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7.7 Reference Temperature
With linear temperature coefficient:
If you use only TC
1
, enter the average product temperature as reference temperature,
rather than the lab temperature of, say, 20°C.
Add a correction value (ϑ
P
- ϑ
Ref
)*TC
1
to the measured value.
A slightly incorrect value entered as TC
1
is the more significant, the greater the difference
ϑ
P
- ϑ
Ref
. If one correlates the count rates entered at operating temperature with the den-
sity values obtained at constant lab temperature, the reading will always be equal to the
density value calculated at lab temperature.
With linear and square temperature coefficient:
In this case, enter the lowest temperature (10°C in the above example) used for calcula-
tion of the temperature coefficient as reference temperature.
7.8 Temperature Coefficient Calculation without Table
Values
Linear temperature coefficient
If you don’t know the temperature coefficient of the product you want to measure, you
can calculate it using the method described below. This requires that calibration with at
least two value pairs has already been performed at reference temperature.
Fill measuring path with the product to be measured. The density should be about the
average value of the requested measuring range.
Disable temperature compensation (instrument configuration without TC).
Start measurement and wait for a short time until the reading shows the value of the
product in the measuring path.
Write down the density or concentration value ρ
1
.
Read off product temperature ϑ
1
, write it down and enter it in reference temperature.
Change temperature of product in the measuring path through heating or cooling by ap-
prox. 10 to 15°C.
Note this density or concentration value ρ
2
, and also the associated temperature ϑ
2
.
Calculate the temperature coefficient as follows:
-
-
- = TC
21
21
1
ϑϑ
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