Precisa 360 ES Series, Руководство по эксплуатации

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■ 16 Minimum original weight ("MIN.-WEIGHT")
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• Extension factor (k) (generally 2 or 3) :
The extension factor determines the likelihood of occurrence. The factor is defined by the user or is
defaulted.
The minimum original weight is calculated as follows:
Example of figures for the MSW in accordance with the USP:
If work is conducted in accordance with the USP (United States Pharmacopoeia), the following parameters
are given:
•
Repeatability:
Standard deviation if the same weight is placed on ten times.
• Extension factor:
k=3
• Rel. uncertainty:
U=0.1%
The repeatability of an XR125SM in the tare range between 0 and 35 g was determined as a standard
deviation on site by placing a weight on ten times and measures 0.025 mg.
The minimum original weight is thus calculated as follows:
In compliance with USP24-NF19, the original weight on the XR125SM may not be less than a minimum of
75 mg.
Recommended procedure:
– Conduct the tests on-site and as close to the real situation as possible.
– Try to provide the best possible ambient conditions.
Ensure that these conditions do not deteriorate significantly afterwards in normal operation.
– First of all, configure the "FLOATINGDISPLAY" and "STABILITY" weighing modes (see chapter 16.3.2
"Non-variable menu settings").
– Define the due-date for the next check, "NEXT TEST", in accordance with your QM specifications.
– Define the extension factor and relative uncertainty in accordance with your QM specifications and
describe this under "Test parameters". The test parameters are merely for information purposes.
– Determine the minimum original weight(s) for your balance as follows:
Determining repeatabilities / Defining tare ranges:
First of all, test the behavior of the balance in different tare ranges:
Divide the balance's weighing range into 10g intervals, for example, and measure the repeatability for
each interval.
Draw a graph of the entire weighing range by plotting all the results, joining them together and working
Min. Weight[MIN]
Extension factor[k] Standard deviation[StdD]
⋅
Relative uncertainity[U]
----------------------------------------------------------------------------------------------------------------
=
Min. Weight[MIN]
3 0.025 mg
⋅
0.1%
------------------------------ 100% 75 mg
=
⋅
=