National Institute of

Standards and Technology

Technology Administration

U.S. Department of Commerce

143

2007

NIST

Handbook

Program Handbook

STATE

WEIGHTS

AND

MEASURES

LABORATORIES
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NISTTechnical Publications
STATE 

WEIGHTS AND 

MEASURES 

LABORATORIES 

Program Handbook, 5th Edition 

Editor: 

 Georgia L. Harris 

 NIST Weights and Measures Division 

Gaithersburg, MD 20899 

 Carol T. Hockert, Chief 

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary 

Technology Administration 

Robert Cresanti, Under Secretary 

of Commerce for Technology

National Institute of 

Standards and Technology 

William A. Jeffrey, Director 

NIST Handbook143

2007 Edition 

(Supersedes NIST Handbook 143, 2003 Edition)
Certain commercial entities, equipment, or materials may be identified in this document in order to describe an 

experimental procedure or concept adequately. Such identification is not intended to imply recommendation or 

endorsement by the national Institute of Standards and Technology, nor is it intended to imply that the entities, 

materials or equipment are necessarily the best available for the purpose. 

National Institute of Standards and Technology Handbook 143, 2007 Edition 

Natl. Inst. Stand. Technol. Handb. 143, 2007 Ed., 116 pages (April 2007) 
NIST Handbook 143 April 2007 

iii 

Preface

The National Institute of Standards and Technology (NIST) manages the State Laboratory Program that began with 

the New State Standards Program established by Congress in 1965 as part of its continuing support to the States. 

This program of the NIST Weights and Measures Division (WMD) is designed to provide guidance, technical 

support, and assistance to State legal metrology laboratories to ensure accurate and traceable measurements from 

NIST to the local jurisdictions. The program operates through continued partnership with the State laboratories to 

manage numerous measurement-related activities. 

Significant changes have been made to the program of Recognition for the States and to this Program Handbook 

since the first edition was published in 1985. The program has incorporated national and international standards; 

although WMD does not provide formal accreditation according to ISO standards, and although the program is 

operated independently from the National Voluntary Laboratory Accreditation Program (NVLAP), the general and 

technical criteria used in both programs are nearly identical. 

The following list shows key changes in this edition of the Handbook: 

• Information associated with the National Type Evaluation Program (NTEP) has not been covered in program 

handbooks since 1996. 

• Parts 2 and 3 are policy and procedure information specific to WMD operations and Recognition process; 

Figure 1 is a flow chart showing the Recognition process. 

• Parts 4 and 5 substantially contain ISO/IEC 17025:2005 (previously these sections referenced ANSI/NCSL 

Z540-1-1994 (parts I and II) with NVLAP additions, WMD Notes, and minor editorial changes for clarity). 

WMD Notes added to parts 4 and 5 are additional policy or requirements that apply generally to all legal 

metrology laboratories without regard to Recognition level. 

• Part 6 was originally developed in WMD and published in the NVLAP Calibration Laboratories Draft 

Technical Guide (1994 Draft, as incorporated in the 1996 and 1997 editions of this Handbook), but further 

edited for this publication. WMD and the National Conference on Weights and Measures (NCWM) ISO 9000 

Task Force prepared the mass and volume sections and reviewed them at a special NVLAP workshop in 

December 1992 (mass criteria only); at a NVLAP workshop in November 1993; at all six regional metrology 

meetings in 1993 and 1994; and at the 1994 NCWM meeting. Laboratories performing temperature 

measurements were given the opportunity to review the temperature section. G. Diane Lee (NIST) prepared the 

moisture section; it was reviewed at the Southeastern Measurement Assurance Program (SEMAP) regional 

metrology meeting in 1993. These sections have all been reviewed and updated for this 2007 edition. 

• For the 1997 edition, NIST management made changes in the WMD State Laboratory Program. As a result, the 

1997 Handbook was revised to delete references to accreditation. References to “accreditation” were replaced 

with references to “Recognition;” references to a “certificate of accreditation” were replaced with references to 

a “Certificate of Measurement Traceability;” and references to the WMD State Laboratory Program as an 

“accreditation program” were replaced with references to a “measurement assurance program.” 

Note regarding SI units: This publication conforms to the concept of primary use of the International System of 

Units (SI) recommended in the Omnibus Trade and Competitiveness Act of 1988 by citing SI units before 

customary inch-pound units where both units appear together and placing separate sections containing requirements 

for SI units before corresponding sections containing requirements for customary inch-pound units. In some cases, 

however, laboratory standards and/or trade practice are currently restricted to the use of customary units; therefore, 

some sections in this publication will specify only customary units. Non-SI units are predominately in common use 

in State legal metrology laboratories, and/or the petroleum industry for many volumetric measurements; therefore 

non-SI units have been used to reflect the practical needs of the laboratories performing these measurements as 

appropriate. SI units are used where practical and where use or potential conversion errors will not likely impact the 

quality of laboratory measurement results. 
April 2007 NIST Handbook 143 

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NIST Handbook 143 April 2007 

v 

Acknowledgments and History

This Program Handbook, first published by Henry V. Oppermann and John K. Taylor in 1985, documented and 

formalized the certification program whereby NIST Recognized the capabilities of State legal metrology 

laboratories. Prior to that time, the WMD issued “Certificates of Participation” to States participating in the 

program. In 1985, WMD began certifying laboratories against the criteria in Handbook 143, Program Handbook. 

The 1985 criteria were based on International Standards Organization (ISO/IEC) Guide 25 (1982), General 

Requirements for the Competence of Calibration and Testing Laboratories. 

The WMD began the process of updating this Program Handbook in 1991. Due to the many activities related to ISO 

9000 in the United States at that time and questions regarding how those activities would impact the State 

laboratories, ISO standards were provided to the State laboratories in 1991. 

The National Conference of Standards Laboratories (NCSL), Total Quality Management (TQM) Committee also 

started working on the development and adoption of a single U.S. national standard for calibration laboratories in 

1991. The NCSL TQM Committee included representatives from NIST, Department of Defense, Department of 

Energy, Nuclear Regulatory Commission, Federal Aviation Administration, and numerous industries. 

In 1992, the National Conference on Weights and Measures (NCWM) established an ISO 9000 Task Force. After 

review of the 1985 version of the Program Handbook and ISO/IEC Guide 25 to determine the conformance status of 

State laboratories, the group recommended the use of one standard in the United States (consistent with the NCSL 

position) for the accreditation of calibration laboratories to: 

reduce the number of redundant laboratory audits; 

improve measurement compatibility and acceptance of measurement results between laboratories in the United 

States and internationally; and 

comply with the ISO-series standards for quality and management. 

The NCSL “TQM Committee” became an official ANSI standards writing body (ANSI Committee Z 540) in 1994 

and published the U.S. standard as Z540-1-1994. ANSI/NCSL Z540-1-1994 incorporated ISO Guide 25 and MilStd-45662A. Since NCSL published the standard in 1994: 

1) the Department of Defense rescinded Mil-Std-45662A in favor of the Z540-1-1994 standard; 

2) the NIST National Voluntary Laboratory Accreditation Program (NVLAP) adopted and referenced 

ANSI/NCSL Z540-1-1994; 

3) the American Association for Laboratory Accreditation (A2LA), a private accrediting body, also adopted 

the standard; and 

4) the WMD incorporated the standard into Parts 5 and 6 of the 1996 and 1997 editions of this Handbook. 

Additional requirements consistent with NVLAP requirements and with the needs of the legal metrology 

system were included. 

In 1997, NIST management made the decision that NIST would operate only one formal accreditation program: the 

National Voluntary Laboratory Accreditation Program (NVLAP). Therefore, all references to accreditation by 

WMD were changed to Recognition and WMD ceased issuing Certificates of Accreditation. WMD monitors the 

level of State compliance to this Handbook and other laboratory quality standards to ensure that adequate accuracy, 

traceability, and uniformity are maintained in State weights and measures laboratories. 

In 1999, ISO/IEC Guide 25 was revised and became the international standard ISO/IEC 17025. The 2003 edition of 

NIST Handbook 143 incorporated revisions to the procedures and general requirements of the NIST Weights and 

Measures Division (WMD) Measurement Assurance Program for State Laboratory Recognition. The WMD 

procedures were revised to ensure continued consistency with international standards and guidelines, specifically 

those currently found in ISO/IEC 17025:1999, General requirements for the competence of testing and calibration 

laboratories.
April 2007 NIST Handbook 143 

vi 

In 2003, the requirements in Sections 4 and 5 of that edition were updated to contain clauses 4 and 5 of ISO/IEC 

17025:1999. They must be met in order for a laboratory to be Recognized as competent to carry out tests and/or 

calibrations. Major changes in 2003 included: 

• In Section 4, Management requirements, there were additional or changed requirements in the areas of 

document control; requests, tenders, and contracts; purchasing; non-conforming work; corrective action; 

preventive action; and records. Those additions and changes incorporated changes that were consistent with 

ISO 9001:1994 requirements. A new clause, Service to the customer, prescribed cooperation with customers 

and provided guidance on such cooperation. 

• In Section 5, Technical requirements, the requirements were described in greater detail, but most concepts were 

not “new” for accredited laboratories. There was continued reference to customer needs and greater emphasis 

and/or more detailed requirements on method validation; estimation of measurement uncertainty/traceability for 

testing laboratories; and provision for inclusion of interpretations and opinions on test reports. A sampling plan 

was to be required where methods or specifications did not specify sampling procedures. 

This 2007 edition supersedes the 2003 edition of NIST Handbook 143 and includes editorial updates and 

clarifications. Sections 4 and 5 have been updated to incorporate ISO/IEC 17025:2005 to ensure continued 

acceptance of measurement results from State weights and measures laboratories and to ensure consistency with the 

NVLAP Program and other accreditation bodies. 
NIST Handbook 143 April 2007 

vii 

Table of Contents 

Preface ........................................................................................................................................................iii

Acknowledgments and History ..................................................................................................................v

1. Program Summary ..............................................................................................................................1

2. General Information and Operational Requirements .....................................................................3

3. Recognition Process ............................................................................................................................9

 Table 1. Submission requirements for Recognition .....................................................................15

4. Management Requirements for Accreditation ...............................................................................17

5. Technical Requirements for Accreditation .....................................................................................27

 Table 2. Training requirements ....................................................................................................40

6. Specific Technical Guidelines ...........................................................................................................41

 Table 3. Recognition parameter summary ...................................................................................42

 6.1 Technical Criteria for Dimensional Laboratories ..........................................................................43

 6.2 Technical Criteria for Mass Laboratories ......................................................................................47

 Table 4. Mass calibration echelons ..............................................................................................47

 Table 5. Typical ‘Ranges of Recognition’ for mass calibration...................................................48

 Table 6. Environmental facility guidelines for mass laboratories................................................49

 Table 7. Environmental equipment accuracy ...............................................................................50

 Table 8. Summary of technical criteria for mass calibration........................................................53

 6.3 Technical Criteria for Volume Laboratories..................................................................................54

 Table 9. Typical ‘Ranges of Recognition’ for volumetric calibration .........................................54

 Table 10.Environmental facility guidelines for volumetric calibration ........................................56

 Table 11.Environmental equipment accuracy ...............................................................................57

 Table 12. Summary of technical criteria for volume calibration....................................................58

 6.4 Technical Criteria for Hydrometer Laboratories ...........................................................................59

 6.5 Technical Criteria for Thermometer Laboratories .........................................................................62

 6.6 Technical Criteria for Moisture Laboratories ................................................................................68

 Table 13. Moisture determination laboratory classifications .........................................................68

 Table 14. Summary of environmental facility guidelines ..............................................................73

7. References ..........................................................................................................................................75

8. Glossary ..............................................................................................................................................77

Appendix A. List of NIST Services .........................................................................................................81

Appendix B. Request for Recognition, Scope of Recognition, Approved Signatories, 

Authorized Representative ..........................................................................................................83

Appendix C. Laboratory Assessment Checklist ....................................................................................85

Appendix D. Summary of Services for Laboratory Directory ...........................................................113

Appendix E. Uncertainties Chart for Measurement Parameter ........................................................115

 
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NIST Handbook 143 April 2007 

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1. Program Summary 

State legal metrology laboratories are custodians at the State level of measurement standards that serve as the basis 

for ensuring equity in the marketplace and as reference standards for calibration services for indigenous industry. 

As part of its program to encourage a high degree of technical and professional competence in such activities, the 

National Institute of Standards and Technology (NIST) Weights and Measures Division (WMD) has developed 

performance standards and formalized procedures for Recognition of State legal metrology laboratories on a 

voluntary basis. Certificates of Measurement Traceability are issued upon evaluation of the laboratory's ability to 

make reliable metrological measurements (principally mass, volume, length, and temperature). 

Recognition of State Legal Metrology Laboratories 

This Handbook describes the procedures followed in evaluating State (and a few other jurisdictional) legal 

metrology laboratories for competence. To be formally Recognized, a laboratory must satisfy general and technical 

requirements for each measurement area in which recognition is desired (see Appendix B). This program is 

managed by the WMD. 

The general requirements in sections 4 and 5 incorporate ISO/IEC 17025:2005 (as adopted by the NVLAP 

Calibration Laboratories Accreditation Program) and address internationally accepted quality management practices 

for calibration and testing laboratories. In addition to ISO/IEC 17025 and NVLAP requirements, sections 4 and 5 

contain additional general requirements as “notes” that are specific for State legal metrology laboratories. (See 

Section 7, References.) 

The technical criteria in Section 6 amplify general criteria (ISO/IEC 17025) for each specific measurement 

parameter to be used as needed. Technical requirements of the WMD recognition program are nearly identical to 

the NVLAP guidelines published in the NIST/NVLAP Handbook 150-2F (Dimensional) and 150-2G (Mechanical), 

Calibration Laboratories Technical Guides; however, while WMD does not operate a formal accreditation program 

it does use the technical section as requirements rather than as guidelines. The technical requirements include 

demonstration that: 1) suitable test equipment, calibration standards, defined test procedures, and the general 

facilities necessary for good metrological services are available; and 2) that staff have a comprehensive 

understanding of calibration, measurement, and test requirements and are capable of applying them. 

Under this voluntary recognition program, laboratories appraise their compliance with the requirements, completing 

appropriate forms that are reviewed and evaluated by WMD. 

Following review and evaluation, which includes proficiency testing, and may include on-site assessments, WMD 

may issue a Certificate of Measurement Traceability indicating recognized competence areas with defined 

parameters and scope of Recognition. Recognition may be granted for a period up to 2 years, but on an annual basis 

each laboratory must review its status, complete an internal audit, including a management review and management 

system assessment, and submit the evaluation along with a statement that no adverse changes have taken place in 

order for the Recognition to remain in effect. 

Types of assistance available from the National Institute of Standards and Technology are listed in Appendix A. 

General

Each State legal metrology laboratory is encouraged to study this Handbook carefully and to apply for Recognition 

in all areas in which it provides measurement services. WMD reserves the right to deny or withdraw Recognition. 

In such cases, WMD will notify the State in writing of nonconformities, and will provide guidelines for corrective 

action. In the case of withdrawal, NIST will attempt to reach agreement with the State on the timing of the 

corrective action in order to keep the Recognition in force conditionally for legal requirements only. 
April 2007 NIST Handbook 143 

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NIST Handbook 143 April 2007 

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2. General Information and Operational Requirements 

2.1 Purpose 

The NIST Enabling Act (31 Stat. 1449, 15 USC 271, Chapter 6 Weights and Measures), as modified by "authorities 

and functions pursuant to the Omnibus Trade and Competitiveness Act of 1988," provides the legislative authority 

to Recognize qualifying State legal metrology (weights and measures) laboratories. Authorization includes "the 

provision of means and methods for making measurements consistent with those of the national standards." 

Compliance with the criteria contained in this Handbook is the most effective means for ensuring accurate 

measurements consistent with national standards. 

2.2 Description, Quality Policy, and Objectives 

In 1965, Congress funded NIST to establish the State Standards Program to provide new standards of mass, volume, 

and length to the States, the District of Columbia, Puerto Rico, and the Virgin Islands to update their legal metrology 

(weights and measures) laboratories and increase their measurement capabilities. The program also provided the 

laboratory equipment necessary for the States to use the standards in their measurement services. 

As part of the States' responsibilities in the distribution of standards and equipment, each jurisdiction was required to 

provide an acceptable laboratory facility meeting specifications established under the State Standards Program and 

to maintain acceptable staffing. The laboratory metrologist was required to complete training at NIST in the use of 

the standards and equipment. 

State Laboratory Program Quality Policy: 

It is the policy of the State Laboratory Program to help all State laboratories achieve and maintain Recognition and 

to enable State legal metrology laboratories to provide their customers accurate and traceable measurement services 

in an atmosphere of continuous quality improvement. 

As part of its continuing support to the States, NIST manages the State Laboratory Program. This is a program of 

the WMD designated to provide guidance, technical support, and assistance to State legal metrology laboratories to 

ensure accurate and traceable measurements from NIST to the local jurisdictions. The program operates through 

continued partnership with the State laboratories to manage numerous activities within the program. 

WMD objectives are to: 

1) support the basic level of measurement services required for legal metrology enforcement/oversight 

activities; 

2) provide technical support for the accuracy and traceability of State legal metrology laboratories to the 

national standards through development, training, publication of, and use of standard procedures, protocols, 

proficiency testing, and measurement assurance programs; 

3) provide and maintain the Recognition program for State legal metrology laboratories as evidence of 

continuing measurement traceability to include auditing of the use and care of the physical standards of 

mass, length, and volume; and 

4) assist the States to upgrade and expand the measurement services of State legal metrology laboratories to 

satisfy the changing needs of the legal metrology system and laboratory customers. 
April 2007 NIST Handbook 143 

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2.3 Scope of Recognition 

2.3.1 Voluntary and non-contractual 

The Recognition function for State legal metrology laboratories is a voluntary, non-regulated program of support to 

the States. It provides a cost-effective means for providing evidence of measurement accuracy and traceability (See 

sections 2.9.8 and 2.9.9). 

2.3.2 Legal compliance requirements 

Although there are currently no Federal requirements for Recognition, some States have weights and measures laws 

that require continued formal accreditation, certification, approval, or other form of Recognition by NIST as 

evidence of maintaining measurement traceability for reference [primary] standards used in the enforcement of 

weights and measures laws. 

2.3.3 Limitations 

The WMD Recognition program is limited in scope. It is provided for government legal metrology laboratories 

only. The NIST National Voluntary Laboratory Accreditation Program (NVLAP) offers accreditation services to all 

laboratories and is not limited in the scope of whom they may accredit. 

2.3.4 Liability

NIST Recognition does not certify individual measurements made by a State, but formally Recognizes that the State 

legal metrology laboratory has traceable standards, the capability to perform reliable measurements, and that the 

metrologist has been trained in the proper procedures to provide these measurements and has demonstrated 

measurement proficiency. Recognition also indicates that the metrologist has submitted technical data, records, and 

documentation as specifically requested by NIST. NIST assumes no liability for the accuracy and traceability of 

individual measurement results provided by a Recognized laboratory. 

2.4 Technical Support and Assistance 

WMD offers consultative and technical support through informal and formal means to all State legal metrology 

laboratories regardless of their Recognition status. Informal assistance may be in the form of telephone, facsimile, 

e-mail, or mailed responses. Formal support and assistance are available through the training program and the 

Regional Measurement Assurance Program (RMAP) of the State Laboratory Program (See Appendix A for types of 

technical assistance available). 

2.5 Confidentiality 

To the extent permitted by applicable laws, WMD seeks to ensure the confidentiality of all information obtained 

relating to the application, on-site assessment, evaluation, and Recognition of laboratories, unless the laboratory 

provides permission to share such information. Exceptions: see section 2.9.9, Proficiency Testing. 

Results of proficiency tests are discussed openly at annual RMAP meetings in the spirit of continuous improvement 

and teamwork. Proficiency testing confidentiality is addressed as a part of NISTIR 7082 “Proficiency Test Policy 

and Plan (for State Weights & Measures Laboratories)” and NISTIR 7214 “Weights and Measures Division Quality 

Manual For Proficiency Testing and Interlaboratory Comparisons.” The policy is stated as follows: “It is the policy 

of NIST WMD that all PT/ILC activities are completely open, with no coded or confidential information. All 

participants must agree to these conditions before being qualified to participate in PT/ILC activities.” 
NIST Handbook 143 April 2007 

5

2.6 Development of Requirements 

2.6.1 Use of national and international standards wherever available

When national or international standards are available in the area of accreditation requirements for calibration 

laboratories, WMD will adopt such standards as program criteria after suitable review. Adoption of national or 

international standards, rather than independent development of standards, is required by Federal law whenever 

feasible and appropriate. 

2.6.2 Laboratory review, solicitation of comment by those affected

The technical requirements associated with the current version of Handbook 143 were developed in conjunction 

with an ISO 9000 Task Force of the National Conference on Weights and Measures. The technical requirements for 

dimensional (length) and mechanical (mass and volume) measurements have been incorporated into NIST 

Handbook 150-2F and 150-2G, Calibration Laboratories Technical Guides. Draft laboratory publications are 

reviewed by affected laboratories prior to publication. This version of Handbook 143 was posted for comment 

between October 2005 and March 2007. 

2.7 Documentation 

General and technical requirements for Recognition and additional documents and records to support the program 

for State legal metrology laboratories are maintained and published by the WMD. 

Other publications that include the general and technical requirements for State laboratory Recognition, are also 

available: 

1) NIST Special Publication (SP) 791, State Weights and Measures Laboratories: State Standards 

Program Description and Directory, 2000. This electronic document contains a general program 

description and laboratory directory. It is updated periodically and is only available on the NIST Internet 

site. 

2) NIST Handbook 145 Handbook for the Quality Assurance of Metrological Measurements, 1986. This 

Handbook contains laboratory procedures that are used in WMD Training Program and are recommended 

for use in State legal metrology laboratories. Adequate data and evidence of measurement impact must be 

provided by the laboratory to justify deviating from documented procedures. This Handbook includes 

Good Laboratory Practices (GLPs), Good Measurement Practices (GMPs), and Standard Operating 

Procedures (SOPs). A number of the GLPs, GMPs, and SOPs from Handbook 145 have been updated or 

superseded by NISTIR 5672, NISTIR 6176, NISTIR 6969, and NISTIR 7383, and this Program Handbook. 

NISTIR publications are official publications and procedures of the NIST Weights and Measures Division 

that are intended to be used by the State laboratories. 

3) NISTIR 5672, Advanced Mass Measurements and Measurement Assurance Program for State 

Calibration Laboratories, (2005 Ed.). This publication documents guidelines for facilities, equipment, 

standards, and training recommended for precision mass calibration and measurement control programs. It 

is consistent with the technical criteria for mass calibration and is available on the NIST Internet site. This 

publication was originally published in 1995. The 2005 edition contains updated Standard Operating 

Procedures 5 and 28 for three-one and advanced weighing designs. 

4) NISTIR 6176, Process Measurement Assurance Program for U.S. State Metrology Laboratories, 

June 1998. This publication contains guidance for implementing a process measurement assurance 

program and PMAP software in the State laboratories. It contained the first draft of SOP 30 for process 

measurement assurance programs. The guidance and implementation does not require the use of PMAPTM 

software. SOP 30 was updated as a part of NISTIR 6969 in 2003. 
April 2007 NIST Handbook 143 

6 

5) NISTIR 6969, Selected Laboratory and Measurement Practices, and Procedures, to Support Basic 

Mass Calibrations, March 2003, with on-line updates December 2003. This publication contains 

updated procedures for Basic and Intermediate Mass calibrations. Many of the procedures were included on 

the NIST Special Publication 1001 and 1001-S, Basic Mass Metrology CD-ROM training course. New 

GLPs, GMPs, and SOPs that were not published as a part of the original NIST Handbook 145 were 

included. 

6) NISTIR 7383, Selected Procedures for Volumetric Calibrations, November 2006. This publication 

contains updated procedures for Volumetric calibrations. New SOPs that were not published as a part of 

the original NIST Handbook 145 were included. 

7) NISTIR 5802, Quality Manual Template, December 1999. This publication was a quality manual 

template developed as a model for State legal metrology laboratories. It conformed to ISO/IEC Guide 25, 

ANSI/NCSL Z540-1-1994, and earlier NVLAP documentation requirements. It is available on the NIST 

Internet site, but is no longer recommended as a model due to more recent updates in ISO/IEC 17025. The 

recommended model is now, NISTIR 7028, the Quality Manual for the National Type Evaluation Program, 

although care must be taken to remove references to type evaluation and testing terminology (in favor of 

calibration terminology). 

8) NISTIR 7028, Type Evaluation Laboratory Quality Manual Template, Developed for U.S. Type 

Evaluation Laboratories, July 2003. As part of its technical support to the U.S. commercial weights and 

measures system, WMD created this quality manual template to assist type evaluation laboratories in 

documenting their management systems. As such, this quality manual template is specifically designed for 

type evaluation testing laboratories. The quality manual template is based on ISO/IEC 17025 requirements. 

Although this manual is not numerically formatted identical to the ISO/IEC 17025 standard, the 

requirements of the standard are addressed in the quality manual. Each Section of the quality manual is 

cross-referenced to the ISO/IEC 17025 requirements so that auditors and others can locate where the 

requirements are addressed in the quality manual. 

9) NISTIR 7082, Proficiency Test Policy and Plan (for State Weights & Measures Laboratories), 

January 2004. This document was prepared by Jeff C. Gust (Quametec Corp., under contract) in 

collaboration with WMD staff, with input from State metrologists and NVLAP staff, as a first step in the 

process of enabling State weights and measures laboratories to comply with criteria for proficiency testing 

as noted in this Handbook and as needed for accreditation programs. The publication aligned NIST 

policies with international mutual recognition arrangement requirements, and intended to ensure that 

proficiency tests developed within this program meet all international requirements for design, 

development, execution, analysis and reporting of proficiency tests. 

10) NISTIR 7214, Weights and Measures Division Quality Manual For Proficiency Testing and 

Interlaboratory Comparisons, March 2005. This document was prepared by Jeff C. Gust (Quametec 

Corp., under contract) in collaboration with WMD, with input from State metrologists and NVLAP staff, to 

enable State Weights and Measures Laboratories to comply with criteria for proficiency testing as noted in 

this Handbook and as needed for accreditation programs. It provides the basic quality system for 

Proficiency Testing and Interlaboratory Comparisons developed by WMD. 
NIST Handbook 143 April 2007 

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2.8 Records 

Records related to Recognition or accuracy and traceability of measurements and standards for each State are 

maintained in the WMD. Procedures regarding record retention are maintained in the WMD. These documents 

include, but are not limited to, the following: 

1) traceability records for reference [primary] standards, working standards, and check standards (includes 

traceability hierarchies and calibration reports); 

2) measurement assurance data (control charts and surveillance tests) – latest year; 

3) uncertainty tables – latest year; 

4) training records and records related to completion of Laboratory Auditing Program (LAP) problems; 

5) quality manuals, administrative procedures, and associated appendices – latest version; 

6) proficiency testing (round robin reports of the RMAPs); 

7) internal audits (including management review); and 

8) on-site assessment reports. 

Letters verifying the status of a laboratory’s Recognition level, traceability, and accompanying records may be 

provided on behalf of the State to customers when formally requested to WMD in writing on official letterhead. A 

copy of the laboratory’s Certificate of Measurement Traceability should suffice for all routine applications and these 

are posted on the WMD internet site. Facsimile or e-mail requests are not acceptable. 

2.9 Rights, Duties, Responsibilities of the Recognized Laboratory 

2.9.1 Display of Certificates of Measurement Traceability

The laboratory is encouraged to post its Certificate of Measurement Traceability in the laboratory and may copy it 

for customer use as evidence of traceability. The Certificate includes the Scope of Recognition. 

2.9.2 Use of Recognition or traceability status on calibration certificates or test reports

The laboratory may reference its Recognition status or traceability status on calibration certificates or test reports 

only if the laboratory is Recognized in that particular measurement parameter and scope at the level specified on the 

calibration report. The laboratory must make no statements regarding Recognition for measurement parameters or 

levels of uncertainty that are not covered by the Certificate of Measurement Traceability and scope. 

2.9.3 Reference to Recognition status

A laboratory may reference its Certificate of Measurement Traceability in promotional literature provided that it is 

consistent with NIST legal policy (15 CFR Ch. 11, 200.113) on the use of the NIST name (or NVLAP name and 

logo if applicable and according to NVLAP policies). This policy has been circulated to all State laboratories, and is 

available in the WMD as well as most local libraries. A general condition on the use of the NIST name is that it 

may not be used for endorsement purposes, but may be used to make factual statements regarding Recognition or 

traceability. 

2.9.4 Notification of change 

A laboratory must advise the WMD of any changes that might affect the quality of measurement services it 

provides. This includes, but is not limited to: changes in staff, relocation and renovation of its laboratory, damage 

to or loss of environmental controls in its facility, damage or change of laboratory equipment used to provide 

measurement services, and damage, replacement, or recalibration of reference [primary] standards used to provide 

measurement services (including improvements as well as adverse changes). Any change that might adversely 

affect the quality of measurement results is particularly important and must be reported. 
April 2007 NIST Handbook 143 

8 

2.9.5 Provide timely submissions

WMD solicits information from all laboratories each year as a reminder of the Recognition requirements. The 

laboratory must submit a report between October 1 and November 15 annually. This submission must include those 

items specifically requested, but is not limited to the items listed in the Recognition process. Requests for technical 

assistance may be made at the same time. Routine failure of a laboratory to provide requested material in a timely 

manner will prevent 2-year Recognition and may result in limited or Conditional Recognition. 

2.9.6 Reciprocity with other WMD-Recognized laboratories

Recognized State laboratories may have reciprocity with other Recognized or accredited State laboratories as a part 

of the voluntary registration program for service agents. Reciprocal acceptance of calibration reports should be 

limited to laboratories that have maintained full (not Conditional) Recognition with WMD or formal accreditation. 

Calibration reports from laboratories that have failed to maintain Recognition, formal accreditation, or are 

Conditionally Recognized, should be refused. Information on Recognition status is available through the online 

Special Publication 791, Laboratory Directory and through individual status requests. 

2.9.7 Subcontracting 

State legal metrology laboratories conduct little or no subcontracting. In the event that a laboratory determines that 

it is in its best interst to subcontract calibrations, it should subcontract only to other Recognized or accredited 

laboratories. 

2.9.8 Failure to maintain Recognition

Any laboratory that fails to maintain Recognition will be encouraged to correct nonconformities and be given an 

opportunity to submit evidence of corrective action for whatever nonconformity exists. A laboratory that has lost 

Recognition status may subsequently comply with the Recognition criteria. Laboratories are encouraged to work 

closely with the WMD to reestablish Recognition as soon as possible. WMD will assist each laboratory as much as 

possible based on need and resources available. 

2.9.9 Notification of status 

The WMD reserves the right to notify State and Federal agencies as well as any indigenous industry of a State 

regarding Recognition or accreditation status. This is generally accomplished through the periodic publication of a 

laboratory directory and may include periodic memoranda to affected parties. 

2.9.10 Response to nonconformities and corrective action requests 

A laboratory will have a specified amount of time to respond to nonconformities addressed through annual review, 

internal management review, WMD review, or through an on-site assessment conducted by NIST staff or its 

designated technical experts (TEs). At the end of the specified time period, the laboratory may be given a 

"Conditional Recognition” detailed later in this publication. In the event that the laboratory fails to respond, or fails 

to respond adequately, it will not be Recognized in the particular area under question until such time as it responds 

or corrects nonconformities. The laboratory has the right to appeal WMD decisions as described later in this 

publication. 
NIST Handbook 143 April 2007 

9

3. Recognition Process 

A flowchart depicting the Recognition process is shown in Figure 1. Details of this process are provided in this 

section. An overview of the Recognition process includes: 

1) an annual solicitation by WMD; 

2) technical review of submitted material (see list in Table 1 and associated guidelines); 

3) review of on-site assessment results; 

4) review of proficiency testing results; and 

5) issuance of a Certificate of Measurement Traceability, which includes the scope of Recognition. 

3.1 Requests for Recognition and Fees 

Each State legal metrology laboratory, plus those of Puerto Rico, the District of Columbia, the Virgin Islands, Los 

Angeles County, and the Grain Inspection and Packers and Stockyards Administration (GIPSA) Master Scale Depot, 

may seek Recognition. The annual Request for Recognition must detail the requested Scope of Recognition 

(Appendix B), include all additional requested components, and will include an annual evaluation will conducted by 

WMD. 

Responsibility for measurement accuracy and traceability as used in commerce is cooperatively shared by a number 

of Federal and State agencies. An excellent working partnership exists between the State legal metrology 

laboratories and WMD. The laboratories provide payment-in-kind through voluntary efforts for many of the 

activities needed to maintain the Recognition process, procedure development, instruction at training seminars, and 

the coordination and analysis of proficiency testing in partnership with WMD. As a result of this partnership and 

shared responsibilities, fees are not charged to these laboratories to support the Recognition process. 

3.2 Annual Solicitation 

Material for Recognition and issuance of Certificates of Measurement Traceability is annually solicited by WMD 

via a detailed memorandum between August 1 and September 15. 

3.2.1 Annual submission period 

Laboratories are to submit the Request for Recognition, along with specifically requested items, each year between 

October 1 and November 15. If a laboratory fails to submit material in a timely manner, there is a risk that the 

Certificate of Measurement Traceability will not be renewed by the expiration date of the previous certificate. 

Certificates expire December 31 each year (or every 2 years) and are renewed January 1. Material must be 

submitted each year for the certificate to remain in effect. Material that is received significantly late may not be 

reviewed until the next review cycle. 

3.2.2 Information to be submitted 

The information to be submitted annually depends on the particular circumstances of a laboratory's Recognition and 

will be detailed in the solicitation memorandum. Requested information is always related to specific criteria as 

described in this Handbook. 

Generally, a Request for Recognition and all applicable items must be submitted each time the laboratory's 

Certificate of Measurement Traceability expires. A list of items is detailed in Table 1 and includes the associated 

guidelines. If the Certificate of Measurement Traceability has lapsed for any reason, it is treated as a renewal and a 

complete submission must be made. 
April 2007 NIST Handbook 143 

10 

3.3 On-site Assessments (Monitoring and Requested)

Since all laboratories were established with the technical support and guidance of the WMD in the late 1960's or 

early 1970's and have been visited by WMD staff, all on-site assessments initiated by WMD are considered to be 

technical assistance visits and/or monitoring assessments. Essential monitoring assessments are conducted 

periodically, generally in conjunction with training or regional meetings. Additional on-site assessments may be 

requested by the laboratory and will be conducted as feasible. 

The primary objectives of on-site assessments are to: 1) ensure that the laboratories maintain laboratory quality by 

complying with documented criteria and 2) assist the laboratories to improve their overall operations, facilities, 

equipment, standards, or staff to ensure adequate accuracy and traceability to meet State legal requirements. On-site 

assessments may be conducted by NIST staff or by contracted Technical Experts (TEs). 

Staff and TEs use checklists (and forms), and all assessment reports follow the same general format to ensure 

consistency from one laboratory assessment to another. Assessments generally take between one and three days and 

are conducted to minimize disruption of normal laboratory operations. Since most State laboratories operate with 

minimal staff, as much advance notice as possible of the assessment date is given for scheduling purposes. 

All WMD records concerning a given laboratory are available to WMD staff, NVLAP staff (if the laboratory has 

applied to NVLAP for formal accreditation), or an assigned TE for evaluation. These include quality manuals, 

administrative procedures, associated appendices, uncertainty tables, training records, RMAP attendance records, 

results of internal and on-site audits, management review summaries, results of interlaboratory comparisons or other 

proficiency tests, control charts, NIST calibration reports, reports of tests, and any previous correspondence with the 

laboratory. During the on-site assessment, the assessor verifies information contained in the files through meetings 

with management and laboratory staff, by examination of facility, equipment, standards, test reports, quality 

documents, and procedures, and by observation of procedures. The assessor need not be given any information that 

violates individual privacy such as salary, medical information, or performance reviews outside the scope of the 

Recognition program. 

3.3.1 NIST staff 

On-site assessments of laboratories may or may not be conducted by WMD staff. However, WMD staff will 

prepare all final laboratory assessment reports and communicate assessment results to the management and staff of 

each laboratory. 

3.3.2 Technical Experts (TEs) 

TEs are metrologists with technical expertise, appropriate auditing training and skills, and discretion, who have been 

selected to conduct on-site assessments for the State Laboratory Program. Criteria for selection are based on 

professional and academic achievement and are maintained in the WMD. 

WMD strives to ensure fairness and impartiality in its assessments. TEs are required to sign a form regarding 

laboratory confidentiality. Concerns regarding any TEs should be brought to WMD's attention in writing. Records 

are maintained for the assessments that each TE has conducted. NIST may provide additional training in auditing 

techniques. TEs may draft assessment reports; however, these reports are reviewed and finalized by WMD staff. 

3.3.3 Assessment report and invitation to respond 

Either a draft assessment report or the assessor's notes may be left with laboratory staff or management at the close 

of a formal assessment. A formal assessment report may be issued to the laboratory detailing nonconformities and 

the expected preventive or corrective action. The laboratory is given an opportunity to respond or appeal stated 

nonconformities. An assessor may or may not be fully aware of specific laboratory conditions and clarification may 

be appropriate, thus the laboratory response may include clarification. The laboratory is expected to correct 

nonconformities as soon as possible and to implement preventive action as a normal course of operations. The 
NIST Handbook 143 April 2007 

11

Criteria Developed

Peer Review

NIST/WMD Review,

Approval, Publication

Annual Solicitation

(Aug 1 - Sept 15)

Internal Assessment,

Management Quality

Review, and Request

for Recognition

NIST/WMD Review of

Submission

NIST/WMD

Recognition

NIST/WMD On-site

Assessment

feedback to laboratory

Issue Certificate of

Meaurement Traceability,

Scope (or conditional

Recogntion and

limitations)

Yes

Withdrawal or Denial

and Laboratory

Notification

No

Corrective Action(s) or

Appeal

(or lack of submission)

Figure 1. Recognition Process.
April 2007 NIST Handbook 143 

12 

laboratory must submit a corrective action plan to WMD within thirty days of receiving a final report. This does not 

mean that nonconformities must be corrected within that time period; rather, it means that a plan for corrective 

action must be completed and submitted or that other steps have already been taken to address the nonconformities. 

WMD will respond to the laboratory regarding the acceptability of the laboratory response. 

3.3.4 Contents of assessment report 

The assessment report will contain, as a minimum, the following information: 

1) name and address of the laboratory; 

2) date of the assessment; 

3) criteria used to conduct the assessment; 

4) parameters and scope of Recognition for the assessment; 

5) name(s) of the assessors and affiliations; 

6) name(s) of laboratory management and staff contacted during assessment; 

7) list of additional records reviewed in addition to the on-site assessment (such as the quality manual, training 

records, control charts, or proficiency test results maintained by WMD); 

8) references to the Program Handbook when nonconformities are identified; 

9) recommendations and preventive action for laboratory improvement and discussion related to cited 

observations; and 

10) nonconformities and corrective action required to meet program criteria and discussion related to cited 

observations. 

3.4 Proficiency Testing 

Interlaboratory comparisons (round robins) are conducted nationally and as a part of each regional measurement 

assurance program (RMAP) and constitute one of the primary methods used for assessment of competence. The 

other primary method is the assignment of Laboratory Auditing Program (LAP) problems upon the completion of 

each training seminar. However, on-site assessments may include demonstration of procedures, retest of a 

calibration item, or test of artifacts submitted directly to the laboratory. 

Acceptable results of proficiency tests are essential for Recognition to be granted; further investigation will be 

conducted to resolve any nonconformities. Proficiency testing results will be analyzed against accepted and/or 

standardized data analysis methods. As with on-site assessments and Recognition decisions, the laboratory may 

contact WMD regarding proficiency testing results if they believe an analysis was incorrect or if insufficient 

information was available for a complete evaluation. 

Proficiency testing nonconformities are defined as, but not limited to, one or more of the following: 

1) failure to meet specified proficiency testing performance requirements or objectives prescribed at the outset 

of the interlaboratory comparison; 

2) failure to participate in a regularly scheduled round of proficiency testing for which the laboratory has 

received instructions and/or materials and for which the laboratory is seeking recognition in compliance 

with the WMD policies; 

3) failure to submit laboratory control data as required specific to each interlaboratory comparison; 

4) performance as a statistically outlying laboratory in two successive rounds of proficiency testing or 

showing a general pattern of outlying results over three or more rounds; and 

5) failure to produce acceptable calibration or test results when using special artifacts whose properties are 

well-characterized and known to WMD. 

3.5 NIST Technical Evaluation 

Technical evaluation is conducted prior to awarding a Certificate of Measurement Traceability, and includes a full 

review of all available technical information regarding the laboratory. This may include annual submissions, control 

charts, quality manuals, associated appendices, administrative procedures, assigned training problems, on-site 
NIST Handbook 143 April 2007 

13

assessment reports, results of proficiency tests, training records, attendance and participation at RMAPs, formal 

accreditation, plus any other relevant information affecting the quality of the laboratory's measurement results. 

3.5.1 Review of submissions

Submissions will be reviewed and feedback provided to laboratories with the same level of significance as an on-site 

assessment. Preventive action will be recommended and corrective action will be required for noted 

nonconformities. 

3.5.1.1 New, renewal, or expansion

Any laboratory that is to receive a new certificate for January 1 must submit laboratory material between October 1 

and November 15. Material will be reviewed by WMD between November 15 and December 31. 

3.5.1.2 Maintenance

If a laboratory has multi-year Recognition, WMD will review material between November 15 and March 1 of the 

following year. In the event that material is not submitted during the appropriate time frame, WMD will review the 

material, as time is available, giving preference to laboratories without current Recognition. 

3.6 Recognition Periods and Policy

Selection of Recognition periods is based on WMD judgment of the degree to which a laboratory meets criteria in 

this Handbook and whether the laboratory routinely submits data in a timely manner. While minor nonconformities 

may not affect a laboratory's ability to establish Recognition, they will result in a shorter Recognition period to 

encourage the necessary oversight to achieve corrective action. 

Each laboratory will be given every opportunity to provide input to WMD for evaluation and to provide feedback to 

WMD assessments and evaluations. Any laboratory has the right to appeal Recognition decisions in writing to the 

WMD. Appeal responses will likely include a full independent on-site assessment of the laboratory according to the 

criteria in this Handbook. 

Complaints regarding the operation of the Recognition program, on-site assessments, document review by NIST or 

any NIST-assigned technical expert should be forwarded to the WMD in writing. 

3.6.1 Full renewal - Two year

For those laboratories fully meeting criteria in this Handbook, a two-year Certificate of Measurement Traceability 

may be issued; however, additional data must continue to be submitted annually for review as requested. 

NOTE: Until the criteria in this Handbook are fully met (including documentation), a laboratory will not be 

issued a 2-year Certificate of Measurement Traceability. 

3.6.2 One-year renewal

For laboratories where WMD management and oversight are required, or when minor nonconformities exist, a oneyear Certificate of Measurement Traceability may be issued based on the judgment of WMD staff that acceptable 

measurements will continue to be provided to laboratory customers. Any laboratory that cannot meet the criteria in 

this Handbook should not apply for NVLAP formal accreditation. 
April 2007 NIST Handbook 143 

14 

3.6.3 Conditional renewal

A one-year Conditional Certificate of Measurement Traceability may be granted when multiple nonconformities 

exist in the facilities, equipment, standards, staff, or overall laboratory operations, and the laboratory has provided 

ongoing evidence that it is working to meet criteria in this Handbook. Conditional Recognition will be issued only 

to meet legal weights and measures requirements and limitations will be stated in writing. Conditional Recognition 

will be marked on the certificate. WMD plans to minimize the use of Conditional Recognition in the future. 

3.6.4 Maintenance 

If a Certificate of Measurement Traceability for a laboratory has not expired, an annual review of submitted data and 

any laboratory on-site assessments may be conducted; however, no new certificate will be issued since the current 

certificate is valid. 

3.6.5 Suspension, withdrawal, denial

In the event that circumstances change significantly during a Recognition cycle, it is the responsibility of the 

laboratory to notify WMD. Any situation that critically affects the laboratory's ability to provide accurate and 

traceable measurements may be cause for temporary (which may be formal or informal) suspension of the 

Certificate of Measurement Traceability until criteria are met. 

A laboratory may choose to withdraw from specific levels of Recognition based on circumstances in the laboratory, 

but may be reinstated any time it has demonstrated that it fully meets criteria in this Handbook. 

The result of an on-site assessment or of document review may include denial or withdrawal of Recognition. Clear 

evidence of nonconformities will be provided to the laboratory in writing along with the required minimum 

corrective action. Denial of Recognition may be modified based on the laboratory response or resolution of an 

appeal. 
NIST Handbook 143 April 2007 

15

Table 1. Submission requirements for Recognition 

Reference Description Guidance Submission 

Appendix B 

Request for Recognition, 

Parameters and Scope, 

Approved Signatories, 

Authorized Representative 

Include entire scope of 

laboratory services annually. 

Yes: all laboratories annually. 

Yes: when changes occur. 

Appendix E Uncertainty Charts 

Must be complete for entire 

scope, reviewed annually, 

updated as needed, and 

submitted annually. 

Laboratories accredited by 

NVLAP may submit NVLAP 

Scope. Alternative formats 

(e.g., Excel files) are 

acceptable. 

Yes: all laboratories annually. 

Yes: for expanding Scope. 

3.3.4, k 

5.9 

4.15 

Proficiency Testing 

Follow-up Forms 

Include evidence of corrective 

action or plan when 

appropriate. Alternative formats 

are acceptable provided they 

are integrated into the 

laboratory management system 

and completely address the PT 

results and corrective action. 

Multi-year assessments may be 

requested to determine 

completion of previous 

corrective action and 

compliance to PT/ILC policy. 

Yes: all laboratories annually, for 

each completed PT. 

3.5.1 

Previously identified 

nonconformities or 

requests. 

Review previous feedback for 

assurance of compliance. 

Submit necessary evidence. 

Yes: all laboratories annually. 

Appendix D Laboratory Contacts 

Used to update laboratory 

directory and contacts database. 

Review each year. 

Yes: when changes occur. 

Yes: when requested. 

Appendix C Internal Assessment of 

Management System 

Complete as a form with crossreferences and details. 

Yes: if laboratory does not have 

current or full Recogntion. 

Yes: for renewals. 

Yes: when requested. 

4.14.1 Internal Technical 

Assessment 

Appendix C does not provide a 

complete technical audit. 

Contact WMD for guidance if 

system is not already in place. 

Yes: if laboratory does not have 

current or full Recogntion. 

Yes: for renewals. 

Yes: when requested. 

4.15 Management Review 

Follow Handbook 143, Section 

4.15. Provide a signed report 

that includes a laboratory 

management review. 

Yes: if laboratory does not have 

current or full Recogntion. 

Yes: for renewals. 

Yes: when requested. 
April 2007 NIST Handbook 143 

16 

Reference Description Guidance Submission 

4.2 

4.14 

Laboratory Quality 

Manual and Associated 

Appendices 

Must include complete set of 

laboratory-developed reference 

documents. New or major 

revisions must include the 

internal laboratory assessment 

of the manual and its 

references. 

Yes: if laboratory does not have 

current or full Recogntion. 

Yes: when changes occur. 

Yes: when requested. 

4.2 

4.14 

Laboratory Administrative 

Procedures 

Must include complete set of 

laboratory-developed reference 

documents. New or major 

revisions must include the 

internal laboratory assessment 

of the manual and its 

references. 

Yes: if laboratory does not have 

current or full Recogntion. 

Yes: when changes occur. 

Yes: when requested. 

5.2 

Table 2 

Laboratory Auditing 

Program (LAP) problems 

assigned in Training 

Program 

Required as specified in Table 

2. Yes: when complete. 

5.4 Laboratory-Developed 

Calibration Procedures 

Submit copies of laboratorydeveloped calibration 

procedures (and significant 

modifications of published 

procedures) with evidence of 

validation. 

Yes: when new procedures are 

developed. 

Yes: when requested. 

5.6 Calibration Reports 

Only needed for calibrations of 

standards obtained during the 

year from other laboratories. 

Yes: submit new reports during 

annual review cycle. 

5.9 Measurement Assurance 

& Control Charts 

Must be in place for all 

measurement services; see 

section 5.9 in this Handbook. 

Yes: if laboratory does not have 

current or full Recogntion. 

Yes: when requested. 

Other Special Technical 

Requests 

May be used for national 

assessments and summaries as 

needed. Will reference 

Handbook criteria. 

Yes: if laboratory does not have 

current or full Recogntion. 

Yes: when requested. 

Examples of Special 

Technical Requests: 

Training Records, 

Training Plan, Succession 

Planning, 

Assessment of Laboratory 

Environmental Conditions, 

Summary of Laboratory 

Equipment and Suitability, 

Traceability Hierarchy 

Assessments, 

5.2 

5.3 

5.5 

5.6 

5.10 Samples of Calibration 

Reports 

Guidance will be provided 

when requests are made. Yes: when requested. 
NIST Handbook 143 April 2007 

17

4. Management Requirements for Accreditation1

4.1 Organization 

4.1.1 The laboratory or the organization of which it is part shall be an entity that can be held legally responsible. 

4.1.2 It is the responsibility of the laboratory to carry out its testing and calibration activities in such a way as to 

meet the requirements of this Handbook and to satisfy the needs of the customer, the regulatory authorities or 

organizations providing Recognition. 

4.1.3 The laboratory management system shall cover work carried out in the laboratory’s permanent facilities, at 

sites away from its permanent facilities, or in associated temporary or mobile facilities. 

4.1.4 If the laboratory is part of an organization performing activities other than testing and/or calibration, the 

responsibilities of key personnel in the organization that have an involvement or influence on the testing and/or 

calibration activities of the laboratory shall be defined in order to identify potential conflicts of interest. 

NOTE 1: Where a laboratory is part of a larger organization, the organizational arrangements should be such that 

departments having conflicting interests, such as production, commercial marketing or financing do not adversely 

influence the laboratory's compliance with the requirements of this Handbook. 

NOTE 2: If the laboratory wishes to be Recognized as a third-party laboratory, it should be able to demonstrate 

that it is impartial and that it and its personnel are free from any undue commercial, financial and other pressures 

which might influence their technical judgment. The third-party testing or calibration laboratory should not engage 

in any activities that may endanger the trust in its independence of judgment and integrity in relation to its testing or 

calibration activities. 

4.1.5 The laboratory shall: 

1) have managerial and technical personnel who, irrespective of other responsibilities, have the authority and 

resources needed to carry out their duties, including the implementation, maintenance and improvement of 

the management system, and to identify the occurrence of departures from the management system or from 

the procedures for performing tests and/or calibrations, and to initiate actions to prevent or minimize such 

departures (see also 5.2); 

2) have arrangements to ensure that its management and personnel are free from any undue internal and 

external commercial, financial and other pressures and influences that may adversely affect the quality of 

their work; 

3) have policies and procedures to ensure the protection of its customers’ confidential information and 

proprietary rights, including procedures for protecting the electronic storage and transmission of results; 

4) have policies and procedures to avoid involvement in any activities that would diminish confidence in its 

competence, impartiality, judgment or operational integrity; 

5) define the organization and management structure of the laboratory, its place in any parent organization, 

and the relationships between quality management, technical operations and support services; 

6) specify the responsibility, authority and interrelationships of all personnel who manage, perform or verify 

work affecting the quality of the tests and/or calibrations; 

7) provide adequate supervision of testing and calibration staff, including trainees, by persons familiar with 

methods and procedures, purpose of each test and/or calibration, and with the assessment of the test or 

calibration results; 

 

1

 Section 4 substantially references the text of ISO/IEC 17025:2005, with additional NVLAP notes, WMD notes, 

and minor editorial changes for clarity. Where “this Handbook” is used in Section 4, it refers to the criteria in 

ISO/IEC 17025 as applied to this Program Handbook unless otherwise stated. WMD does not accredit laboratories; 

however, WMD assesses State laboratories that participate in the Recognition program for conformance to these 

requirements. 
April 2007 NIST Handbook 143 

18 

8) have technical management which has overall responsibility for the technical operations and the provision 

of the resources needed to ensure the required quality of laboratory operations; 

9) appoint a member of staff as quality manager (however named) who, irrespective of other duties and 

responsibilities, shall have defined responsibility and authority for ensuring that the management system 

related to quality is implemented and followed at all times; the quality manager shall have direct access to 

the highest level of management at which decisions are made on laboratory policy or resources; 

10) appoint deputies for key managerial personnel (see Note); 

11) ensure that its personnel are aware of the relevance and importance of their activities and how they 

contribute to the achievement of the objectives of the management system. 

NOTE: Individuals may have more than one function and it may be impractical to appoint deputies for each 

function. 

4.1.6 Top management shall ensure that appropriate communication processes are established within the 

laboratory and that communication takes place regarding the effectiveness of the management system. 

4.2 Management System 

4.2.1 The laboratory shall establish, implement and maintain a management system appropriate to the scope of 

its activities. The laboratory shall document its policies, systems, programs, procedures and instructions to the 

extent necessary to assure the quality of the test and/or calibration results. The system’s documentation shall be 

communicated to, understood by, available to, and implemented by the appropriate personnel. 

4.2.2 The laboratory’s management system policies related to quality, including a quality policy statement 

shall be defined in a quality manual (however named). The overall objectives shall be established, and shall be 

reviewed during management review. The quality policy statement shall be issued under the authority of top 

management. It shall include at least the following: 

1) the laboratory management's commitment to good professional practice and to the quality of its testing and 

calibration in servicing its customers; 

2) the management’s statement of the laboratory's standard of service; 

3) the purpose of the management system related to quality; 

4) a requirement that all personnel concerned with testing and calibration activities within the laboratory 

familiarize themselves with the quality documentation and implement the policies and procedures in their 

work; and 

5) the laboratory management's commitment to comply with this Handbook and to continually improve the 

effectiveness of the management system. 

NOTE: The quality policy statement should be concise and may include the requirement that tests and/or 

calibrations shall always be carried out in accordance with stated methods and customers’ requirements. When the 

test and/or calibration laboratory is part of a larger organization, some quality policy elements may be in other 

documents. 

4.2.3 Top management shall provide evidence of commitment to the development and implementation of the 

management system and to continually improving its effectiveness. 

4.2.4 Top management shall communicate to the organization the importance of meeting customer 

requirements as well as statutory and regulatory requirements. 

4.2.5 The quality manual shall include or make reference to the supporting procedures including technical 

procedures. It shall outline the structure of the documentation used in the management system. 

4.2.6 The role and responsibilities of technical management and the quality manager, including their 

responsibility for ensuring compliance with this Handbook, shall be defined in the quality manual. 
NIST Handbook 143 April 2007 

19

4.2.7 Top management shall ensure that the integrity of the management system is maintained when changes to 

the management system are planned and implemented. 

WMD NOTE: The list of items in this section is not a complete list of all items that must be included in a quality 

manual. In addition to the items in this section, the laboratory’s quality manual must also address each of the 

requirements in Sections 4 and 5 of this Handbook. The WMD provides NISTIR 5802, Quality Manual Template 

for the State laboratories (ISO/IEC Guide 25 compliant) and NISTIR 7028, Type Evaluation Laboratory Quality 

Manual Template (ISO/IEC 17025:1999 compliant) to use as a baseline which must be sufficiently modified to 

match specific program details and the requirements of Sections 4 and 5 of this Handbook. All modifications must 

be evaluated against these criteria. All updates must be submitted for review. 

4.3 Document Control 

4.3.1 General 

The laboratory shall establish and maintain procedures to control all documents that form part of its management 

system (internally generated or from external sources), such as regulations, standards, other normative documents, 

test and/or calibration methods, as well as drawings, software, specifications, instructions and manuals. 

NOTE 1: In this context "documents" could be policy statements, procedures, specifications, calibration tables, 

charts, text books, posters, notices, memoranda, software, drawings, plans, etc. These may be on various media, 

whether hard copy or electronic, and they may be digital, analog, photographic or written. 

NOTE 2: The control of data related to testing and calibration is covered in 5.4.7. The control of records is 

covered in 4.13. 

4.3.2 Document approval and issue 

4.3.2.1 All documents issued to personnel in the laboratory as part of the management system shall be reviewed 

and approved for use by authorized personnel prior to issue. A master list or an equivalent document control 

procedure identifying the current revision status and distribution of documents in the quality system shall be 

established and be readily available to preclude the use of invalid and/or obsolete documents. 

4.3.2.2 The procedure(s) adopted shall ensure that: 

1) authorized editions of appropriate documents are available at all locations where operations essential to the 

effective functioning of the laboratory are performed; 

2) documents are periodically reviewed and, where necessary, revised to ensure continuing suitability and 

compliance with applicable requirements; 

3) invalid or obsolete documents are promptly removed from all points of issue or use, or otherwise assured 

against unintended use; 

4) obsolete documents retained for either legal or knowledge preservation purposes are suitably marked. 

4.3.2.3 Management system documents generated by the laboratory shall be uniquely identified. Such 

identification shall include the date of issue and/or revision identification, page numbering, the total number of 

pages or a mark to signify the end of the document, and the issuing authority(ies). 

4.3.3 Document changes 

4.3.3.1 Changes to documents shall be reviewed and approved by the same function that performed 

the original review unless specifically designated otherwise. The designated personnel shall have access to pertinent 

background information upon which to base their review and approval. 
April 2007 NIST Handbook 143 

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4.3.3.2 Where practicable, the altered or new text shall be identified in the document or the appropriate 

attachments. 

4.3.3.3 If the laboratory's documentation control system allows for the amendment of documents by hand 

pending the reissue of the documents, the procedures and authorities for such amendments shall be defined. 

Amendments shall be clearly marked, initialed and dated. A revised document shall be formally reissued as soon as 

practicable. 

4.3.3.4 Procedures shall be established to describe how changes in documents maintained in computerized systems 

are made and controlled. 

4.4 Review of Requests, Tenders and Contracts 

4.4.1 The laboratory shall establish and maintain procedures for the review of requests, tenders and contracts. 

The policies and procedures for these reviews leading to a contract for testing and/or calibration shall ensure that: 

1) the requirements, including the methods to be used, are adequately defined, documented and understood 

(see 5.4.2); 

2) the laboratory has the capability and resources to meet the requirements; and 

3) the appropriate test and/or calibration method is selected and is capable of meeting the customers’ 

requirements (see 5.4.2). 

Any differences between the request or tender and the contract shall be resolved before any work commences. Each 

contract shall be acceptable both to the laboratory and the customer. 

NOTE 1: The request, tender and contract review should be conducted in a practical and efficient manner, and the 

effect of financial, legal and time schedule aspects should be taken into account. For internal customers, reviews of 

requests, tenders and contracts can be performed in a simplified way. 

NOTE 2: The review of capability should establish that the laboratory possesses the necessary physical, personnel 

and information resources, and that the laboratory's personnel have the skills and expertise necessary for the 

performance of the tests and/or calibrations in question. The review may also encompass results of earlier 

participation in interlaboratory comparisons or proficiency testing and/or the running of trial test or calibration 

programs using samples or items of known value in order to determine uncertainties of measurement, limits of 

detection, confidence limits, etc. 

NOTE 3: A contract may be any written or oral agreement to provide a customer with testing and/or calibration 

services. 

4.4.2 Records of reviews, including any significant changes, shall be maintained. Records shall also be 

maintained of pertinent discussions with a customer relating to the customer’s requirements or the results of the 

work during the period of execution of the contract. 

NOTE: For review of routine and other simple tasks, the date and the identification (e.g., the initials) of the 

person in the laboratory responsible for carrying out the contracted work are considered adequate. For repetitive 

routine tasks, the review need be made only at the initial enquiry stage or on granting of the contract for ongoing 

routine work performed under a general agreement with the customer, provided that the customer’s requirements 

remain unchanged. For new, complex or advanced testing and/or calibration tasks, a more comprehensive record 

should be maintained. 

4.4.3 The review shall also cover any work that is subcontracted by the laboratory. 

4.4.4 The customer shall be informed of any deviation from the contract. 

4.4.5 If a contract is to be amended after work has commenced, the same contract review process shall be 

repeated and any amendments shall be communicated to all affected personnel. 
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4.5 Subcontracting of Tests and Calibrations 

4.5.1 When a laboratory subcontracts work whether due to unforeseen reasons (e.g., workload, need for further 

expertise or temporary incapacity) or on a continuing basis (e.g., through permanent subcontracting, agency or 

franchising arrangements), this work shall be placed with a competent subcontractor. A competent subcontractor is 

one that, for example, complies with this Handbook for the work in question. 

4.5.2 The laboratory shall advise the customer of the arrangement in writing and, when appropriate, gain the 

approval of the customer, preferably in writing. 

4.5.3 The laboratory is responsible to the customer for the subcontractor’s work, except in the case where the 

customer or a regulatory authority specifies which subcontractor is to be used. 

4.5.4 The laboratory shall maintain a register of all subcontractors that it uses for tests and/or calibrations and a 

record of the evidence of compliance with this Handbook for the work in question. 

4.6 Purchasing Services and Supplies 

4.6.1 The laboratory shall have a policy and procedure(s) for the selection and purchasing of services and 

supplies it uses that affect the quality of the tests and/or calibrations. Procedures shall exist for the purchase, 

reception and storage of reagents and laboratory consumable materials relevant for the tests and calibrations. 

4.6.2 The laboratory shall ensure that purchased supplies and reagents and consumable materials that affect the 

quality of tests and/or calibrations are not used until they have been inspected or otherwise verified as complying 

with standard specifications or requirements defined in the methods for the tests and/or calibrations concerned. 

These services and supplies used shall comply with specified requirements. Records of actions taken to check 

compliance shall be maintained. 

4.6.3 Purchasing documents for items affecting the quality of laboratory output shall contain data describing 

the services and supplies ordered. These purchasing documents shall be reviewed and approved for technical 

content prior to release. 

NOTE: The description may include type, class, grade, precise identification, specifications, drawings, inspection 

instructions, other technical data including approval of test results, the quality required, and the management system 

standard under which they were made. 

4.6.4 The laboratory shall evaluate suppliers of critical consumables, supplies and services which affect the 

quality of testing and calibration, and shall maintain records of these evaluations and list those approved. 

4.7 Service to the Customer 

4.7.1 The laboratory shall be willing to cooperate with customers or their representatives in clarifying the 

customer’s request and in monitoring the laboratory’s performance in relation to the work performed, provided that 

the laboratory ensures confidentiality to other customers. 

NOTE 1: Such cooperation may include: 

1) providing the customer or the customer’s representative reasonable access to relevant areas of the 

laboratory for the witnessing of tests and/or calibrations performed for the customer; and 

2) preparation, packaging, and dispatch of test and/or calibration items needed by the customer for verification 

purposes. 

NOTE 2: Customers value the maintenance of good communication, advice and guidance in technical matters, and 

opinions and interpretations based on results. Communication with the customer, 
April 2007 NIST Handbook 143 

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especially in large assignments, should be maintained throughout the work. The laboratory should inform the 

customer of any delays or major deviations in the performance of the tests and/or calibrations. 

4.7.2 The laboratory shall seek feedback, both positive and negative, from its customers. The feedback shall be 

used and analyzed to improve the management system, testing and calibration activities and customer service. 

NOTE: Examples of the types of feedback include customer satisfaction surveys and review of test or calibration 

reports with customers. 

4.8 Complaints 

The laboratory shall have a policy and procedure for the resolution of complaints received from customers or other 

parties. Records shall be maintained of all complaints and of the investigations and corrective actions taken by the 

laboratory (see also 4.11). 

4.9 Control of Non-conforming Testing and/or Calibration Work 

4.9.1 The laboratory shall have a policy and procedures that shall be implemented when any aspect of its 

testing and/or calibration work, or the results of this work, do not conform to its own procedures or the agreed 

requirements of the customer. The policy and procedures shall ensure that: 

1) the responsibilities and authorities for the management of non-conforming work are designated and actions 

(including halting of work and withholding of test reports and calibration certificates, as necessary) are 

defined and taken when non-conforming work is identified; 

2) an evaluation of the significance of the non-conforming work is made; 

3) correction is taken immediately, together with any decision about the acceptability of the non-conforming 

work; 

4) where necessary, the customer is notified and work is recalled; and 

5) the responsibility for authorizing the resumption of work is defined. 

NOTE: Identification of non-conforming work or problems with the management system or with testing and/or 

calibration activities can occur at various places within the management system and technical operations. Examples 

are customer complaints, quality control, instrument calibration, checking of consumable materials, staff 

observations or supervision, test report and calibration certificate checking, management reviews and internal or 

external audits. 

4.9.2 Where the evaluation indicates that the non-conforming work could recur or that there is doubt about the 

compliance of the laboratory's operations with its own policies and procedures, the corrective action procedures 

given in 4.11 shall be promptly followed. 

4.10 Improvement

The laboratory shall continually improve the effectiveness of its management system through the use of the quality 

policy, quality objectives, audit results, analysis of data, corrective and preventive actions and management review. 

4.11 Corrective Action 

4.11.1 General 

The laboratory shall establish a policy and procedure and shall designate appropriate authorities for implementing 

corrective action when non-conforming work or departures from the policies and procedures in the management 

system or technical operations have been identified. 
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NOTE: A problem with the management system or with the technical operations of the laboratory may be 

identified through a variety of activities, such as control of non-conforming work, internal or external audits, 

management reviews, feedback from customers and from staff observations. 

4.11.2 Cause analysis 

The procedure for corrective action shall start with an investigation to determine the root cause(s) of the problem. 

NOTE: Cause analysis is the key and sometimes the most difficult part in the corrective action procedure. Often 

the root cause is not obvious and thus a careful analysis of all potential causes of the problem is required. Potential 

causes could include customer requirements, the samples, sample specifications, methods and procedures, staff skills 

and training, consumables, or equipment and its calibration. 

4.11.3 Selection and implementation of corrective actions 

Where corrective action is needed, the laboratory shall identify potential corrective actions. It shall select and 

implement the action(s) most likely to eliminate the problem and to prevent recurrence. 

Corrective actions shall be to a degree appropriate to the magnitude and the risk of the problem. 

The laboratory shall document and implement any required changes resulting from corrective action investigations. 

4.11.4 Monitoring of corrective actions 

The laboratory shall monitor the results to ensure that the corrective actions taken have been effective. 

4.11.5 Additional audits 

Where the identification of nonconformities or departures casts doubts on the laboratory's compliance with its own 

policies and procedures, or on its compliance with this Handbook, the laboratory shall ensure that the appropriate 

areas of activity are audited in accordance with 4.14 as soon as possible. 

NOTE: Such additional audits often follow the implementation of the corrective actions to confirm their 

effectiveness. An additional audit should be necessary only when a serious issue or risk to the business is identified. 

4.12 Preventive Action 

4.12.1 Needed improvements and potential sources of nonconformities, either technical or concerning the 

management system, shall be identified. When improvement opportunities are identified or if preventive action is 

required, action plans shall be developed, implemented and monitored to reduce the likelihood of the occurrence of 

such nonconformities and to take advantage of the opportunities for improvement. 

4.12.2 Procedures for preventive actions shall include the initiation of such actions and application of controls to 

ensure that they are effective. 

NOTE 1: Preventive action is a proactive process to identify opportunities for improvement rather than a reaction 

to the identification of problems or complaints. 

NOTE 2: Apart from the review of the operational procedures, the preventive action might involve analysis of data, 

including trend and risk analyses and proficiency testing results. 
April 2007 NIST Handbook 143 

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4.13 Control of Records 

4.13.1 General 

4.13.1.1 The laboratory shall establish and maintain procedures for identification, collection, indexing, access, 

filing, storage, maintenance and disposal of quality and technical records. Quality records shall include reports from 

internal audits and management reviews as well as records of corrective and preventive actions. 

4.13.1.2 All records shall be legible and shall be stored and retained in such a way that they are readily retrievable 

in facilities that provide a suitable environment to prevent damage or deterioration and to prevent loss. Retention 

times of records shall be established. 

NOTE: Records may be in any media, such as hard copy or electronic media. 

4.13.1.3 All records shall be held secure and in confidence. 

4.13.1.4 The laboratory shall have procedures to protect and back up records stored electronically and to prevent 

unauthorized access to or amendment of these records. 

4.13.2 Technical records 

4.13.2.1 The laboratory shall retain records of original observations, derived data and sufficient information to 

establish an audit trail, calibration records, staff records and a copy of each test report or calibration certificate 

issued, for a defined period. The records for each test or calibration shall contain sufficient information to facilitate, 

if possible, identification of factors affecting the uncertainty and to enable the test or calibration to be repeated under 

conditions as close as possible to the original. The records shall include the identity of personnel responsible for the 

sampling, performance of each test and/or calibration and checking of results. 

NOTE 1: In certain fields it may be impossible or impracticable to retain records of all original observations. 

NOTE 2: Technical records are accumulations of data (see 5.4.7) and information which result from carrying out 

tests and/or calibrations and which indicate whether specified quality or process parameters are achieved. They may 

include forms, contracts, work sheets, work books, check sheets, work notes, control graphs, external and internal 

test reports and calibration certificates, customers’ notes, papers and feedback. 

4.13.2.2 Observations, data and calculations shall be recorded at the time they are made and shall be identifiable 

to the specific task. 

4.13.2.3 When mistakes occur in records, each mistake shall be crossed out, not erased, made illegible or deleted, 

and the correct value entered alongside. All such alterations to records shall be signed or initialed by the person 

making the correction. In the case of records stored electronically, equivalent measures shall be taken to avoid loss 

or change of original data. 

4.14 Internal Audits 

4.14.1 The laboratory shall periodically, and in accordance with a predetermined schedule and procedure, 

conduct internal audits of its activities to verify that its operations continue to comply with the requirements of the 

management system and this Handbook. The internal audit program shall address all elements of the management 

system, including the testing and/or calibration activities. It is the responsibility of the quality manager to plan and 

organize audits as required by the schedule and requested by management. Such audits will be carried out by 

trained and qualified personnel who are, wherever resources permit, independent of the activity to be audited. 

NOTE: The cycle for internal auditing should normally be completed in one year. 
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4.14.2 When audit findings cast doubt on the effectiveness of the operations or on the correctness or validity of 

the laboratory's test or calibration results, the laboratory shall take timely corrective action, and shall notify 

customers in writing if investigations show that the laboratory results may have been affected. 

4.14.3 The area of activity audited, the audit findings and corrective actions that arise from them shall be 

recorded. 

4.14.4 Follow-up audit activities shall verify and record the implementation and effectiveness of the corrective 

action taken. 

4.15 Management Reviews 

4.15.1 In accordance with a predetermined schedule and procedure, the laboratory’s top management shall 

periodically conduct a review of the laboratory's management system and testing and/or calibration activities to 

ensure their continuing suitability and effectiveness, and to introduce necessary changes or improvements. The 

review shall take account of: 

— the suitability of policies and procedures; 

— reports from managerial and supervisory personnel; 

— the outcome of recent internal audits (see 4.13); 

— corrective and preventive actions; 

— assessments by external bodies; 

— the results of interlaboratory comparisons or proficiency tests; 

— changes in the volume and type of the work; 

— customer feedback; 

— complaints; 

— recommendations for improvement; 

— other relevant factors, such as quality control activities, resources and staff training. 

NOTE 1: A typical period for conducting a management review is once every 12 months. 

NOTE 2: Results should feed into the laboratory planning system and should include the goals, objectives and 

action plans for the coming year. 

NOTE 3: A management review includes consideration of related subjects at regular management meetings. 

4.15.2 Findings from management reviews and the actions that arise from them shall be recorded. The 

management shall ensure that those actions are carried out within an appropriate and agreed timescale. 
April 2007 NIST Handbook 143 

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NIST Handbook 143 April 2007 

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5. Technical Requirements for Accreditation2

5.1 General 

5.1.1 Many factors determine the correctness and reliability of the tests and/or calibrations performed by a 

laboratory. These factors include contributions from: 

— human factors (5.2); 

— accommodation and environmental conditions (5.3); 

— test and calibration methods and method validation (5.4); 

— equipment (5.5); 

— measurement traceability (5.6); 

— sampling (5.7); 

— the handling of test and calibration items (5.8). 

5.1.2 The extent to which the factors contribute to the total uncertainty of measurement differs considerably 

between (types of) tests and between (types of) calibrations. The laboratory shall take account of these factors in 

developing test and calibration methods and procedures, in the training and qualification of personnel, and in the 

selection and calibration of the equipment it uses. 

5.2 Personnel 

5.2.1 The laboratory management shall ensure the competence of all who operate specific equipment, perform 

tests and/or calibrations, evaluate results, and sign test reports and calibration certificates. When using staff who are 

undergoing training, appropriate supervision shall be provided. Personnel performing specific tasks shall be 

qualified on the basis of appropriate education, training, experience and/or demonstrated skills, as required. 

NOTE 1: In some technical areas (e.g., nondestructive testing) it may be required that the personnel performing 

certain tasks hold personnel certification. The laboratory is responsible for fulfilling specified personnel 

certification requirements. The requirements for personnel certification might be regulatory, included in the 

standards for the specific technical field, or required by the customer. 

NOTE 2: The personnel responsible for the opinions and interpretation included in test reports should, in addition 

to the appropriate qualifications, training, experience and satisfactory knowledge of the testing carried out, also 

have: 

— relevant knowledge of the technology used for the manufacturing of the items, materials, products, etc. 

tested, or the way they are used or intended to be used, and of the defects or degradations which may occur 

during or in service; 

— knowledge of the general requirements expressed in the legislation and standards; and 

— an understanding of the significance of deviations found with regard to the normal use of the items, 

materials, products, etc., concerned. 

5.2.2 The management of the laboratory shall formulate the goals with respect to the education, training and 

skills of the laboratory personnel. The laboratory shall have a policy and procedures for identifying training needs 

and providing training of personnel. The training program shall be relevant to the present and anticipated tasks of 

the laboratory. The effectiveness of the training actions taken shall be evaluated. 

 

2 Section 5 substantially references the text of ISO/IEC 17025:2005, with additional NVLAP notes, WMD notes, 

and minor editorial changes for clarity. Where “this Handbook” is used in Section 5, it refers to the criteria in 

ISO/IEC 17025 as applied to this Program Handbook unless otherwise stated. WMD does not Accredit laboratories; 

however, WMD assesses State laboratories that participate in the Recognition program for conformance to these 

requirements. 
April 2007 NIST Handbook 143 

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5.2.3 The laboratory shall use personnel who are employed by, or under contract to, the laboratory. Where 

contracted and additional technical and key support personnel are used, the laboratory shall ensure that such 

personnel are supervised and competent and that they work in accordance with the laboratory's management system. 

5.2.4 The laboratory shall maintain current job descriptions for managerial, technical and key support 

personnel involved in tests and/or calibrations. 

NOTE: Job descriptions can be defined in many ways. As a minimum, the following should be defined: 

— the responsibilities with respect to performing tests and/or calibrations; 

— the responsibilities with respect to the planning of tests and/or calibrations and evaluation of results; 

— the responsibilities for reporting opinions and interpretations; 

— the responsibilities with respect to method modification and development and validation of new methods; 

— expertise and experience required; 

— qualifications and training programs; 

— managerial duties. 

5.2.5 The management shall authorize specific personnel to perform particular types of sampling, test and/or 

calibration, to issue test reports and calibration certificates, to give opinions and interpretations and to operate 

particular types of equipment. The laboratory shall maintain records of the relevant authorization(s), competence, 

educational and professional qualifications, training, skills and experience of all technical personnel, including 

contracted personnel. This information shall be readily available and shall include the date on which authorization 

and/or competence is confirmed. 

WMD NOTE 1: This requirement also applies to Approved Signatories. 

WMD NOTE 2: The WMD provides training to State legal metrology laboratories. State metrologists are required 

to complete the appropriate level of training as indicated in Table 2, for the laboratory to be Recognized at 

designated levels. Information regarding the training program is maintained in the WMD. 

5.3 Accommodation and Environmental Conditions 

5.3.1 Laboratory facilities for testing and/or calibration, including but not limited to energy sources, lighting 

and environmental conditions, shall be such as to facilitate correct performance of the tests and/or calibrations. 

The laboratory shall ensure that the environmental conditions do not invalidate the results or adversely affect the 

required quality of any measurement. Particular care shall be taken when sampling and tests and/or calibrations are 

undertaken at sites other than a permanent laboratory facility. The technical requirements for accommodation and 

environmental conditions that can affect the results of tests and calibrations shall be documented. 

5.3.2 The laboratory shall monitor, control and record environmental conditions as required by the relevant 

specifications, methods and procedures or where they influence the quality of the results. Due attention shall be 

paid, for example, to biological sterility, dust, electromagnetic disturbances, radiation, humidity, electrical supply, 

temperature, and sound and vibration levels, as appropriate to the technical activities concerned. Tests and 

calibrations shall be stopped when the environmental conditions jeopardize the results of the tests and/or 

calibrations. 

5.3.3 There shall be effective separation between neighboring areas in which there are incompatible activities. 

Measures shall be taken to prevent cross-contamination. 

5.3.4 Access to and use of areas affecting the quality of the tests and/or calibrations shall be controlled. The 

laboratory shall determine the extent of control based on its particular circumstances. 

5.3.5 Measures shall be taken to ensure good housekeeping in the laboratory. Special procedures shall be 

prepared where necessary. 
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5.4 Test and Calibration Methods and Method Validation 

5.4.1 General 

The laboratory shall use appropriate methods and procedures for all tests and/or calibrations within its scope. These 

include sampling, handling, transport, storage and preparation of items to be tested and/or calibrated, and, where 

appropriate, an estimation of the measurement uncertainty as well as statistical techniques for analysis of test and/or 

calibration data. 

The laboratory shall have instructions on the use and operation of all relevant equipment, and on the handling and 

preparation of items for testing and/or calibration, or both, where the absence of such instructions could jeopardize 

the results of tests and/or calibrations. All instructions, standards, manuals and reference data relevant to the work 

of the laboratory shall be kept up to date and shall be made readily available to personnel (see 4.3). Deviation from 

test and calibration methods shall occur only if the deviation has been documented, technically justified, authorized, 

and accepted by the customer. 

NOTE: International, regional or national standards or other recognized specifications that contain sufficient and 

concise information on how to perform the tests and/or calibrations do not need to be supplemented or rewritten as 

internal procedures if these standards are written in a way that they can be used as published by the operating staff in 

a laboratory. It may be necessary to provide additional documentation for optional steps in the method or additional 

details. 

WMD NOTE: The WMD maintains NIST Handbook 145, Handbook for the Quality Assurance of Metrological 

Measurements and its interim updates that are published in NISTIR form until the entire Handbook is updated. 

States must reference this Handbook (or its interim procedures) and use it for all applicable measurement procedures 

unless data or other evidence is available to support acceptable results using another procedure. Other procedures 

must be submitted to WMD for review and approval by the WMD. Use of uniform procedures is critical for 

maintaining the integrity of the legal measurement system. 

5.4.2 Selection of methods 

The laboratory shall use test and/or calibration methods, including methods for sampling, which meet the needs of 

the customer and which are appropriate for the tests and/or calibrations it undertakes. Methods published in 

international, regional or national standards shall preferably be used. The laboratory shall ensure that it uses the 

latest valid edition of a standard unless it is not appropriate or possible to do so. When necessary, the standard shall 

be supplemented with additional details to ensure consistent application. 

When the customer does not specify the method to be used, the laboratory shall select appropriate methods that have 

been published either in international, regional or national standards, or by reputable technical organizations, or in 

relevant scientific texts or journals, or as specified by the manufacturer of the equipment. Laboratory-developed 

methods or methods adopted by the laboratory may also be used if they are appropriate for the intended use and if 

they are validated. The customer shall be informed as to the method chosen. The laboratory shall confirm that it 

can properly operate standard methods before introducing the tests or calibrations. If the standard method changes, 

the confirmation shall be repeated. 

The laboratory shall inform the customer when the method proposed by the customer is considered to be 

inappropriate or out of date. 

5.4.3 Laboratory-developed methods 

The introduction of test and calibration methods developed by the laboratory for its own use shall be a planned 

activity and shall be assigned to qualified personnel equipped with adequate resources. 

Plans shall be updated as development proceeds and effective communication amongst all personnel involved shall 

be ensured. 
April 2007 NIST Handbook 143 

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5.4.4 Non-standard methods 

When it is necessary to use methods not covered by standard methods, these shall be subject to agreement with the 

customer and shall include a clear specification of the customer’s requirements and the purpose of the test and/or 

calibration. The method developed shall have been validated appropriately before use. 

NOTE: For new test and/or calibration methods, procedures should be developed before tests and/or calibrations 

are performed and should contain at least the following information: 

1) appropriate identification; 

2) scope; 

3) description of the type of item to be tested or calibrated; 

4) parameters or quantities and ranges to be determined; 

5) apparatus and equipment, including technical performance requirements; 

6) reference standards and reference materials required; 

7) environmental conditions required and any stabilization period needed; 

8) description of the procedure, including: 

— affixing of identification marks, handling, transporting, storing and preparation of items, 

— checks to be made before the work is started, 

— checks that the equipment is working properly and, where required, calibration and adjustment of the 

equipment before each use, 

— the method of recording the observations and results; 

— any safety measures to be observed; 

9) criteria and/or requirements for approval/rejection; 

10) data to be recorded and method of analysis and presentation; 

11) the uncertainty or the procedure for estimating uncertainty. 

5.4.5 Validation of methods 

5.4.5.1 Validation is the confirmation by examination and the provision of objective evidence that the particular 

requirements for a specific intended use are fulfilled. 

5.4.5.2 The laboratory shall validate non-standard methods, laboratory-designed/developed methods, standard 

methods used outside their intended scope, and amplifications and modifications of standard methods to confirm 

that the methods are fit for the intended use. The validation shall be as extensive as necessary to meet the needs of 

the given application or field of application. The laboratory shall record the results obtained, the procedure used for 

the validation, and a statement as to whether the method is fit for the intended use. 

NOTE 1: Validation may include procedures for sampling, handling and transportation. 

NOTE 2: The techniques used for the determination of the performance of a method should be one of, or a 

combination of, the following: 

— calibration using reference standards or reference materials; 

— comparison of results achieved with other methods; 

— interlaboratory comparisons; 

— systematic assessment of the factors influencing the result; 

— assessment of the uncertainty of the results based on scientific understanding of the theoretical principles of 

the method and practical experience. 

NOTE 3: For changes in the validated non-standard methods, their influence should be documented and, if 

appropriate, another validation should be carried out. 

5.4.5.3 The range and accuracy of the values obtainable from validated methods (e.g., the uncertainty of the 

results, detection limit, selectivity of the method, linearity, limit of repeatability and/or reproducibility, robustness 

against external influences and/or cross-sensitivity against interference from the matrix of the sample/test object), as 

assessed for the intended use, shall be relevant to the customer’s needs. 
NIST Handbook 143 April 2007 

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NOTE 1: Validation includes specification of the requirements, determination of the characteristics of the methods, 

a check that the requirements can be fulfilled by using the method, and a statement on the validity. 

NOTE 2: As method development proceeds, regular review should be carried out to verify that the needs of the 

customer are still being fulfilled. Any change in requirements requiring modifications to the development plan 

should be approved and authorized. 

NOTE 3: Validation is always a balance between costs, risks and technical possibilities. There are many cases in 

which the range and uncertainty of the values (e.g., accuracy, detection limit, selectivity, linearity, repeatability, 

reproducibility, robustness and cross-sensitivity) can only be given in a simplified way due to lack of information. 

5.4.6 Estimation of uncertainty of measurement 

5.4.6.1 A calibration laboratory, or a testing laboratory performing its own calibrations, shall have and shall 

apply a procedure to estimate the uncertainty of measurement for all calibrations and types of calibrations. 

5.4.6.2 Testing laboratories shall have and shall apply procedures for estimating uncertainty of measurement. In 

certain cases the nature of the test method may preclude rigorous, metrologically and statistically valid, calculation 

of uncertainty of measurement. In these cases the laboratory shall at least attempt to identify all the components of 

uncertainty and make a reasonable estimation, and shall ensure that the form of reporting of the result does not give 

a wrong impression of the uncertainty. Reasonable estimation shall be based on knowledge of the performance of 

the method and on the measurement scope and shall make use of, for example, previous experience and validation 

data. 

NOTE 1: The degree of rigor needed in an estimation of uncertainty of measurement depends on factors such as: 

 

— the requirements of the test method; 

— the requirements of the customer; and 

— the existence of narrow limits on which decisions on conformity to a specification are based. 

NOTE 2: In those cases where a well-recognized test method specifies limits to the values of the major sources of 

uncertainty of measurement and specifies the form of presentation of calculated results, the laboratory is considered 

to have satisfied this clause by following the test method and reporting instructions (see 5.10). 

5.4.6.3 When estimating the uncertainty of measurement, all uncertainty components which are of importance in 

the given situation shall be taken into account using appropriate methods of analysis. 

NOTE 1: Sources contributing to the uncertainty include, but are not necessarily limited to, the reference standards 

and reference materials used, methods and equipment used, environmental conditions, properties and condition of 

the item being tested or calibrated, and the operator. 

NOTE 2: The predicted long-term behavior of the tested and/or calibrated item is not normally taken into account 

when estimating the measurement uncertainty. 

NOTE 3: For further information, see ISO 5725 and the Guide to the Expression of Uncertainty in Measurement 

(see References). 

WMD NOTE: ANSI/NCSL Z540-2-1997 and NIST Technical Note 1297 are considered to be equivalent to the 

Guide to the Expression of Uncertainty in Measurement (GUM). SOP 29 contains procedures for implementing this 

requirement. 

5.4.7 Control of data 

5.4.7.1 Calculations and data transfers shall be subject to appropriate checks in a systematic manner. 
April 2007 NIST Handbook 143 

32 

5.4.7.2 When computers or automated equipment are used for the acquisition, processing, recording, reporting, 

storage or retrieval of test or calibration data, the laboratory shall ensure that: 

1) computer software developed by the user is documented in sufficient detail and is suitably validated as 

being adequate for use; 

2) procedures are established and implemented for protecting the data; such procedures shall include, but not 

be limited to, integrity and confidentiality of data entry or collection, data storage, data transmission and 

data processing; 

3) computers and automated equipment are maintained to ensure proper functioning and are provided with the 

environmental and operating conditions necessary to maintain the integrity of test and calibration data. 

NOTE: Commercial off-the-shelf software (e.g., word processing, database and statistical programs) in general 

use within their designed application range may be considered to be sufficiently validated. However, laboratory 

software configuration/modifications should be validated as in 5.4.7.2a. 

5.5 Equipment 

5.5.1 The laboratory shall be furnished with all items of sampling, measurement and test equipment required 

for the correct performance of the tests and/or calibrations (including sampling, preparation of test and/or calibration 

items, processing and analysis of test and/or calibration data). In those cases where the laboratory needs to use 

equipment outside its permanent control, it shall ensure that the requirements of this Handbook are met. 

5.5.2 Equipment and its software used for testing, calibration and sampling shall be capable of achieving the 

accuracy required and shall comply with specifications relevant to the tests and/or calibrations concerned. 

Calibration programs shall be established for key quantities or values of the instruments where these properties have 

a significant effect on the results. Before being placed into service, equipment (including that used for sampling) 

shall be calibrated or checked to establish that it meets the laboratory's specification requirements and complies with 

the relevant standard specifications. It shall be checked and/or calibrated before use (see 5.6). 

5.5.3 Equipment shall be operated by authorized personnel. Up-to-date instructions on the use and 

maintenance of equipment (including any relevant manuals provided by the manufacturer of the equipment) shall be 

readily available for use by the appropriate laboratory personnel. 

5.5.4 Each item of equipment and its software used for testing and calibration and significant to the result 

shall, when practicable, be uniquely identified. 

5.5.5 Records shall be maintained of each item of equipment and its software significant to the tests and/or 

calibrations performed. The records shall include at least the following: 

1) the identity of the item of equipment and its software; 

2) the manufacturer's name, type identification, and serial number or other unique identification; 

3) checks that equipment complies with the specification (see 5.5.2); 

4) the current location, where appropriate; 

5) the manufacturer's instructions, if available, or reference to their location; 

6) dates, results and copies of reports and certificates of all calibrations, adjustments, acceptance criteria, and 

the due date of next calibration; 

7) the maintenance plan, where appropriate, and maintenance carried out to date; 

8) any damage, malfunction, modification or repair to the equipment. 

5.5.6 The laboratory shall have procedures for safe handling, transport, storage, use and planned maintenance 

of measuring equipment to ensure proper functioning and in order to prevent contamination or deterioration. 

NOTE: Additional procedures may be necessary when measuring equipment is used outside the permanent 

laboratory for tests, calibrations or sampling. 

5.5.7 Equipment that has been subjected to overloading or mishandling, gives suspect results, or has been 

shown to be defective or outside specified limits, shall be taken out of service. It shall be isolated to prevent its use 
NIST Handbook 143 April 2007 

33

or clearly labeled or marked as being out of service until it has been repaired and shown by calibration or test to 

perform correctly. The laboratory shall examine the effect of the defect or departure from specified limits on 

previous tests and/or calibrations and shall institute the "Control of non-conforming work" procedure (see 4.9). 

5.5.8 Whenever practicable, all equipment under the control of the laboratory and requiring calibration shall be 

labeled, coded or otherwise identified to indicate the status of calibration, including the date when last calibrated and 

the date or expiration criteria when recalibration is due. 

5.5.9 When, for whatever reason, equipment goes outside the direct control of the laboratory, the laboratory 

shall ensure that the function and calibration status of the equipment are checked and shown to be satisfactory before 

the equipment is returned to service. 

5.5.10 When intermediate checks are needed to maintain confidence in the calibration status of the equipment, 

these checks shall be carried out according to a defined procedure. 

5.5.11 Where calibrations give rise to a set of correction factors, the laboratory shall have procedures to ensure 

that copies (e.g., in computer software) are correctly updated. 

5.5.12 Test and calibration equipment, including both hardware and software, shall be safeguarded from 

adjustments which would invalidate the test and/or calibration results. 

WMD NOTE: The quality manual templates contain a chart to list equipment and its current performance 

evaluation. This information will be requested during on-site assessments, and the chart may be requested annually 

for review with measurement control documents. 

5.6 Measurement Traceability 

5.6.1 General 

All equipment used for tests and/or calibrations, including equipment for subsidiary measurements (e.g., for 

environmental conditions) having a significant effect on the accuracy or validity of the result of the test, calibration 

or sampling shall be calibrated before being put into service. The laboratory shall have an established program and 

procedure for the calibration of its equipment. 

NOTE: Such a program should include a system for selecting, using, calibrating, checking, controlling and 

maintaining measurement standards, reference materials used as measurement standards, and measuring and test 

equipment used to perform tests and calibrations. 

5.6.2 Specific requirements

5.6.2.1 Calibration 

5.6.2.1.1 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). 

A calibration laboratory establishes traceability of its own measurement standards and measuring instruments to the 

SI by means of an unbroken chain of calibrations or comparisons linking them to relevant primary standards of the 

SI units of measurement. The link to SI units may be achieved by reference to national measurement standards. 

National measurement standards may be primary standards, which are primary realizations of the SI units or agreed 

representations of SI units based on fundamental physical constants, or they may be secondary standards which are 

standards calibrated by another national metrology institute. When using external calibration services, traceability 

of measurement shall be assured by the use of calibration services from laboratories that can demonstrate 

competence, measurement capability and traceability. The calibration certificates issued by these laboratories shall 

contain the measurement results, including the measurement uncertainty and/or a statement of compliance with an 

identified metrological specification (see also 5.10.4.2). 
April 2007 NIST Handbook 143 

34 

NOTE 1: Calibration laboratories fulfilling the requirements of this Handbook are considered to be competent. A 

calibration certificate bearing an accreditation body logo from a calibration laboratory accredited to this 

Handbook, for the calibration concerned, is sufficient evidence of traceability of the calibration data reported. 

NOTE 2: Traceability to SI units of measurement may be achieved by reference to an appropriate primary standard 

(see VIM:1993, 6.4) or by reference to a natural constant, the value of which in terms of the relevant SI unit is 

known and recommended by the General Conference of Weights and Measures (CGPM) and the International 

Committee for Weights and Measures (CIPM). 

NOTE 3: Calibration laboratories that maintain their own primary standard or representation of SI units based on 

fundamental physical constants can claim traceability to the SI system only after these standards have been 

compared, directly or indirectly, with other similar standards of a national metrology institute. 

NOTE 4: The term "identified metrological specification" means that it must be clear from the calibration 

certificate which specification the measurements have been compared with, by including the specification or by 

giving an unambiguous reference to the specification. 

NOTE 5: When the terms "international standard" or "national standard" are used in connection with traceability, it 

is assumed that these standards fulfill the properties of primary standards for the realization of SI units. 

NOTE 6: Traceability to national measurement standards does not necessarily require the use of the national 

metrology institute of the country in which the laboratory is located. 

NOTE 7: If a calibration laboratory wishes or needs to obtain traceability from a national metrology institute other 

than in its own country, this laboratory should select a national metrology institute that actively participates in the 

activities of BIPM either directly or through regional groups. 

NOTE 8: The unbroken chain of calibrations or comparisons may be achieved in several steps carried out by 

different laboratories that can demonstrate traceability. 

5.6.2.1.2 Some calibrations cannot currently be made strictly in SI units. In these cases, calibration shall provide 

confidence in measurements by establishing traceability to appropriate measurement standards, such as: 

— the use of certified reference materials provided by a competent supplier to give a reliable physical or 

chemical characterization of a material; 

— the use of specified methods and/or consensus standards that are clearly described and agreed by all parties 

concerned. 

Participation in a suitable program of interlaboratory comparisons is required whenever possible. 

5.6.2.2 Testing 

5.6.2.2.1 For testing laboratories, the requirements given in 5.6.2.1 apply for measuring and test equipment with 

measuring functions used, unless it has been established that the associated contribution from the calibration 

contributes little to the total uncertainty of the test result. When this situation arises, the laboratory shall ensure that 

the equipment used can provide the uncertainty of measurement needed. 

NOTE: The extent to which the requirements in 5.6.2.1 should be followed depends on the relative contribution 

of the calibration uncertainty to the total uncertainty. If calibration is the dominant factor, the requirements should 

be strictly followed. 

5.6.2.2.2 Where traceability of measurements to SI units is not possible and/or not relevant, the same requirements 

for traceability to, for example, certified reference materials, agreed methods and/or consensus standards, are 

required as for calibration laboratories (see 5.6.2.1.2). 
NIST Handbook 143 April 2007 

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5.6.3 Reference standards and reference materials

5.6.3.1 Reference standards

The laboratory shall have a program and procedure for the calibration of its reference standards. Reference standards 

shall be calibrated by a body that can provide traceability as described in 5.6.2.1. Such reference standards of 

measurement held by the laboratory shall be used for calibration only and for no other purpose, unless it can be 

shown that their performance as reference standards would not be invalidated. Reference standards shall be 

calibrated before and after any adjustment. 

5.6.3.2 Reference materials 

Reference materials shall, where possible, be traceable to SI units of measurement, or to certified reference 

materials. Internal reference materials shall be checked as far as is technically and economically practicable. 

5.6.3.3 Intermediate checks 

Checks needed to maintain confidence in the calibration status of reference, primary, transfer or working standards 

and reference materials shall be carried out according to defined procedures and schedules. 

5.6.3.4 Transport and storage 

The laboratory shall have procedures for safe handling, transport, storage and use of reference standards and 

reference materials in order to prevent contamination or deterioration and in order to protect their integrity. 

NOTE: Additional procedures may be necessary when reference standards and reference materials are used 

outside the permanent laboratory for tests, calibrations or sampling. 

WMD NOTE: Copies of calibration reports for reference [primary] standards used in the laboratory are maintained 

in the WMD. The laboratory must submit updated calibration reports as available. If reports are not from NIST, 

they should be from a NIST-Recognized laboratory or a laboratory with formal accreditation from an accreditation 

body that is a signatory to the ILAC MRA (International Laboratory Accreditation Council, Mutual Recognition 

Arrangement. 

5.7 Sampling 

5.7.1 The laboratory shall have a sampling plan and procedures for sampling when it carries out sampling of 

substances, materials or products for subsequent testing or calibration. The sampling plan as well as the sampling 

procedure shall be available at the location where sampling is undertaken. Sampling plans shall, whenever 

reasonable, be based on appropriate statistical methods. The sampling process shall address the factors to be 

controlled to ensure the validity of the test and calibration results. 

NOTE 1: Sampling is a defined procedure whereby a part of a substance, material or product is taken to provide for 

testing or calibration of a representative sample of the whole. Sampling may also be required by the appropriate 

specification for which the substance, material or product is to be tested or calibrated. In certain cases (e.g., forensic 

analysis), the sample may not be representative but is determined by availability. 

NOTE 2: Sampling procedures should describe the selection, sampling plan, withdrawal and preparation of a 

sample or samples from a substance, material or product to yield the required information. 

5.7.2 Where the customer requires deviations, additions or exclusions from the documented sampling 

procedure, these shall be recorded in detail with the appropriate sampling data and shall be included in all 

documents containing test and/or calibration results, and shall be communicated to the appropriate personnel. 

5.7.3 The laboratory shall have procedures for recording relevant data and operations relating to sampling that 

forms part of the testing or calibration that is undertaken. These records shall include the sampling procedure used, 
April 2007 NIST Handbook 143 

36 

the identification of the sampler, environmental conditions (if relevant) and diagrams or other equivalent means to 

identify the sampling location as necessary and, if appropriate, the statistics the sampling procedures are based upon. 

5.8 Handling of Test and Calibration Items 

5.8.1 The laboratory shall have procedures for the transportation, receipt, handling, protection, storage, 

retention and/or disposal of test and/or calibration items, including all provisions necessary to protect the integrity of 

the test or calibration item, and to protect the interests of the laboratory and the customer. 

5.8.2 The laboratory shall have a system for identifying test and/or calibration items. The identification shall 

be retained throughout the life of the item in the laboratory. The system shall be designed and operated so as to 

ensure that items cannot be confused physically or when referred to in records or other documents. The system 

shall, if appropriate, accommodate a subdivision of groups of items and the transfer of items within and from the 

laboratory. 

5.8.3 Upon receipt of the test or calibration item, abnormalities or departures from normal or specified 

conditions, as described in the test or calibration method, shall be recorded. When there is doubt as to the suitability 

of an item for test or calibration, or when an item does not conform to the description provided, or the test or 

calibration required is not specified in sufficient detail, the laboratory shall consult the customer for further 

instructions before proceeding and shall record the discussion. 

5.8.4 The laboratory shall have procedures and appropriate facilities for avoiding deterioration, loss or damage 

to the test or calibration item during storage, handling and preparation. Handling instructions provided with the item 

shall be followed. When items have to be stored or conditioned under specified environmental conditions, these 

conditions shall be maintained, monitored and recorded. Where a test or calibration item or a portion of an item is to 

be held secure, the laboratory shall have arrangements for storage and security that protect the condition and 

integrity of the secured items or portions concerned. 

NOTE 1: Where test items are to be returned into service after testing, special care is required to ensure that they 

are not damaged or injured during the handling, testing or storing/waiting processes. 

NOTE 2: A sampling procedure and information on storage and transport of samples, including information on 

sampling factors influencing the test or calibration result, should be provided to those responsible for taking and 

transporting the samples. 

NOTE 3: Keeping a test or calibration item secure can be for reasons of record, safety or value, or to enable 

complementary tests and/or calibrations to be performed later. 

5.9 Assuring the Quality of Test and Calibration Results 

5.9.1 The laboratory shall have quality control procedures for monitoring the validity of tests and calibrations 

undertaken. The resulting data shall be recorded in such a way that trends are detectable and, where practicable, 

statistical techniques shall be applied to the reviewing of results. This monitoring shall be planned and reviewed and 

may include, but need not be limited to, the following: 

1) regular use of certified reference materials and/or internal quality control using secondary reference 

materials; 

2) participation in interlaboratory comparison or proficiency-testing programs; 

3) replicate tests or calibrations using the same or different methods; 

4) retesting or recalibration of retained items; 

5) correlation of results for different characteristics of an item. 

NOTE: The selected methods should be appropriate for the type and volume of the work undertaken. 

WMD NOTE: The laboratory shall maintain a list of control charts, surveillance activities, and proficiency tests 

maintained or participated in by the laboratory. Measurement control requirements must be in place for each 
NIST Handbook 143 April 2007 

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measurement service provided by the laboratory. The quality manual templates (NISTIR 5802 and NISTIR 7028) 

contain forms that may be used by the laboratory to list control charts, surveillance activities, and proficiency tests. 

This documentation must be available during on-site assessments and submitted to the WMD as requested. 

5.9.2 Quality control data shall be analyzed and, where they are found to be outside pre-defined criteria, 

planned action shall be taken to correct the problem and to prevent incorrect results from being reported. 

5.10 Reporting the Results 

5.10.1 General 

The results of each test, calibration, or series of tests or calibrations carried out by the laboratory shall be reported 

accurately, clearly, unambiguously and objectively, and in accordance with any specific instructions in the test or 

calibration methods. 

The results shall be reported, usually in a test report or a calibration certificate (see note 1), and shall include all the 

information requested by the customer and necessary for the interpretation of the test or calibration results and all 

information required by the method used. This information is normally that required by 5.10.2, and 5.10.3 or 5.10.4. 

In the case of tests or calibrations performed for internal customers, or in the case of a written agreement with the 

customer, the results may be reported in a simplified way. Any information listed in 5.10.2 to 5.10.4 which is not 

reported to the customer shall be readily available in the laboratory which carried out the tests and/or calibrations. 

NOTE 1: Test reports and calibration certificates are sometimes called test certificates and calibration reports, 

respectively. 

 

NOTE 2: The test reports or calibration certificates may be issued as hard copy or by electronic data transfer 

provided that the requirements of this Handbook are met. 

5.10.2 Test reports and calibration certificates 

Each test report or calibration certificate shall include at least the following information, unless the laboratory has 

valid reasons for not doing so: 

1) a title (e.g., "Test Report" or "Calibration Certificate"); 

2) the name and address of the laboratory, and the location where the tests and/or calibrations were carried 

out, if different from the address of the laboratory; 

3) unique identification of the test report or calibration certificate (such as the serial number), and on each 

page an identification in order to ensure that the page is recognized as a part of the test report or calibration 

certificate, and a clear identification of the end of the test report or calibration certificate; 

4) the name and address of the customer; 

5) identification of the method used; 

6) a description of, the condition of, and unambiguous identification of the item(s) tested or calibrated; 

7) the date of receipt of the test or calibration item(s) where this is critical to the validity and application of the 

results, and the date(s) of performance of the test or calibration; 

8) reference to the sampling plan and procedures used by the laboratory or other bodies where these are 

relevant to the validity or application of the results; 

9) the test or calibration results with, where appropriate, the units of measurement; 

10) the name(s), function(s) and signature(s) or equivalent identification of person(s) authorizing the test report 

or calibration certificate; 

11) where relevant, a statement to the effect that the results relate only to the items tested or calibrated. 

NOTE 1: Hard copies of test reports and calibration certificates should also include the page number and total 

number of pages. 
April 2007 NIST Handbook 143 

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NOTE 2: It is recommended that laboratories include a statement specifying that the test report or calibration 

certificate shall not be reproduced except in full, without written approval of the laboratory. 

WMD NOTE: WMD defines the person(s) who authorizes the test report or calibration certificate as the Approved 

Signatory. 

5.10.3 Test reports 

5.10.3.1 In addition to the requirements listed in 5.10.2, test reports shall, where necessary for the interpretation of 

the test results, include the following: 

1) deviations from, additions to, or exclusions from the test method, and information on specific test 

conditions, such as environmental conditions; 

2) where relevant, a statement of compliance/non-compliance with requirements and/or specifications; 

3) where applicable, a statement on the estimated uncertainty of measurement; information on uncertainty is 

needed in test reports when it is relevant to the validity or application of the test results, when a customer’s 

instruction so requires, or when the uncertainty affects compliance to a specification limit; 

4) where appropriate and needed, opinions and interpretations (see 5.10.5); 

5) additional information which may be required by specific methods, customers or groups of customers. 

5.10.3.2 In addition to the requirements listed in 5.10.2 and 5.10.3.1, test reports containing the results of 

sampling shall include the following, where necessary for the interpretation of test results: 

1) the date of sampling; 

2) unambiguous identification of the substance, material or product sampled (including the name of the 

manufacturer, the model or type of designation and serial numbers as appropriate); 

3) the location of sampling, including any diagrams, sketches or photographs; 

4) a reference to the sampling plan and procedures used; 

5) details of any environmental conditions during sampling that may affect the interpretation of the test 

results; 

6) any standard or other specification for the sampling method or procedure, and deviations, additions to or 

exclusions from the specification concerned. 

5.10.4 Calibration certificates 

5.10.4.1 In addition to the requirements listed in 5.10.2, calibration certificates shall include the following, where 

necessary for the interpretation of calibration results: 

1) the conditions (e.g., environmental) under which the calibrations were made that have an influence on the 

measurement results; 

2) the uncertainty of measurement and/or a statement of compliance with an identified metrological 

specification or clauses thereof; 

3) evidence that the measurements are traceable (see note 2 in 5.6.2.1.1). 

5.10.4.2 The calibration certificate shall relate only to quantities and the results of functional tests. If a statement 

of compliance with a specification is made, this shall identify which clauses of the specification are met or not met. 

When a statement of compliance with a specification is made omitting the measurement results and associated 

uncertainties, the laboratory shall record those results and maintain them for possible future reference. 

When statements of compliance are made, the uncertainty of measurement shall be taken into account. 

5.10.4.3 When an instrument for calibration has been adjusted or repaired, the calibration results before and after 

adjustment or repair, if available, shall be reported. 
NIST Handbook 143 April 2007 

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5.10.4.4 A calibration certificate (or calibration label) shall not contain any recommendation on the calibration 

interval except where this has been agreed with the customer. This requirement may be superseded by legal 

regulations. 

5.10.5 Opinions and interpretations 

When opinions and interpretations are included, the laboratory shall document the basis upon which the opinions 

and interpretations have been made. Opinions and interpretations shall be clearly marked as such in a test report. 

NOTE 1: Opinions and interpretations should not be confused with inspections and product certifications as 

intended in ISO/IEC 17020 and ISO/IEC Guide 65. 

NOTE 2: Opinions and interpretations included in a test report may comprise, but not be limited to, the following: 

— an opinion on the statement of compliance/noncompliance of the results with requirements; 

— fulfillment of contractual requirements; 

— recommendations on how to use the results; 

— guidance to be used for improvements. 

NOTE 3: In many cases it might be appropriate to communicate the opinions and interpretations by direct dialogue 

with the customer. Such dialogue should be written down. 

5.10.6 Testing and calibration results obtained from subcontractors 

When the test report contains results of tests performed by subcontractors, these results shall be clearly identified. 

The subcontractor shall report the results in writing or electronically. 

When a calibration has been subcontracted, the laboratory performing the work shall issue the calibration certificate 

to the contracting laboratory. 

5.10.7 Electronic transmission of results 

In the case of transmission of test or calibration results by telephone, telex, facsimile or other electronic or 

electromagnetic means, the requirements of this Handbook shall be met (see also 5.4.7). 

5.10.8 Format of reports and certificates 

The format shall be designed to accommodate each type of test or calibration carried out and to minimize the 

possibility of misunderstanding or misuse. 

NOTE 1: Attention should be given to the layout of the test report or calibration certificate, especially with regard 

to the presentation of the test or calibration data and ease of assimilation by the reader. 

NOTE 2: The headings should be standardized as far as possible. 

5.10.9 Amendments to test reports and calibration certificates 

Material amendments to a test report or calibration certificate after issue shall be made only in the form of a further 

document, or data transfer, which includes the statement: 

"Supplement to Test Report [or Calibration Certificate], serial number ... [or as otherwise identified]," 

or an equivalent form of wording. 

Such amendments shall meet all the requirements of this Handbook. 
April 2007 NIST Handbook 143 

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When it is necessary to issue a complete new test report or calibration certificate, this shall be uniquely identified 

and shall contain a reference to the original that it replaces. 

Table 2. Training requirements 

NOTE: The Quality Manual Templates (NISTIR 5802 and NISTIR 7028) contain a form that can be used to 

document training and dates. 

Recognition Level Training Required For Whom How Often 

Basic Laboratory Metrology Seminar (2 

weeks) 

Basic LAP problems - acceptable 

completion 

Usually all staff, at 

least one staff 

member 

Once Initially 

Refresher 

recommended 

every 10 years 

Once 

Minimum (for legal 

metrological activities) 

Attendance at Regional Measurement 

Assurance Program meeting annually 

At least one staff 

member Annually 

Calibration 

All of the above, plus: 

Intermediate Laboratory Metrology 

Seminar (1 week) 

Intermediate LAP problems - acceptable 

completion 

Usually all staff; at 

least one 

Every 3 to 4 years 

unless attending 

RMAP annually 

Advanced mass 

calibration 

All of the above, plus: 

Advanced Mass Measurements Seminar 

Advanced LAP problems completed 

At least one if 

working at this level 

At least once; for 

updates as needed 

Thermometry Attendance at a NIST Precision 

Thermometry Seminar 

At least one as 

needed 

At least once; for 

updates as needed 
NIST Handbook 143 April 2007 

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6. Specific Technical Guidelines

The material in this section is primarily from the Calibration Laboratories Technical Guide, NIST Handbooks 150-

2A through H (2004), and is modified and used here as the technical guidelines for evaluation of traceability 

resulting in the issuance of a Certificate of Measurement Traceability. The following quote, taken from the 

applicable NVLAP Guide is should be considered in its application. 

"This guide...was developed from a NIST measurement laboratory perspective and provides 

examples and guidelines (not requirements) to assessors and interested calibration laboratories on 

good laboratory practices and recommended standards The guide language reflects this 

philosophy through the use of "shoulds" instead of "shalls" (along with other less prescriptive 

language) when describing criteria. The requirements presented here are not absolute since 

specific requirements depend on the measurement uncertainty for which an applicant laboratory 

wishes to be accredited. This is a business decision for each laboratory and beyond the scope of 

this voluntary program. Simply stated, to be [Recognized or] accredited an applicant laboratory 

must have a quality system and be able to prove (and document) that it does what it says it does 

(i.e., correctly calibrate to a stated uncertainty). 

This guide is dynamic in that new parameters may be added and existing criteria updated and 

improved." 

WMD NOTE: WMD uses the technical section as requirements rather than as guidelines. Deviation from these 

criteria must have a technical basis, data, and technical analysis to support variances. 
April 2007 NIST Handbook 143 

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Recognition Parameter Summary

Each laboratory must specify the range and uncertainty level for each parameter for which it requests Recognition. 

Uncertainties must be defined at each level. For example, a chart must be available that will state each nominal 

mass, each nominal volume, and so on, with the associated uncertainty. 

Table 3. Recognition parameter summary

Parameter Range/Application Expanded Uncertainty

Mass laboratory to detail nominal ranges and uncertainties: e.g., 30 kg to 1 mg; Echelon II 

Echelon I ASTM Class 0, 1, OIML Class E1, E2

Echelon II ASTM Class 2, 3, OIML Class F1, F2

Echelon III 

ASTM Class 4, 5, 6, 7, OIML Class M1, M1-2, M2, M2-3, 

M3

NIST Class F, legal/regulatory enforcement 

Weight Carts NIST Handbook 105-8 

Must be less than 1/3 of the applicable 

tolerances within the Echelon. 

Length laboratory to specify range: e.g., 10 cm to 20 meter tapes 

Tapes, bench method up to 25 m (100 ft) 0.0 001 m to 0.000 14 m 

Tapes, tape method up to 25 m (100 ft) 0.000 15 m to 0.000 25 m 

Rules, direct comparison up to 0.5 cm (18 in) < 0.000 05 m 

Volume laboratory to specify ranges: e.g., 2 μL micropipettes to 2000 mL glass flasks 

Gravimetric syringes, micropipettes, glass standards, and metal 

provers 

0.000 10 mL/L 

Volume transfer glass standards and metal provers < 0.001 mL/L 

Temperature laboratory to specify type and ranges: e.g., -10 °C to 200 °C; Echelon II 

Echelon I SPRT's ≤ ± 0.005 °C 

Echelon II Thermistors, thermocouples > ± 0.005 °C to ≤ ± 0.05 °C 

Echelon III Liquid-in-glass thermometers > ± 0.05 °C to ≤ ± 0.20 °C 

Echelon IV Liquid-in-glass, dial type, pyrometers > ± 0.20 °C to ≤ ± 1.0 °C 

Echelon V Infrared sensors, thermographs > ± 1.0 °C to ≤ ± 5.0 °C 

Tuning Forks as used for law enforcement 0.05 mph, estimate based on 

interlaboratory tests 

Hydrometers sugar, syrup, petroleum Estimates noted on charts 

Time stopwatches used for law enforcement significantly less than tolerances; 

estimated at 2 s for a 24 hr test 

Grain Moisture programs for testing grain and commodity moisture 

Oven Methods 0.2 % moisture content 

Chemical Methods 

laboratory to specify methods and products 

0.2 % moisture content
NIST Handbook 143 April 2007 

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6.1 Technical Criteria for Dimensional Laboratories3

6.1.1 Scope 

The purpose of this section is to identify the specific technical criteria needed to meaningfully assess the competence 

of a calibration laboratory that performs dimensional calibrations. The artifact calibrations currently included in the 

Recognition program are: 

1) steel tapes; and 

2) rigid rules. 

NOTE: Much of this section applies to dimensional measurements that are more complex than the calibration of 

tapes and rules; however, it is the responsibility of the laboratory to determine which sections are applicable. 

6.1.2 References 

[1] ANSI/ASME B 89.6.2, Temperature and Humidity Environment for Dimensional Measurements (1973, 

Reaffirmed 2003). 

6.1.3 Statistical process control 

6.1.3.1 All sources of variability for the calibration should be monitored by subsystem calibration (e.g., 

thermometer, force gage calibration) and the use of check standards to ensure that the calibrations are carried out 

under controlled conditions. The laboratory should maintain and document some form of statistical process control 

(SPC) commensurate with the uncertainty levels of the calibration. The SPC control parameters should be based on 

measurements of check standards (or closure parameters resulting from self-calibration or ratio methods) and the 

repeatability of multiple measurements. The frequency and number of process control checks should be appropriate 

for the number of calibrations as well as the level of uncertainty and reliability claimed for the calibration. 

6.1.3.2 The laboratory should have control artifacts that adequately span the range of materials and sizes 

normally calibrated by the laboratory. Every measured value of each control should be recorded and compared to its 

historical value to determine that the process is in control. The comparison may be made via a plotted control chart 

with appropriate control limits or by numerical comparison using the t-distribution. The expected control values 

should be updated at least yearly using the most current one of more years of data. 

6.1.4 Accommodation and environment 

6.1.4.1 The temperature in the calibration area should nominally be 20 °C (degrees Celsius) with a maximum 

variation and rate of change depending on the materials and the uncertainty level needed for the calibration. 

Measurements at temperatures other than 20 °C may be made if the proper thermal expansion corrections are 

applied and the component of uncertainty reflecting the uncertainty in thermal expansion coefficients of the artifacts 

is calculated and added to the total uncertainty of the calibration. For comparison measurements the uncertainty 

component should reflect the uncertainty in the thermal expansion of both the master and unknown artifacts. 

6.1.4.2 For length calibrations of the type in legal metrology laboratories, the immediate environment should be 

20 °C ± 2 °C, and should be measured with an accuracy of 0.5 °C. The temperature variation should be less than ± 

1 °C over 24 h and ± 0.5 °C during any 1-h period. Other environmental conditions may be acceptable as long as 

the effects are included in the uncertainty determination. 

6.1.4.3 The measured length should be corrected to a reference temperature of 20 °C using the known linear 

thermal expansion coefficient of the material. 

 

3 This section is adapted from the NVLAP Handbook 150-2F, Calibration Laboratories Technical Guide and is 

modified for WMD application. 
April 2007 NIST Handbook 143 

44 

6.1.4.4 The temperature stability of the environment should be sufficient for the gage and measurement system 

to be in thermal equilibrium. Measurements may be made in slowly changing environments if a suitable 

measurement model, that includes the effects of the drift, is used. Theoretical and experimental verification of the 

model should be available. 

6.1.4.5 For typical gages made of well characterized materials (steel, carbide or ceramic), 0.000 001 per °C 

should be used as the thermal expansion coefficient uncertainty unless there is documentation of a lower value. 

6.1.4.6 The relative humidity in the calibration area should not exceed 50 percent to avoid problems with 

dimensional standards related to rust or other corrosion. 

6.1.4.7 Excessive vibration should be avoided in the calibration room. If an obvious source of vibration exists, 

precautions should be taken to prevent adverse effects on the laboratory's measurements. 

6.1.4.8 The laboratory should have a documented policy regarding responses to problems with the environment. 

6.1.5 Equipment and reference materials 

6.1.5.1 The laboratory should have the equipment needed to make auxiliary measurements on artifacts (e.g., 

flatness of gage blocks, roundness of ring gages). 

6.1.5.2 The laboratory should have temperature measuring capabilities suitable to the calibration procedure. 

Calibrations involving direct comparisons of artifacts of similar size and materials will, in general, have modest 

requirements. Absolute calibrations or comparisons between artifacts of different sizes and/or materials will require 

more accurate temperature measurement. 

6.1.5.3 A laboratory that certifies artifacts to tolerance grades should demonstrate a measurement uncertainty 

which does not exceed 25 % of the tolerance (unless otherwise stated in normative standards). Exceptions to this 

ratio should be accepted for measurement systems that are documented to be the state-of-the-art and approved by the 

customer. 

6.1.5.4 A laboratory that makes mechanical comparisons of masters and test pieces of dissimilar materials 

should have force measuring equipment to determine the force on the probe or probes. A correction for differential 

probe penetration should be applied as long as the probe has maintained its rounded shape. On old comparators the 

probe radius may be altered to the point where a correction would induce error. 

6.1.5.5 A laboratory that makes absolute measurements using displacement measuring sensors, such as 

interferometers or linear scales, should have environmental monitoring equipment appropriate to the sensor. 

6.1.5.6 A laboratory that makes absolute measurements using a contact device should have force measuring 

equipment to determine the force on the probe or probes. A correction for probe penetration should be applied if 

appropriate. 

6.1.5.7 A laboratory that makes interferometric measurements should have: (1) equipment for making highaccuracy temperature measurements, and (2) equipment for determining the index of refraction of air. 

6.1.6 Calibration methods

6.1.6.1 When calibrations are made by comparison to master gages of the different nominal sizes the 

temperature control of the gages and the measurement environment should be improved. 

6.1.6.2 The laboratory should have a manual outlining the procedures to be followed for each type of calibration. 

For calibration of graded sets, the procedure should name the grades that are calibrated by the procedure. 

6.1.6.3 The procedures used for related services, such as checks of roundness, relapping, repair, or replacement 

of damaged or out-of-tolerance gages should be clearly stated. 
NIST Handbook 143 April 2007 

45

6.1.6.4 Procedures related to the calibration of rigid rules and tapes used by legal metrology laboratories are as 

follows from NIST Handbook 145: 

1) Bench method for tapes (SOP 11); 

2) Tape to tape method for tapes (SOP 12); 

3) Rigid rule calibration (SOP 10); and 

4) Pi tape calibration (SOP 23 - draft). 

6.1.7 Handling of calibration items 

6.1.7.1 Artifacts should be cleaned and stored in a manner to prevent accidental contact with material which 

could damage the gaging surfaces. 

6.1.7.2 Care should be taken to prevent steel artifacts from rusting. Steel artifacts should be coated with a rust 

inhibiting grease whenever there is a potential for exposure to an environment over 50 % relative humidity. If 

artifacts cannot be greased other materials (e.g., rust inhibiting paper) or methods should be used to inhibit rust. 

6.1.7.3 After cleaning, artifacts should be allowed to come to adequate thermal equilibrium in the calibration 

environment before measurement. Artifacts should be placed on a soaking plate or in position on the measuring 

machine long enough to ensure that they are at the proper temperature. The soaking time will depend on the size 

and the thermal properties of the artifacts and plate. Specific guidelines for soaking times should be stated in the 

measurement procedure. The heating effects from optical radiation, body heat, and system location should be 

minimized. 

6.1.7.4 In general, to prevent thermal changes and corrosion of the gaging surfaces, artifacts should not be 

handled with bare hands. Gloves or tongs should be used whenever possible. 

6.1.8 Calibration certificates and test reports 

6.1.8.1 In addition to meeting the criteria in section 5.10 of this handbook, all calibration certificates or test 

reports of calibration should contain an uncertainty statement which is scientifically determined from measurement 

data and which agrees with the laboratory's stated definition. 

6.1.8.2 The uncertainty should be derived from a model of the measurement system that includes (as applicable) 

the uncertainties caused by: 

1) master artifact calibration; 

2) long term reproducibility of measurement system; 

3) thermal expansion correction for gages and measurement scales; 

a. thermometer calibration, 

b. thermal expansion coefficient, 

c. thermal gradients (internal, gage-gage, gage-scale), 

4) interferometry; 

a. measurement uncertainty of refractometer, 

b. index of refraction formula, 

c. environmental measurements (air temperature, air pressure, humidity, etc.), 

d. calibration of light source frequency, 

e. phase correction for reflected light, 

f. obliquity and slit corrections, 

5) instrument geometry; 

a. abbe offset and instrument geometry errors, 

b. scale and gage alignment (cosine errors), 

c. gage support geometry (anvil flatness, block flatness), 

6) probe penetration correction; 

7) rotary axis errors (radial and axial displacements, tilt); 

8) analysis algorithms (data fitting, filtering); and other factors as appropriate. 
April 2007 NIST Handbook 143 

46 

The method used to affix the calibration items should be described in detail. In general, differences in fixture 

configurations between calibration and use will introduce errors in the calibration. 
NIST Handbook 143 April 2007 

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6.2 Technical Criteria for Mass Laboratories4

6.2.1 Scope 

The purpose of this section is to specify the specific technical criteria needed to meaningfully assess the competence 

of a calibration laboratory that performs mass calibrations. 

6.2.1.1 A laboratory should declare its measurement capability in terms of uncertainties for each mass value. 

For many laboratories these uncertainties correspond to three arbitrary echelons of measurements that roughly 

correspond to weight classifications at nominal mass value ranges of measurements. For laboratories seeking 

Recognition at an uncertainty range that corresponds to a specific echelon, the scope of Recognition should follow 

the echelons as defined in Table 4 with a declared range of nominal mass values and their associated uncertainties. 

Recommended ranges of mass values are provided in Table 5. A summary of sections 6.2.3, 6.2.5.1, 6.2.5.6, and 

6.2.6.1 are provided in Table 8. 

6.2.1.2 The echelon stated by the laboratory is associated with the standards, procedures, measurement control, 

facilities, equipment, staff capability, and the overall level of performance according to Table 4, and is specifically 

defined by the expanded uncertainty. However, echelons are evaluated by all of the factors in Table 8 in addition to 

the laboratory’s reported uncertainties. 

Table 4. Mass calibration echelons 

Echelon Verification Levels Expanded Uncertainty of the 

Measurements 

I, (Extra Fine Accuracy) OIML Classes E1, E2

ASTM Classes 0, 1 

II, (Fine Accuracy) OIML Classes F1, F2

ASTM Classes 2, 3 

III, (Medium Accuracy) 

OIML Classes 

M1, M1-2, M2, M2-3, M3

ASTM Classes 4, 5, 6, 7 

NIST Class F 

The expanded uncertainty must be 

less than 1/3 of stated tolerances at 

all levels. 

 

4 This section was originally developed by WMD for adoption in the NVLAP Calibration Laboratories Technical 

Guide (NIST HB 150-2G); it is modified here for WMD application.
April 2007 NIST Handbook 143 

48 

Table 5. Typical "Ranges of Recognition" for mass calibration

Echelon Ranges of Recognition 

Nominal Value Ranges 

≥ 30 kg (define limit) 

30 kg to 1 mg 

1 kg to 1 mg 

I 

100 g to 1 mg 

≥ 30 kg (define limit) for special applications: 

30 kg to 1 mg ≥ 1000 lb (define limit) 

1 kg to 1 mg ≥ 50 lb (define limit) 

II 

100 g to 1 mg 50 lb to 0.001 lb 

≥ 30 kg (define limit) normal applications: 

30 kg to 1 g ≥ 1000 lb (define limit) 

1 kg to 1 g ≥ 50 lb (define limit) III 

100 g to 1 g 50 lb to 0.001 lb 

6.2.1.3 The reported uncertainty of mass standards calibrated by a mass calibration laboratory will vary 

depending on available balances, the uncertainty of reference standards, and the nominal value of the mass standard 

being tested. Thus, a laboratory may perform calibrations at Echelon I in some ranges, for example at 1 kg, and may 

perform calibrations at Echelon II, e.g., 20 kg, in other ranges. The laboratory performs calibrations in a specified 

range as requested; however, all laboratories may not be capable of meeting the requirements of all echelons. 

Differing equipment, skills, knowledge, measurement control, and demonstrated competence are required for each 

of the echelons. Demonstrated competence in one echelon is not sufficient to guarantee adequate performance in the 

others. 

6.2.2 References 

[1] ANSI/ASTM E 617-97, Standard Specification for Laboratory Weights and Precision Mass Standards, 

March 1998. 

[2] OIML R 111-1, Weights of classes E1, E2, F1, F2, M1, M1–2, M2, M2–3 and M3 

Part 1: Metrological and technical requirements, 2004. 

[3] NIST Handbook 105-1, 105-8, Specifications and Tolerances for Reference Standards and Field Standard 

Weights and Measures, Specifications and Tolerances for Field Standard Weights, (NIST Class F), 1990, 

and Field Standard Weight Carts, 2003. 

[4] NBS Technical Note 844, Designs for the Calibration of Small Groups of Standards in the Presence of 

Drift, Cameron, J. M., Hailes, G. E., 1974. 

[5] NBS Technical Note 952, Designs for the Calibration of Standards of Mass, Cameron, J. M., Croarkin, 

M. C., Raybold, R. C., 1977. 

[6] NISTIR 5672, Advanced Mass Calibrations and Measurement Assurance Program Requirements for 

State Calibration Laboratories, Fraley, K. L., Harris, G. L., 2005. 

[7] NISTIR 6969, Selected Laboratory and Measurement Practices, and Procedures, to Support Basic Mass 

Calibrations, Harris, G. L., Torres, J. A., 2003. 
NIST Handbook 143 April 2007 

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6.2.3 Statistical process control

6.2.3.1 Appropriate measurement assurance programs should be in place and available for review for each 

echelon and nominal mass range for which calibration data is provided. Note Table 8 for appropriate measurement 

control programs for each echelon. Appropriate data includes balance standard deviations that represent process 

variation and well-characterized check standard values. 

6.2.3.2 Measurement assurance techniques should exhibit results consistent with the procedures used to perform 

calibrations and should be integral to the measurement to accurately reflect the measurement process. For those 

situations where statistical information is not inherent to the process, i.e., simple measurements without built-in 

redundancy checks, additional measurements should be made to provide experimental characterization of the 

measurement sufficient for an adequate estimation of the process uncertainty. Those data should be available for 

review. 

6.2.4 Accommodation and environment 

6.2.4.1 To be deemed capable of making adequate measurements, calibration laboratories should provide an 

environment with adequate environmental controls appropriate for the level of measurements to be made, according 

to echelons defined herein. The environmental conditions are summarized in Table 6. 

Table 6. Environmental facility guidelines for mass laboratories

Echelon Temperature Limits* Relative Humidity Limits 

(maximum change per 4 h) 

I 20 °C to 23 °C, a set point + 1 °C 

maximum change 0.5 °C/h 40 % to 60 % + 5 % 

II 20 °C to 23 °C, a set point + 2 °C 

maximum change 1 °C/h 40 % to 60 % + 10 % 

III 18 °C to 27 °C, 

maximum change 1 °C/h 40 % to 60 % + 20 % 

*Limits established in this table are intended to provide basic parameters to ensure temperature and humidity 

stability in the laboratory. While maximum changes are noted, they do not imply rate of change or a net change 

over time. Environmental changes at these limits within a very short period of time will adversely affect mass 

measurements. 

6.2.4.2 Environmental conditions must be within the specifications of the weighing instruments where 

applicable. Environmental deviations from those specified must address possible measurement impacts, identify 

appropriate laboratory procedures that are used to minimize measurement errors, and have components incorporated 

into measurement uncertainties. Deviations for temperature and relative humidity controls are not necessarily 

corrected by performing buoyancy corrections and may adversely affect measurement results. Errors due to thermal 

convection currents or changes to moisture layers on the surface of mass standards may be significant when the 

environment is not controlled to within these limits and/or when artifacts are not allowed to equilibrate properly. 

6.2.4.3 Cleanliness guidelines are usually met without clean-room type air handling systems by maintaining 

clean-room type practices with suitable filtration. The laboratory must maintain limited access to the calibration 

area and minimize contamination (provide a clean surface) for locations where calibration items are being tested. 

Activities such as smoking, eating, or drinking and items such as paper products, printers, and files contribute to the 

difficulty of maintaining adequate cleanliness and are not recommended. Excessive air exchange rates negatively 

affect balance performance; therefore, air flow is generally minimized to the extent possible. A positive pressure, 

laminar-type air flow is usually needed to maintain cleanliness recommendations and to minimize air currents. 

6.2.4.4 Vibration should not diminish the performance of precision analytical balances and mass comparators. 

Proximity to heavy machinery, railways, heavily traveled highways, or similar sources of known vibration is not 

recommended. Steps are often taken to attenuate vibration to an acceptable level of stability with methods such as 

massive piers (solid marble or concrete tables), isolated foundations, or elimination of the source. Balances and 
April 2007 NIST Handbook 143 

50 

mass comparators used for Echelons I and II generally require massive piers, independent piers, and/or an isolated 

foundation; pneumatic or hydraulic tables are inappropriate. 

6.2.4.5 Undesirable effects due to static electricity should be controlled, if needed, with methods such as 

humidity, antistatic deionizing radiation devices, the grounding of balances or operators, or with the use of special 

conductive flooring and selection of proper clothing for staff. 

6.2.5 Equipment and reference materials

6.2.5.1 Minimum reference standards should be available at each echelon and range, for which the laboratory is 

Recognized, as recommended in Table 8. Sufficient historical data and uncertainty analysis should be available to 

support the standards used. 

6.2.5.2 The accuracy of auxiliary instruments for Echelons I and II, (e.g., scale, analytical balance, and mass 

comparator) is less important than the precision of the instrument due to algorithms used in mass calibration. 

However if such equipment is repaired, it should be reevaluated to ascertain its current level of precision prior to 

use, and the uncertainty estimate should reflect the post repair performance. 

6.2.5.3 The precision of the scale, analytical balance, or mass comparator, as determined through appropriate 

process control charts, should be suitable for the echelon at which it is used. For an application where external 

standards are used for comparison, appropriate control charts should be maintained to evaluate the process standard 

deviation. Note Table 8 summary for further evaluation. 

6.2.5.4 Means should be provided to measure barometric air pressure, air temperature, and relative humidity of 

the laboratory environment as indicated in Table 7; documentation of the accuracy and traceability is required. 

These instruments should be used in close proximity to the balance being used. For Echelon I, temperature may be 

measured inside the weighing chamber when there is a difference between the air temperature in the balance 

chamber and the surrounding area. For Echelon III, where buoyancy corrections are generally negligible, recording 

environmental data provides evidence to support compliance with general environmental requirements of the 

previous section but the accuracy generally does not affect measurement results when appropriate artifact 

equilibration occurs. 

Table 7. Environmental equipment accuracy (expanded uncertainty) 

Parameter Barometric Pressure Temperature Relative Humidity 

Echelon I ± 65 Pa (0.5 mm Hg) ± 0.1 °C ± 5 % 

Echelon II ± 135 Pa (1.0 mm Hg) ± 0.5 °C ± 10 % 

Echelon III The laboratory maintains documented accuracy. 

6.2.5.5 For Echelon I, the laboratory should state the presence of a possible systematic error in the combined 

uncertainty associated with the use of an assumed density in the primary or reference standards (additional Type B 

component) or the laboratory should have appropriate means to measure the density of mass standards. If the 

magnetic susceptibility of the mass standards is evaluated, it should be indicated on calibration reports. The 

methods used to determine density or magnetic susceptibility should be documented. 

6.2.5.6 Each mass standard used as a reference standard by the laboratory should be calibrated by NIST or by an 

accredited or Recognized laboratory with capability adequate to sustain the accuracy required and maintain 

traceability to the SI. The laboratory should provide evidence, such as periodic surveillance, that the standard is, in 

principle, acceptable for providing calibration services at each echelon. Note Table 8 for traceability guidelines. 

6.2.5.7 Balances used as a direct comparison to the mass unit, should be given a verification test or calibration 

prior to use. For an application requiring balance accuracy, the laboratory should choose appropriate and correct 

calibration algorithms. Balances used as dividers and multipliers of the mass unit should be capable of the 

appropriate accuracy and linearity requirements of the accuracy class for which they are used. Calibration of built-
NIST Handbook 143 April 2007 

51

in standards should be performed periodically and should be verified prior to use. History from measurement 

control programs (surveillance testing) may be used to determine calibration intervals. 

Instruments used to monitor environmental conditions in the laboratory should be traceable to a suitable national 

laboratory (directly or via an accredited or Recognized laboratory) and be recalibrated periodically unless defining 

standards are employed. Calibration periods will be documented by the laboratory. 

6.2.5.7 Balances used as a direct comparison to the mass unit, should be given a verification test or calibration 

prior to use. For an application requiring balance accuracy, the laboratory should choose appropriate and correct 

calibration algorithms. Balances used as dividers and multipliers of the mass unit should be capable of the 

appropriate accuracy and linearity requirements of the accuracy class for which they are used. Calibration of builtin standards should be performed periodically and should be verified prior to use. History from measurement 

control programs (surveillance testing) may be used to determine calibration intervals. 

6.2.5.8 Instruments used to monitor environmental conditions in the laboratory should be traceable to a suitable 

national laboratory (directly or via an accredited or Recognized laboratory) and be recalibrated periodically unless 

defining standards are employed. Calibration periods will be documented by the laboratory. 

6.2.6 Calibration methods 

6.2.6.1 The algorithm chosen for the measurement, the reference standard to be used, and the equipment to be 

used for a particular calibration should provide acceptable levels of uncertainty for that calibration. A documented 

procedure should be available in the laboratory to determine the correct algorithm. Note Table 8 for guidelines. 

6.2.6.2 Computer programs should have passed software quality analysis. Computer programs should be tested, 

using standard data sets designed to magnify errors, as an effective way of showing that program errors are not 

present which do not affect some measurements but cause others to be incorrect. Computer programs should be 

documented in detail. The documentation should include technical references that provide the basis for the 

algorithm, the weighing equation, and the data set used to test the program for errors. 

6.2.7 Handling of calibration items 

6.2.7.1 The laboratory should have documented procedures to ensure adequate chain-of-custody of calibration 

items if required by law. 

6.2.7.2 The laboratory will document appropriate procedures to ensure that cleaning, if performed, ensures the 

integrity of the standards, and to provide for thermal conditioning, where appropriate. 

6.2.7.3 The laboratory must allow adequate stabilization time for mass standards to ensure environmental and 

thermal stability prior to calibration. 

6.2.7.4 Documented procedures to ensure adequate tracking of calibration items should be appropriate to the 

class of mass standard. Strings, tags, or labels fastened to the standard are inappropriate. 

6.2.8 Calibration certificates and test reports 

6.2.8.1 In addition to meeting the criteria in section 5.10 of this handbook, calibration certificates and test reports 

should describe the mass standards mentioned in the report with sufficient detail to avoid any ambiguity. For 

Echelons I and II, additional items to be included on a test report, are: mass (true mass) values, conventional 

(apparent) mass values, reference density, uncertainties, material, thermal coefficient of expansion (if used in 

calculations), construction, density (measured or assumed), and any identifying markings. 

6.2.8.2 Environmental parameters measured during the test should be provided on certificates and reports for 

Echelons I and II. Typical ranges are acceptable for reporting conditions for Echelon III. These include laboratory 

temperature, barometric pressure and relative humidity. 
April 2007 NIST Handbook 143 

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6.2.8.3 Information regarding cleaning methods (if requested) should be provided on the test report. 

6.2.8.4 Reports may include reference to NIST, OIML or ASTM classification schemes and tolerances. 

Calibration items being tested should meet appropriate specifications for evaluation as well as tolerances. It is the 

responsibility of the requestor of the calibration to select classifications acceptable for their needs. In the case where 

magnetism, surface finish, and density are not tested for Echelon I and II, a statement to that effect should be 

included on the calibration report. 

6.2.8.5 The weight surface of a mass standard should be free of any sign of abuse or damage. Signs of abuse or 

misuse include the placement of labels, tags, wires or other material on mass standards. In addition, visible dirt and 

fingerprints are signs of misuse for Echelons I and II. It is recommended that the calibration laboratory establish 

appropriate means for notifying customers regarding any unusual factors such as signs of abuse regarding the mass 

standard being tested should be included on the report. Out of tolerance conditions should be reported when 

significant or when requested.
NIST Handbook 143 April 2007 

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Table 8. Summary of technical criteria for mass calibration

Echelon 

Minimum 

Measurement 

Assurance 

(5.9) 

Minimum Reference 

Standards (5.6) 

Minimum 

Traceability 

(5.6) 

Minimum 

Calibration 

Methods (5.4) 

I (Extra 

Fine) 

• Process control charts 

• Check standards for each 

decade, with long term 

standard deviation 

• Surveillance of all standards 

• Proficiency Testing 

-on-site assessment 

-round robin participation 

• OIML Class E1, or E2

 Or 

• ASTM Class 0, 1 

• single piece, highly 

polished 

• NIST, or other national 

level calibration every 2 

to 5 years based on 

measurement process 

data and independent 

verification, and 

• Suitable surveillance 

testing and 

participation in PTs at 

this level 

• Documented with GMP 

11 and 13 

• Documented 

weighing designs 

consisting of 

redundant 

comparisons, with 

built-in process 

controls such as 

those used at the 

national level. 

For example: 

• Technical Notes, 

952 and 844, 

SOP 5, SOP 28 

II (Fine) 

• Process control charts 

• Check standards for each 

decade, with long term 

standard deviation, per 

SOP 9 

• Surveillance of selected 

standards Proficiency 

Testing 

• -on-site assessment 

• -round robin participation 

• OIML Class E1, or E2

• ASTM Class 0, 1; or 

• single piece, highly 

polished 

• NIST calibration every 

2 to 5 years based on 

measurement process 

data and independent 

verification, or 

• Calibration by 

accredited or 

Recognized Echelon I 

laboratory, if 

uncertainty 

requirements can be 

met. 

• Documented with GMP 

11 and 13 

• Documented 

comparison 

calibration 

procedure 

For example: 

• NISTIR 6969, 

SOP 4, SOP 5, 

or equivalent 

validated 

procedure 

III 

(Medium) 

• Process control charts 

• Check standards for each 

balance per SOP 9 

• Proficiency Testing 

 -on-site assessment 

 -round robin participation 

• Working standards such 

as: 

• ASTM Class 2, 3 

Or 

• OIML Class F1

• two piece acceptable, 

fine finish 

• Calibration of all 

working standards by 

NIST every 2 to 5 years 

based on measurement 

process data and 

independent 

verification, or 

• Calibration of all 

working standards by 

an Echelon I or II 

accredited or 

Recognized labs every 

2 to 5 years based on 

measurement process 

data and independent 

verification 

• Documented with 

GMP 11 and 13 

• Use of annually 

calibrated 

balance with 

documented and 

validated 

verification 

procedure prior 

to each use 

• NISTIR 6969, 

SOP 8, SOP 7 

• Other 

documented and 

verified 

procedure 
April 2007 NIST Handbook 143 

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6.3 Technical Criteria for Volume Laboratories5

6.3.1 Scope 

The purpose of this section is to specify the specific technical criteria needed to meaningfully assess the competence 

of a calibration laboratory that performs volume calibrations. It should be noted that the procedures affect the 

achievable uncertainty. 

Table 9. Typical “Ranges of Recognition” for volumetric calibration

Procedure 

Types 

& Echelon 

Scope of Recognition 

Nominal Value Range

Glassware 

Standard Pipettes & Syringes 

Metal Test Measures or Provers 

≥ 1 L ≥ 2 000 L or ≥ 500 gal 

1 L to 100 mL 100 L < V < 2 000 L or 25 < V < 500 gal 

Echelon I 

Gravimetric

100 mL to 1 μL 100 mL to 1 μL ≤ 100 L or ≤ 25 gal 

Glassware Metal Test Measures or Provers 

≥ 1 L or 1 qt ≥ 2 000 L or ≥ 500 gal 

100 mL < V < 1 L or 1 gill < V < 1 qt 100 L < V < 2 000 L or 25 < V < 500 gal 

Echelon II 

Volume 

Transfer 

... ≤ 100 L or ≤ 25 gal 

6.3.1.1 Volumetric units are derived from mass units. Volume calibrations may be determined by either a 

gravimetric (weighing procedure) or a volume transfer (comparative) method. The two methods require different 

technical requirements and both are defined here. The measurement of volume by metering methods (and meter 

calibration) is outside the scope of this document. 

6.3.1.2 The gravimetric procedure is based on the conservation of mass principle where a determination of the 

mass of water contained in or delivered from the vessel that is being calibrated is used to define volume. The mass 

values are determined in air, are corrected for air buoyancy effects, and are corrected to appropriate reference 

temperatures. The accuracy and precision will vary depending on balances used, the purity of the water, the ability 

to make accurate temperature measurements, the nominal value of the volume standard being tested, and the ability 

to make adequate mass measurements. 

6.3.1.3 In the volume transfer procedure, water is delivered from a primary volume standard to the vessel under 

test. Temperature corrections are made to compensate for the cubical coefficients of thermal expansion of the 

standard, test vessel, and water to a specified reference temperature. The accuracy and precision will vary 

considerably depending on the presence of a meniscus, the cleanliness and drain characteristics of the container, the 

cleanliness and purity of the water, and the ability to make adequate temperature measurements. 

6.3.2 References

[1] ANSI/ASTM E 287-02, Standard Specification for Laboratory Glass Graduated Burets (2002). 

 

5 This section was originally developed by WMD for adoption in the NVLAP Calibration Laboratories Draft 

Technical Guide (NIST HB 150-2G); it is modified here for WMD application.
NIST Handbook 143 April 2007 

55

[2] ANSI/ASTM E 288-06, Standard Specification for Laboratory Glass Volumetric Flasks (2006). 

[3] ANSI/ASTM E 438-92 e1, Standard Specification for Glasses in Laboratory Apparatus (2006). 

[4] ANSI/ASTM E 542-01, Standard Practice for Calibration of Volumetric Apparatus (2001). 

[5] ANSI/ASTM E 694-99, Standard Specification for Laboratory Glass Volumetric Apparatus (2005). 

[6] ANSI/ASTM E 969-02, Standard Specification for Glass Volumetric (Transfer) Pipets (2002). 

[7] OIML R 4, Volumetric Flasks (one mark) in Glass (1972). 

[8] OIML R 40, Graduated Pipettes for Verification Officers (1981). 

[9] OIML R 41, Standard Burettes for Verification Officers (1981). 

[10] OIML R 43, Standard Graduated Glass Flasks for Verification Officers (1981). 

[11] NIST Handbook 105-2, 105-3, 105-4, 105-7 Specifications and Tolerances for Reference Standards and 

Field Standard Weights and Measures; Specifications and Tolerances for Field Standard Glass Flasks, 

Open-neck Provers, LPG Volumetric Provers, Dynamic Small Volume Provers. 

[12] API Manual of Petroleum Measurement Standards, Chapter 4 - Proving Systems; Section 3, Small 

Volume Provers, 1988; Section 4, Tank Provers, 1998 (Reaffirmed November 2005); Section 7, Field 

Standard Test Measures, 1998 (Reaffirmed October 2003). 

[13] NISTIR 7383, Selected Procedures for Volumetric Calibrations, November 2006. 

[14] NIST Special Publication, 250-72, NIST Calibration Services for Liquid Volume, March 2006. 

6.3.3 Statistical process control

6.3.3.1 Appropriate measurement control programs should be in place and available for review for each 

measurement type (based on procedures) and nominal volume range for which calibration data is provided. Note 

Table 12 for appropriate measurement control programs for each measurement type. Appropriate data includes 

standard deviations and range values that represent process variation and well characterized check standard values. 

6.3.3.2 Measurement control techniques should exhibit results consistent with the procedures used to perform 

calibrations and should be integrated into the measurement to accurately reflect the measurement process. For those 

situations where statistical information is not inherent to the process, i.e., simple measurements without built-in 

redundancy checks, additional measurements should be made to provide experimental characterization of the 

measurement sufficient for an adequate estimation of the process uncertainty. Those data should be available for 

review. 

6.3.4 Accommodation and environment

6.3.4.1 To be deemed capable of making adequate measurements, calibration laboratories should provide a 

facility with adequate environmental controls appropriate for the level of measurements to be made, according to 

procedure types as shown in Table 10. Lower relative humidity may increase measurement error due to evaporation. 
April 2007 NIST Handbook 143 

56 

Table 10. Environmental facility guidelines for volumetric calibration

Echelon & Procedure Temperature Relative Humidity 

(maximum range per 4 hours) 

I 

Gravimetric 

20 °C to 23 °C, set point ± 2 °C 

maximum change 1.0 °C/h 40 % to 60 % ± 10 % 

II 

Volume Transfer 

18 °C to 27 °C 

maximum change 2.0 °C/h 40 % to 60 % ± 20 % 

NOTE: The environmental conditions should also be within the specifications of applicable equipment. 

Gravimetric calibrations must comply with the comparable sections of 6.2 for mass calibrations because this 

procedure is a high-precision mass calibration with additional complexities. 

6.3.4.2 The environment in which testing activities are undertaken should not invalidate the results or adversely 

affect the required accuracy. Particular care should be taken when such calibration practices are undertaken at sites 

other than the permanent laboratory facility to minimize the effects of uncontrolled environments (e.g., outside or in 

open bays.) 

6.3.4.3 Vibration, air currents, rapid temperature fluctuations, and other environmental concerns should not 

diminish the accuracy and precision of volume transfer methods or the performance of precision balances or scales 

when gravimetric methods are used. 

6.3.4.4 The quality of water used as a calibration medium should be of adequate purity (potable) and cleanliness, 

and should be free from excess air entrapment. For gravimetric procedures the density should be 

calculated/measured to the nearest 0.00001 g/cm3

. 

6.3.5 Equipment and reference materials 

6.3.5.1 Mass standards used as reference standards should be traceable to a national laboratory (such as NIST) 

and be available at each class and range, for which the laboratory is Recognized, as recommended in Table 12. 

Sufficient historical data and uncertainty analysis should be available to support the standards used. 

6.3.5.2 Volume standards used as reference standards in the laboratory should be traceable to a national 

laboratory (such as NIST) and the laboratory should have appropriate procedures in place for verification and 

recalibration. The accuracy of the primary volume standards of the laboratory should be appropriate for the 

accuracy class of services provided. 

6.3.5.3 Gravimetric methods, which generally use water as calibration media, require the verification of an 

adequate supply of deionized or distilled water. 

6.3.5.4 Gravimetric methods require the use of weighing equipment with adequate accuracy and precision for the 

uncertainty of the measurement procedure. Appropriate control charts or range charts should be maintained to 

verify the measurement process. 

6.3.5.5 Gravimetric methods require the means to adequately measure barometric air pressure, air temperature, 

water temperature, and relative humidity of the laboratory environment. Volumetric methods require temperature 

measurements. Environmental measuring equipment should be available with the accuracy indicated in Table 11. 

Relative humidity may need to be monitored more closely if evaporation is a concern. 
NIST Handbook 143 April 2007 

57

Table 11. Environmental equipment accuracy (expanded uncertainty) 

Procedure Type Barometric 

Pressure 

Temperature 

water/air Relative Humidity 

Gravimetric ± 135 Pa 

(1.0 mm Hg) ± 0.1 °C / ± 0.5 °C ± 10 % 

Volume Transfer Not essential ± 0.5 °C Not essential 

6.3.6 Calibration methods 

6.3.6.1 The algorithm chosen for the measurement, the reference standard to be used, and the equipment to be 

used for a particular calibration should be correct for that calibration. A documented procedure should be available 

in the laboratory to determine the correct algorithm. (Examples are provided in NIST Handbook 145 Standard 

Operating Procedures, SOPs.) 

6.3.6.2 Computer programs should have passed software quality analysis. Computer programs should be 

documented in detail. The documentation should include technical references that provided the basis for the 

algorithm, any weighing equations, and data set used to test the program for errors. 

6.3.7 Handling of calibration items 

6.3.7.1 The laboratory should have documented procedures to ensure adequate chain-of-custody of calibration 

items if required by law. 

6.3.7.2 Appropriate procedures should be documented to ensure adequate tracking of calibration items that are 

appropriate for glass or metal volumetric standards. 

6.3.8 Calibration certificates and test reports 

6.3.8.1 In addition to meeting the criteria in section 5.10 of this handbook, calibration certificates and test reports 

should describe the volume standards mentioned in the report with sufficient detail to avoid any ambiguity. 

Additional items to be included on a test report are: volume, uncertainty, reference temperature, material, thermal 

coefficient of expansion (assumed or measured), construction, any identifying markings, and any tolerances if 

appropriate. 

Environmental parameters measured during the test should be provided on the test report as appropriate. These 

include laboratory temperature, volume standard temperature, barometric pressure and relative humidity. 

6.3.8.3 Volume standards being tested should meet the appropriate specifications such as NIST, ASTM, API, or 

OIML, if required by laboratory customers. It is the responsibility of laboratory customers to determine acceptable 

accuracy levels for their needs. 

6.3.8.4 The calibration item (volume standard) should be free of any sign of abuse or damage. Signs of abuse or 

misuse include dents, chips, improper draining due to lack of cleanliness, and dirty sight gages. Out of tolerance 

conditions should be reported. 
April 2007 NIST Handbook 143 

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Table 12. Summary of technical criteria for volumetric calibration

Echelon 

Minimum 

Measurement 

Control 

Minimum 

Reference 

Standard 

Minimum 

Traceability 

Minimum 

Calibration 

Methods 

I 

Gravimetric 

• Process control 

charts 

• Check standards 

• Surveillance of all 

standards used to 

provide 

measurement 

services 

• Proficiency 

testing 

- On-site assessment 

- Round robin 

participation 

• Appropriate 

mass standards 

- ASTM Class 2 

or 3; or 

- OIML Class F1

or F2; 

or 

- Calibrated 

Balance 

• NIST, or national 

level calibration 

periodically, based 

on independent 

historical data 

verification 

or 

• - Test of weighing 

equipment using 

correct methods of 

calibration and 

adjustment with 

traceable mass 

standards 

• Documented 

comparison 

calibration procedure 

or 

• NISTIR 7383, SOP 14 

(for example) 

or 

• Use of calibrated 

balance 

II 

Volume 

Transfer 

• Process control 

charts 

• Check standards 

• Surveillance of 

selected 

standards 

• Proficiency 

testing 

- On-site assessment 

- Round robin 

participation 

Primary volume 

standards with 

accuracy and 

repeatability 

characteristics 

acceptable for the 

type of service 

provided 

• Original NIST 

calibration and 

periodic independent 

verification 

or 

• Calibration by 

accredited or 

Recognized 

laboratory, if 

uncertainty 

requirements can be 

met 

Documented volume 

transfer (or water 

draw) procedure 

recognized by NIST, 

OIML, ASTM, or API
NIST Handbook 143 April 2007 

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6.4 Technical Criteria for Hydrometer Laboratories6

6.4.1 Scope 

This section outlines the specific technical requirements in accordance with which a laboratory should demonstrate 

that it operates if it is to be Recognized as competent to carry out calibrations of hydrometers. 

6.4.2 References 

[1] ASTM E 100-05: Standard Specification for ASTM Hydrometers (2005). 

[2] ASTM E 126-05a: Standard Test Method for Inspection, Calibration, and Verification of ASTM 

Hydrometers (2005). 

6.4.3 Statistical process control 

6.4.3.1 All sources of variability for the hydrometer calibration should be monitored. Check standards should be 

used to ensure that the calibrations are carried out under controlled conditions. The laboratory should maintain 

statistical process control (SPC) commensurate with the accuracy levels needed for the calibration. The SPC control 

parameters should be based on measurements of check standards (or closure parameters) and the repeatability of 

multiple measurements. The frequency and number of process control checks should be appropriate for the level of 

uncertainty claimed for the calibration. 

6.4.3.2 The laboratory should have control hydrometers that adequately span the range of materials and sizes 

normally calibrated by the laboratory. Every measured value of each control should be recorded and compared to its 

historic value to determine whether or not the process is in control. These values should be plotted on a control 

chart that has upper and lower control limits. 

6.4.4 Accommodation and environment

6.4.4.1 The environmental conditions (i.e., temperature, atmospheric pressure and relative humidity) in the 

hydrometer calibration area should have no more than the maximum variations permitted, depending on the 

materials and the accuracy level needed for the calibration. The reference temperature for a particular hydrometer 

scale may vary from 15.56 °C (15.56 °C is approximately 60 °F, which is the reference temperature for petroleum 

products in the United States) to 20 °C. The laboratory should have the appropriate instrumentation required to 

measure the environmental conditions. 

6.4.4.2 The density of the water used in hydrometer calibrations should be known to within 0.000005 g/cm3. 

Specific gravity is expressed as the ratio of the density of a liquid to the density of water at a specified temperature. 

6.4.4.3 Vibration of equipment used in the hydrometer calibrations should be reduced to non-influential levels. 

If an obvious source of vibration exists, it should not adversely affect the laboratory's claimed uncertainty level. 

6.4.4.4 Any laboratory that makes hydrometer comparisons should have an appropriate supply of calibration 

fluids with suitable surface tensions. Hydrometers should be calibrated in the liquids in which they are to be used. 

6.4.4.5 Calibration liquids should be stored in an approved safety cabinet. Laboratories that make hydrometer 

comparisons should abide by all safety requirements set forth by a regulatory counsel, (e.g., chemical labeling, EPA 

and OSHA guidelines, etc.). 

 

6

 This section is adapted from the NVLAP Calibration Laboratories Draft Technical Guide (NIST HB 150-2G); it is 

modified here for WMD application. 
April 2007 NIST Handbook 143 

60 

6.4.5 Equipment and reference materials 

6.4.5.1 The laboratory should have the appropriate equipment required to perform hydrometer calibrations at the 

Recognized level. All equipment should be properly maintained. 

6.4.5.2 The laboratory that performs hydrometer comparisons should have master hydrometers for which the 

calibrations are directly traceable to the appropriate national standards laboratory. The appropriate calibration 

corrections to these master hydrometers should be applied. 

6.4.5.3 The laboratory should have the equipment needed to make auxiliary measurements of hydrometers, (e.g., 

balances, mass standards, knowledge of water density, etc.). 

6.4.5.4 Any laboratory that makes hydrometer comparisons should abide by all safety requirements set forth by a 

regulatory counsel, (e.g., chemical labeling, EPA and OSHA guidelines, etc.). 

6.4.5.5 The laboratory should have temperature measuring capabilities suitable to the calibration procedure. In 

the case of measuring the specific gravity of a liquid with a master hydrometer, temperature measurement of the 

liquid accurate to ± 0.01 °C is required. 

6.4.5.6 A laboratory that makes hydrometer comparisons should have a ventilated chemical hood to exhaust any 

harmful fumes from the working area. 

6.4.6 Calibration methods 

6.4.6.1 The wide use of hydrometers for many different purposes has led to various stem scales for unique 

applications (e.g., specific gravity, percentage alcohol, degrees API, degrees Baume and Brix). The appropriate 

stem scale should be evaluated. 

6.4.6.2 Ideally, hydrometers under test are compared directly to master hydrometers in the kinds of liquids in 

which they are to be used. This comparison is performed in a clear, smooth glass cylinder of suitable size. The 

calibration liquid should be well stirred before each comparison to minimize temperature gradient in the liquid. 

6.4.6.3 The laboratory should have a manual detailing the procedures to follow for each type of hydrometers 

being calibrated. This manual should contain all pertinent information needed for calibration at a given Recognition 

level. 

6.4.7 Handling of calibration items 

6.4.7.1 Hydrometers should be cleaned and stored in a manner that prevents accidental contact with material that 

could damage the calibration surfaces. Since hydrometers are made of glass and can be easily broken, they should 

be handled only by an experienced operator. 

6.4.7.2 Inspection should be made of all hydrometers for calibration for bent stems, twisted scales, and loose 

material inside the body of the hydrometer. 

6.4.7.3 The hydrometer should be wiped with alcohol and dried to ensure a clean surface before it is immersed in 

the calibration liquid. 

6.4.8 Calibration certificates and test reports 

6.4.8.1 Summary sheets and data sheets should be used to document all calibrations. This documentation should 

be dated and initialed by the operator. A historical registry should be kept. 

6.4.8.2 The uncertainty reported for the hydrometer should be derived from a model of the measurement system 

that includes, as applicable, the uncertainties due to: 
NIST Handbook 143 April 2007 

61

1) master hydrometer; 

2) long-term reproducibility of measurement system 

3) thermal expansion; and 

4) other appropriate factors. 
April 2007 NIST Handbook 143 

62 

6.5 Technical Criteria for Thermometer Laboratories7

6.5.1 Scope 

6.5.1.1 This section contains the specific technical criteria in accordance with which a laboratory should 

demonstrate that it operates, if it is to be Recognized as competent to carry out thermometer calibrations. 

6.5.1.2 This section may also be used as a guide by thermometer calibration laboratories in the development and 

implementation of their quality systems. 

Echelon: Level of performance associated with the level of total uncertainty, according to the following table: 

Echelon Expanded Uncertainty 

I ≤ ± 0.005 °C 

II > ± 0.005 °C to ≤ ± 0.05 °C 

III > ± 0.05 °C to ≤ ± 0.20 °C 

IV > ± 0.20 °C to ≤ ± 1.0 °C 

V > ± 1.0 °C to ≤ ± 5.0 °C 

NOTE: The uncertainty of thermometers calibrated by the laboratory will vary depending upon the temperature 

range of application, even for the same thermometer. Thus, a laboratory may perform calibrations at Echelon II in 

some cases and Echelon III or IV in other cases because of the temperature ranges involved. Also, the echelon 

assigned is dependent on the types of thermometers calibrated. 

6.5.2 References 

[1] ASTM Annual Book of Standards, Volume 14.03, Standards Relating to Temperature Measurement 

(2007).

[2] NIST Handbook 105-6, Specifications and Tolerances for Field Standard Thermometers (1997). 

[3] NIST SP 250-23, Liquid-In-Glass Thermometer Calibration Service (1988).

[4] NBS Monograph 174, Thermometer Calibration, A Model for State Calibration Laboratories (Appendix 

A: NBS Monograph 150, Liquid-In-Glass Thermometry) (1985).

6.5.3 Statistical process control 

6.5.3.1 Fixed-point cell and triple point of water as the reference standards 

When the reference standard used by the laboratory is a fixed-point cell, the three action items described below are 

required as indicated by the application table that follows their description. 

6.5.3.1.1 Records of complete phase equilibrium plateaus obtained for each cell upon receipt and every six months 

thereafter should be maintained. This should include either manually recorded temperatures at consistent intervals, 

or a graphical representation of the equilibrium plateau, as measured by the monitoring sensor. 

6.5.3.1.2 A separate check thermometer should be used for each cell and control charts maintained. 

6.5.3.1.3 The triple point of water should be measured after every measurement at another temperature. 

 

7 This section is adapted from the NVLAP Calibration Laboratories Draft Technical Guide (NIST HB 150-2H); it is 

modified here for WMD application. 
NIST Handbook 143 April 2007 

63

Echelon 

Item 

I II III IV V 

6.5.3.1.1 X X X X 

6.5.3.1.2 X X X X 

6.5.3.1.3 X 

6.5.3.2 SPRT or RIRT as the reference standard

When the reference standard used by the laboratory is a standard platinum resistance thermometer (SPRT) or a 

rhodium-iron resistance thermometer (RIRT), the two action items described below are recommended as indicated 

by the application table that follows them. 

6.5.3.2.1 There should be documentation (i.e., control charts) to show that the resistance of the instrument at the 

triple point of water has not changed since its last calibration by more than the equivalent shown in the table below. 

6.5.3.2.2 If a digital voltmeter (DVM), digital multi-meter (DMM), or digital temperature indicator is used, the 

calibration of the temperature indicating system (indicator and sensor) should be checked periodically at either the 

water triple point or at the ice point. 

Echelon 

Item 

I II III IV V 

6.5.3.2.1 2 mK 2 mK 5 mK 10 mK 10 mK 

6.5.3.2.2 X X X X 

6.5.3.3 Thermistor thermometer as the reference standard

When the reference standard used by the laboratory is a thermistor thermometer, the two action items described 

below are recommended as indicated by the application table that follows them. 

6.5.3.3.1 The calibration of the thermistor thermometer should be checked frequently (monthly or weekly) 

depending on the particular application, and control charts should be kept. 

6.5.3.3.2 If, since the last calibration, the resistance of the thermistor thermometer has changed at a reference 

check point (fixed-point, preferably) by the equivalent shown in the next table, a new calibration should be done. 

Echelon Item 

I II III IV V 

6.5.3.3.1 x x x x 

6.5.3.3.2 2 mK 5 mK 10 mK 

6.5.3.4 Thermocouple as the reference standard 

When the reference standard used by the laboratory is a thermocouple, control charts should show the 

reproducibility at appropriate fixed points. 
April 2007 NIST Handbook 143 

64 

6.5.3.4.1 Liquid-in-glass thermometer as the reference standard

When the reference standard used by the laboratory is a liquid-in-glass thermometer, the two action items described 

below are recommended as indicated by the application table that follows them. 

6.5.3.4.1.1 The total-immersion mercury-in-glass thermometer should be checked according to good laboratory 

practice. One method is to check at the ice point on a daily basis after use and maintain records. 

6.5.3.4.1.2 The total-immersion liquid-in-glass thermometer should be checked according to good laboratory 

practice. One method is to check at the ice point weekly and maintain control charts. 

Echelon 

Item 

I II III IV V 

6.5.3.4.1.1 X X 

6.5.3.4.1.2 X 

6.5.4 Accommodation and environment 

6.5.4.1 For all echelons, the environmental conditions of the laboratory should be controlled. 

6.5.4.2 The temperature of the laboratory should be controlled to ± 2 °C. 

6.5.4.3 The relative humidity should be controlled between 40 % and 60 %. 

6.5.4.4 Vibrations in the laboratory should be minimized. 

6.5.5 Equipment and reference materials 

6.5.5.1 Reference standards 

The following table indicates which reference standard is acceptable for each echelon. 

Echelon 

Acceptable reference standard I II III IV V 

Fixed-point cell X X X X 

SPRT and/or RIRT X X X X X 

Thermistor thermometer X X X X 

Gold/platinum thermocouple X X X X 

Type S, R or B thermocouple X X X 

Total-immersion liquid-in-glass X X X 

6.5.5.2 Fixed-point cell as the reference standard

6.5.5.2.1 The purity of the fixed-point material should be at least 99.999 9 % and the other starting materials of 

construction of the cells should be of ultra-high purity also. If the cells are unsealed, they should be filled at all 

times with an inert gas such as argon. 

6.5.5.2.2 The cells should be of the defining fixed points of the ITS 90, or well-characterized, stable and 

reproducible secondary fixed points. 

6.5.5.3 SPRT or RIRT as the reference standard
NIST Handbook 143 April 2007 

65

6.5.5.3.1 A system having adequate resolution and uncertainty should be used to measure a reference SPRT or 

RIRT. Recommendations for specific situations are given below. 

6.5.5.3.2 A resistance bridge having at least the resolution shown below, as a function of claimed total uncertainty, 

is recommended. A ratio bridge and standard resistors may also be used: 

Echelon Claimed expanded 

uncertainty 

Minimum 

bridge resolution 

I ≤ ± 0.01 °C 10 μΩ

II ± 0.05 °C 50 μΩ

III near ± 0.20 °C 200 μΩ

IV near ± 1.0 °C 1 mΩ

6.5.5.3.3 Alternatively, a DVM or DMM with the resolution shown below, and a constant-current source with 

provision for reversing the current, may be used. The current should be known to the same accuracy as the DVM or 

DMM. 

Echelon DVM or DMM resolution 

(digits) 

I 6.5 

II 6.5 

III 6.5 

IV 6.5 

6.5.5.4 Thermocouple as the reference standard 

If the reference standard is a noble metal thermocouple used with a scanner, a scanner with low thermal switches 

should be used. 

6.5.6 Measurement traceability and calibration 

6.5.6.1 Fixed-point cell as the reference standard 

When the reference standard is a fixed-point cell, the four action items described below are recommended as 

indicated by the application table that follows them. 

6.5.6.1.1 The cell should be evaluated by NIST; or 

6.5.6.1.2 The cell may have been evaluated by the supplier, if the supplier documented in detail the preparation 

and evaluation, showing direct traceability to NIST, or is NVLAP accredited; or 

6.5.6.1.3 The cell should have been evaluated by a NVLAP accredited supplier. 

6.5.6.1.4 The maximum uncertainty of the temperature of the cell should be as indicated in the next table: 
April 2007 NIST Handbook 143 

66 

Echelon Item 

I II III IV 

6.5.6.1.1 X X* 

6.5.6.1.2 X** 

6.5.6.1.3 X X 

6.5.6.1.4 ± l mK ≤ ± 0.005 °C 0.01 °C ± 0.02 °C 

 * for total uncertainties ≤± 0.01 °C 

 ** for total uncertainties in range ± 0.01 °C to ± 0.05 °C 

6.5.6.2 SPRT or RIRT as the reference standard 

When the reference standard is an SPRT or RIRT, the four action items described below are recommended as 

indicated by the application table that follows them. 

6.5.6.2.1 The SPRT or RIRT should be calibrated by NIST or a NVLAP accredited laboratory every 2 years but 

may be calibrated by NIST every 2 to 5 years if adequate measurement process data is evident. 

6.5.6.2.2 The SPRT or RIRT should be calibrated annually, and all reference resistors used with the bridge should 

be calibrated traceable to NIST. 

6.5.6.2.3 If a bridge is used, it should be calibrated annually, and all reference resistors used with the bridge should 

be calibrated traceable to NIST. 

6.5.6.2.4 If a DVM or DMM is used, it should be calibrated annually. 

Echelon Item 

I II III IV V 

6.5.6.2.1 X X X X 

6.5.6.2.2 X 

6.5.6.2.3 X X X X 

6.5.6.2.4 X X X X X 

6.5.6.3 If a thermistor thermometer is the reference standard, it should be calibrated traceable to NIST. 

6.5.6.4 If a thermocouple is the reference standard, documentation should show that its calibration is traceable to 

NIST and indicate the annealing procedure used during the thermocouple's use. 

6.5.6.5 If a liquid-in-glass thermometer is the reference standard, it should be calibrated traceable to NIST. 

6.5.7 Calibration methods 

6.5.7.1 All computer programs used in data logging and analysis should be documented in detail. Also, all 

algorithms and equipment should be correct for the task. 

6.5.7.2 When calibrations are performed by comparison against an SPRT or an RIRT, or a thermistor 

thermometer, or a liquid-in-glass thermometer, the five action items described below are recommended as indicated 

by the application table that follows them. 

6.5.7.2.1 f a liquid medium is used, it should be stirred vigorously and a comparison block should be located in the 

bath to aid in improving the uniformity. 
NIST Handbook 143 April 2007 

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6.5.7.2.2 If a liquid medium is used, it should be adequately stirred and a comparison block should be located in 

the bath to aid in improving the uniformity. 

6.5.7.2.3 If the comparison medium is a liquid, it should be adequately stirred. 

6.5.7.2.4 The uniformity of the comparison medium should be measured by means of a fast-responding 

thermometer. 

6.5.7.2.5 The temperature stability and uniformity of the comparison medium should be as shown in the next table. 

Echelon Item 

I II III IV V 

6.5.7.2.1 X X 

6.5.7.2.2 X X 

6.5.7.2.3 X 

6.5.7.2.4 X X 

6.5.7.2.5 ± 0.5 mK ± 0.5 mK* (a) (a) (a) 

*

For claimed expanded uncertainty < ± 0.01 °C. For claimed expanded uncertainty > ± 0.01 °C, at least 10 times 

better than the claimed expanded uncertainty. 

(a) At least 10 times better than the claimed expanded uncertainty. 

6.5.7.3 When the reference standard is a total-immersion mercury-in-glass thermometer, corrections obtained 

from measurements at the ice point should be made for all temperature measurements. 

6.5.7.4 The ice-point bath should be made according to accepted procedures from ice made from distilled water. 

This applies to Echelons III, IV and V. 

6.5.8 Handling of calibration items 

In addition to the general requirements set forth for all calibration items, it should be noted that SPRT's are 

susceptible to and need protection from shock and vibration in shipping, handling, and storage. 
April 2007 NIST Handbook 143 

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6.6 Technical Criteria for Moisture Laboratories8- Grain and/or Commodities 

6.6.1 Scope 

6.6.1.1 The purpose of this section is to specify the specific technical criteria needed to meaningfully assess the 

competence of a testing laboratory that performs moisture analyses. 

6.6.1.2 This document may also be used as a guide by moisture laboratories in the development and 

implementation of their quality systems. 

6.6.1.3 Laboratories may be Recognized based on procedures used to determine moisture. These four procedural 

categories identify the method of moisture determination and the reference methods. The scope of Recognition 

follows the categories as defined in Table 13. Laboratories may be Recognized under two or more categories if they 

have the necessary equipment, skills, knowledge, measurement control and demonstrated competence to perform 

adequately in each category. 

NOTE: The national laboratory for grain moisture in the United States is the Grain Inspection Packers and 

Stockyards Administration (GIPSA) formerly known as the Federal Grain Inspection Service (FGIS). The standard 

method recognized by the GIPSA laboratory is the Air Oven Method. Grain moisture testing laboratories should 

reference the Air Oven Method and participate in interlaboratory comparisons to ensure comparability of 

measurements with the national laboratory. 

Table 13. Moisture determination laboratory classifications

Procedural 

Category Moisture Determination Method Reference Methods

Ia Air Oven 

GIPSA, Technical Services Division, Air 

Oven Moisture Reference Laboratory 

Working Instructions 

I 

Oven Methods 

Ib Vacuum Oven 

AOAC Official Methods of Analysis, 17th 

ed. Revision 1, 2002, vacuum oven 

methods, Sec. 32 

IIa Karl Fischer chemical 

analysis 

AOAC Official Methods of Analysis, 17th 

ed. Revision 1, 2002, Karl Fischer methods 

AOAC, Automatic Karl Fischer Titration of 

Moisture in Grain, (Vol. 64, No. 6, 1981) II 

Chemical Method 

IIb Basic Reference Method ISO 711, Cereals and Cereal ProductsDetermination of Moisture Content 

6.6.1.4 Laboratories should document the grains and/or commodities tested and maintain replicate results within 

± 0.2 %. The scope of Recognition should indicate identified grains and/or commodities and the uncertainty limits. 

Uncertainty analysis should be completed according to the ISO Guide for the Expression of Uncertainty in 

Measurement. 

 

8 This section was originally developed by WMD. 
NIST Handbook 143 April 2007 

69

6.6.1.5 Important definitions in this section follow: 

Moisture content - The loss in mass, expressed as a percentage, undergone by the product under the conditions 

specified in this document. 

Air Oven - A device that uses gravity convection or mechanical convection (forced-draft) to heat air in a chamber to 

its controlled temperature. 

Vacuum Oven - A device that uses a vacuum to alter the pressure within the oven chamber and maintain a 

temperature at that specific pressure. 

Karl Fischer Titration - A procedure that involves the simultaneous grinding of grain/commodity and extraction of 

the water with methanol and the subsequent titration of the extract with Karl Fisher reagent. 

Basic Reference Method - An ISO procedure (ISO Guide 711) using oven and chemicals to determine moisture 

content of a product. 

6.6.2 References 

[1] United States Department of Agriculture, Grain Inspection Packers and Stockyards Administration, 

(GIPSA), Technical Services Division, Air Oven Moisture Reference Laboratory Working Instructions, 

September 2002 (Internal Documents). 

[2] ASTM E 145-94, Standard Specification for Gravity Convection and Forced-Ventilation Ovens (2006). 

[3] Association of Official Analytical Chemists (AOAC), Official Methods of Analysis, 17th Edition 

Revision 1, 2002. 

[4] AOAC, Automatic Karl Fischer Titration of Moisture in Grain, Volume 64, No. 6, 1981. 

[5] Anderson, J. E. "Storage of Cereal Grains and Their Products," Chapter 1, Moisture - Its Significance, 

Behavior, and Measurement. (Hunt, W. Haward, Pixton, S. W.). 

[6] ISO 711, International Standard, Cereals and Cereal Products - Determination of Moisture Content 

(Basic Reference Method) Second edition, 1985. 

[7] Scholz, Eugen, Karl Fischer Titration, 1984. 

6.6.3 Statistical process control 

6.6.3.1 An appropriate statistical process control system should be in place including procedures for 

measurement verification through participation in interlaboratory comparisons between the laboratory, GIPSA and 

other laboratories. 

6.6.3.2 It is critical that testing results remain consistent with previous laboratory test results; repeated tests 

should remain within the laboratories documented uncertainties and be evaluated using statistical methods. 

 

6.6.3.3 A laboratory should have an operating procedure to review data for trends and failures to indicate where 

failure has occurred. Records of corrective action, repair, or recalibration should also be maintained. 

6.6.4 Accommodation and environment 

6.6.4.1 To make adequate measurements, moisture determination laboratories should have a facility with 

adequate environmental controls appropriate for the laboratory classification. 

 
April 2007 NIST Handbook 143 

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6.6.4.2 Due to the extreme hygroscopic properties of ground grain (oven methods) and methanol (Karl Fischer 

chemical method), humidity and temperature should be controlled within the following parameters: 

Temperature: 20 °C to 23 °C, set point ± 2 °C, maximum change of 1.0 °C/h; and 

Humidity: 40 % to 60 % ± 10 % 

NOTE: Sample exposure to the environment should be minimized throughout the collection, storage, and testing 

process. 

6.6.4.3 To prevent contamination of test samples, from grain and/or commodity dust particles, adequate 

cleanliness should be maintained. 

6.6.4.4 Adequate space should be available for sample storage, preparation and testing and be appropriately 

organized for efficient operation. Laboratory equipment should be logically placed to accommodate handling of 

samples, operation and maintenance of equipment and to prevent accidental sample substitution. 

6.6.4.5 Grains and/or commodities under test should be kept in refrigerated storage areas. The refrigerated 

storage areas should be maintained between 1.5 °C and 7.0 °C. 

6.6.4.6 Excess vibration may adversely affect the performance of precision analytical balances and mass 

comparators and should be prevented. Proximity to heavy machinery, railways, heavily traveled highways, or 

similar sources of known vibration is not recommended. Steps should be taken to reduce vibration to an acceptable 

level of stability with methods such as isolated foundations for balances or elimination of the source. 

6.6.4.7 Laboratories should ensure that electrical disturbances that affect moisture results are kept at a minimum. 

6.6.4.8 Undesirable effects due to static electricity should be controlled as needed by maintaining appropriate 

laboratory humidity or with antistatic deionizing radiation devices. The grounding of balances or operators, or the 

use of special conductive flooring may also be used. 

6.6.5 Equipment and reference materials 

6.6.5.1 Standard reference materials 

6.6.5.1.1 Category Ia and Ib laboratories - The grains and/or commodities are prepared for use as reference 

standards according to documented procedures for oven testing. During preparation, storage and distribution, care 

should be taken to ensure reference sample integrity. 

6.6.5.1.2 Category IIa and IIb laboratories - Specified reagents are used according to manufacturers' instructions 

for the specific type of Karl Fischer titration equipment in use. Category IIb laboratories generally should use 

chemicals specified in International Standard ISO 711, Sec. 7. During sample preparation, the integrity of the 

reagents and samples is critical. 

6.6.5.2 Primary equipment - oven methods 

6.6.5.2.1 Category Ia laboratories should have appropriate equipment for the moisture determination of grain 

and/or commodity moisture: mechanical (forced draft) or gravity convection ovens, desiccator, mill, moisture 

dishes, and analytical balance. Reference GIPSA Technical Services Division, Air Oven Moisture Reference 

Laboratory Working Instructions for equipment specifications. 

NOTE 1: The use of a mechanical convection (forced draft) oven is strongly recommended. Tests have shown that 

ovens of the forced-draft type have more uniform temperature due to heat circulation, the temperature recovery is 

more rapid after insertion of samples and will accommodate more samples than gravity convection ovens. 

NOTE 2: Laboratories should have temperature monitoring devices with suitable accuracy and traceability to 

record oven temperatures during moisture testing. 
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6.6.5.2.2 Category Ib laboratories should have appropriate equipment for the moisture determination of grain 

and/or commodities: vacuum oven desiccator, mill, moisture dishes, and analytical balance with the same 

requirements as class Ia laboratories. Reference AOAC, Official Methods of Test for equipment specifications. 

6.6.5.3 Primary equipment - Karl Fischer chemical analysis 

6.6.5.3.1 Category IIa laboratories should have appropriate equipment for the moisture determination of grain 

and/or commodities: Karl Fischer Titration Assembly (manual or automatic with a stirrer), mill, centrifuge, and 

analytical balance. Reference manufacturers' instructions and Karl Fischer Titration, Eugen Scholz, 1984. 

6.6.5.3.2 Category IIb laboratories should have appropriate equipment for the moisture determination of grain 

and/or commodities: analytical balance, apparatus for reducing pressure, mill, dishes, cup, drying tube, oven, airdrying train, and desiccator. Reference International Standard ISO 711 for equipment specifications. 

6.6.5.4 Secondary equipment

6.6.5.4.1 Laboratories should measure air temperature and relative humidity of the laboratory environment. 

Instruments are used in close proximity to the grain and/or commodity tested. Laboratory ovens should be equipped 

with calibrated, accurate and traceable thermometers (accurate within ± 0.5 C) to ensure the accuracy of the oven 

temperature. 

6.6.5.4.2 Samples should be stored in clean, air-tight and moisture-proof glass containers or plastic bags to prevent 

the loss or gain of moisture in the product. Plastic bags should have a thickness of at least 0.1 mm (4 mil, 0.004 in). 

A thickness of 0.15 mm (6 mil, 0.006 in) is preferred due to greater durability. 

6.6.6 Measurement traceability and calibration 

6.6.6.1 Since direct traceability to a standard (national measurement unit) is not possible for moisture 

measurements of the type described here, and the Federal standard for grain moisture is defined by comparison to 

GIPSA results, it is critical for the laboratory to participate in interlaboratory comparison programs to establish 

"comparability" of the results between the laboratories. 

6.6.6.2 It is essential that moisture testing equipment that affects the accuracy of the moisture measurement (e.g., 

to include thermometers and balances) be periodically calibrated or verified for accuracy and traceability. 

6.6.6.3 Balances used in determining moisture content should be periodically verified or calibrated prior to use. 

6.6.6.4 Instruments used to monitor environmental conditions in the laboratory should be periodically 

recalibrated. Appropriate calibration intervals should be established and documented by the laboratory. 

6.6.7 Moisture determination methods

6.6.7.1 The types of moisture determination methods employed, and equipment used, should be appropriate for 

the grains and/or commodities being tested based on the procedural category. Measurement methods should provide 

acceptable repeatability. A documented procedure for each method should be available. 

6.6.7.2 Computer programs used in the moisture determination of grains and/or commodities should have passed 

software quality analysis. Computer programs may be tested, using standard data sets designed to magnify errors, as 

an effective way of showing that program errors do not effect some measurements but cause others to be incorrect. 

Computer programs should be documented in detail. Documentation should include technical references that 

provide the basis for the algorithm, the moisture equations, and the data set used to test the program for errors. 
April 2007 NIST Handbook 143 

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6.6.8 Handling of grain and/or commodities for moisture determination 

6.6.8.1 The laboratory should have documented procedures to ensure that all samples are properly and uniquely 

marked upon receipt to include: the type of sample and a nonrepetitive identification number to ensure adequate 

tracking of samples in laboratory and field. 

6.6.8.2 The laboratory should document appropriate procedures for proper cleaning and storage of samples to 

ensure integrity. 

6.6.8.3 Documented procedures should be maintained that ensure that subportions of the sample under test are 

representative of the whole. 

NOTE: Care should be taken during sample collection and handling to prevent contamination of the sample with 

body oil or moisture, and to protect the sample from extreme environmental moisture and temperature. 

6.6.9 Test reports

6.6.9.1 In addition to meeting the criteria in section 5.10 of this handbook, test reports when necessary, should 

include: moisture determination results, sample type, condition and identification number, type of moisture 

determination used to ascertain the results, and the precision of measurement (repeatability between the dishes or 

duplicate runs.) 

6.6.9.2 Environmental parameters measured during the test should be provided on reports. These include 

laboratory temperature and relative humidity. 

6.6.9.3 Information regarding cleaning methods (if performed) should be provided on the test report. 
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Table 14. Summary of environmental facility guidelines (as described in Section 6) 

Parameter, 

Echelon 

Temperature 

range °C 

(set point) 

± Temp 

variability

°C 

Max 

change per 

hour °C 

± Temp 

accuracy °C

Relative 

Humidity (RH) 

% range 

RH % 

accuracy 

(max 

change per 

4 h) 

Pressure 

accuracy

Pa 

Mass I 20 to 23 1.0 0.5 0.1 40 to 60 5 65 

Mass II 20 to 23 2.0 1.0 0.5 40 to 60 10 135 

Mass III 18 to 27 2.0 40 to 60 20 

Gravimetric I 

 Volume 

20 to 23 2.0 1.0 0.1/0.5 

(H2O, air) 40 to 60 10 

Volume 

Transfer II 18 to 27 2.0 2.0 0.5 40 to 60 20 135 

Dimensional 20 (18 to 22) 1.0 0.5 < 50 20 

Temperature 2.0 40 to 60 10 

Tuning Forks 

Hydrometers 0.01 (bath) 

Time 

Grain 

Moisture 20 to 23 2.0 1.0 0.5 40 to 60 
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7. References

Asia Pacific laboratory Accreditation Cooperation (APLAC) SEC 045, Procedure for Management Review and 

Internal Audits, Issue No. 4, July 2006. 

APLAC TC 002, Internal Audits for Laboratories and Inspection Bodies, Issue No. 3, May 2006. 

ANSI/NCSL Z540.1-1994 (R2002), American National Standards Institute, National Conference of Standards 

Laboratories, American National Standard, General Requirements for Calibration Laboratories and Measuring and 

Test Equipment. 

ISO/IEC 10012-1, International Organization for Standardization, International Standard 10012-1, Quality 

Assurance Requirements for Measuring Equipment, Part 1, Metrological Confirmation System for Measuring 

Equipment, 1992. 

ISO/IEC 17025, International Organization for Standardization, General Requirements for the Competence of 

Testing and Calibration Laboratories, 2005. 

International Vocabulary of Basic and General Terms in Metrology (VIM), BIPM, IEC, IFCC, ISO, IUPAC, 

IUPAP, OIML, Definition 6.10, 2nd ed., 1993. 

NCSL Recommended Practice RP-7: Laboratory Design, November 2000. 

NBS Handbook 145, Handbook for the Quality Assurance of Metrological Measurements, Oppermann, H.V., 

Taylor, J., 1986. 

NIST Handbook 150, National Voluntary Laboratory Accreditation Program, NVLAP, Procedures and General 

Requirements, Faison, C. D., Horlick, J., Merkel, W. R., White, V. R., Editors, February 2006. 

NIST HB 150-2F, NVLAP Calibration Laboratories Technical Guide for Dimensional Measurements, Faison, C. D. 

and Brickenkamp, C. S., Editors, September 2003. 

NIST HANDBOOK 150-2G, Calibration Laboratories Technical Guide for Mechanical Measurements, Faison, C. 

D. and Brickenkamp, C. S, Editors, March 2004. 

NIST HANDBOOK 150-2H, Calibration Laboratories Technical Guide for Thermodynamic Measurements, 

Faison,C.D. and Brickenkamp,C.S. Editors, February 2004. 

NIST Special Publication (SP) 791, State Weights and Measures Laboratories: State Standards Program 

Description and Directory, Harris, G. L., 2000. 

NISTIR 5672, Advanced Mass Measurements and Measurement Assurance Program for State Calibration 

Laboratories, (2005 Ed.), Fraley, K. L., Harris, G. L., 2005. 

NISTIR 6176, Process Measurement Assurance Program For U.S. State Metrology Laboratories, Everhart, J. L., 

Harris, G. L., June 1998. 

NISTIR 6969, Selected Laboratory and Measurement Practices, and Procedures, to Support Basic Mass 

Calibrations, Harris, G. L., Torres, J. A., March 2003, with on-line updates December 2003. 

NISTIR 7383, Selected Procedures for Volumetric Calibrations, Harris, G. L., November 2006. 

NISTIR 5802, Quality Manual Template for State Weights and Measures Laboratories, Lee, G. D., 1995. 
April 2007 NIST Handbook 143 

76 

NISTIR 7028, Type Evaluation Laboratory Quality Manual Template, Developed for U.S. Type Evaluation 

Laboratories, Lee, G. D. July 2003. 

NISTIR 7082, Proficiency Test Policy and Plan (for State Weights & Measures Laboratories), Gust, J., Harris, G. 

L., January 2004. 

NISTIR 7214, Weights and Measures Division Quality Manual For Proficiency Testing and Interlaboratory 

Comparisons, Gust, J., Harris, G. L., March 2005. 
NIST Handbook 143 April 2007 

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8. Glossary

The following section contains the definitions of a number of terms in the sense in which they are used throughout 

this Handbook. Where applicable, definitions are taken from: 1) NIST Handbook 150, NVLAP Procedures and 

General Requirements, 2006 wherever possible; 2) The International Vocabulary of Basic and General Terms in 

Metrology (VIM:1994); or 3) NIST Handbook 143, Program Handbook, 2003 edition. Many of the NIST 

Handbook 150 definitions are taken from the VIM:1994. 

Accreditation - a formal Recognition that a laboratory is competent to carry out specific tests or calibrations or types 

of tests or calibrations. (HB 150) 

Accreditation Process - the process of demonstrating whether a calibration laboratory is capable of fulfilling 

specified accreditation requirements. 

Approved Signatory (of an accredited laboratory) - an individual who is Recognized by WMD as competent to sign 

official laboratory calibration certificates or test reports. (HB 150, modified) 

5) NOTE: The Approved Signatory is responsible for the technical content of the report and is the person to 

be contacted by WMD, laboratory customers, or others in case of questions or problems with the report. 

Approved Signatories shall be persons with responsibility, authority, and technical capability within the 

organization for the results produced. The laboratory must maintain a list of Approved Signatories and 

make that list available for review during on-site assessments and to WMD upon request. 

Authorized Representative (of a Recognized laboratory) - an individual who is authorized by the laboratory or the 

parent organization to sign the WMD Request for Recognition form and commit the laboratory to fulfill the WMD 

requirements. The Authorized Representative reports to NIST/WMD changes that may affect the laboratory’s 

capability, scope of recognition, or compliance with recognition requirements. (The Authorized Representative may 

also be recommended by the laboratory as an Approved Signatory. Only the Authorized Representative can 

authorize a change in the scope or nature of the laboratory's Request for Recognition.) (HB 150, modified) 

Calibration - a set of operations which establish, under specified conditions, the relationship between values 

indicated by a measuring instrument or measuring system, or values represented by a material measure, and the 

corresponding known values of a measurand. (HB 150) 

 

Also: comparison of a measurement standard or instrument with another standard or instrument to detect, correlate, 

report, or eliminate by adjustment any inaccuracy of the compared. 

Certificate of Measurement Traceability - a certificate issued to a State legal metrology laboratory indicating that 

the laboratory has traceable standards, can make and provide traceable measurements, and complies with the 

requirements of NIST Handbook 143, Program Handbook. 

Corrective Action - an action taken to eliminate the causes of an existing nonconformity or other undesirable 

situation in order to prevent recurrence. 

Customer - any person or organization that engages the services of a testing or calibration laboratory. (HB 150)

Good Laboratory Practices (GLP) - an acceptable way to perform some basic operation or activity in a laboratory, 

that is known, or believed to influence, the quality of its outputs. GLPs ordinarily are essentially independent of the 

measurement techniques used. (HB 143, 1997) 

Good Measurement Practices (GMP) - an acceptable way to perform some operation associated with a specific 

measurement technique, and which is known or believed to influence the quality of the measurement. (HB 143, 

1997) 
April 2007 NIST Handbook 143 

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Interlaboratory Comparisons - organization, performance and evaluation of calibrations or tests on the same or 

similar items or materials by two or more laboratories in accordance with predetermined conditions. (HB 150) 

Internal Assessment - the process of self-appraisal of a calibration or testing laboratory using specified general and 

technical criteria and checklists to evaluate compliance to Recognition (or accreditation) requirements; may be used 

as a management system review as well. 

Laboratory - an organization that performs tests and/or calibrations. When a laboratory is part of an organization 

that carries out activities additional to calibration and testing, the term "laboratory" refers only to those parts of that 

organization that are involved in the calibration and testing process. A laboratory’s activities may be carried out at a 

permanent location, temporary, or remote location. A laboratory may be further defined as being a physical entitythat is, a testing or calibration facility that is separate and apart physically from any other laboratory whether or not 

sharing common ownership, management, or management systems with any other laboratory(s). (HB 150, 

modified) 

Length Laboratory - a specific area, within a metrology laboratory, that is used solely for calibration or tolerance 

testing of length standards. (HB 143, 1997) 

Management system – system to establish policy and objectives and to achieve those objectives. 

NOTE A management system of an organization may include different management systems, such as a quality 

management system, a financial management system, or an environmental management system. (HB 150, ISO 

9000:2000, 2.2.2) 

Mass Laboratory - a specific area, within a metrology laboratory, that is used solely for calibration or tolerance 

testing of mass standards or test weights; generally divided into small mass (≤ 10 kg) and large mass (> 10 kg) areas. 

(HB 143, 1997) 

Measurement Assurance - a process to ensure adequate measurement results that may include, but is not limited to: 

1) use of good experimental design principles so that the entire measurement process, its components, and relevant 

influence factors can be well characterized, monitored, and controlled; 2) complete experimental characterization of 

the measurement process uncertainty including statistical variations, contributions from all known or suspected 

influence factors, imported uncertainties, and the propagation of uncertainties throughout the measurement process; 

and 3) continuously monitoring the performance and state of statistical control of the measurement process with 

proven statistical process control techniques including the measurement of well-characterized check standards along 

with the normal workload and the use of appropriate control charts. (HB 150) 

Measuring and test equipment (M & TE) – all of the measuring instruments, measurement standards, reference 

materials, auxiliary apparatus and instructions that are necessary to perform a measurement. This term includes 

measuring equipment used in the course of testing and inspection, as well as that used in calibration. 

NOTE In the context of this handbook, the term “measuring and test equipment” is taken to encompass 

“measurement instruments” and “measurement standards.” Moreover, a “reference material” is considered to be a 

type of “measurement standard.” (HB 150) 

NVLAP - the NIST National Voluntary Laboratory Accreditation Program. 

Nonconformity - the non-fulfillment of NIST/WMD conditions and/or criteria for Recognition (or accreditation); 

previously referred to as a deficiency. (HB 150, modified) 

On-Site Assessment - systematic, independent, documented process for determining laboratory competence and for 

obtaining records, statements of fact or other relevant information by assessors at the laboratory facilities and other 

places where test or calibration services are provided with the objective of determining the extent to which the 

criteria of this handbook are fulfilled. (HB 150) 
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Proficiency Testing - the determination of laboratory performance by means of comparing and evaluating 

calibrations or tests on the same or similar items or materials by two or more laboratories in accordance with 

predetermined conditions. (HB 150, modified) 

Preventive Action - an action taken to eliminate the cause of a potential nonconformity or other undesirable situation 

in order to prevent occurrence. 

Quality Audit - a systematic and independent examination to determine whether quality activities and related results 

comply with planned arrangements and whether these arrangements are implemented effectively, and are suitable to 

achieve objectives. (HB 150) 

Quality Control - the operational techniques and activities that are used to fulfill requirements for quality. 

Quality Manual - a document stating the quality policy, management system, and quality practices of an 

organization. The quality manual may reference other laboratory documentation. (HB 150, modified) 

Recognition - the evaluation and issuance of a Certificate of Measurement Traceability and letter regarding the 

laboratory management system for State weights and measures metrology laboratories (not a formal accreditation). 

RMAP - Regional Measurement Assurance Program. A regional approach to ensuring measurement assurance 

through periodic gathering to conduct training, interlaboratory comparisons, and continuous improvement activities. 

WMD jointly operates six regional MAPs in cooperation with the State laboratories. 

Scope of Recognition - a statement or document issued by NIST/WMD which lists the test methods or services, or 

calibration services for which the laboratory is recognized. The scope for each measurement area includes the range 

at each level. 

Standard, Check (or control) - a standard that is used as part of a process measurement assurance program to 

provide a "check" on the process and standards to ensure that the standards, measurement results, and measurement 

processes are within acceptable statistical limits. 

Standard, Intrinsic - intrinsic standards are based on well-characterized laws of physics, fundamental constants, or 

invariant properties of materials, and they make ideal stable, precise, and accurate measurement standards if 

properly designed, characterized, operated, monitored and maintained. (NCSL, Traceability Resolution Meeting. 

1/25/96) 

Standard, Primary - a standard that is designated or widely acknowledged as having the highest metrological 

qualities and whose value is accepted without reference to other standards of the same quantity. (HB 150) 

Standard, Reference - a standard, generally of the highest metrological quality available at a given location, from 

which measurements made at that location are derived. (HB 150) 

Standard, Secondary - a standard whose value is assigned by comparison with a reference [primary] standard of the 

same quantity. (HB 150) 

Standard, Working - a standard that is usually calibrated against a reference standard, and is used routinely to 

calibrate or check material measures, measuring instruments, or reference materials. (HB 150) 

Standard Operating Procedure (SOP) - a procedure adopted for repetitive use when performing a specific 

measurement or sampling operation. It may be a standard method or one developed by the user. (HB 143, 1997) 

State Laboratory Program - a program of the NIST Weights and Measures Division designated to provide guidance, 

technical support, and assistance to State legal metrology laboratories to ensure accurate and traceable 

measurements from NIST to the local jurisdictions. 
April 2007 NIST Handbook 143 

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Temperature Laboratory - a specific area, within a metrology laboratory, that is used solely for calibration or 

tolerance testing of temperature standards. 

Tolerance Testing - a measurement operation performed to determine whether the actual value of a standard, 

artifact, or instrument is within a permitted tolerance of its nominal value. An error and uncertainty value must first 

be determined before one can assess the tolerance status. (HB 143, 1997) 

Traceability - the property of the result of a measurement or the value of a standard whereby it can be related to 

stated references, usually national or international standards, through an unbroken chain of comparisons all having 

stated uncertainties. (VIM:1993) 

A measurement quality assurance system and periodic verification are required to ensure that the accuracy of the 

measurement is within the stated limits of uncertainty. 

Uncertainty - parameter, associated with the result of a measurement, that characterizes the dispersion of the values 

that could reasonably be attributed to the measurand. (HB 150) 

Volume Laboratory - a specific area, within a metrology laboratory, that is used solely for calibration or tolerance 

testing of volume standards; generally divided into small volume (≤ 20 L) and large volume (> 20 L) areas. (HB 

143, 1997) 

WMD - the NIST Weights and Measures Division; Formerly NIST Office of Weights and Measures (OWM). 
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Appendix A. List of Services Available from NIST

It is the objective of NIST to encourage all State laboratories to seek full Recognition and formal accreditation. 

Technical assistance and consultation includes the following: 

1. BASIC metrology training in mass, length, and volume (2 week seminar). Corresponding NIST Special 

Publication 1001 and 1001-S, Basic Mass Metrology CD-ROM training course (English & Spanish). 

2. INTERMEDIATE metrology training in mass, length, and volume (1 week seminar). Prerequisite 

completion of BASIC course and BASIC LAP problems or equivalent. 

3. NIST Precision Measurement Seminars. Seminars on special measurement techniques (2 to 5 day 

duration). Examples - Precision Thermometry Seminar, Advanced Mass Seminar. 

4. Recommended standard operating procedures, good laboratory practices, and good measurement practices 

for: 

 a. mass calibrations: three Echelons 

 - weighing designs 

 - comparison procedures 

 - weight carts 

 c. volume calibration: two Echelons 

 - gravimetric 

 - volume transfer 

 - dynamic small volume provers 

 d. length calibration 

 - length bench 

 - tape to tape 

 - rigid rules 

 - pi tapes 

 e. temperature NBS Monograph 150 

5. Time and frequency information Special Publication 960-12, Stopwatch and Timer Calibrations, Gust, J. 

C., Graham, R. M., Lombardi, M. A., May 2004. 

6. Measurement assurance information NBSIR 77 1240, six regional measurement assurance programs, and 

proficiency testing nationally and through the regional groups: 

 - Caribbean Measurement Assurance Program, CaMAP 

 - Southeast Measurement Assurance Program, SEMAP 

 - Northeast Measurement Assurance Program, NEMAP 

 - Southwest Assurance Program, SWAP 

 - Western Regional Assurance Program, WRAP 

 - MidAmerican Measurement Assurance Program, MidMAP. 

7. NIST evaluation of laboratory auditing program problems. 

8. NIST evaluation of laboratory facilities by on site visit. 

9. Measurement assurance programs in selected measurement areas. 

For further details on any of the above, general information, or assistance in areas not listed above, or in the case of 

special measurement problems, contact: 
April 2007 NIST Handbook 143 

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Weights and Measures Division 

National Institute of Standards and Technology 

Gaithersburg, MD 20899 

Phone: 301/975-4004 

Fax: 301/975-8091 

http://www.nist.gov/labmetrology
NIST Handbook 143 April 2007 

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Appendix B. Request for Recognition, Scope of Recognition, Approved 

Signatories, Authorized Representative

Name of laboratory

Address of laboratory

Scope of Recognition - complete Appendix D with uncertainty estimates included 

Approved Signatories - have assigned responsibility for validity of laboratory reports 

Authorized Representative - contact for administration of laboratory Recognition 
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Appendix C. Laboratory Assessment Checklist 

(from NVLAP Handbook 150, 2006) 

GENERAL OPERATIONS CHECKLIST 

Instructions to the Assessor (or Quality Manager): This checklist addresses the general accreditation criteria 

prescribed in NIST Handbook 150, NVLAP Procedures and General Requirements (2006 edition). The checklist items 

are numbered to correspond to the requirements found in 4 and 5 of the Handbook. 

Place an "X" beside each checklist item that represents nonconformity. Place a "C" beside each item on which you 

are commenting for other reasons. Record the item number and written noncomformity explanation and/or 

comment on the comment sheet(s) at the end of the checklist. Write "OK" beside all other items you observed or 

verified as compliant at the laboratory. Identify policies and procedures where called for. 

4 Management requirements for accreditation

4.1 Organization 

___ 4.1.1 The laboratory or the organization of which it is part shall be an entity that can be held legally 

responsible. 

 

 Legal name of laboratory ownership: ___________________________________ 

 

___ 4.1.2 It is the responsibility of the laboratory to carry out its testing and calibration activities in such a 

way as to meet the requirements of this Handbook and to satisfy the needs of the customer, the 

regulatory authorities or organizations providing recognition. 

 

___ 4.1.3 The laboratory management system shall cover work carried out in the laboratory’s permanent 

facilities, at sites away from its permanent facilities, or in associated temporary or mobile 

facilities. 

 

___ 4.1.4 If the laboratory is part of an organization performing activities other than testing and/or 

calibration, the responsibilities of key personnel in the organization that have an involvement or 

influence on the testing and/or calibration activities of the laboratory shall be defined in order to 

identify potential conflicts of interest. 

NOTE 1: Where a laboratory is part of a larger organization, the organizational arrangements should be 

such that departments having conflicting interests, such as production, commercial marketing or financing 

do not adversely influence the laboratory's compliance with the requirements of this Handbook. 

NOTE 2: If the laboratory wishes to be Recognized as a third-party laboratory, it should be able to 

demonstrate that it is impartial and that it and its personnel are free from any undue commercial, financial 

and other pressures which might influence their technical judgment. The third-party testing or calibration 

laboratory should not engage in any activities that may endanger the trust in its independence of judgment 

and integrity in relation to its testing or calibration activities. 

 
April 2007 NIST Handbook 143 

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4.1.5 The laboratory shall: 

___ 1) have managerial and technical personnel who, irrespective of other responsibilities, have the 

authority and resources needed to carry out their duties, including the implementation, 

maintenance and improvement of the management system, and to identify the occurrence of 

departures from the management system or from the procedures for performing tests and/or 

calibrations, and to initiate actions to prevent or minimize such departures (see also 5.2); 

___ 2) have arrangements to ensure that its management and personnel are free from any undue internal 

and external commercial, financial and other pressures and influences that may adversely affect 

the quality of their work; 

___ 3) have policies and procedures to ensure the protection of its customers’ confidential information 

and proprietary rights, including procedures for protecting the electronic storage and transmission 

of results; 

 

___ 4) have policies and procedures to avoid involvement in any activities that would diminish 

confidence in its competence, impartiality, judgment or operational integrity; 

 

___ 5) define the organization and management structure of the laboratory, its place in any parent 

organization, and the relationships between quality management, technical operations and support 

services; 

 

___ 6) specify the responsibility, authority and interrelationships of all personnel who manage, perform 

or verify work affecting the quality of the tests and/or calibrations; 

 

___ 7) provide adequate supervision of testing and calibration staff, including trainees, by persons 

familiar with methods and procedures, purpose of each test and/or calibration, and with the 

assessment of the test or calibration results; 

 

___ 8) have technical management which has overall responsibility for the technical operations and the 

provision of the resources needed to ensure the required quality of laboratory operations; 

 

 Name of person: __________________________________________________ 

 Area of responsibility: ______________________________________________ 

 Repeat as necessary: ______________________________________________ 

 

___ 9) appoint a member of staff as quality manager (however named) who, irrespective of other duties 

and responsibilities, shall have defined responsibility and authority for ensuring that the 

management system related to quality is implemented and followed at all times; the quality 

manager shall have direct access to the highest level of management at which decisions are made 

on laboratory policy or resources; 

 

 Name of person: __________________________________________________ 

___ 10) appoint deputies for key managerial personnel (see note). 

 

 Name(s): ________________________________________________________ 

___ 11) ensure that its personnel are aware of the relevance and importance of their activities and how they 

contribute to the achievement of the objectives of the management system. 

 

NOTE: Individuals may have more than one function and it may be impractical to appoint deputies for 

every function. 
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___ 4.1.6 Top management shall ensure that the appropriate communication processes are established 

within the laboratory and that communication takes place regarding the effectiveness of the 

management system.

4.2 Management system 

 4.2.1 

 

___ 1) The laboratory shall establish, implement and maintain a management system appropriate to the 

scope of its activities. 

 

___ 2) The laboratory shall document its policies, systems, programs, procedures and instructions to the 

extent necessary to assure the quality of the test and/or calibration results. 

 

___ 3) The system’s documentation shall be communicated to, understood by, available to, and 

implemented by the appropriate personnel. 

 

___ 4.2.2 The laboratory’s management system policies related to quality, including a quality policy 

statement, shall be defined in a quality manual (however named). The overall objectives shall be 

established, and shall be reviewed during management review. The quality policy statement shall 

be issued under the authority of top management. It shall include at least the following: 

 

___ 1) the laboratory management's commitment to good professional practice and to the quality of its 

testing and calibration in servicing its customers; 

 

___ 2) the management’s statement of the laboratory's standard of service; 

 

___ 3) the purpose of the management system related to quality; 

 

___ 4) a requirement that all personnel concerned with testing and calibration activities within the 

laboratory familiarize themselves with the quality documentation and implement the policies and 

procedures in their work; and 

 

___ 5) the laboratory management's commitment to comply with this Handbook and to continually 

improve the effectiveness of the management system. 

 

NOTE: The quality policy statement should be concise and may include the requirement that tests and/or 

calibrations shall always be carried out in accordance with stated methods and customers’ requirements. 

When the test and/or calibration laboratory is part of a larger organization, some quality policy elements 

may be in other documents. 

4.2.3 Top management shall provide evidence of commitment to the development and implementation 

of the management system and to continually improve its effectiveness. 

___ 4.2.4 Top management shall communicate to the organization the importance of meeting customer 

requirements as well as statutory and regulatory requirements. 

___ 4.2.5 

___ 1) The quality manual shall include or make reference to the supporting procedures including 

technical procedures. 

___ 2) It shall outline the structure of the documentation used in the management system. 
April 2007 NIST Handbook 143 

88 

4.2.6 The roles and responsibilities of technical management and the quality manager, including their 

responsibility for ensuring compliance with this Handbook, shall be defined in the quality manual. 

4.2.7 Top management shall ensure that the integrity of the management system is maintained when 

changes to the management system are planned and implemented. 

4.3 Document control 

 4.3.1 General 

___ The laboratory shall establish and maintain procedures to control all documents that form part of its 

management system (internally generated or from external sources), such as regulations, standards, other 

normative documents, test and/or calibration methods, as well as drawings, software, specifications, 

instructions and manuals. 

NOTE 1 In this context "document" could be policy statements, procedures, specifications, calibration 

tables, charts, text books, posters, notices, memoranda, software, drawings, plans, etc. These may be on 

various media, whether hard copy or electronic, and they may be digital, analog, photographic or written. 

 

NOTE 2 The control of data related to testing and calibration is covered in 5.4.7. The control of records is 

covered in 4.13. 

 4.3.2 Document approval and issue 

 4.3.2.1 

___

1) All documents issued to personnel in the laboratory as part of the management system shall be 

reviewed and approved for use by authorized personnel prior to issue. 

 

___ 2) A master list or an equivalent document control procedure identifying the current revision status 

and distribution of documents in the management system shall be established and be readily 

available to preclude the use of invalid and/or obsolete documents. 

 4.3.2.2 The procedure(s) adopted shall ensure that: 

___ 1) authorized editions of appropriate documents are available at all locations where operations 

essential to the effective functioning of the laboratory are performed; 

 

___ 2) documents are periodically reviewed and, where necessary, revised to ensure continuing suitability 

and compliance with applicable requirements; 

 

___ 3) invalid or obsolete documents are promptly removed from all points of issue or use, or otherwise 

assured against unintended use; 

 

___ 4) obsolete documents retained for either legal or knowledge preservation purposes are suitably 

marked. 

4.3.2.3 Management system documents generated by the laboratory shall be uniquely identified. 

Such identification shall include: 

 

___ 1) the date of issue and/or revision identification, 

 

___ 2) page numbering, 

 

___ 3) the total number of pages or a mark to signify the end of the document, and 
NIST Handbook 143 April 2007 

89

___ 4) the issuing authority(ies). 

 4.3.3 Document changes 

___ 4.3.3.1 Changes to documents shall be reviewed and approved by the same function that performed 

the original review unless specifically designated otherwise. The designated personnel shall 

have access to pertinent background information upon which to base their review and 

approval.

 

___ 4.3.3.2 Where practicable, the altered or new text shall be identified in the document or the 

appropriate attachments. 

 

4.3.3.3 

___ 1) If the laboratory's documentation control system allows for the amendment of documents by hand 

pending the reissue of the documents, the procedures and authorities for such amendments shall be 

defined. 

 

___ 2) Amendments shall be clearly marked, initialed and dated. A revised document shall be formally 

reissued as soon as practicable. 

___ 4.3.3.4 Procedures shall be established to describe how changes in documents maintained in 

computerized systems are made and controlled. 

 

4.4 Review of requests, tenders and contracts 

___ 4.4.1 The laboratory shall establish and maintain procedures for the review of requests, tenders and 

contracts. The policies and procedures for these reviews leading to a contract for testing and/or 

calibration shall ensure that: 

___ 1) the requirements, including the methods to be used, are adequately defined, documented and 

understood (see 5.4.2); 

 

___ 2) the laboratory has the capability and resources to meet the requirements; 

 

___ 3) the appropriate test and/or calibration method is selected and is capable of meeting the customers’ 

requirements (see 5.4.2). 

 

___ 4) Any differences between the request or tender and the contract shall be resolved before any work 

commences. Each contract shall be acceptable both to the laboratory and the customer . 

NOTE 1: The request, tender and contract review should be conducted in a practical and efficient manner, 

and the effect of financial, legal and time schedule aspects should be taken into account. For internal 

customers, reviews of requests, tenders and contracts can be performed in a simplified way. 

 

NOTE 2: The review of capability should establish that the laboratory possesses the necessary physical, 

personnel and information resources, and that the laboratory's personnel have the skills and expertise 

necessary for the performance of the tests and/or calibrations in question. The review may also encompass 

results of earlier participation in interlaboratory comparisons or proficiency testing and/or the running of 

trial test or calibration programs using samples or items of known value in order to determine uncertainties 

of measurement, limits of detection, confidence limits, etc. 

 

NOTE 3: A contract may be any written or oral agreement to provide a customer with testing and/or 

calibration services. 
April 2007 NIST Handbook 143 

90 

___ 4.4.2 Records of reviews, including any significant changes, shall be maintained. Records shall also be 

maintained of pertinent discussions with a customer relating to the customer’s requirements or the 

results of the work during the period of execution of the contract. 

NOTE: For review of routine and other simple tasks, the date and the identification (e.g., the initials) of 

the person in the laboratory responsible for carrying out the contracted work are considered adequate. For 

repetitive routine tasks, the review need be made only at the initial enquiry stage or on granting of the 

contract for ongoing routine work performed under a general agreement with the customer, provided that 

the customer’s requirements remain unchanged. For new, complex or advanced testing and/or calibration 

tasks, a more comprehensive record should be maintained. 

___ 4.4.3 The review shall also cover any work that is subcontracted by the laboratory. 

 

___ 4.4.4 The customer shall be informed of any deviation from the contract. 

 

___ 4.4.5 If a contract needs to be amended after work has commenced, the same contract review process 

shall be repeated and any amendments shall be communicated to all affected personnel. 

4.5 Subcontracting of tests and calibrations 

___ 4.5.1 When a laboratory subcontracts work whether because of unforeseen reasons (e.g., workload, need 

for further expertise or temporary incapacity) or on a continuing basis (e.g., through permanent 

subcontracting, agency or franchising arrangements), this work shall be placed with a competent 

subcontractor. A competent subcontractor is one that, for example, complies with this Handbook 

for the work in question. 

 

__ 4.5.2 The laboratory shall advise the customer of the arrangement in writing and, when appropriate, gain 

the approval of the customer, preferably in writing. 

 

___ 4.5.3 The laboratory is responsible to the customer for the subcontractor’s work, except in the case 

where the customer or a regulatory authority specifies which subcontractor is to be used. 

 

__ 4.5.4 The laboratory shall maintain a register of all subcontractors that it uses for tests and/or 

calibrations and a record of the evidence of compliance with this Handbook for the work in 

question. 

4.6 Purchasing services and supplies 

___ 4.6.1 The laboratory shall have a policy and procedure(s) for the selection and purchasing of services 

and supplies it uses that affect the quality of the tests and/or calibrations. Procedures shall exist 

for the purchase, reception and storage of reagents and laboratory consumable materials relevant 

for the tests and calibrations. 

 4.6.2 

___ 1) The laboratory shall ensure that purchased supplies and reagents and consumable materials that 

affect the quality of tests and/or calibrations are not used until they have been inspected or 

otherwise verified as complying with standard specifications or requirements defined in the 

methods for the tests and/or calibrations concerned. These services and supplies used shall 

comply with specified requirements. 

 

___ 2) Records of actions taken to check compliance shall be maintained. 

 
NIST Handbook 143 April 2007 

91

___ 4.6.3 Purchasing documents for items affecting the quality of laboratory output shall contain data 

describing the services and supplies ordered. These purchasing documents shall be reviewed and 

approved for technical content prior to release. 

NOTE The description may include type, class, grade, precise identification, specifications, drawings, 

inspection instructions, other technical data including approval of test results, the quality required and the 

management system standard under which they were made. 

 4.6.4 

 

___ 1) The laboratory shall evaluate suppliers of critical consumables, supplies and services which affect 

the quality of testing and calibration, and 

 

___ 2) shall maintain records of these evaluations and list those approved. 

4.7 Service to the customer 

 

___ The laboratory shall be willing to cooperate with customers or their representatives in clarifying the 

customer’s request and in monitoring the laboratory's performance in relation to the work performed, 

provided that the laboratory ensures confidentiality to other customers. 

 

NOTE 1: Such cooperation may include: 

 

 1) providing the customer or the customer’s representative reasonable access to relevant areas of the 

laboratory for the witnessing of tests and/or calibrations performed for the customer; 

 

 2) preparation, packaging, and dispatch of test and/or calibration items needed by the customer for 

verification purposes. 

 

NOTE 2: Customers value the maintenance of good communication, advice and guidance in technical 

matters, and opinions and interpretations based on results. Communication with the customer, especially in 

large assignments, should be maintained throughout the work. The laboratory should inform the customer 

of any delays or major deviations in the performance of the tests and/or calibrations. 

___ 

4.7.2 The laboratory shall seek feedback, both positive and negative, from its customers. The feedback 

shall be used and analyzed to improve the management system, testing and calibration activities 

and customer service. 

NOTE: Examples of the types of feedback include customer satisfaction surveys and review of test or 

calibration reports with customers. 

4.8 Complaints

___ 4.8.1 The laboratory shall have a policy and procedure for the resolution of complaints received from 

customers or other parties. 

 

___ 4.8.2 Records shall be maintained of all complaints and of the investigations and corrective actions 

taken by the laboratory (see also 4.11).

4.9 Control of non-conforming testing and/or calibration work 

___ 4.9.1 The laboratory shall have a policy and procedures that shall be implemented when any aspect of 

its testing and/or calibration work, or the results of this work, do not conform to its own 

procedures or the agreed requirements of the customer. The policy and procedures shall ensure 

that: 

 
April 2007 NIST Handbook 143 

92 

___ 1) the responsibilities and authorities for the management of non-conforming work are designated 

and actions (including halting of work and withholding of test reports and calibration certificates, 

as necessary) are defined and taken when non-conforming work is identified; 

 

___ 2) an evaluation of the significance of the non-conforming work is made; 

 

___ 3) correction is taken immediately, together with any decision about the acceptability of the nonconforming work; 

 

___ 4) where necessary, the customer is notified and work is recalled; 

 

___ 5) the responsibility for authorizing the resumption of work is defined. 

 

NOTE: Identification of non-conforming work or problems with the management system or with testing 

and/or calibration activities can occur at various places within the management system and technical 

operations. Examples are customer complaints, quality control, instrument calibration, checking of 

consumable materials, staff observations or supervision, test report and calibration certificate checking, 

management reviews and internal or external audits. 

___ 4.9.2 Where the evaluation indicates that the non-conforming work could recur or that there is doubt 

about the compliance of the laboratory's operations with its own policies and procedures, the 

corrective action procedures given in 4.11 shall be promptly followed. 

4.10 Improvement 

___ The laboratory shall continually improve the effectiveness of its management system through the 

use of the quality policy, quality objectives, audit results, analysis of data, corrective and 

preventive actions and management review. 

4.11 Corrective action 

 4.11.1 General 

___ The laboratory shall establish a policy and procedure and shall designate appropriate authorities for 

implementing corrective action when non-conforming work or departures from the policies and procedures 

in the management system or technical operations have been identified. 

 

NOTE: A problem with the management system or with the technical operations of the laboratory may be 

identified through a variety of activities, such as control of non-conforming work, internal or external 

audits, management reviews, feedback from customers and from staff observations. 

 4.11.2 Cause analysis 

___ The procedure for corrective action shall start with an investigation to determine the root cause(s) of the 

problem. 

 

NOTE: Cause analysis is the key and sometimes the most difficult part in the corrective action procedure. 

Often the root cause is not obvious and thus a careful analysis of all potential causes of the problem is 

required. Potential causes could include customer requirements, the samples, sample specifications, 

methods and procedures, staff skills and training, consumables, or equipment and its calibration. 
NIST Handbook 143 April 2007 

93

 4.11.3 Selection and implementation of corrective actions 

___ 1) Where corrective action is needed, the laboratory shall identify potential corrective actions. It 

shall select and implement the action(s) most likely to eliminate the problem and to prevent 

recurrence. 

 

___ 2) Corrective actions shall be to a degree appropriate to the magnitude and the risk of the problem. 

___ 3) The laboratory shall document and implement any required changes resulting from corrective 

action investigations. 

 4.11.4 Monitoring of corrective actions 

___ The laboratory shall monitor the results to ensure that the corrective actions taken have been effective. 

 4.11.5 Additional audits 

___ Where the identification of nonconformities or departures casts doubts on the laboratory's compliance with 

its own policies and procedures, or on its compliance with this Handbook, the laboratory shall ensure that 

the appropriate areas of activity are audited in accordance with 4.14 as soon as possible. 

 

NOTE Such additional audits often follow the implementation of the corrective actions to confirm their 

effectiveness. An additional audit should be necessary only when a serious issue or risk to the business is 

identified. 

4.12 Preventive action 

 4.12.1 

___ 1) Needed improvements and potential sources of nonconformities, either technical or concerning the 

management system, shall be identified. 

 

___ 2) When improvement opportunities are identified or if preventive action is required, action plans 

shall be developed, implemented and monitored to reduce the likelihood of the occurrence of such 

nonconformities and to take advantage of the opportunities for improvement. 

 

___ 4.12.2 Procedures for preventive actions shall include the initiation of such actions and application of 

controls to ensure that they are effective. 

NOTE 1 Preventive action is a proactive process to identify opportunities for improvement rather than a 

reaction to the identification of problems or complaints. 

NOTE 2 Apart from the review of the operational procedures, the preventive action might involve 

analysis of data, including trend and risk analyses and proficiency-testing results. 

4.13 Control of records 

 4.13.1 General 

___ 4.13.1.1 The laboratory shall establish and maintain procedures for identification, collection, indexing, 

access, filing, storage, maintenance and disposal of quality and technical records. Quality 

records shall include reports from internal audits and management reviews as well as records 

of corrective and preventive actions. 
April 2007 NIST Handbook 143 

94 

 4.13.1.2 

___ 1) All records shall be legible and shall be stored and retained in such a way that they are readily 

retrievable in facilities that provide a suitable environment to prevent damage or deterioration and 

to prevent loss. 

 

___ 2) Retention times of records shall be established. 

NOTE Records may be in any media, such as hard copy or electronic media. 

 

___ 4.13.1.3 All records shall be held secure and in confidence. 

___ 4.13.1.4 The laboratory shall have procedures to protect and back up records stored electronically and 

to prevent unauthorized access to or amendment of these records. 

 4.13.2 Technical records 

 4.13.2.1 

___ 1) The laboratory shall retain records of original observations, derived data and sufficient 

information to establish an audit trail, calibration records, staff records and a copy of each test 

report or calibration certificate issued, for a defined period. 

 

___ 2) The records for each test or calibration shall contain sufficient information to facilitate, if possible, 

identification of factors affecting the uncertainty and to enable the test or calibration to be repeated 

under conditions as close as possible to the original. 

 

___ 3) The records shall include the identity of personnel responsible for the sampling, performance of 

each test and/or calibration and checking of results. 

 

NOTE 1: In certain fields it may be impossible or impracticable to retain records of all original 

observations. 

 

NOTE 2: Technical records are accumulations of data (see 5.4.7) and information which result from 

carrying out tests and/or calibrations and which indicate whether specified quality or process parameters 

are achieved. They may include forms, contracts, work sheets, work books, check sheets, work notes, 

control graphs, external and internal test reports and calibration certificates, customers’ notes, papers and 

feedback. 

___ 4.13.2.2 Observations, data and calculations shall be recorded at the time they are made and shall be 

identifiable to the specific task. 

 4.13.2.3 

___ 1) When mistakes occur in records, each mistake shall be crossed out, not erased, made illegible or 

deleted, and the correct value entered alongside. All such alterations to records shall be signed or 

initialed by the person making the correction. 

 

___ 2) In the case of records stored electronically, equivalent measures shall be taken to avoid loss or 

change of original data. 
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4.14 Internal audits 

 4.14.1 

___ 1) The laboratory shall periodically, and in accordance with a predetermined schedule and procedure, 

conduct internal audits of its activities to verify that its operations continue to comply with the 

requirements of the management system and this Handbook. The internal audit program shall 

address all elements of the management system, including the testing and/or calibration activities. 

It is the responsibility of the quality manager to plan and organize audits as required by the 

schedule and requested by management. 

 

___ 2) Such audits shall be carried out by trained and qualified personnel who are, wherever resources 

permit, independent of the activity to be audited. 

NOTE: The cycle for internal auditing should normally be completed in one year. 

___ 4.14.2 When audit findings cast doubt on the effectiveness of the operations or on the correctness or 

validity of the laboratory's test or calibration results, the laboratory shall take timely corrective 

action, and shall notify customers in writing if investigations show that the laboratory results 

may have been affected. 

 

___ 4.14.3 The area of activity audited, the audit findings and corrective actions that arise from them shall 

be recorded. 

 

___ 4.14.4 Follow-up audit activities shall verify and record the implementation and effectiveness of the 

corrective action taken. 

 

4.15 Management reviews 

___ 4. 15.1 In accordance with a predetermined schedule and procedure, the laboratory's top management 

shall periodically conduct a review of the laboratory's management system and testing and/or 

calibration activities to ensure their continuing suitability and effectiveness, and to introduce 

necessary changes or improvements. The review shall take account of: 

 

___ 1) the suitability of policies and procedures; 

 

___ 2) reports from managerial and supervisory personnel; 

 

___ 3) the outcome of recent internal audits; 

 

___ 4) corrective and preventive actions; 

 

___ 5) assessments by external bodies; 

 

___ 6) the results of interlaboratory comparisons or proficiency tests; 

 

___ 7) changes in the volume and type of the work; 

 

___ 8) customer feedback; 

 

___ 9) complaints; 

 

___ 10) recommendations for improvement; 

 

___ 11) other relevant factors, such as quality control activities, resources and staff training. 
April 2007 NIST Handbook 143 

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NOTE 1: A typical period for conducting a management review is once every 12 months. 

 

NOTE 2: Results should feed into the laboratory planning system and should include the goals, objectives 

and action plans for the coming year. 

 

NOTE 3: A management review includes consideration of related subjects at regular management 

meetings. 

 4.15.2 

___ 1) Findings from management reviews and the actions that arise from them shall be recorded. 

 

___ 2) The management shall ensure that those actions are carried out within an appropriate and agreed 

timescale. 

5 Technical requirements for accreditation 

5.1 General 

 5.1.1 Many factors determine the correctness and reliability of the tests and/or calibrations performed by 

a laboratory. These factors include contributions from: 

 

 ___ human factors (5.2); 

 

 ___ accommodation and environmental conditions (5.3); 

 

 ___ test and calibration methods and method validation (5.4); 

 

 ___ equipment (5.5); 

 

 ___ measurement traceability (5.6 and Annex B); 

 

 ___ sampling (5.7); 

 

 ___ the handling of test and calibration items (5.8). 

 

___ 5.1.2 The extent to which the factors contribute to the total uncertainty of measurement differs 

considerably between (types of) tests and between (types of) calibrations. The laboratory shall 

take account of these factors in developing test and calibration methods and procedures, in the 

training and qualification of personnel, and in the selection and calibration of the equipment it 

uses. 

5.2 Personnel 

 5.2.1 

___ 1) The laboratory management shall ensure the competence of all who operate specific equipment, 

perform tests and/or calibrations, evaluate results, and sign test reports and calibration certificates. 

 

___ 2) When using staff who are undergoing training, appropriate supervision shall be provided. 

Personnel performing specific tasks shall be qualified on the basis of appropriate education, 

training, experience and/or demonstrated skills, as required. 
NIST Handbook 143 April 2007 

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NOTE 1: In some technical areas (e.g., nondestructive testing) it may be required that the personnel 

performing certain tasks hold personnel certification. The laboratory is responsible for fulfilling specified 

personnel certification requirements. The requirements for personnel certification might be regulatory, 

included in the standards for the specific technical field, or required by the customer. 

 

NOTE 2: The personnel responsible for the opinions and interpretation included in test reports should, in 

addition to the appropriate qualifications, training, experience and satisfactory knowledge of the testing 

carried out, also have: 

 

___ relevant knowledge of the technology used for the manufacturing of the items, materials, products, 

etc., tested, or the way they are used or intended to be used, and of the defects or degradations 

which may occur during or in service; 

 

 ___ knowledge of the general requirements expressed in the legislation and standards; and 

 

 ___ an understanding of the significance of deviations found with regard to the normal use of the 

items, materials, products, etc. concerned. 

 5.2.2 

___ 1) The management of the laboratory shall formulate the goals with respect to the education, training 

and skills of the laboratory personnel. 

 

___ 2) The laboratory shall have a policy and procedures for identifying training needs and providing 

training of personnel. 

 

___ 3) The training program shall be relevant to the present and anticipated tasks of the laboratory. 

___ 4) The effectiveness of the training actions taken shall be evaluated. 

 5.2.3 

___ 1) The laboratory shall use personnel who are employed by, or under contract to, the laboratory. 

 

___ 2) Where contracted and additional technical and key support personnel are used, the laboratory shall 

ensure that such personnel are supervised and competent and that they work in accordance with 

the laboratory's management system. 

___ 5.2.4 The laboratory shall maintain current job descriptions for managerial, technical and key support 

personnel involved in tests and/or calibrations. 

NOTE: Job descriptions can be defined in many ways. As a minimum, the following should be defined: 

 

 ___ the responsibilities with respect to performing tests and/or calibrations; 

 

 ___ the responsibilities with respect to the planning of tests and/or calibrations and evaluation of 

results; 

 

 ___ the responsibilities for reporting opinions and interpretations; 

 

 ___ the responsibilities with respect to method modification and development and validation of new 

methods; 

 

 ___ expertise and experience required; 

 

 ___ qualifications and training programs; 
April 2007 NIST Handbook 143 

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 _____ managerial duties. 

 5.2.5 

 

___ 1) The management shall authorize specific personnel to perform particular types of sampling, test 

and/or calibration, to issue test reports and calibration certificates, to give opinions and 

interpretations and to operate particular types of equipment. 

 

___ 2) The laboratory shall maintain records of the relevant authorization(s), competence, educational 

and professional qualifications, training, skills and experience of all technical personnel, including 

contracted personnel. 

 

___ 3) This information shall be readily available and shall include the date on which authorization 

and/or competence is confirmed. 

 

WMD Note: This requirement also applies to Approved Signatories (see 1.5.4). 

5.3 Accommodation and environmental conditions 

 5.3.1 

___ 1) Laboratory facilities for testing and/or calibration, including but not limited to energy sources, 

lighting and environmental conditions, shall be such as to facilitate correct performance of the 

tests and/or calibrations. 

 

 The laboratory shall ensure that the environmental conditions do not invalidate the results or 

adversely affect the required quality of any measurement. Particular care shall be taken when 

sampling and tests and/or calibrations are undertaken at sites other than a permanent laboratory 

facility. 

 

___ 2) The technical requirements for accommodation and environmental conditions that can affect the 

results of tests and calibrations shall be documented. 

 5.3.2 

___ 1) The laboratory shall monitor, control and record environmental conditions as required by the 

relevant specifications, methods and procedures or where they influence the quality of the results. 

Due attention shall be paid, for example, to biological sterility, dust, electromagnetic disturbances, 

radiation, humidity, electrical supply, temperature, and sound and vibration levels, as appropriate 

to the technical activities concerned. 

 

___ 2) Tests and calibrations shall be stopped when the environmental conditions jeopardize the results of 

the tests and/or calibrations. 

___ 5.3.3 There shall be effective separation between neighboring areas in which there are incompatible 

activities. Measures shall be taken to prevent cross-contamination. 

 

___ 5.3.4 Access to and use of areas affecting the quality of the tests and/or calibrations shall be controlled. 

The laboratory shall determine the extent of control based on its particular circumstances. 

 

___ 5.3.5 Measures shall be taken to ensure good housekeeping in the laboratory. Special procedures shall 

be prepared where necessary. 
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5.4 Test and calibration methods and method validation 

 5.4.1 General 

____ 1) The laboratory shall use appropriate methods and procedures for all tests and/or calibrations 

within its scope. These include sampling, handling, transport, storage and preparation of items to 

be tested and/or calibrated, and, where appropriate, an estimation of the measurement uncertainty 

as well as statistical techniques for analysis of test and/or calibration data. 

 

___ 2) The laboratory shall have instructions on the use and operation of all relevant equipment, and on 

the handling and preparation of items for testing and/or calibration, or both, where the absence of 

such instructions could jeopardize the results of tests and/or calibrations. 

 

___ 3) All instructions, standards, manuals and reference data relevant to the work of the laboratory shall 

be kept up to date and shall be made readily available to personnel (see 4.3). 

 

___ 4) Deviation from test and calibration methods shall occur only if the deviation has been 

documented, technically justified, authorized, and accepted by the customer. 

NOTE: International, regional or national standards or other recognized specifications that contain 

sufficient and concise information on how to perform the tests and/or calibrations do not need to be 

supplemented or rewritten as internal procedures if these standards are written in a way that they can be 

used as published by the operating staff in a laboratory. It may be necessary to provide additional 

documentation for optional steps in the method or additional details. 

 5.4.2 Selection of methods 

___ 1) The laboratory shall use test and/or calibration methods, including methods for sampling, which 

meet the needs of the customer and which are appropriate for the tests and/or calibrations it 

undertakes. Methods published in international, regional or national standards shall preferably be 

used. The laboratory shall ensure that it uses the latest valid edition of a standard unless it is not 

appropriate or possible to do so. 

 

___ 2) When necessary, the standard shall be supplemented with additional details to ensure consistent 

application. 

 

___ 3) When the customer does not specify the method to be used, the laboratory shall select appropriate 

methods that have been published either in international, regional or national standards, or by 

reputable technical organizations, or in relevant scientific texts or journals, or as specified by the 

manufacturer of the equipment. Laboratory-developed methods or methods adopted by the 

laboratory may also be used if they are appropriate for the intended use and if they are validated. 

 

___ 4) The customer shall be informed as to the method chosen. 

 

___ 5) The laboratory shall confirm that it can properly operate standard methods before introducing the 

tests or calibrations. If the standard method changes, the confirmation shall be repeated. 

 

___ 6) The laboratory shall inform the customer when the method proposed by the customer is 

considered to be inappropriate or out of date. 

 5.4.3 Laboratory-developed methods 

___ 1) The introduction of test and calibration methods developed by the laboratory for its own use shall 

be a planned activity and shall be assigned to qualified personnel equipped with adequate 

resources. 
April 2007 NIST Handbook 143 

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___ 2) Plans shall be updated as development proceeds and effective communication amongst all 

personnel involved shall be ensured. 

 5.4.4 Non-standard methods 

___ 1) When it is necessary to use methods not covered by standard methods, these shall be subject to 

agreement with the customer and shall include a clear specification of the customer’s requirements 

and the purpose of the test and/or calibration. 

 

___ 2) The method developed shall have been validated appropriately before use.

NOTE: For new test and/or calibration methods, procedures should be developed prior to the tests and/or 

calibrations being performed and should contain at least the following information: 

 

 1) appropriate identification; 

 

 2) scope; 

 

 3) description of the type of item to be tested or calibrated; 

 

 4) parameters or quantities and ranges to be determined; 

 

 5) apparatus and equipment, including technical performance requirements; 

 

 6) reference standards and reference materials required; 

 

 7) environmental conditions required and any stabilization period needed; 

 

 8) description of the procedure, including: 

 ___

 

affixing of identification marks, handling, transporting, storing and preparation of items, 

 ___ checks to be made before the work is started, 

 ___

 

checks that the equipment is working properly and, where required, calibration and adjustment of 

the equipment before each use, 

 ___

 

the method of recording the observations and results, 

 ___

 

any safety measures to be observed; 

 9) criteria and/or requirements for approval/rejection; 

 

 10) data to be recorded and method of analysis and presentation; 

 

 11) the uncertainty or the procedure for estimating uncertainty. 

 5.4.5 Validation of methods 

 5.4.5.1 Validation is the confirmation by examination and the provision of objective evidence that the 

particular requirements for a specific intended use are fulfilled. 
NIST Handbook 143 April 2007 

101

 5.4.5.2 

___ 1) The laboratory shall validate non-standard methods, laboratory-designed/developed methods, 

standard methods used outside their intended scope, and amplifications and modifications of 

standard methods to confirm that the methods are fit for the intended use. The validation shall be 

as extensive as is necessary to meet the needs of the given application or field of application. 

 

___ 2) The laboratory shall record the results obtained, the procedure used for the validation, and a 

statement as to whether the method is fit for the intended use. 

NOTE 1: Validation may include procedures for sampling, handling and transportation. 

 

NOTE 2: The techniques used for the determination of the performance of a method should be one of, or a 

combination of, the following: 

 

 ___ calibration using reference standards or reference materials; 

 

 ___ comparison of results achieved with other methods; 

 

 ___ interlaboratory comparisons; 

 

 ___ systematic assessment of the factors influencing the result; 

 

 ___ assessment of the uncertainty of the results based on scientific understanding of the theoretical 

principles of the method and practical experience. 

NOTE 3: When some changes are made in the validated non-standard methods, the influence of such 

changes should be documented and, if appropriate, a new validation should be carried out. 

___ 5.4.5.3 The range and accuracy of the values obtainable from validated methods (e.g., the uncertainty 

of the results, detection limit, selectivity of the method, linearity, limit of repeatability and/or 

reproducibility, robustness against external influences and/or cross-sensitivity against 

interference from the matrix of the sample/test object), as assessed for the intended use, shall be 

relevant to the customer’s needs.

 

NOTE 1: Validation includes specification of the requirements, determination of the characteristics of the 

methods, a check that the requirements can be fulfilled by using the method, and a statement on the 

validity. 

 

NOTE 2: As method-development proceeds, regular review should be carried out to verify that the needs 

of the customer are still being fulfilled. Any change in requirements requiring modifications to the 

development plan should be approved and authorized. 

NOTE 3: Validation is always a balance between costs, risks and technical possibilities. There are many 

cases in which the range and uncertainty of the values (e.g., accuracy, detection limit, selectivity, linearity, 

repeatability, reproducibility, robustness and cross-sensitivity) can only be given in a simplified way due to 

lack of information. 

 5.4.6 Estimation of uncertainty of measurement 

___ 5.4.6.1 A calibration laboratory, or a testing laboratory performing its own calibrations, shall have and 

shall apply a procedure to estimate the uncertainty of measurement for all calibrations and types 

of calibrations.

 
April 2007 NIST Handbook 143 

102 

___ 5.4.6.2 Testing laboratories shall have and shall apply procedures for estimating uncertainty of 

measurement. In certain cases the nature of the test method may preclude rigorous, 

metrologically and statistically valid, calculation of uncertainty of measurement. In these cases 

the laboratory shall at least attempt to identify all the components of uncertainty and make a 

reasonable estimation, and shall ensure that the form of reporting of the result does not give a 

wrong impression of the uncertainty. Reasonable estimation shall be based on knowledge of the 

performance of the method and on the measurement scope and shall make use of, for example, 

previous experience and validation data. 

NOTE: The degree of rigor needed in an estimation of uncertainty of measurement depends on factors 

such as: 

 

 the requirements of the test method; 

 

 the requirements of the customer; 

 

 the existence of narrow limits on which decisions on conformity to a specification are based. 

NOTE 2: In those cases where a well recognized test method specifies limits to the values of the major 

sources of uncertainty of measurement and specifies the form of presentation of calculated results, the 

laboratory is considered to have satisfied this clause by following the test method and reporting instructions 

(see 5.10). 

___ 5.4.6.3 When estimating the uncertainty of measurement, all uncertainty components which are of 

importance in the given situation shall be taken into account using appropriate methods of 

analysis. 

NOTE 1: Sources contributing to the uncertainty include, but are not necessarily limited to, the reference 

standards and reference materials used, methods and equipment used, environmental conditions, properties 

and condition of the item being tested or calibrated, and the operator. 

 

NOTE 2: The predicted long-term behavior of the tested and/or calibrated item is not normally taken into 

account when estimating the measurement uncertainty. 

 

NOTE : For further information, see ISO 5725 and the Guide to the Expression of Uncertainty in 

Measurement (see 1.4). 

 

WMD NOTE: ANSI/NCSL Z540-2 and NIST Technical Note 1297, are considered to be equivalent to 

the Guide to the Expression of Uncertainty in Measurement (GUM). SOP 29 contains procedures for 

implementing this requirement. 

 5.4.7 Control of data 

___ 5.4.7.1 Calculations and data transfers shall be subject to appropriate checks in a systematic manner.

5.4.7.2 When computers or automated equipment are used for the acquisition, processing, recording, 

reporting, storage or retrieval of test or calibration data, the laboratory shall ensure that: 

___ 1) computer software developed by the user is documented in sufficient detail and is suitably 

validated as being adequate for use; 

 

___ 2) procedures are established and implemented for protecting the data; such procedures shall 

include, but not be limited to, integrity and confidentiality of data entry or collection, data 

storage, data transmission and data processing; 

 

___ 3) computers and automated equipment are maintained to ensure proper functioning and are 

provided with the environmental and operating conditions necessary to maintain the integrity of 

test and calibration data. 
NIST Handbook 143 April 2007 

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NOTE: Commercial off-the-shelf software (e.g., word processing, database and statistical programs) in 

general use within their designed application range may be considered to be sufficiently validated. 

However, laboratory software configuration/modifications should be validated as in 5.4.7.2a). 

5.5 Equipment 

 5.5.1 

___ 1) The laboratory shall be furnished with all items of sampling, measurement and test equipment 

required for the correct performance of the tests and/or calibrations (including sampling, 

preparation of test and/or calibration items, processing and analysis of test and/or calibration data). 

 

___ 2) In those cases where the laboratory needs to use equipment outside its permanent control, it shall 

ensure that the requirements of this Handbook are met. 

 5.5.2 

___ 1) Equipment and its software used for testing, calibration and sampling shall be capable of 

achieving the accuracy required and shall comply with specifications relevant to the tests and/or 

calibrations concerned. 

 

___ 2) Calibration programs shall be established for key quantities or values of the instruments where 

these properties have a significant effect on the results. 

 

___ 3) Before being placed into service, equipment (including that used for sampling) shall be calibrated 

or checked to establish that it meets the laboratory's specification requirements and complies with 

the relevant standard specifications. It shall be checked and/or calibrated before use (see 5.6). 

___ 5.5.3 Equipment shall be operated by authorized personnel. Up-to-date instructions on the use and 

maintenance of equipment (including any relevant manuals provided by the manufacturer of the 

equipment) shall be readily available for use by the appropriate laboratory personnel. 

 

___ 5.5.4 Each item of equipment and its software used for testing and calibration and significant to the 

result shall, when practicable, be uniquely identified. 

___ 5.5.5 Records shall be maintained of each item of equipment and its software significant to the tests 

and/or calibrations performed. The records shall include at least the following: 

___ 1) the identity of the item of equipment and its software; 

 

___ 2) the manufacturer's name, type identification, and serial number or other unique identification; 

 

___ 3) checks that equipment complies with the specification (see 5.5.2); 

 

___ 4) the current location, where appropriate; 

 

___ 5) the manufacturer's instructions, if available, or reference to their location; 

___ 6) dates, results and copies of reports and certificates of all calibrations, adjustments, acceptance 

criteria, and the due date of next calibration; 

 

___ 7) the maintenance plan, where appropriate, and maintenance carried out to date; 

 

___ 8) any damage, malfunction, modification or repair to the equipment. 
April 2007 NIST Handbook 143 

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___ 5.5.6 The laboratory shall have procedures for safe handling, transport, storage, use and planned 

maintenance of measuring equipment to ensure proper functioning and in order to prevent 

contamination or deterioration. 

NOTE: Additional procedures may be necessary when measuring equipment is used outside the 

permanent laboratory for tests, calibrations or sampling. 

 

 5.5.7 

___ 1) Equipment that has been subjected to overloading or mishandling, gives suspect results, or has 

been shown to be defective or outside specified limits, shall be taken out of service. It shall be 

isolated to prevent its use or clearly labeled or marked as being out of service until it has been 

repaired and shown by calibration or test to perform correctly. 

 

___ 2) The laboratory shall examine the effect of the defect or departure from specified limits on previous 

tests and/or calibrations and shall institute the "Control of non-conforming work" procedure (see 

4.9). 

___ 5.5.8 Whenever practicable, all equipment under the control of the laboratory and requiring calibration 

shall be labeled, coded or otherwise identified to indicate the status of calibration, including the 

date when last calibrated and the date or expiration criteria when recalibration is due. 

 

___ 5.5.9 When, for whatever reason, equipment goes outside the direct control of the laboratory, the 

laboratory shall ensure that the function and calibration status of the equipment are checked and 

shown to be satisfactory before the equipment is returned to service. 

___ 5.5.10 When intermediate checks are needed to maintain confidence in the calibration status of the 

equipment, these checks shall be carried out according to a defined procedure. 

 

___ 5.5.11 Where calibrations give rise to a set of correction factors, the laboratory shall have procedures 

to ensure that copies (e.g., in computer software) are correctly updated. 

 

___ 5.5.12 Test and calibration equipment, including both hardware and software, shall be safeguarded 

from adjustments which would invalidate the test and/or calibration results. 

5.6 Measurement traceability 

 5.6.1 General 

___ 1) All equipment used for tests and/or calibrations, including equipment for subsidiary measurements 

(e.g., for environmental conditions) having a significant effect on the accuracy or validity of the 

result of the test, calibration or sampling shall be calibrated before being put into service. 

 

___ 2) The laboratory shall have an established program and procedure for the calibration of its 

equipment. 

NOTE: Such a program should include a system for selecting, using, calibrating, checking, controlling 

and maintaining measurement standards, reference materials used as measurement standards, and 

measuring and test equipment used to perform tests and calibrations. 

 
NIST Handbook 143 April 2007 

105

 5.6.2 Specific requirements 

 5.6.2.1 Calibration 

 5.6.2.1.1 

___ 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). 

 

 A calibration laboratory establishes traceability of its own measurement standards and measuring 

instruments to the SI by means of an unbroken chain of calibrations or comparisons linking them 

to relevant primary standards of the SI units of measurement. The link to SI units may be 

achieved by reference to national measurement standards. National measurement standards may 

be primary standards, which are primary realizations of the SI units or agreed representations of 

SI units based on fundamental physical constants, or they may be secondary standards which are 

standards calibrated by another national metrology institute. 

___ 2) When using external calibration services, traceability of measurement shall be assured by the use 

of calibration services from laboratories that can demonstrate competence, measurement capability 

and traceability. 

 

___ 3) The calibration certificates issued by these laboratories shall contain the measurement results, 

including the measurement uncertainty and/or a statement of compliance with an identified 

metrological specification (see also 5.10.4.2). 

NOTE 1: Calibration laboratories fulfilling the requirements of this Handbook are considered to be 

competent. A calibration certificate bearing an accreditation body logo from a calibration laboratory 

accredited to this Handbook, for the calibration concerned, is sufficient evidence of traceability of the 

calibration data reported. 

NOTE 2: Traceability to SI units of measurement may be achieved by reference to an appropriate primary 

standard (see VIM:1993, 6.4) or by reference to a natural constant, the value of which in terms of the 

relevant SI unit is known and recommended by the General Conference of Weights and Measures (CGPM) 

and the International Committee for Weights and Measures (CIPM). 

NOTE 3: Calibration laboratories that maintain their own primary standard or representation of SI units 

based on fundamental physical constants can claim traceability to the SI system only after these standards 

have been compared, directly or indirectly, with other similar standards of a national metrology institute. 

NOTE 4: The term "identified metrological specification" means that it must be clear from the calibration 

certificate which specification the measurements have been compared with, by including the specification 

or by giving an unambiguous reference to the specification. 

NOTE 5: When the terms "international standard" or "national standard" are used in connection with 

traceability, it is assumed that these standards fulfill the properties of primary standards for the realization 

of SI units. 

NOTE 6: Traceability to national measurement standards does not necessarily require the use of the 

national metrology institute of the country in which the laboratory is located. 

NOTE 7: If a calibration laboratory wishes or needs to obtain traceability from a national metrology 

institute other than in its own country, this laboratory should select a national metrology institute that 

actively participates in the activities of BIPM either directly or through regional groups. 
April 2007 NIST Handbook 143 

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NOTE 8: The unbroken chain of calibrations or comparisons may be achieved in several steps carried out 

by different laboratories that can demonstrate traceability. 

___ 5.6.2.1.2 There are certain calibrations that currently cannot be strictly made in SI units. In these cases 

calibration shall provide confidence in measurements by establishing traceability to 

appropriate measurement standards such as: 

 

___ 1) the use of certified reference materials provided by a competent supplier to give a reliable physical 

or chemical characterization of a material; 

 

___ 2) the use of specified methods and/or consensus standards that are clearly described and agreed by 

all parties concerned. 

 

___ 3) Participation in a suitable program of interlaboratory comparisons is required where possible. 

 5.6.2.2 Testing 

___ 5.6.2.2.1 For testing laboratories, the requirements given in 5.6.2.1 apply for measuring and test 

equipment with measuring functions used, unless it has been established that the associated 

contribution from the calibration contributes little to the total uncertainty of the test result. 

When this situation arises, the laboratory shall ensure that the equipment used can provide the 

uncertainty of measurement needed. 

NOTE: The extent to which the requirements in 5.6.2.1 should be followed depends on the relative 

contribution of the calibration uncertainty to the total uncertainty. If calibration is the dominant factor, the 

requirements should be strictly followed. 

 

___ 5.6.2.2.2 Where traceability of measurements to SI units is not possible and/or not relevant, the same 

requirements for traceability to, for example, certified reference materials, agreed methods 

and/or consensus standards, are required as for calibration laboratories (see 5.6.2.1.2). 

 5.6.3 Reference standards and reference materials 

 5.6.3.1 Reference standards 

___ 1) The laboratory shall have a program and procedure for the calibration of its reference standards. 

 

___ 2) Reference standards shall be calibrated by a body that can provide traceability as described in 

5.6.2.1. 

 

___ 3) Such reference standards of measurement held by the laboratory shall be used for calibration only 

and for no other purpose, unless it can be shown that their performance as reference standards 

would not be invalidated. Reference standards shall be calibrated before and after any adjustment. 

 5.6.3.2 Reference materials 

___ Reference materials shall, where possible, be traceable to SI units of measurement, or to certified reference 

materials. Internal reference materials shall be checked as far as is technically and economically 

practicable. 

 

 5.6.3.3 Intermediate checks 

___ Checks needed to maintain confidence in the calibration status of reference, primary, transfer or working 

standards and reference materials shall be carried out according to defined procedures and schedules 
NIST Handbook 143 April 2007 

107

 5.6.3.4 Transport and storage 

___ The laboratory shall have procedures for safe handling, transport, storage and use of reference standards 

and reference materials in order to prevent contamination or deterioration and in order to protect their 

integrity. 

 

NOTE: Additional procedures may be necessary when reference standards and reference materials are 

used outside the permanent laboratory for tests, calibrations or sampling. 

5.7 Sampling 

 5.7.1 

___ 1) The laboratory shall have a sampling plan and procedures for sampling when it carries out 

sampling of substances, materials or products for subsequent testing or calibration. 

 

___ 2) The sampling plan as well as the sampling procedure shall be available at the location where 

sampling is undertaken. Sampling plans shall, whenever reasonable, be based on appropriate 

statistical methods. The sampling process shall address the factors to be controlled to ensure the 

validity of the test and calibration results. 

NOTE 1: Sampling is a defined procedure whereby a part of a substance, material or product is taken to 

provide for testing or calibration of a representative sample of the whole. Sampling may also be required 

by the appropriate specification for which the substance, material or product is to be tested or calibrated. In 

certain cases (e.g., forensic analysis), the sample may not be representative but is determined by 

availability. 

NOTE 2: Sampling procedures should describe the selection, sampling plan, withdrawal and preparation 

of a sample or samples from a substance, material or product to yield the required information. 

___ 5.7.2 Where the customer requires deviations, additions or exclusions from the documented sampling 

procedure, these shall be recorded in detail with the appropriate sampling data and shall be 

included in all documents containing test and/or calibration results, and shall be communicated to 

the appropriate personnel. 

 

___ 5.7.3 The laboratory shall have procedures for recording relevant data and operations relating to 

sampling that forms part of the testing or calibration that is undertaken. These records shall 

include the sampling procedure used, the identification of the sampler, environmental conditions 

(if relevant) and diagrams or other equivalent means to identify the sampling location as necessary 

and, if appropriate, the statistics the sampling procedures are based upon. 

5.8 Handling of test and calibration items 

___ 5.8.1 The laboratory shall have procedures for the transportation, receipt, handling, protection, storage, 

retention and/or disposal of test and/or calibration items, including all provisions necessary to 

protect the integrity of the test or calibration item, and to protect the interests of the laboratory and 

the customer. 

5.8.2 

___ 1) The laboratory shall have a system for identifying test and/or calibration items. 

 

___ 2) The identification shall be retained throughout the life of the item in the laboratory. 

 

___ 3) The system shall be designed and operated so as to ensure that items cannot be confused 

physically or when referred to in records or other documents. 

 
April 2007 NIST Handbook 143 

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___ 4) The system shall, if appropriate, accommodate a sub-division of groups of items and the transfer 

of items within and from the laboratory. 

 5.8.3 

___ 1) Upon receipt of the test or calibration item, abnormalities or departures from normal or specified 

conditions, as described in the test or calibration method, shall be recorded. 

 

___ 2) When there is doubt as to the suitability of an item for test or calibration, or when an item does not 

conform to the description provided, or the test or calibration required is not specified in sufficient 

detail, the laboratory shall consult the customer for further instructions before proceeding and shall 

record the discussion. 

 5.8.4 

___ 1) The laboratory shall have procedures and appropriate facilities for avoiding deterioration, loss or 

damage to the test or calibration item during storage, handling and preparation. 

 

___ 2) Handling instructions provided with the item shall be followed. 

 

___ 3) When items have to be stored or conditioned under specified environmental conditions, these 

conditions shall be maintained, monitored and recorded. 

 

___ 4) Where a test or calibration item or a portion of an item is to be held secure, the laboratory shall 

have arrangements for storage and security that protect the condition and integrity of the secured 

items or portions concerned. 

NOTE 1: Where test items are to be returned into service after testing, special care is required to ensure 

that they are not damaged or injured during the handling, testing or storing/waiting processes. 

NOTE 2: A sampling procedure and information on storage and transport of samples, including 

information on sampling factors influencing the test or calibration result, should be provided to those 

responsible for taking and transporting the samples. 

NOTE 3: Reasons for keeping a test or calibration item secure can be for reasons of record, safety or 

value, or to enable complementary tests and/or calibrations to be performed later. 

5.9 Assuring the quality of test and calibration results 

5.9.1 

 

___ 1) The laboratory shall have quality control procedures for monitoring the validity of tests and 

calibrations undertaken. 

 

___ 2) The resulting data shall be recorded in such a way that trends are detectable and, where 

practicable, statistical techniques shall be applied to the reviewing of the results. 

 

___ 3) This monitoring shall be planned and reviewed and may include, but not be limited to, the 

following: 

 ____ a) regular use of certified reference materials and/or internal quality control using secondary 

reference materials; 

 

 ____ b) participation in interlaboratory comparison or proficiency-testing programs; 

 

 ____ c) replicate tests or calibrations using the same or different methods; 
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 ____ d) retesting or recalibration of retained items; 

 

 ____ e) correlation of results for different characteristics of an item. 

 

NOTE: The selected methods should be appropriate for the type and volume of the work undertaken. 

___ 5.9.2 Quality control data shall be analyzed and, where they are found to be outside pre-defined 

criteria, planned action shall be taken to correct the problem and to prevent incorrect results from 

being reported. 

5.10 Reporting the results 

 5.10.1 General 

___ 1) The results of each test, calibration, or series of tests or calibrations carried out by the laboratory 

shall be reported accurately, clearly, unambiguously and objectively, and in accordance with any 

specific instructions in the test or calibration methods. 

 

___ 2) The results shall be reported, usually in a test report or a calibration certificate (see note 1), and 

shall include all the information requested by the customer and necessary for the interpretation of 

the test or calibration results and all information required by the method used. This information 

is normally that required by 5.10.2, and 5.10.3 or 5.10.4. 

 

___ 3) In the case of tests or calibrations performed for internal customer, or in the case of a written 

agreement with the customer, the results may be reported in a simplified way. Any information 

listed in 5.10.2 to 5.10.4 which is not reported to the customer shall be readily available in the 

laboratory which carried out the tests and/or calibrations. 

NOTE 1: Test reports and calibration certificates are sometimes called test certificates and calibration 

reports, respectively. 

 

NOTE 2: The test reports or calibration certificates may be issued as hard copy or by electronic data 

transfer provided that the requirements of this Handbook are met. 

 5.10.2 Test reports and calibration certificates 

 Each test report or calibration certificate shall include at least the following information, unless the 

laboratory has valid reasons for not doing so: 

___ 1) a title (e.g., "Test Report" or "Calibration Certificate"); 

 

___ 2) the name and address of the laboratory, and the location where the tests and/or calibrations were 

carried out, if different from the address of the laboratory; 

___ 3) unique identification of the test report or calibration certificate (such as the serial number), and on 

each page an identification in order to ensure that the page is recognized as a part of the test report 

or calibration certificate, and a clear identification of the end of the test report or calibration 

certificate; 

___ 4) the name and address of the customer; 

 

___ 5) identification of the method used; 

 

___ 6) a description of, the condition of, and unambiguous identification of the item(s) tested or 

calibrated; 

 
April 2007 NIST Handbook 143 

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___ 7) the date of receipt of the test or calibration item(s) where this is critical to the validity and 

application of the results, and the date(s) of performance of the test or calibration; 

___ 8) reference to the sampling plan and procedures used by the laboratory or other bodies where these 

are relevant to the validity or application of the results; 

 

___ 9) the test or calibration results with, where appropriate, the units of measurement; 

 

___ 10) the name(s), function(s) and signature(s) or equivalent identification of person(s) authorizing the 

test report or calibration certificate; 

 

___ 11) where relevant, a statement to the effect that the results relate only to the items tested or calibrated. 

 

NOTE 1: Hard copies of test reports and calibration certificates should also include the page number and 

total number of pages. 

 

NOTE 2: It is recommended that laboratories include a statement specifying that the test report or 

calibration certificate shall not be reproduced except in full, without written approval of the laboratory. 

WMD NOTE: WMD defines the person(s) who authorizes the test report or calibration certificate as the 

Approved Signatory.

 5.10.3 Test reports 

 5.10.3.1 In addition to the requirements listed in 5.10.2, test reports shall, where necessary for the 

interpretation of the test results, include the following: 

___ 1) deviations from, additions to, or exclusions from the test method, and information on specific test 

conditions, such as environmental conditions; 

___ 2) where relevant, a statement of compliance/non-compliance with requirements and/or 

specifications; 

 

___ 3) where applicable, a statement on the estimated uncertainty of measurement; information on 

uncertainty is needed in test reports when it is relevant to the validity or application of the test 

results, when a customer’s instruction so requires, or when the uncertainty affects compliance to a 

specification limit; 

 

___ 4) where appropriate and needed, opinions and interpretations (see 5.10.5); 

 

___ 5) additional information which may be required by specific methods, customers or groups of 

customers. 

 5.10.3.2 In addition to the requirements listed in 5.10.2 and 5.10.3.1, test reports containing the results 

of sampling shall include the following, where necessary for the interpretation of test results: 

___ 1) the date of sampling; 

___ 2) unambiguous identification of the substance, material or product sampled (including the name of 

the manufacturer, the model or type of designation and serial numbers as appropriate); 

___ 3) the location of sampling, including any diagrams, sketches or photographs; 

 

___ 4) a reference to the sampling plan and procedures used; 

___ 5) details of any environmental conditions during sampling that may affect the interpretation of the 

test results; 
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___ 6) any standard or other specification for the sampling method or procedure, and deviations, 

additions to or exclusions from the specification concerned. 

 5.10.4 Calibration certificates 

 5.10.4.1 In addition to the requirements listed in 5.10.2, calibration certificates shall include the 

following, where necessary for the interpretation of calibration results: 

___ 1) the conditions (e.g., environmental) under which the calibrations were made that have an influence 

on the measurement results; 

 

___ 2) the uncertainty of measurement and/or a statement of compliance with an identified metrological 

specification or clauses thereof; 

 

___ 3) evidence that the measurements are traceable (see note 2 in 5.6.2.1.1). 

 5.10.4.2 

___ 1) The calibration certificate shall relate only to quantities and the results of functional tests. 

 

___ 2) If a statement of compliance with a specification is made, this shall identify which clauses of the 

specification are met or not met. 

 

___ 3) When a statement of compliance with a specification is made omitting the measurement results 

and associated uncertainties, the laboratory shall record those results and maintain them for 

possible future reference. 

 

___ 4) When statements of compliance are made, the uncertainty of measurement shall be taken into 

account. 

___ 5.10.4.3 When an instrument for calibration has been adjusted or repaired, the calibration results 

before and after adjustment or repair, if available, shall be reported. 

 

___ 5.10.4.4 A calibration certificate (or calibration label) shall not contain any recommendation on the 

calibration interval except where this has been agreed with the customer. This requirement 

may be superseded by legal regulations. 

 5.10.5 Opinions and interpretations 

___ When opinions and interpretations are included, the laboratory shall document the basis upon which the 

opinions and interpretations have been made. Opinions and interpretations shall be clearly marked as such 

in a test report. 

 

NOTE 1: Opinions and interpretations should not be confused with inspections and product certifications 

as intended in ISO/IEC 17020 and ISO/IEC Guide 65. 

 

NOTE 2: Opinions and interpretations included in a test report may comprise, but not be limited to, the 

following: 

 ___ an opinion on the statement of compliance/noncompliance of the results with requirements; 

 

___ fulfillment of contractual requirements; 

 

___ recommendations on how to use the results; 

 
April 2007 NIST Handbook 143 

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___ guidance to be used for improvements. 

NOTE 3: In many cases it might be appropriate to communicate the opinions and interpretations by direct 

dialogue with the customer. Such dialogue should be written down. 

 5.10.6 Testing and calibration results obtained from subcontractors 

___ 1) When the test report contains results of tests performed by subcontractors, these results shall be 

clearly identified. 

 

___ 2) The subcontractor shall report the results in writing or electronically. 

 

___ 3) When a calibration has been subcontracted, the laboratory performing the work shall issue the 

calibration certificate to the contracting laboratory. 

 5.10.7 Electronic transmission of results 

___ In the case of transmission of test or calibration results by telephone, telex, facsimile or other electronic or 

electromagnetic means, the requirements of this Handbook shall be met (see also 5.4.7). 

 5.10.8 Format of reports and certificates 

____ The format shall be designed to accommodate each type of test or calibration carried out and to minimize 

the possibility of misunderstanding or misuse. 

 

NOTE 1: Attention should be given to the layout of the test report or calibration certificate, especially 

with regard to the presentation of the test or calibration data and ease of assimilation by the reader. 

 

NOTE 2: The headings should be standardized as far as possible. 

 5.10.9 Amendments to test reports and calibration certificates 

 

 1) Material amendments to a test report or calibration certificate after issue shall be made only in the 

form of a further document, or data transfer, which includes the statement: 

 "Supplement to Test Report [or Calibration Certificate], serial number ... [or as otherwise 

identified]," or an equivalent form of wording. 

 

___ 2) Such amendments shall meet all the requirements of this Handbook. 

___ 3) When it is necessary to issue a complete new test report or calibration certificate, this shall be 

uniquely identified and shall contain a reference to the original that it replaces. 
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Appendix D. Summary of Services for Laboratory Directory

State 

Recognition Period: __________ 

Laboratory Staff & Titles Address Communications 

 Phone: 

 Fax: 

e-mail: 

URL: 

National Type Evaluation Program (NTEP) 

Address Telephone Number 

 

 

Commercial Measuring Device Testing (non-NTEP) 

Address Telephone Number 

 

 
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Grain Moisture Testing 

Address Telephone Number 

 

 

Petroleum Quality Testing 

Address Telephone Number 

 

 
NIST Handbook 143 April 2007 

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Appendix E. Uncertainties Chart for 

Measurement Parameter & Procedure_________________ 

Laboratory___________________________ 

Range Type A 

Uncertainty 

Type B 

Uncertainty 

Combined 

Uncertainty 

Expanded Standard 

Uncertainty 

(k – 2 or o3) 

Comments 

 
Office of the Director

• National Quality Program 

• International and Academic Affairs

Technology Services 

• Standards Services 

• Technology Partnerships 

• Measurement Services 

• Information Services 

• Weights and Measures 

Advanced Technology Program 

• Economic Assessment 

• Information Technology and Applications

• Chemistry and Life Sciences 

• Electronics and Photonics Technology 

Manufacturing Extension Partnership

Program 

• Regional Programs 

• National Programs 

• Program Development 

Electronics and Electrical Engineering

Laboratory 

• Microelectronics 

• Law Enforcement Standards 

• Electricity 

• Semiconductor Electronics 

• Radio-Frequency Technology1

• Electromagnetic Technology1

• Optoelectronics1

• Magnetic Technology1

Materials Science and Engineering

Laboratory 

• Intelligent Processing of Materials 

• Ceramics 

• Materials Reliability1

• Polymers 

• Metallurgy 

• NIST Center for Neutron Research

Chemical Science and Technology

Laboratory 

• Biotechnology 

• Process Measurements 

• Surface and Microanalysis Science 

• Physical and Chemical Properties2

• Analytical Chemistry 

Physics Laboratory 

• Electron and Optical Physics 

• Atomic Physics 

• Optical Technology 

• Ionizing Radiation 

• Time and Frequency1

• Quantum Physics1

Manufacturing Engineering

Laboratory 

• Precision Engineering 

• Manufacturing Metrology 

• Intelligent Systems 

• Fabrication Technology 

• Manufacturing Systems Integration 

Building and Fire Research

Laboratory 

• Applied Economics 

• Materials and Construction Research

• Building Environment 

• Fire Research

Information Technology Laboratory

• Mathematical and Computational Sciences2

• Advanced Network Technologies 

• Computer Security

• Information Access 

• Convergent Information Systems 

• Information Services and Computing 

• Software Diagnostics and Conformance Testing

• Statistical Engineering

The National Institute of Standards and Technology was established in 1988 by Congress to “assist industryin the development of technology ... needed to improve product quality, to modernize manufacturing

processes, to ensure product reliability ... and to facilitate rapid commercialization ... of products based on new

scientific discoveries.”

NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry’s

competitiveness; advance science and engineering; and improve public health, safety, and the environment. One

of the agency’s basic functions is to develop, maintain, and retain custody of the national standards of

measurement, and provide the means and methods for comparing standards used in science, engineering,

manufacturing, commerce, industry, and education with the standards adopted or recognized by the Federal

Government. 

As an agency of the U.S. Commerce Department’s Technology Administration, NIST conducts basic and

applied research in the physical sciences and engineering, and develops measurement techniques, test methods,

standards, and related services. The Institute does generic and precompetitive work on new and advanced

technologies. NIST’s research facilities are located at Gaithersburg, MD 20899, and at Boulder, CO 80303. Major

technical operating units and their principal activities are listed below. For more information visit the NIST

Website at http://www.nist.gov, or contact the Public Inquiries Desk, 301-975-NIST.

1At Boulder, CO 80303

2Some elements at Boulder, CO
Pentalty for Private Use $300

Official BusinessGaithersburg, MD 20899-0001National Institute of Standards and TechnologyU.S. Department of Commerce