AS/NZS 3580.2.2:20091 AS/NZS 3580.2.2:2009Australian/New Zealand StandardTMMethods for sampling and analysis of ambient airMethod 2.2: Preparation of reference test atmospheresCompressed gas methodPREFACEThis Standard was prepared by the Joint Standards Australia/Standards New Zealand Committee EV-007, Methods for Examination of Air as an Australian/New Zealand Standard to supersede AS 3580.2.21990. The Standard deals with the preparation of reference test atmospheres for ambient air analysers utilizing compressed gas Certified Reference Materials (CRMs).FOREWORDThe calibration and verification of ambient air analyser response is principally carried out utilizing a compressed gas CRM and associated dilution apparatus. This has resulted in a need to standardize the procedures followed and to specify quality assurance requirements.METHOD1 SCOPEThis Standard sets out a method for the preparation of reference test atmospheres containing known concentrations of determinand(s), using a calibration gas dilution method.The method is applicable to components that do not react with each other, the cylinder walls or the dilution gas, and that remain totally vaporized in the cylinder at all pressures and temperatures anticipated during the preparation and use of the reference test atmosphere.2 REFERENCED DOCUMENTSThe following documents are referred to in this Standard: AS2030The verification, filling, inspection, testing and maintenance of cylinders for storage and transport of compressed gases2030.1Part 1: Cylinders for compressed gases other than acetylene2473Valves for compressed gas cylinders2473.1Part 1: Specifications, type testing, and manufacturing tests and inspectionsCOPYRIGHT11AS/NZS 3580.2.2:2009The Standard is downloaded from www.bzfxw.com Standard SharingISOGuide to the expression of uncertainty in measurement (ISO GUM)NATATechnical Note 8In-situ calibration of barometersTechnical Note 19 Liquid-in-glass thermometersSelection, use and calibration checks3 DEFINITIONSFor the purpose of this Standard the following definitions apply:3.1 Certified Reference Material (CRM)Reference material, accompanied by an endorsed document issued by either a NATA/IANZ accredited calibration laboratory, or a calibration laboratory accredited by one of NATA/IANZs Mutual Recognition Agreement (MRA) partners, one or more of whose property values are certified by a procedure which establishes traceability to an accurate realisation of the unit in which the property values are expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence.3.2 Full scaleThe nominated maximum concentration for which an instrument has been calibrated. Selected to cover the normal range of values expected in the sampling environment.3.3 LinearityThe deviation of an analysers output from a line of best fit when subjected to varying test atmospheres.3.4 Parts per million (ppm)A ratio expressing the volume of gaseous pollutant contained in 1 000 000 volumes of atmosphere. It may be expressed in terms of millilitres per cubic metre as the values are identical. Alternatively, it is one million times the ratio of the partial pressure of gaseous pollutant to the pressure of the atmosphere in which it is contained.3.5 Test atmosphereA reference test atmosphere containing a known concentration of pollutant.3.6 U95A measurement uncertainty at a confidence interval of 95% according to ISO GUM.3.7 Zero airAir free from contaminants likely to cause a detectable response on the test analyser.4 PRINCIPLEThe reference test atmosphere is produced by the dilution of a compressed gas CRMutilizing zero air.5 APPARATUS5.1 Certified Reference Material cylinderA gravimetric or volumetric standard compressed gas CRM that serves as a source of determinand of known concentration.COPYRIGHT5.2 Zero airA supply of regulated zero air from either a cylinder or other suitable supply source. The concentration of oxygen in the zero air shall be within 2% v/v of the normal composition of air (20.9% v/v).5.3 Dilution apparatusA device capable of blending zero air with CRM at known concentrations.5.4 Gas transfer linesTubing or manifold used to transport zero air, CRM and the blended product.5.5 Reference flow meterA reference (working standard) flow meter(s), traceable to national standards, is required for the calibration of the dilution apparatus flow controller(s). The reference flow meter uncertainty shall be lesser of 2% U95 at any flow controller test po