Calibration Bangladesh Weighing Balance Part 3 Guidelines on the Calibration of Non-Automatic Weighing Instruments
January 2009
1 Calibration Bangladesh Weighing Balance Part 3 INTRODUCTION
Non-automatic weighing instruments are widely used to determine the quantity of a load in terms of mass. While for some applications specified by national legislation, they are subject to legal metrological control – i.e. type approval, verification etc. – there is an increasing need to have their metrological quality confirmed by calibration, e.g. where required by ISO 9001 or ISO/IEC 17025 standards.
2 Calibration Bangladesh Weighing Balance Part 3 SCOPE
This document contains guidance for the static calibration of self-indicating, non- automatic weighing instruments (hereafter called “instrument”), in particular for
- measurements to be performed,
- calculation of the measuring results,
- determination of the uncertainty of measurement,
- contents of calibration
The object of the calibration is the indication provided by the instrument in response to an applied load. The results are expressed in units of mass. The value of the load indicated by the instrument will be affected by local gravity, the load’s temperature and density, and the temperature and density of the surrounding air.
The uncertainty of measurement depends significantly on properties of the calibrated instrument itself, not only on the equipment of the calibrating laboratory; it can to some extent be reduced by increasing the number of measurements performed for a calibration. This guideline does not specify lower or upper boundaries for the uncertainty of measurement.
It is up to the calibrating laboratory and the client to agree on the anticipated value of the uncertainty of measurement which is appropriate in view of the use of the instrument and in view of the cost of the calibration.
While it is not intended to present one or few uniform procedures the use of which would be obligatory, this document gives general guidance for the establishing of calibration procedures the results of which may be considered as equivalent within the SIM Member Organisations.
Calibration Bangladesh Weighing Balance Part 3
Calibration Bangladesh Weighing Balance Part 3 Any such procedure must include, for a limited number of test loads, the determination of the error of indication and of the uncertainty of measurement assigned to these errors. The test procedure should as closely as possible resemble the weighing operations that are routinely being performed by the user – e.g. weighing discrete loads, weighing continuously upwards and/or downwards, use of tare balancing function.