Contact damian.smeulders@measurement.gov.au to discuss your requirements.

Primary Reference Materials and Certified Reference Gas Mixtures

There are many areas where the measurement of gas composition is essential, such as the determination of energy content of natural gas and other fuel gases, the measurement of stack emissions and the monitoring of air toxics. In each area, quality gas calibration standards are the foundation of making correct measurements.

NMI manufactures a variety of high accuracy gas standards, including primary reference materials (PRMs) which are made by gravimetry and certified reference materials (CRMs) which have a concentration and uncertainty derived from analysis. The use of NMI gas standards will give your business greater confidence that you are delivering a quality service while reporting factual results. The following gas standards are available for purchase:

• automotive exhaust
• natural gas — methane, ethane, propane, butanes, propanes, hexane, nitrogen and carbon dioxide
• liquefied natural gas (LNG) — a natural gas that simulates the compositional changes from liquefaction — mixtures contain methane, ethane, propane, butanes, propanes, hexane and low concentrations of nitrogen and carbon dioxide
• coal seam methane — a simulated coal seam gas containing high concentrations of methane, with small concentrations of light hydrocarbons, nitrogen and hydrogen
• safety mixtures for confined spaces monitoring and coal mine safety — gas mixtures that contain methane or propane at lower explosive limit concentrations, as well as carbon monoxide for monitoring toxic gas concentrations
• a range of binary gas mixtures for the calibration of specific gas and stack analysers — contain a component (e.g. carbon monoxide, carbon dioxide, oxygen, methane, propane) in a matrix 
• custom mixtures — NMI can prepare PRMs on-demand to meet customer specifications

Gas standards made by commercial gas companies can be sent to NMI to have the composition certified by analysis against our PRMs. Certification by NMI is a cost-effective way of guaranteeing the composition of commercially purchased gas standards.

NMI's Reference Gas Mixtures Facility is accredited by NATA to ISO Guide 34 and ISO/IEC 17025 for:

• the production of reference gas mixtures (here are details of our NATA accreditation)
• analysis of gases and aerosols by analysers and gas chromatography (here are details of our NATA accreditation)

NMI gas standards are traceable with known uncertainties to Australia's national standards of mass and thus to the International System of Units (SI).

Gas Testing and Consultancy

NMI offers a gas testing service where concentrations of components are assigned relative to our high accuracy gas standards.

Proficiency Testing

As a local provider of gas proficiency testing (PT) services, NMI is dedicated to partnering with Australian businesses when developing PT studies focussed on local needs and emerging industries. Recent studies have focussed on areas of importance to Australia — including studies on automotive exhaust, natural gas, LNG, coal seam gas, as well as coal mine and confined spaces safety.

Laboratories that participate in PT studies are given a real and ongoing opportunity to learn and make improvements. Comparative information is provided from their peers on the processes, measurements and estimates of gas composition used in the particular study. In addition, confidentiality is maintained in the reporting of results, enabling participants to make a choice whether to inform clients of their performance. For those laboratories that choose not to participate, it is definitely a missed opportunity to determine whether there may be problems with their equipment or procedures. The importance of proficiency testing was outlined in a recent article in Gas Today.

PT studies operate in the following way:

• laboratories register for the study (there is the option of purchasing reference materials and the PT sample at this stage)
• we send the laboratory a gas sample for testing
• the laboratory sends their measurement results and uncertainties to us
• we send the laboratory a report which evaluates and compares results of participating Australian and international laboratories (each laboratory is assigned a code to preserve confidentiality)
• the laboratory returns the sample to us (or by prior arrangement it can be used by the laboratory as a reference material)

Click here for copies of previous proficiency study reports.

The following studies have been undertaken or are planned for 2011:

• RGM 11-01 natural gas (see Figure 1 for typical results)
• RGM 11-02 liquefied natural gas
• RGM 11-03 laser gas (report in press)
• RGM 12-01 raw natural gas (a simulated unprocessed natural gas — gas samples contain high concentrations of carbon dioxide and ethane, along with nitrogen and propane in a methane matrix)
  registrations close on 1 October — click here for the details of the raw natural gas study and to register

You can also contact us to propose studies on gas mixtures relevant to your area of need.  

International Comparisons

NMI has participated in numerous international comparisons of gas standards organised through the Asia Pacific Metrology Programme and BIPM's Consultative Committee for Amount of Substance — Metrology in Chemistry (CCQM). Successful participation in these international comparisons has demonstrated that NMI's gas mixtures are accurate and internationally comparable with those of other national metrology institutes such as NIST (USA), NPL (UK), KRISS (South Korea) and VSL (Netherlands). Figure 2 shows some results for CCQM-K51.

BIPM hosts a key comparison database where you can search for international gas comparisons. 

Figure 1. Results for a laboratory in RGM 11-1 natural gas PT study	Figure 2. CCQM-K51 carbon monoxide (5 µmol/mol) in nitrogen (NMI is represented as NMIA)