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1010PVNFM-3A
Section 2
number indices (labels) to simplify transducer placement. One transducer is located at the
Reference position, while the other one is located at the Number Index position. The Number
Index cannot be directly edited. However, the Spacing Offset can be changed via its option
list. Changing the Spacing Offset will alter the reported Number Index. Maximum spacing
offset provides moderately greater signal levels but, in some cases, slightly decreased zero
flow stability. (NOTE: This mounting method is different for the System 991 Flowmeter.)
If the flow-computer reports “Use Ltn,” you have to measure the distance between the up-
stream and downstream transducers. The flow computer issues the actual distance be-
tween the transducers in inches or millimeters (See Ltn paragraph 2.4.7). Please consult Sec-
tion 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.
The 1010PVN 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 upstream 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 dur-
ing the original installation because to reinstall the flowmeter successfully, you must re-
mount 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 trans-
ducer.
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
2.4.5 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. Ini-
tially, the flow computer bases its Number Index selection on the pipe diameter and esti-
mated liquid sonic velocity (Vs) you entered in the Applcation Data menu. When you invoke
the [Install Completed?] routine, the flow computer actually measures the liquid sonic veloc-
ity (Vs). In some cases, it may prompt you to re-space the transducers to another number
index.
2.4.6 REVIEWING THE SPACING METHOD
The flow computer analyzes your transducer selection, mounting mode and pipe size to deter-
mine the best way to install your transducers. It will recommend the use of either a mounting
track, a spacer bar, or independent mounting. The flow computer will list the part number of
a mounting track or spacer bar. If it decides upon independent mounting, it will report the
distance required between the two transducers. In this case, you have to make sure that when
you mount the transducers, the space between them equals the length specified in the Ltn
menu cell. See Section 3 for details on how to accomplish this.
ENT
Содержание 1010PVDN
Страница 185: ...APPENDIX A Couplant Installation Instructions...