Reference Gas Producers Forum

The host (NATA, Australia) and Chair of the Reference Material Producers (RMP) Accreditation Advisory Committee (AAC), Mr Michael Liddy welcomed all participants to the first NATA Reference Gas Forum. Fourteen participants attended the workshop comprising of AAC members, technical assessors and accredited facilities. He also welcomed Ms Michiko Kawaguchi, attachment staff at NATA from International Accreditation Japan (IAJapan) for her participation and support in organising the Forum.

Mr Liddy went on to highlight the historical background and inception of the program, during which it was initially set-up to ensure the integrity of testing facilities when using reference materials and was not designed for producers of reference materials. He emphasized the importance of metrology and its inherent link to the production of reference materials as ISO/IEC 17025 (previously ISO Guide 25) requirements were then applied. However, as the market matured and international guides and standards were being developed and improved, ISO Guide 34 was chosen as the standard and has been globally accepted by the members of the International Laboratory Accreditation Cooperation (ILAC) to be the accreditation standard for assessing RMP facilities. ISO Guide 34 and its compendium of normative standards (ISO/IEC 17025, ISO Guide 30, ISO Guide 35 and ISO Guide 31) are required for the assessment of a RMP's production process which includes the establishment of metrological traceability, conducting homogeneity/stability trials and management of the distribution of reference materials produced by the facility. He also singled out the production of biological reference materials as requiring a different traceability assessment approach when compared with the production of chemical reference materials.

Mr Liddy informed the participants that the current ISO Guide 30, ISO Guide 31 and ISO Guide 34 (2000) are undergoing revision by ISO/REMCO. Comments are being provided by member bodies at this stage to ISO for the completion of a Committee Draft. He reminded the participants that accreditation of reference material producers is an important activity as the use of appropriate reference material underpins the validity of measurements. Mr Liddy urged NATA to be aware of the needs and concerns of the RMP and the users of reference materials.

He thanked the three speakers Dr Damian Smeulders (NMIA), Mr Jovan Janackovic (Coregas Pty Ltd) and Mr Bang Diep (BOC Gases Pty Ltd) for their time and contribution to the Forum. He also extended his appreciation to the NATA staff for organizing the Forum and invited all participants to use this opportunity to put forward their concerns and considerations for discussion.


Over the rest of the day, a series of four presentations were provided by Mr Mohan Sabaratnam (NATA), Dr Damian Smeulders (NMIA), Mr Jovan Janackovic (Coregas Pty Ltd) and Mr Bang Diep (BOC Gases Pty Ltd). Please refer to Annex for details of the programme.

Mr Mohan Sabaratnam, Program Manager of the NATA Reference Material Producers program explained how the scope of the various ISO standards integrated to provide confidence in the RMP accreditation process. He also discussed in detail the definitions of certified reference materials and reference materials while highlighting the differences in the definitions within the normative standards associated with ISO Guide 34. Mohan highlighted the different models of RMP and collaborator facilities that can exist and concluded that an RMP is the facility that takes the responsibility for the assigned value on the (certified) reference material.

Mohan also provided examples of the different levels of interpretations for the similar clauses found in ISO/IEC 17025 and ISO Guide 34 standards. This, he explained, arose largely because of the limitations set by the intended scopes of the international standards and guides used for the assessment of testing/calibration laboratories and RMP facilities.

General information on the progress and development of the NATA RMP program was highlighted. The questions and critical points raised during this discussion are listed in this report under 'Key points'.

Dr Damian Smeulders, Head, Reference Gas Mixtures Unit, National Measurement Institute Australia (NMIA) and a NATA technical assessor provided a brief introduction and described the services provided by the facility. The facility is currently located at Lindfield (NSW). He outlined the facility's filling and production processes including the proficiency testing (PT) services that his facility is currently providing to gas producers in Australia and abroad. Dr Smeulders also indicated that the facility is currently seeking accreditation to ISO Guide 34 and ISO/IEC 17025 through NATA.

During the presentation, Damian took the participants through the mechanics of two proficiency testing programs conducted by his facility in 2005 (pilot run) and 2007 using natural gas containing N2, CO2, CH4,C2H6, C3H8,n-C4H10, iso-C4H10. An in-depth explanation was provided on the overall PT results obtained in the study. He also highlighted his facility's involvement in the international gas key comparisons conducted through the Consultative Committee for Amount of Substance (CCQM) under the CIPM MRA ( and Asia Pacific Metrology Programme (APMP).

The second presentation by Dr Smeulders discussed the various components that should be considered when establishing a budget for estimating uncertainty of measurement in both gas analysis and reference gas production. The questions and critical points raised during these discussions are listed in this report under 'Key points'.

The third presentation was by Mr Jovan Janackovic, Laboratory Manager, Coregas Pty Ltd. Jovan outlined the concerns and problems that have arisen in the market place amongst gas producers and users of calibration gas mixtures globally. This stimulating presentation encouraged a lot of discussion and highlighted the hard facts of lack of harmonisation in the market on the use of basic metrological terminologies currently used by the accredited gas producer laboratories. Some of the terminologies being used are reference gas, certified reference gas, reference standard, calibration gas mixture, reference gas mixture, working standard etc. Further, due to the different product names used by gas producer companies, NATA was advised that the accreditation process must readily identify the traceability route for each product before the assessment team establishes whether it is a certified reference gas, reference gas or analysed gas. As most Australian gas producers have NATA accreditation for both ISO/IEC 17025 and ISO Guide 34 there is no clear rule as to which accreditation should apply to users when purchasing (certified) reference gases. The questions and critical points raised during this discussion are listed in this report under 'Key points'.

The final presentation was by Mr Bang Diep, Technical Services Manager, BOC Pty Ltd. Mr Diep who is also a NATA technical assessor raised concerns arising from his experiences as an assessor for NATA and being assessed by NATA on many occasions. He highlighted the inconsistencies in assessor assessment approaches primarily when interpreting the ISO standards. He identified the lack of knowledge about ISO Guide 34 accreditation in reference gas users and that NATA should increase awareness of the users (primarily ISO/IEC 17025 accredited laboratories) on the proper selection of (certified) reference gases for their intended work. The questions and critical points raised during this discussion are listed in this report under 'Key points'.

Key points identified during the Forum

The main points that were discussed and their outcomes are listed below:
  • The next Reference Gas PT program planned by the NMIA is scheduled for 2008. The gas composition for the 2008 program will not be the same as the ones run in 2005 and 2007. The 2008 PT program may include ethane, hexane, pentane etc. NMIA will inform the participants when the program is ready. The Forum participants who had also participated in the 2005 & 2007 PT programs provided positive feedback on the NMIA programs;
  • The Chemical Testing Technical Committee for Fuels and Lubricants discussed this issue of lack of availability of Gas PT programs. The NATA representative for Chemical Testing will convey the findings from this Forum to the Chair of the Fuels and Lubricants Technical Committee for their consideration;
  • Specifically for the coal mines industry, the BOC representative at the Forum agreed to prepare sample cylinders for GC analysis for circulation to interested laboratories. However, he indicated that safety issues will have to be addressed before the samples are distributed;
  • Currently, there are no Gas specifiers or associations in Australia to address the issues of the gas producers;
  • In general, published test methods state that reference gases should be used for ensuring traceability/calibration of gas analysers/method validation (previously, NBS type gases were recommended in these methods). The concerns of participants was that there is no clear requirement as to what constitutes certified reference gases and reference gases. In many laboratories, gas mixtures are analysed and the result is used as the assigned value. This gas is then used as a calibrant. However, ISO/IEC 17025 accredited laboratories are primarily assessed and accepted for their competence to do testing. These laboratories do not have the ability or have not been assessed to ensure that they are able to perform acceptable filling processes, conduct stability trials and homogeneity work including having the quality system and knowledge to estimate measurement uncertainty (MU) for establishing CRMs. The MU not only includes uncertainty from the testing but MU from stability trials, homogeneity studies, filling processes etc. Therefore any premixed gases analysed by a ISO/IEC 17025 accredited testing laboratory provides only the test value at that point in use and the gas does not have enough confidence and integrity to be used as a calibrant;
  • All gas producers in conjunction with NATA must attempt to use common terminologies and their functions when being used for method validation, traceability and calibration. The terminologies that require harmonisation in their usage are reference gas mixtures, certified mixtures, calibration gases (vs. analysed gases) and working standards;
  • Scopes of accreditation for accredited gas facilities needs to be sub-categorised, eg. Certified Reference Gas and Certified Gas Mixtures;
  • To refrain from using the term 'Primary' Reference Gas as this is more appropriate for Gases produced by facilities participating in CCQM key comparison studies, eg. NMIA;
  • ISO/IEC 17025 accredited laboratories should be providing test reports only for analysis of gases while ISO Guide 34 accreditation should be used for the production of both Certified Reference Materials/Gas Mixtures produced by gravimetric method and Certified Gas Standards certified by analysis. This means that ISO Guide 34 accreditation should have two sub-categories:
  1. Certified Reference Materials - produced according to ISO 6142 ' Gas Analysis' Preparation of Calibration Gas Mixtures;
  2. Certified Gas Standards - certified by analytical methods.
  • NATA should promote the RMP program and increase awareness of all laboratories on the importance and proper use of appropriate (certified) reference gases for maintaining confidence in their testing/calibration analysis.


A review of the Feedback forms indicated that the Forum participants found the presentations useful and the Forum addressed numerous key, fundamental and practical issues relating to production, analysis and accreditation of gas producing facilities. During the Forum, technical issues were identified and those identified as relevant will be considered. The aim in achieving harmonisation and enhancing confidence in both the RMP program and accredited gas reference material producers was given primary attention and this resulted in many constructive comments that were recorded under the 'Key points' above. Other relevant issues that were discussed related to:
  • consistency in scopes of accreditation
  • use of the COMAR database
  • matrix and other types of reference materials
  • future of NATA accreditation
  • proficiency testing providers and interlaboratory comparison opportunities
The key points and proposals arising from this Forum will be tabled at the next RMP AAC meeting in 2008, for consideration.

Annex : Forum Program



Registration: Friday, 7 December 2007 0900-0920hrs

Time: 0930 - 1500 HRS

Introduction and Welcome: 0930 to 0940 hrs

Purpose and hoped for outcomes of the course by Mr. Michael Liddy, Chair, NATA RMP Accreditation Advisory Committee (AAC).

Session 1 -0940 to 1000 hrs - Introduction - Mr Mohan Sabaratnam, Program Manager - Reference Material Producers, NATA

An overview of NATA accreditation requirements for Reference Material Producers (RMP).

Session 2 -1000 to 1030 hrs - National Gas Standards and Gas Proficiency Testing programs - Dr Damian Smeulders, Project Leader - Reference Gas Mixtures, NMI and NATA RMP Technical Assessor

Traceability of gas mixtures to the national standards and the operation of Proficiency Testing programs.

1030- Break

Session 3 -1100 to 1200 - Example of industry accreditation practices

Concerns and problems arising from NATA assessments and accreditation requirements in the RMP program.
  • Mr J Janackovic, Special Gas Laboratory, Manager Speciality Gases Laboratory, Coregas Pty Ltd (15 minutes)
  • Mr B T Diep, Technical Services Manager, BOC Gases Australia Limited (15 minutes)
  • Questions & Discussion (30 minutes)
1200- Lunch

Session 4 -1300 to 1400 hrs - Approaches to estimating components that contribute to errors in gas production - Dr Damian Smeulders, Project Leader - Reference Gas Mixtures, NMI and NATA RMP Technical Assessor

Session 4 - 1400 to 1530 hrs - Workshop

Groups will discuss:
  • structure of the NATA scope of accreditation
  • production/accreditation of alpha and beta reference gases