A six-place balance will resolve up to sixth decimal place of a gram i. Sometimes not only the resolution but the maximum capacity is also specified for example a g five place balance or a 5 g six place balance.
Vacuum Technology Considerations For Mass Metrology
R , all non-automatic weighing instruments are classified in four accuracy classes. The maximum permissible error MPE of each class of weighing instrument is based on its verification scale interval e and is a function of the applied load on the instrument. The manufacturer for a particular weighing instrument specifies the value of e, if it is not given it is assumed to be equal to the scale interval d.
The correctness of the instrument is defined through the value of the applied load i. This means certain accuracy is required for the standard weight used. All the weights used in trade, commerce, industry and other applications up to 50 kg are classified into seven accuracy classes as per OIMI International Recommendation No.
Automatic Mass Comparators
Appropriate accuracy class weights are used depending on the required accuracy in measurement results. The weighing instrument also contributes to the testing uncertainty and must therefore fulfill certain requirements with regard to its repeatability. Concerning the measurement uncertainty in the non-automatic weighing instrument, OIML R states three important requirements as follows : i Permissible differences between results.
Regardless of what variation of results is permitted, the error of any single weighing result shall by itself not exceed the maximum permissible error for the given load. The difference between the results of several weighing of the same load should not be greater than the absolute value of the maximum permissible error of the instrument for that load. Adjustment of an Electronic Balance. Mechanically balances are normally not adjusted because they indicate weighing differences in mass units using their sensitivity ditermined separately by independent measurement.
But in the case of electromagnetic or electronic balance the indication is adjusted in mass units. Now-a-days, only electronic balances are commonly used.
Mass Metrology | NIST
Normally comparisons of two weights are carried out in air using suitable balance. Thus a balance serves to compare not only the weight forces but also buoyancy forces. For electromagnetic force compensation balances, the indication mw, in units of mass, is proportional to the electromagnetic force F which compensates the weight and buoyancy forces such that: Measuring Procedure.
The mass of a body is determined by weighing i. For differential weighing, following two different weighing principles are normally used : Transposition Gauss Weighing. This principle can be used only with equal-arm balances.
The test weight and the reference weight are interchanged on the pans at least once and the results of the two weighing are averaged. Substitution Borda Weighing.
This principle can be used with all weighing instruments. The test weight and the reference weight are weighed one after another on the same pan.
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In the case of equal arm balances the second pan is loaded with a fixed auxiliary weight. For modern analytical and comparator balance, the substitution principle is generally used because, unlike the Gaussian principle, it allows a simple balance design and offers more ease of handling and, thus, less time of measurement. A number of notebooks and course materials will be provided, so please ensure you have extra luggage space to carry these items. The Mass Metrology Seminar is built on the concepts learned during the Fundamentals of Metrology Seminar, applying units, measurement uncertainty, measurement assurance, traceability and Quality Management System concepts to the mass calibration procedures.
Completing the CD should take 16 to 40 hours.
Mass Comparators and Metrology
If you have problems downloading the material, please send Yvonne Branden link sends e-mail a request to mail a copy of the CD. See Handbook , Program Handbook training requirements. To receive a Training Certificate for this course, successful completion requires participants to actively participate in the entire course e. A written final exam will contribute 50 percent of the grade and the class and laboratory exercises will be 50 percent of the grade.
Table of contents
Physical Measurement Laboratory. Weights and Measures. National Work Group Taximeters: U. Purpose: The Mass Metrology Seminar is a two-week, "hands-on" seminar.
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Learning Objectives: At the end of this seminar, using Standard Operating Procedures 2, 4, 5, 7, 8, 9, 29, and 30 and Good Measurement Practices 10, 11, 12, 13, and 14, participants will be able to: IDENTIFY mass artifacts and use appropriate procedures to ensure good quality, accurate, traceable mass measurement results; EXPLAIN highlights and key concepts of each topic to each other and to your managers using the slides and reference materials; and PERFORM mass calibration procedures, use and validate the job aids, and use reference materials to perform laboratory calibrations, including hands on handling of mass standards and balances, calculation of measurement results, integration of measurement assurance, uncertainty analysis, and software validation to produce valid calibration results and certificates.
Minimum Requirement s : To receive a Training Certificate for this course, successful completion requires participants to actively participate in the entire course e. Audience: This training seminar is open to industry and government metrologists. Participants must have access to Microsoft Excel versions and later are acceptable and can open and effectively create their own spreadsheets to perform calculations, and use template Excel workbooks that will be provided on USB media.