Siemens SITRANS FUH1010PVX, Operating Instructions Manual, Page: 174 / 226

5-2
1010BXFM-3
Section 5
5.2.2 PICKING THE APPROPRIATE TRANSDUCER
To ensure that you select the appropriate transducers for your application, consider the pipe
outer diameter, temperature range and degree of precision required.
Initial transducer size recommendations are based on your pipe outer diameter, wall thick-
ness and pipe material entries. However, you can override the meter recommendations to
accommodate specific situations. For example, you may own a set of transducers whose size
does not appear on the meter list. You may be able to use transducers on a pipe size outside
of their nominal pipe OD range. During transducer install, the computer recommends Spac-
ing Indices (for spacer bars and mounting tracks) or Ltn, (actual distance required between
transducers). Once you mount transducers and invoke the install routine, you can de-
termine the suitability of your transducers by checking the signal strength and comparing
the reported sonic velocity with the actual sonic velocity of the liquid to be measured.
NOTE: Transducer pairs must have matching serial numbers.
5.3 OVERVIEW OF SYSTEM PERFORMANCE
Our system performance specifications are based on acceptable liquid sonic conductivity and
other pertinent application conditions. The diversity that characterizes liquid, makes it im-
possible for us to cover all possible application conditions that have the potential to reduce
performance. Performance within specifications depends primarily on the receive signal’s
signal-to-noise ratio and amplitude. The information below may point to application condi-
tions that could reduce system performance below its normally high level.
5.3.1 ACCURACY
Two common data-entry mistakes may reduce performance. If you enter an incorrect liquid
viscosity value, incorrectly identifying the transducers will reduce accuracy. Measured sonic
velocity (Vs) errors will usually reveal this problem and simply returning to the appropriate
menu cells, entering the correct values, then repeating the transducer installation will re-
solve it.
5.3.2 REPEATABILITY
Some applications require repeatability rather than absolute accuracy. System 1010 features
excellent repeatability specifications since its digital “no moving parts” design avoids the
adverse effects of hysteresis and other wear mechanisms typical of mechanical devices.
5.3.3 DATA STABILITY
Two main factors influence the system’s data stability: Data Scatter and Drift.
Data Scatter
Data scatter is a rapid variation in readings (within a span of about 0.1 to 5 seconds). Minimal
data scatter (approximately 0.01 to 0.03 ft/sec) is a natural by-product of digital computation
that extracts the extremely small difference in the up verses down sonic transit
time. Minimal data scatter will not influence integration. Poor liquid sonic conductivity may
attenuate sonic signal to a level that increases data scatter. You should check the signal level
(Valc %) item on the Diagnostic Menu. Usually, this is indicated by a low Valc % value (less
than 30). System 1010BX does not exhibit inertia since it has no moving parts. It takes read-
ings at ten times per second. It can detect and track very brief fluctuations that are beyond the