How To Select A Xdcr Mount Mode; Reviewing The Spacing Method; How To Use The Spacing Offset - Siemens SITRANS F Instruction Manual

Section 2
To move the cursor to the desired transducer size press
To select the transducer press

2.4.3 HOW TO SELECT A XDCR MOUNT MODE

The flowmeter recommends the transducer mounting mode [Direct or Reflect]. In almost all cases it will
be Reflect, since this is the most desirable configuration. Reflect mode allows you to mount the transduc-
ers on pipes that do not permit back or side access. Reflect mode provides inherent compensation for
flow profile distortion (crossflow) that could be the result of unfavorable application conditions such as
an insufficient upstream straight run. In addition, Reflect mode supports the AutoZero function, which
sets the zero flow velocity automatically.
Direct mounting may produce a stronger transducer signal and requires less mounting length than
Reflect mounting. This can be important if the liquid or pipe material exhibits high sonic attenuation,
thereby preventing operation in the Reflect configuration.
NOTE: We recommend using Direct Mount with plastic pipes.
To select a Xdcr Mounting Mode:
To access the Xdcr Mount option list press
To move the cursor to the required mounting type press
To store selection press

2.4.4 REVIEWING THE SPACING METHOD

The flow computer analyzes your transducer selection, mounting mode and pipe size to determine 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 transduc-
ers. 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.

2.4.5 HOW TO USE THE SPACING OFFSET

After you select the mounting method, the flow computer checks your entries for pipe size, transducer
type etc., and then recommends a spacing offset. This is the first step in establishing the correct distance
between the transducers. Spacer bars and mounting tracks utilize number indices (labels) to simplify
transducer placement. One transducer is located at the Reference position, while the other one is lo-
cated 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.
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