Transcript Traceability to the SI: What does it

Traceability to the SI: What
does it mean in practice?
Ms. Sally Bruce
and
Ms. Dana Leaman
National Voluntary Laboratory Accreditation
Program
NIST
Reference Information
– ISO/IEC 17025:2005, Section 5.6
Measurement Traceability
– JCGM 200:2008 – International
vocabulary of metrology – Basic and
general concepts and associated terms
(VIM)
– NIST Traceability Policy
– ILAC P10:2002 – ILAC Policy on
Traceability of Measurement Results
– NIST Handbook 150:2006 – Procedures
and General Requirements: Annex B,
Implementation of traceability policy in
accredited laboratories
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ISO/IEC 17025:2005 Clause 5.6.2
Measurement Traceability
• 5.6.2.1 “For calibration laboratories,
the program for calibration of
equipment shall be designed and
operated so as to ensure that
calibrations and measurements
made by the laboratory are
traceable to the International
System of Units(SI) (Système
international d’unités).”
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Defining Traceability
The definition for a metrology laboratory:
VIM3: The 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.
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NIST Policy on Traceability
NIST Traceability Policy
– Supplementary Materials –
Resource on FAQs regarding
traceability
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SI Base Units
Base Quantity
Name
Symbol
Length
meter
m
Mass
kilogram
kg
Time
second
s
Electric Current
ampere
A
Thermodynamic
Temperature
kelvin
K
Luminous Intensity
candela
Cd
Amount of
Substance
mole
mol
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The SI Brochure
http://www.bipm.org
/en/si/si_brochure/
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The Traceability Chain: Mass
The sequence of
measurement
standards and
calibrations that is
used to relate a
measurement result
to a reference.
The farther your
measurements are
down in the
traceability chain, the
higher the
uncertainty of the
measurement.
Figure courtesy of the BIPM website
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Benefits of Traceability
• Essential requirement of a
quality management system for
calibration laboratories
• Means to Ensure Accuracy
• Competiveness and Operation in
a Global environment –
Facilitation of Trade
• A concept in the standardization
of measurements
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Realization of the SI
in each Country or
Economy
Photo courtesy of BIPM
Understanding the International
BIG Picture
Copyright Robert Rathe
The National Institute of Standards and
Technology is the National Metrology Institute
in the United States
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Understanding the International
BIG Picture
The CIPM MRA (Mutual Recognition
Arrangement of the International
Committee of Weights and Measures)
creates a framework for the NMIs*.
All the laboratories that meet the
requirements of the MRA have
agreed to recognize the Calibration
and Measurement Capabilities and
national measurement standards of
the other participants.
*currently 86 Institutes have signed the
CIPM MRA additionally it covers 137
designated institutes
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Mutual Recognition
Arrangements for Accreditation
Bodies
ILAC
APLAC
A2LA
ACLASS
International Laboratory
Accreditation Cooperation (ILAC)
EA
IAS
IAAC
LAB
NVLAP
Regional
Accreditation
Cooperations
PJLA
AB’s in the US that are signatories to the
ILAC MRA*
*Currently 88 economies are represented in the ILAC network;
~35,000 laboratories are accredited world-wide by ILAC signatories
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ILAC P10:2002
• Section 1.4: Characteristics of
traceability
– Unbroken chain of comparisons
– Uncertainty of measurement
– Documentation of the chain
– Competence of the calibration
provider
– Reference to SI units
– Calibration intervals
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ILAC P10:2002
• Section 2: ILAC Policy on Traceability
of Measurement Results
– Accredited labs shall demonstrate
calibration of measurements are
traceable to SI units
– Accredited labs shall in all cases derive
their traceability either:
• Appropriate NMI; or
• Calibration Lab that can demonstrate
competence, measurement capability, and
traceability with appropriate measurement
uncertainty
– Labs holding management certification
not deemed acceptable as demonstrating
necessary competence
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Accreditation Body (AB)
Requirements
• Each AB will have a policy
• Common Characteristics of
each policy
– Use of a National Metrology
Institute (NMI) that is signatory
to the CIPM MRA
– Use of accredited calibration
laboratory accredited by Mutual
Recognition Arrangement (MRA)
partner under ILAC
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Is my measurement traceable?
• What must you know to
prove your measurement is
the result of an unbroken
chain of calibrations?
• Does that chain of
calibrations lead back to the
SI unit realized by the NMI?
• How do you know? Is a
statement of traceability on a
calibration certificate
enough?
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Why should we be concerned?
• Greater awareness of the importance
of measurement in all areas of
science and technology.
• Understanding the fundamental basis
that metrology plays.
• Focused attention on its impact.
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Benefits of Traceability
• Competiveness and Operation in a
Global environment – Trade
• Means to Guarantee Accuracy
• Essential part of a quality
management system
• Link in the chain of techniques and
measurements in a large, diverse
measurement community
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Reference Information
Acronyms:
AB – Accreditation Body
APLAC – Asia Pacific Laboratory Accreditation
Cooperation
BIPM – Bureau International des Poids & Mesures
CIPM – International Committee for Weights and
Measures (Comité International des Poids et
Mesures)
CGPM – General Conference on Weights and
Measures (Conférence Générale des Poids et
Mesures)
EA – European Co-Operation for Accreditation
IAAC – Inter American Accreditation Cooperation
ILAC – International Laboratory Accreditation
Cooperation
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Reference Information
Acronyms: continued
• JCGM – Joint Committee for Guides in
Metrology (Comité commun pour les
guides en métrologie)
• KCDB – Key Comparison Database
• MRA – Mutual Recognition
Arrangement
• NIST – National Institute of
Standards and Technology
• NMI – National Metrology Institute
• SI –
International System of Units
• VIM – International Vocabulary of
Metrology
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Reference Information
Acronyms: continued
U.S. Accreditation Bodies that issue scopes of
accreditation to Calibration Laboratories • A2LA: American Association for Laboratory
Accreditation
• ACLASS: Assured Calibration and Laboratory
Accreditation Select Services
• IAS: International Accreditation Service,
Inc.
• L-A-B:
Laboratory Accreditation Bureau
• NVLAP: National Voluntary Laboratory
Accreditation Program
• PJLA: Perry Johnson Laboratory
Accreditation, Inc.
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Reference Information
Publications:
• APLAC PR008 International Recognition of Test,
Calibration and Inspection Reports, Issue No. 38, 2009.
• BIPM International System of Units, 8th edition, 2006.
• ILAC P8:07 ILAC Mutual Recognition
Arrangement(Arrangement): Supplementary
Requirements and Guidelines for the Use of
Accreditation Symbols and for Claims of Accreditation
Status by Accredited Laboratories, 2006.
• ILAC P10 ILAC Policy on Traceability of Measurement
Results, 2002.
• ISO 17025 General Requirements for the Competence of
Testing and Calibration Laboratories, 2nd edition, 2005.
• JCGM 200 International Vocabulary of metrology – Basic
and general concepts and associated terms (VIM), 2008.
• NIST Handbook 150 Procedures and General
Requirements, 2006 edition.
• NIST Special Publication 330 The International System
of Units (SI), 2008 edition.
• NIST Special Publication 811 Guide for the Use of
International System of Units (SI), 2008 edition.
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Reference Information
Websites:
• APLAC – www.aplac.org
• BIPM – www.bipm.org
• EA – www.europeanaccreditation.org
• IAAC – www.iaac.org.mx
• ILAC – www.ilac.org
• NIST – www.nist.gov
• NVLAP – www.nist.gov/nvlap
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