On a routine basis, many users weigh very small test samples.
Typically, they use only 1-10% of a scale's weighing capacity. But
it's in this area that measurement uncertainties are at their highest.
It is common to weigh 2 to 20 mg to prepare a standard solution for
liquid or gas chromatography analysis. The key question now is whether
this quantity to be weighed is compatible with QA (Quality Assurance)
requirements and balance performance.
Minimum weighing increases the certainty that whenever a scale
user weighs more than the minimum weight, his measurements are within
the tolerances required to ensure product quality.
This knowledge provides the certainty that the factory always
produces products of consistent quality, or that the laboratory always
carries out analyses of consistent quality. Quality established for
the process with the right weighing instrument, not quality obtained
with a lot of analysis and sorting of products that didn't meet specifications.
What's more, the user has the peace of mind of knowing that he
can easily pass the next audit or inspection, because now he has the
documentation to show that his instruments comply with the process
requirements.
This article proposes a solution to this tricky question, based
on a number of different situations.
As is customary in the industry, we use the term "kg" instead
of "mass".