The Value of Calibration in Testing · give you what you need! • Calibration vendors offer different types of calibrations • Make sure your cal provider’s measurement capabilities

The Value of Calibration in TestingHelga AlexanderProgram Manager

Calibration Laboratories

MFRPA, Houston, TX10 April 2019

About IAS

• A non-profit accreditation body.

• Providing accreditation services since 1975.

• Headquartered in Brea, California

• Accredits a wide range of companies and organizations, including governmental

entities, commercial businesses, and professional associations.

• Signatory to the three primary international organizations that form a unified

system for evaluating and recognizing competent accreditation bodies worldwide

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Building Department Accreditation

Building Department Service Providers

Calibration Laboratories

Commissioning Training and Certification

Agencies

Curriculum Development

Fabricator Inspection

Field Evaluation Bodies

Fire Prevention and Life Safety

Departments

IAS FDA FSMA Program

IAS Accreditation Programs

Inspection Agencies

Management System Certification Bodies

Manufacturers of Cold-Formed Steel

Components

Metal Building Inspection

Metal Building Assemblers Inspection

Personnel Certification Bodies

Product Certification Agencies

Special Inspection Agencies

Testing Laboratories

Training Agencies

Medical Laboratory

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Why do we test?

• To find out something we don’t know about

the test sample

• To verify that the test sample meets certain

specifications

• To characterize the test sample’s properties

under certain conditions

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yes

What gives us confidence in our test results?

• Establish a test plan or protocol• Establish the properties to be tested

• Establish the test method

• Determine the type and accuracy of equipment needed for a given test

• Validate the test method (ensure method is suitable to provide the desired results, fit for purpose)

• Verify that we can perform the chosen method • Properly trained technicians

• Suitable equipment (e.g. capable of measuring over the range needed, accuracy needed to give meaningful results)

• Ensure repeatability and/or reproducibility of tests

• Ensure that measurement uncertainty of results is within acceptable levels

• Compare our results to those of our peers

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Why calibrate?

• To ensure valid test results!!!!! – Primary reason!!!!

• To ensure test equipment performs as expected

• To ensure that test results are reproducible

• To ensure that my test results can be compared with those obtained by others

• To save money??? -- maybe

• Because my accreditation body, regulator or published test method makes me?

• WRONG ANSWER!

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Calibration Definition

From JCGM 200:2012 (International Vocabulary of Metrology or VIM)

• 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

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What is calibration?

In simpler terms…

Calibration – comparing an instrument to be calibrated to a more accurate

instrument which serves as a traceable reference standard• Doing so at set intervals

• Using validated procedures and

• Competent personnel

• Determining the uncertainty of the calibration

– Maintaining appropriate documentation

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What is calibration?

Calibration is NOT:

• a quick confidence check by comparing to

another piece of equipment

• running a QC check sample

• intermediate check or verification between

calibrations

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Metrological traceability

• In order to make a meaningful comparison between two measurement results, they must be traceable to the same metrological reference and ultimately to the International System of Units (SI).

• Metrological traceability of a measurement result is achieved through • an established calibration hierarchy achieved through an

unbroken chain of calibrations

OR

• certified values of certified reference material (CRM) from reference material producers conforming to ISO 17034

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Calibration Hierarchy

Increasin

g measu

remen

t un

certainty

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If it can’t be adjusted, it can’t be calibrated—TRUE or FALSE?

CALIBRATION ≠ ADJUSTMENTCALIBRATION =

THE ACT OF COMPARING A UNIT UNDER TEST TO A KNOWN STANDARD

Too many engineers and scientists equate calibration with tweaking a potentiometer or assigning new calibration constants in an instrument’s firmware so that specs are met ➔ MISCONCEPTION: If it can’t be tweaked, it can’t be calibrated, not so!

Your resistor, gage block, graduated flask, etc. can be calibrated by comparing it to a reference standard and establishing a relationship between the two!

Common Misconception

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The term “calibrate” by itself on your P.O. may not give you what you need!

• Calibration vendors offer different types of calibrations

• Make sure your cal provider’s measurement capabilities are adequate for the job

• If you need your instrument adjusted back to nominal, make sure your vendor can do so!

• Make sure you get the data before and after an adjustment!

Importance of specifying your calibration needs

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• Make sure you examine and understand your calibration report or certificate!– Evaluate the impact on previous test results if test equipment was

found out of tolerance before it was adjusted back to nominal!– Evaluate the impact of a calibration data point close to the

specification limit if the instrument was not adjusted back to nominal—will your future measurements be ok until your next calibration?

• Make sure you agree to and understand the cal vendor’s decision rule—how did they take measurement uncertainty into account when making Pass/Fail decisions?

• Call your calibration supplier if you have questions about your certificate or report (don’t just file it away!)

• Evaluate and adjust your calibration interval if necessary based on the calibration results

Importance of specifying your calibration needs

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Technical competence• You are assured that the calibration was performed by a

technically competent laboratory

Quality• You know the laboratory is managed under a management

system that assures the quality of their work.

Extra value• The calibration certificate or report will provide you with

additional information such as measurement uncertainty, proof of metrological traceability to the SI through national standards

• You may not necessarily get this information from non-accredited calibration providers

Note that all the above also applies to ISO 17034 accredited reference material producers.

Why choose ISO/IEC 17025 accredited calibration providers?

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Incorrect test results cost money!• Calibration ensures validity of your test results! • Protects your organization’s reputation!

• Prevents re-testing! Calibration provides valuable information on test

system and test equipment• Helps you choose the right equipment for your

tests• Helps you trouble shoot strange or inconsistent test

results• Calibration data may allow you to increase your

calibration intervals

Calibrations are expensive – how can it help save money?

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THANK YOU!

Contact me at [email protected]