Ametek 1400700, Руководство пользователя

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14 1400700-101 Rev. A
What is refractometry?
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Examples
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This was pretty easy. Take care, that the brix value considers the temperature and you do not have to apply
a temperature correction.
Let us observe an example that is a little bit more exciting: the brix scale itself. For instance, you have this
table with values at 20.0°C:
Refractive Index Brix
1.332986 0
1.347824 10
1.363842 20
1.381149 30
1.399860 40
1.420087 50
1.441928 60
We call this seven values the support points of the polynomial fit.
If your calculator is able to compute a best-fit curve, it would show you the following formula:
Brix = 0.358 + 549.396 · r
So if you want to type in the coefficients for the special scale you have to use 0.358 for c
1
and 549.396 for
c
2
. The coefficients c
3
to c
8
would be zero.
Optionally you can even determine a parabola with the least-squares method, the formula would
look like that:
Brix = -1.90 + 682.773 · r - 1167.678 · r
2
Results compared to the set values:
Refractive Index brix
set value straight line parabola
1.332986 0 2.0 0.1
1.347824 10 10.2 9.9
1.363842 20 19.0 19.9
1.381149 30 28.5 30.0
1.399860 40 38.7 40.1
1.420087 50 49.9 50.1
1.441928 60 61.9 59.9
Refractometry
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