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Mixtures Grade Specifications Praxair Grades Environmental Grades ■ NTRM – NIST Traceable Reference Materials are certified by the National Institute of Standards and Technology (NIST) and accepted by the Environ- mental Protection Agency (EPA), as the highest accuracy standards com- mercially available. These standards are the regulatory equivalent to NIST’s Standard Reference Materials (SRMs) and are made up of the same compon- ents and are within the analytical range of NIST SRMs. ■ EPA Protocols – Used for the calibration and audit of Continuous Emission Moni - tors (CEMs), Praxair EPA Protocols are NIST traceable and produced in accor- dance with the latest EPA specifications found in document-600/R97/121 Rev. 9/97. ■ Primary Master – High accuracy mix- tures prepared gravimetrically on electronic high-precision balances. These standards are analyzed and named against NIST traceable reference materials. ■ Certified Master – These routine cali- bration mixtures are prepared by either gravimetric, volumetric or partial pressure methods and analyzed against NIST traceable reference materials. ■ Dynamic-Blend Master – These zero blend tolerance mixtures are prepared on an instrument based dynamic blending system. Batches of cylinders from two to one hundred can be produced with the identical concentrations. ■ Dynamic-Blend Standard – These mix- tures are prepared similarly to the Dynamic Blend Master. Certification of the mixtures is based on process accuracy and Praxair Primary Laboratory Standards (PPLS). All master gases are analyzed and named against NIST traceable materials. Standard Grades ■ Primary Standard – Highly accurate mixtures prepared gravimetrically on high-precision electronic balances. These standards are analyzed against Praxair Primary Laboratory Standards (PPLS) and named to a gravimetrically generated concentration. ■ Certified Standard – These routine calibration mixtures are prepared by either gravimetric, volumetric or partial pressure methods. These standards are analyzed against Praxair Primary Laboratory Standards (PPLS). ■ Non-Certified – Mixtures are prepared by the same methods and the same care used for Certified Standard Grades. Analyses are not reported. ■ Custom – Mixtures prepared to the exact blend tolerance and analytical uncertainty requested. Example: Blend Tolerance Relative Value Blend Tolerance Requested Concentration 5.10% 5.20% 4.75% Absolute Value ± 5% of minor ± 0.25% component Analytical Uncertainty ± 2% of minor ± 0.10% component 5% Reported Concentration Certification Accuracy 5.25% Mixture Grade NTRM Order EV – Environmental Grades(1) T EPA Protocol E Primary Master N Mixture Component Blend N/A 2 ppm - 25 ppm 25.1 - 49.9% 1 ppm - 9.9 ppm 10 ppm - 25 ppm Certified Master M Dynamic Blend D Master Dynamic Blend Y Standard ST – Standard Grades Primary Standard P 1 ppm - 25 ppm 1 ppm - 99 ppm 100 ppm - 49.9% 1 ppm - 99.9 ppm 100 ppm - 49.9% 1 ppm - 9.9 ppm 10 ppm - 25 ppm Certified Standard C Non-Certified U Standard Custom Standard Z * Whichever is smaller. (1) 1 ppm - 99.9 ppm 1 ppm - 999 ppm 0.1% - 49.9% 1 ppm - 49.9% N/A ± 10% ± 5% ± 10% ± 10% 25.1 ppm - 9999 ppm ± 5% 1.0% - 49.9% ± 2% 25.1 ppm -999 ppm ± 10% 0.1% - 49.9% ± 20% ± 5% Zero Zero Zero Zero ±10% ±10% 25.1 ppm - 999 ppm ±5% 0.1% - 49.9% ±2% 100 ppm - 999 ppm ±10% 0.1% - 49.9% ±20% ±5% ±20% ±10% TBD Analytical Reference Concentration Range Tolerance Uncertainty ≤ 1% ± 1% ± 1% ± 0.1 ppm ± 1% ± 1% ± 1% or 0.02% abs* ± 5% ± 2% ± 2% ± 2% ± 1% ± 5% ± 2% ±0.1 ppm ±1% ±1% ±1% or 0.02% abs* ±5% ±2% ±2% N/A TBD All Environmental Grades are NIST traceable. Actual ranges, blend tolerance and analytical uncertainty are based on available National Institute of Standards and Technology (NIST) SRM concentrations. Please see individual components for specific information. Note: For all mixtures, blend tolerance and analytical uncertainty specification may vary depending on the chemical characteristics of the component and the cylinder size. For mixtures outside of these ranges, please contact your local Praxair representative. D 1 1-877-PRAXAIR www.praxair.com/specialtygases