Calibration

Calibration is the activity of checking, by comparison with a standard, the accuracy of a measuring instrument of any type. It may also include adjustment of the instrument to bring it into alignment with the standard

1. Poornima Institute of Engineering & Technology A presentation on Calibration

2. Electronics Test & Development Center

3. NPL India NPL, UK NIST, USA ERTL-E ERTL-W ERTL-N ERTL-S OTHER ETDC States OTHER LAB ETDC States ETDC States ETDC States Calibration labs NPL – National Physical Laboratory. ERTL – Electronics Regional Test Laboratory. ETDC – Electronics Test and Development Center

4. About NCQC - Calibration Laboratory in India National Centre for Quality Calibration Laboratory The NCQC was founded in 1998 for instrument calibration laboratory. Since then, It has steadily grown by adding many new facilities, capabilities including primary and secondary instrumentation to become leading NABL calibration laboratory in India . They provide calibration services to customers in either their own environmentally controlled multi-laboratory facility or on-site at their location. They are NABL accredited Calibration Lab is having wide scope of thermal, mechanical and electro-technical instrument calibration. It has branches in Gandhidham, Ankleshwar, Bhavnagar, Rajkot and Vapi.

5. TYPES OF MEASUREMENT STANDARDS

6. Traceability Traceable to a national standards. In India it is with National Physical Laboratories, New Delhi.

7. About ETDC Government of India, provides quality assurance services in the area of Electronics and IT through countrywide network laboratories and centers. The service includes Testing, Calibration, IT & e-governance, Training & Certification to public and private organizations.

8. What is Calibration? Calibration is the activity of checking, by comparison with a standard, the accuracy of a measuring instrument of any type. It may also include adjustment of the instrument to bring it into alignment with the standard.

9. Why is Calibration Necessary? It is impossible to make perfect hardware that would not need any form of error correction. Even making the hardware good enough to eliminate the need for error correction for most devices would be extremely expensive. The best balance is to make the hardware as good as practically possible, balancing performance and cost. Calibration is then a very useful tool to improve measurement accuracy.

10. Importance of Calibration Calibration of a measuring equipment or working standard enables the user to take note of the deviations and errors from the nominal values so that corrections can be made to minimize the errors during measurement. A well-calibrated instrument provides the confidence to the user as well as the consumer that the service or the product meets the required specifications and ensures the acceptance in international market.

11. Purpose of Calibration Calibration refers to the act of evaluating and adjusting the precision and accuracy of measurement equipment. Instrument calibration is intended to eliminate or reduce bias in an instrument's readings over a range for all continuous values. Precision  is the degree to which repeated measurements under unchanged conditions show the same result. Accuracy  is the degree of closeness of measurements of a quantity to its actual true value.

12. Types of Calibration Calibration is basically of three types: Electro-technical Calibration: It consist calibration of electronic devices like resister, capacitor etc. Non Electrical Calibration: It consist calibration of mass, pressure etc. On Site Calibration: It consist calibration of any other type of quantity which contain both quantities.

13. Where to Calibrate? Calibration is performed in the I/II/III party laboratory under controlled environment. (The environment need only to be controlled to the extent required.) Accredited Calibration Laboratory Manufacturer’s / Supplier’s Laboratory ensuring valid traceability

14. Location – Permanent/On-site Equipment Calibration laboratory - basic requirements Temperature Humidity Air flow Filtration Electromagnetic Screening Noise Level Vibration EMI/EMC Cleanliness Lighting Power supply Accessibility Receiving & Calibration area Reference standards Transfer Standards Working standards Connecting leads adaptors/accessories Subsidiary equipment Computers & automation software Training Authority Responsibility Technical Competence Documents Records Calibration Environment Staff Management

15. Requirements of Calibration Management System Each instrument requires: Unique identification A recorded history and current calibration status Use appropriate for the function of the instrument Calibration procedures require Approved procedures for calibration Schedule for calibration Process range limits Calibration standards and test equipment Must be more accurate than the required accuracy of the instrument Traceable back to national or international standards Personnel Proof of appropriate training Perform within an established change management process

16. Common measurements I nspection, M easurement, and T est E quipment (IM&TE) To calibrate any equipment, it is necessary to generate a known amount of the variable to be measured and apply it to the unit under test. Variable can be generated by using known generator (i.e. gage block) or unknown generator (in the case it must be measured simultaneously with calibrated device). Where IM&TE is also a generator then the output must be known.

17. COMMON MEASUREMENTS (cont’d) Laboratory Measurement of Temperature : Liquid-in-glass thermometers must be immersed in the calibration bath to a predefined depth. Resistance-Temperature-Devices work on the basis of temperature versus resistance characteristics. Optical Pyrometer is used to measure temperatures above 200 C by measuring the color of the object from the distance.

18. Equipment used for temperature calibration Equipments like RTD, Oil temperature bath and highly accurate glass thermometers are used for temperature calibration.

19. COMMON MEASUREMENTS (cont’d) Laboratory Measurement of Humidity : Humidity is best measured using a chilled mirror hydrometer. Psychomotor measures humidity by comparing the temperature near a dry bulb with that of a wet bulb (the lower the humidity the greater the cooling)

20. COMMON MEASUREMENTS (cont’d) Laboratory Measurement of Pressure : The most accurate way to measure pressure is to generate it (weight divided by the area). Low pressures can be measured using manometer (column of liquid responds to positive and negative pressures). The Bourdon gage measures pressure by mechanical means of elasticity (elastic element used).

21. Measurement of pressure (cont’d) The Quartz Bourdon gage measures pressure by means of electronic transducer.

22. COMMON MEASUREMENTS (cont’d) Laboratory Measurement of Torque : Torque is difficult to generate and measure. Greatest uncertainty, when it comes to measuring torque, is the distance from the center of the mass to the center of the rotating lever arm

23. COMMON MEASUREMENTS (cont’d) Laboratory Measurement of Force : Force is generate by hanging calibrated weights on the unit under test (requires correction to local gravity).

24. COMMON MEASUREMENTS (cont’d) Laboratory Measurement of Mass : Masses are calibrated by comparison to known and traceable reference standards. Gravity correction required????? No, if the materials of the standard are the same as of the unit under test. Yes, where there is difference in materials.

25. Equipments used for mass calibration

26. COMMON MEASUREMENTS (cont’d) Laboratory Measurement of Electrical Quantity: Electronic Calibrators, Capacitors and Inductors, Digital Multimeters, Null Indicators, Bridges and Transfer Standards. Number of digits on the display does NOT mean that the same level of accuracy has been achieved. In case where DC is used, special attention should be paid to high and low voltage (potential results distortion)

27. Measurement of electric quantity (cont’d) Electric equipments like Multimeter , clamp meter, voltmeter are calibrated.

28. COMMON MEASUREMENTS (cont’d) Laboratory Measurement of Time and Frequency : GPS ( G lobal P ositioning S ystem) signal is considered traceable to national standards and has output of about 10MHz (at full capacity).

29. Standard Equipments

30. Calibration Report Calibration Report A calibration report usually provides a set of results that show the performance of the instrument being calibrated in comparison to a reference instrument or standard. Measurements are recorded for each function, range and points tested, and the uncertainty of each measurement is reported.

31. Calibration Certificates Calibration Certificate A calibration certificate usually states the compliance of an instrument with the manufacturer's specification. Measurements made by the instrument being calibrated are compared to the manufacturer's specification. If the instrument is within specification, a statement that the instrument meets the manufacturer's specification at the points tested is made in the conformance certificate.

32. Futures of Calibration System at NCQC Identifies instruments that can be calibrated Determines calibration requirements for instruments Establishes calibration procedures Develops corrective action procedures Documents calibration results and activities Supports audit trails for calibration system

33. Futures of Calibration System at NCQC Identifies instruments that can be calibrated Determines calibration requirements for instruments Establishes calibration procedures Develops corrective action procedures Documents calibration results and activities Supports audit trails for calibration system

34. References www.calibrationlaboratory.in www.stqc.gov.in www.diety.gov.in www.rscalibration.com www.wikipedia.com

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