transducers must be determined (e.g., 1011 Transducers in Direct Mode), the Inter-
face Detector issues the actual distance between the transducers in inches or millimeters
(Ltn). Please review Section 3 for details on how to use the Ltn measurement.
NOTE: You must connect the Up Transducer cable to the transducer mounted on the
upstream end of the mounting track.
It is important that you note each transducer’s serial number, its Index position during the
original installation, and whether it is in the upstream or downstream position. If you cannot
recreate the original installation’s exact physical arrangement, it will be necessary to do a
“New Install.” In addition, please note that transducer pairs have matching serial numbers
except for the appended letters “A” and “B.” These letter designations help you identify each
transducer.
2.4.7 THE NUMBER INDEX MENU CELL
Selecting the Spacing Offset allows the computer to calculate the Number Index. The Number
Index establishes the spacing between a pair of transducers. You cannot override this recom-
mendation. 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
computer bases its Number Index selection on the pipe diameter and estimated liquid sonic
velocity (Vs) you entered in the Pipe Data menu. When you Invoke the [Install Completed?]
routine, the computer actually measures the liquid sonic velocity (Vs). In some cases, it may
prompt you to re-space the transducers to another number index.
ENT
To move the cursor to the desired offset press
To store selection press
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