Density Meter LB 444 SECTION 2. SYSTEM DESCRIPTION
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Parameter
Productselect No. 1/2/3/4:
Parameters (calibration data, temperature coefficients, current output range,
limit values etc.) for max. 4 different products can be entered and stored. These
parameters must be entered separately and the calibration must be performed
for each product. The calibration data measured for a product can also be cop-
ied to other data sets. Thus, the same product can be measured with different
measuring ranges or different limit values. In the normal measurement mode the
product for the current measurement is selected here.
Detector and Isotope:
Code: Detector-specific code number for taking into account the parameters to
be defaulted for the measuring geometry and the detector version (see
TECHNICAL DATA). Enter the operating code for the detector (max. 2 digits).
Isotope: Select the isotope used for the measuring configuration so that the nu-
clide-specific factor for the automatic half-life correction becomes effective.
Measuring Path (0.1 to 9999.9 cm):
Enter the measuring path in the product in cm. With 90° irradiation to the pipe-
line axis, the measuring path is equal to the internal diameter of the pipeline.
With an irradiation angle of 45° or 30°, the internal diameter of the pipeline must
be multiplied by factor
2
or 2 respectively. The actual measuring path in the
product must be entered here when working with S or U-shaped measuring
paths where the pipeline is irradiated along the longitudinal axis, or when per-
forming measurements in a container.
The data should be entered accurately if only one-point calibration of the meas-
uring system is possible. With two or multi-point calibration the input accuracy is
less important, since the computer corrects the absorption coefficients accord-
ingly.
Select: Measure Mode:
Continuous measure: continuous measurement.
Batch via keyboard: batch measurement with Start/Stop via keyboard.
Batch external: batch measurement with external Start/Stop signal
Digital input 22a and 22c.
We recommend using the “Batch measurement” mode, for example, when a
pipeline or a container is filled briefly and then emptied again. In this case,
shorter measuring times can be realized.
Time constant:
Enter the time constant of the instrument system. It determines the average cal-
culation of the counts supplied by the detector. In order to reduce statistical
variations, select the highest time constant that is permissible. It is dependent
upon the permissible error during the maximum possible density rate-of –
change. A time constant of less than 20s will therefore be required only in
exceptional cases. Typical input values are between 30 and 300 s.
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