Metrohm 873 Biodiesel Rancimat Manual - Manual (Page 74)

4.5 Methods ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
66 ￭￭￭￭￭￭￭￭ 873 Biodiesel Rancimat
Range 0 ... 100 h
Evaluation suppression
Start
Time from the start of the determination to the start of the evaluation sup-
pression.
Range 0 ... 100 h
End
Time from the start of the determination to the end of the evaluation sup-
pression.
Range 0 ... 100 h
Evaluation sensitivity
This value defines the minimum value which the maximum of the curve of
the second derivative has to reach in order to be accepted as a result. The
result, i.e. the induction time, is the time until the first accepted maximum.
The default value "1" will lead to the correct result for most applications.
Smaller values will cause the acceptance of smaller maximums of the second
derivative. Higher values require a higher maximum.
Range 0.1 ... 9999
Induction time
The induction time is the time to the break point of the curve conduc-
tivity vs. time recorded with the Biodiesel Rancimat. The induction time is a
parameter for the oxidation stability.
For automatic determination of the induction time, the second derivative of
the measured curve is used, which exhibits a maximum at the break point
and which can be displayed in the window Live graph. To enable detection
of a break point, certain criteria must be fulfilled with regard to the height
and width of the peak in the second derivative. The break point can also be
determined manually as the intersection point of the two tangents at the
extended straight branches of the curve (see "Setting tangents manually",
page 112).