Density Meter LB 444 SECTION 6. BASICS OF DENSITY MEASUREMENTS
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b)
Calibrate mode 2
: Linear curve fit
Select lin
This calibration mode must be chosen
• only two value pairs are available.
This calibration mode should also be selected when
• several calibration points are available which are very closely adja-
cent, so that not the entire measuring range is covered by samples.
With minor errors occurring during sampling or in the lab, the calibra-
tion curve may be significantly falsified. In this case it may even be
better to do only one-point calibration (see Figures 28 and 29).
or
• the unit g/cm
3
has been selected
or
• sampling can only be done very inaccurately, so that the samples are
subject to errors.
c) Calibrate mode 3
: Curve fit with linear and square coefficients (squ) can
be selected when
• the entire measuring range has been covered evenly by several (at
least 3) calibration points.
• the measurement is run in % concentration, °Bx or another unit which
is not in linear proportion to the density.
d) Calibrate mode 4
: Curve fit with linear, square and cubic coefficients
(cub) can be selected
• when the same conditions exist as under b), but at least 4 value pairs
are available and the actual measurement shows that with calibration
mode 3 deviations occur in parts of the measuring range.
e) Calibrate mode 5
(auto)
The program selects the best curve fit; square or cubic curve fits are se-
lected only after strict tests have been performed in order to rule out incor-
rect use of a curve function due to random dispersion of the data.
At least 4 value pairs have to be available for this calibration mode.
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