Mass and Balance Calibration

Purpose

To define the methods for calibrating weights (conventional mass by comparison) and non-automatic weighing instruments (repeatability, errors of indication, eccentricity and uncertainty of weighing results), following EURAMET cg-18 and OIML R 111 principles, with uncertainty evaluated per SOP-16 and reporting per SOP-18.

What is inside

10 sections, about 5 pages when printed.

1. 1. Purpose
2. 2. Scope
3. 3. References
4. 4. Definitions
5. 5. Responsibilities
6. 6. Procedure
7. Records generated by this procedure
8. Monitoring and performance indicators
9. Assessment readiness notes
10. Related documents

Records it generates

Applying this procedure produces the following records, which are the evidence an assessor samples.

• –Calibration worksheet with raw data, environment, equipment and calculations
• –Instrument / logger data files
• –Job uncertainty evaluation
• –Certificate and review checklist
• –QC / check standard results

What an assessor looks for

The document closes with these points, so you can check your own practice before someone else does.

• –Reviewing the weighing scheme, raw readings and buoyancy correction for a sampled weight.
• –Checking that the reference weights' class and uncertainty support the test weights' class (U <= 1/3 MPE).
• –Checking the instrument calibration covers repeatability, errors of indication and eccentricity with the weights identified, and that on-site conditions were recorded.
• –Asking how the uncertainty of a weighing result was derived when reported.
• –Confirming acclimatisation times.

Before you use it

• Replace every square-bracket token, starting with [LABORATORY NAME], [ADDRESS] and [EFFECTIVE DATE]. The full token list is in GD-01 Read Me First.
• Have the content technically reviewed against how your laboratory actually works, then approved by the responsible manager before it becomes a controlled document.
• Update the Word fields after editing so the table of contents and page numbers are correct: select all, then press F9.
• Record the document in your own document register and set its review date.
• Delete the assessment readiness notes if you do not want them in your controlled version; they are guidance for you, not requirements.

Related documents

• QM-01

  Quality Manual

  Top-level description of the management system against every clause of ISO/IEC 17025:2017.

• SOP-13

  Selection, Verification and Validation of Methods

  Choosing appropriate methods, verifying standard methods, validating non-standard and laboratory-developed methods.

• SOP-16

  Evaluation of Measurement Uncertainty

  GUM-based uncertainty evaluation, budgets, CMC consistency and reporting, aligned with UKAS M3003 principles.

• SOP-21

  Temperature Calibration

  Comparison calibration of thermometers, PRTs, thermocouples, indicators and data loggers in baths, dry blocks and chambers.

• SOP-22

  Humidity Calibration

  Calibration of hygrometers, RH probes and loggers against a reference hygrometer in a humidity generator or chamber.

• SOP-23

  Pressure Calibration

  Calibration of gauges, transducers and indicators against pressure balances and reference transducers.

• SOP-24

  Electrical Calibration

  DC and low-frequency calibration of multimeters, calibrators and process instruments.

• SOP-25

  Dimensional Calibration

  Calibration of callipers, micrometers, gauge blocks, dial indicators and rules by comparison to reference standards.