CONCEPTS OF METROLOGY AND IMPORTANCE OF CALIBRATION

1. Bangladesh BEST Programme CONCEPTS OF METROLOGY AND IMPORTANCE OF CALIBRATION NihalGunasekara Sri Lanka

2. Bangladesh BEST Programme KEY WORDS • CALIBRATION – Comparison • METROLOGY – Science of Measurement • TRACEABILITY – Unbroken Chain of Comparisons • UNCERTAINTITY – Error in Measurement • ACCREDITATION – Third Party Ascertain • CALIBRATION INTERVAL – Equipment Remains Reliable

3. Bangladesh BEST Programme Experiment or test CAN BE SEEN EVERYWHERE Everything has to do with measurement Designing Conducting Analyzing Results Allowing people to plan their lives and make commercial exchange with confidence within the Metrology realm WHAT IS METROLOGY SCIENCE OF MEASUREMENTS 3

4. Bangladesh BEST Programme METROLOGY • Metrology Covers Three Main Tasks: • The definition of internationally accepted units of measurement • The realization of units of measurement by scientific method • Establishment of traceability chain in documenting the accuracy of a measurement • “Metrology is essential in scientific research”

5. Bangladesh BEST Programme CATEGORIES OF METROLOGY • Scientific Metrology – Development of measurement standards • Industrial Metrology – To ensure the adequate functioning of measurement instruments used in industry, production & testing laboratories • Legal Metrology or • Weights & Measures – Accuracy of measurement where these have influence on the transparency of economic transactions, health & safety

6. Bangladesh BEST Programme AREAS OF INDUSTRIAL METROLOGY • Mechanical Metrology – Realises , maintains and disseminates the national measurement standards in the areas of Mass, Volume, Pressure and Dimension • Electrical Metrology –– Realises , maintains and disseminates the national measurement standards in the areas of AC/DC, low frequency, time & frequency and temperature

7. Bangladesh BEST Programme LEGAL METROLOGY • Services offered by legal metrology are: • Mass measurements verification: verification of all mass measuring instruments (balances, trade masses etc.) • Volume measuring instruments : verification of fuel dispensers, tankers , meters etc. • Prepackaging control :verification of quantities in prepackaged products (mass, volume, length, number etc.)

8. Bangladesh BEST Programme Calibration (Old Definition) “Calibration is the comparing of an unknown measurement device against equal or better known standard under specified conditions”

9. Bangladesh BEST Programme Calibration “Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties, and in a second step, uses this information to establish a relation for obtaining a measurement result from an indication ” International Vocabulary of Metrology ) ( JCGM 200:2012 – International Vocabulary of Metrology )

10. Bangladesh BEST Programme Units of Measurement SI Units published by BIPM(Bureau of Weights and Measures) Base Units… Quantity Unit Symbol Length metre m Mass kilogram kg Time second s Temperature kelvin K Electric current ampere A Luminous intensity candela cd Amount of substance mole mol

11. Bangladesh BEST Programme Metrology Laboratories • Primary Laboratories NML, NMI, NPL etc • Reference Laboratories • Calibration Laboratories

12. Bangladesh BEST Programme Measurement Uncertainty “ non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used” It arises due to the imperfections in the measurement system No measurement system is perfect !!!!!

13. Bangladesh BEST Programme Uncertainty An estimate of the possible error in a measurement Type A evaluation A series of repeated observations is obtained to determine the standard deviation of the measurement result. Type B evaluation The evaluation is carried out using available information found in calibration reports, certificates, specifications etc.

14. Expanded Uncertainty Bangladesh BEST Programme Calculate combined standard uncertainties Type A Type B Exp. Unc. U = Combined Uncertainty X Coverage factor

15. Ishikawa diagram Bangladesh BEST Programme Reference T/C Digital Thermometer Calibration (B) Resolution (B) Scatter (A) CJC (B) Uncertainty of an oven Test oven Resolution (B)

16. Confidence Level Bangladesh BEST Programme Gaussian probability distribution -kσ +kσ 68% Within 1σ of mean 95% Within 2σ of mean 99% Within 3σ of mean

17. Bangladesh BEST Programme Metrological Traceability ”property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty” or “HOW TO ENSURE THAT TWO MEASUREMENTS OF THE SAME QUANTITIES ARE COMPATIBLE”

18. How Do We Get Traceability ? Common point of reference Bangladesh BEST Programme Your laboratory My laboratory Their laboratory 18

19. NMI: The Link Organisation to the International Arena Bangladesh BEST Programme International standards National Metrology Institute National community that is using measurements 19

20. HIERACHY OF MEASUREMENT STANDARDS Bangladesh BEST Programme HIERARCHY OF MEASUREMENTS Primary Standards Traceable to BIPM Secondary Standards Working Standards Instruments Used in Lab/ Industry

21. Bangladesh BEST Programme Metal fixed-point

22. BIPM Kilogram National Kilogram Class E1, E2,F1, F2 Masses OIML M1,M2,M3 Masses OIML R47 Masses Analytical &Top loading Precision Balances Platform & Top loading balances Weighing Bridges TRADE MASSES Bangladesh BEST Programme CALIBRATION HIERARCHY OF MASS STANDARDS

23. EXAMPLE Traceable to MASS COMPARATOR USE Transfer Prototype 1kg Traceable to SI Units Calibrate Analytical Balance Set of Classes E2, F1, F2, and M1 Bangladesh BEST Programme BIPM Prototype 1kg 23

24. Bangladesh BEST Programme GAUGE BLOCK COMPARATOR Primary Standard Traceable to Laser interferometer Compare USE Grade K set Calibrate Grade 1 set

25. Bangladesh BEST Programme Examples 1. Performance Test on a Incubator at 35 + 0.5 oC

26. P S Q C R Bangladesh BEST Programme 2. Performance Test on a Water Bath at 50 oC Uniformity : 0.61 oC Stability : 0.33 oC

27. Bangladesh BEST Programme MASS Reference and Auxiliary Equipment • COMPARATOR BALANCES • CLASS E1 1 kg • CLASS E1 SET • CLASS E2 SET • CLASS F1 SET • CLASS F2 SET • CLASS M1 SET

28. Bangladesh BEST Programme CALBRATION INTERVALS What is Calibration interval ??? Period of time of use to ensure the equipment remains reliable Interval is too short : Calibration $$$$$ Interval too long : Risk of bad measurements

29. Bangladesh BEST Programme CALBRATION INTERVALS • ISO 17025 Requirements: • Capable of achieving required accuracy • Comply with specifications relevant to test/calibration method • Use under established calibration programme • Therefore need to : • Define required accuracy • Identify the equipment that can affect it • Manage all equipment under a calibration programme

30. Bangladesh BEST Programme RECOMMENDED CALBRATION INTERVALS • N No single correct answer Calibration represents an instantaneous snapshot of actual condition • Depend upon • Level of stress - subjected • Stability of past calibration • Allowable tolerance range • Required accuracy • Quality Assurance Requirements

31. Bangladesh BEST Programme RECOMMENDED CALBRATION INTERVALS Final AnalysisPeriod between two calibrations Determined & Monitored USER HIMSELF

32. Bangladesh BEST Programme HOW TO ESTABLISH CALIBRATION INTERVAL • Consider influencing factors and existing knowledge : eg • Accuracy sought & consequences of error • Manufacture’s recommendations • Accommodation & environment • Purpose and usage • Maintenance & servicing • Trends from previous calibration • Frequency of checks • Etc. etc. etc. …. • Ref. - ILAC – G 24 : Guidelines for determination of calibration interval of measuring instruments

33. Bangladesh BEST Programme RECOMMENDED PRACTICES • Calibration at (planned) periodic intervals to ensure acceptable accuracy & reliability • Shorten the intervals when results of previous calibration suggest it • May lengthen intervals on basis of demonstrated performance • Documented procedure for assigning and adjusting calibration intervals • Fully documented re-calibration system 33 33

34. Bangladesh BEST Programme CALIBRATION OF VOLUMETRIC GLASSWARE • FLASKS • CYLINDERS • BURETTES • PIPETTES ACCURACY CLASSES CLASS A – Higher grade CLASS B – Lower grade

35. Bangladesh BEST Programme Example - Pipettes METHOD Gravimetric Method – IS0 4787 -2010 (Laboratory Glassware- Volumetric instruments- Method of Testing of capacity and for use)

36. Bangladesh BEST Programme IN-HOUSE PERFORMANCE CHECKS (During Calibration Interval) • ANALYTICAL BALANCES – Using a Calibrated Weight • INCUBATORS - Using a Calibrated Thermocouple • GLASS THERMOMETERS- Ice Point

37. Bangladesh BEST Programme Importanceof Calibration • Assurance of accurate of measurements • Ability to trace measurements to International standards • International acceptance of test/calibration reports • Correct diagnosis of illness (medical reports) • Consumer protection (legal metrology) • Meeting the requirements of ISO 9000 and 17025 37

38. ACCREDITATION Bangladesh BEST Programme How we ensure Technical Competence of Calibration Laboratories & Measurements are traceable to SI Units

39. Defined Criteria for Laboratory AccreditationMetrology Laboratory Bangladesh BEST Programme Organization Laboratory Quality System Qualified personnel Range of the work capabilities and test methods Laboratory practices and management system Reliable standards and measuring devices Laboratory facilities Adequate measuring capabilities Traceability maintenance Calibration records Satisfactory completion of internal audits

40. Bangladesh BEST Programme QUALITY SYSTEM ISO/IEC 17025 • QUALITY MANUAL • PROCEDURE MANUAL • METHOD MANUAL • FACILITIES MANUAL • SAFETY MANUAL

41. Bangladesh BEST Programme ACCREDITEDLABORATORY • IMPLEMENTATION OF ISO 17025 MANAGEMENT REQUIREMENTS TECHNICAL REQUIREMENTS • TRACEABILITY • MAINTENANCE OF ENVIRONMENTAL CONDITIONS • TRAINED STAFF 41

42. Bangladesh BEST Programme ENVIRONMENTAL CONDITIONS • TEMPERATURE • HUMIDITY • AIR VELOCITY • FREE OF VIBRATION • ILLUMINANCE 42

43. Bangladesh BEST Programme ACCREDITEDMASS LABORATORY ENVIRONMENTAL CONDITIONS: TEMPERATURE: 23 ± 0.5 0C , HUMIDITY : 50 ±10%

44. Bangladesh BEST Programme ACCREDITED TEMPERATURE LABORATORY ENVIRONMENTAL CONDITIONS: TEMPERATURE: 23 ±1 0C , HUMIDITY : 50 ±10% 44

45. Bangladesh BEST Programme CONTENTSOF CALIBRATION CERTIFICATE • NAME AND ADDRESS : CUSTOMER/ LABORATORY • METHOD • CONDITION RECEIVED • IDENTIFICATION • DATE OF CALIBRATION • DATE OF RECALIBRATION ? • CALIBRATION RESULTS • UNCERTAINTY OF MEASUREMENT • TRACEABILITY • ENVIRONMENTAL CONDITION 46

46. SAMPLE OFSCOPE OF ACCREDITATION CALIBRATION • RANGE C.M.C • ONE MARK PIPETTE 0 to 200 0.01 • GRADUATED PIPETTE 0 to 25 0.001 • BURETTE 0 to 200 0.01 • VOLUMETRIC FLASK 0 to 2000 0.01 • GRADUATED MEASURING CYLINDER 0 to 2000 0.01 mL mL Bangladesh BEST Programme

47. Bangladesh BEST Programme Accredited Metrology Facilities Ensure Traceable Measurements Technical Competency Industries Better Place in Global Market ISO Certified QMS Products Quality Life

48. Bangladesh BEST Programme “Calibration of laboratory equipment is important to obtain reliable test results” Thank you