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9.3 Phase Angle Rotation Correction (Details)
This section describes the special setups and actions required for cases of measuring high density. In
normal measurement, it is unnecessary to be aware of the phase angle rotation correction, which is
performed automatically.
9.3.1
Care point concerning phase angle rotation
As described in 9.2.1, the number of phase angle rotations N is incremented or decreased judging from
the values before and after the measured value. Such a processing requires the condition that the
measured phase value varies continuously in accordance with the density of the measured matter. If the
tank or the piping system (where the density meter is installed) is empty, however, the continuity of
measured phase values is damaged thus making a normal phase angle rotation correction impossible,
which in turn may cause the number of phase angle rotations to jump to a faulty value. If the number of
phase angle rotations N is inappropriate, the density calculation result will also turn out to be erroneous.
Once such a trouble occurs, it is necessary to reset the number of phase angle rotations N to an
appropriate value through manual input.
9.3.2
Phase angle rotation in external synchronized operation
The trouble previously described will be solved by performing the "external synchronized operation"
incorporated into this density meter. In the external synchronized operation, if the contact signal is
switched OFF synchronized with the pump shutdown, not only the output is switched to the simulated
one but also the immediately preceding value is kept as the number of phase angle rotations N.
9.3.3
Outline of automatic adjustment function of phase angle rotations
Furthermore, this density meter is equipped with the function of "automatic adjustment of phase angle
rotations." This function judges whether the measured density calculated with the number of phase
angle rotations N is proper or not in terms of the set density measurement range, etc. and then adjusts the
number of phase angle rotations either incrementally or decreasingly if necessary. Even when the tank
or the piping system (where the density meter is installed) is temporarily made empty thus causing the
number of phase angle rotations N to jump to an inappropriate value, this function is also used to fill up
the density meter detector once again with the matter to be measured and automatically adjust the
number of phase angle rotations N to an appropriate value, which in turn will render an appropriate
value for the measured density. While the tank or the piping system (where the density meter is
installed) is left empty, the measured phase value itself comes to have an indefinite value, which in turn
will render the measured density indefinite. Therefore, if the tank or the piping system (where the
density meter is installed) could be made empty, it is desirable to perform the external synchronized
operation.
9.3.4
Judgment conditions and adjustments for automatic adjustment of phase angle rotations
The judgment conditions and adjustments regarding the automatic adjustment of phase angle rotations
and the measured density are listed in Table 9.3.1.
77
6 F 8 A 0 7 8 7
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