Siemens SITRANS LUT400, Руководство по эксплуатации, Страница: 578 / 601

A5E33329501 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS Page 265
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Volume Calculation
The SITRANS LUT400 provides a variety of volume calculation features (see
2.6.Volume
).
If the vessel does not match any of the eight preset vessel shape calculations, a
Universal Volume calculation may be used. Use the level/volume graph or chart provided
by the vessel fabricator (or create one based on the vessel dimensions). Based on the
graph, choose the Universal Volume calculation, and select the level vs. volume
breakpoints to be entered (32 max). Generally, the more breakpoints entered, the greater
the accuracy.
2.6.1.Vessel Shape
set to Universal, Linear
This volume calculation creates a piece-wise linear approximation of the level/volume
curve. This option provides best results if the curve has sharp angles joining relatively
linear sections.
Enter a Level Breakpoint at each point where the level/volume curve bends sharply (2
minimum).
For combination curves (mostly linear but include one or more arcs), enter numerous
breakpoints along the arc, for best volume calculation accuracy.
2.6.1.Vessel Shape
set to Universal, Curved
This calculation creates a cubic spline approximation of the level/volume curve, providing
best results if the curve is non-linear, and there are no sharp angles.
Select at least enough breakpoints from the curve to satisfy the following:
• two breakpoints very near the minimum level
• one breakpoint at the tangent points of each arc
• one breakpoint at each arc apex
• two breakpoints very near the maximum level
For combination curves, enter at least two breakpoints immediately before and after any
sharp angle (as well as one breakpoint exactly at the angle) on the curve.