Page 93 - Praxair - Specialty Gases and Equipment Reference Guide
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Grade Specifications






              Mixture            Order         Mixture Component     Blend Pre-    Analytical
              Grade              Reference     Concentration Range   Tolerance     Uncertainty
                 EV – Environmental Grades (1)
              NTRM               T             N/A                   N/A           ± 1%
              EPA Protocol       E             2 - 25 ppm            ± 10%         ± 1%
                                               25.1 - 49.9%          ± 5%          ± 1%
              Primary Master     PM            1 - 9.9 ppm           ± 10%         ± 0.1 ppm
                                               10 - 25 ppm           ± 10%         ± 1%
                                               25.1 - 9999 ppm       ± 5%          ± 1%
                                               1.0 - 49.9%           ± 2%          ± 1%
              Certified Master   CM            1 - 9.9 ppm           ± 20%         ± 0.2 ppm
                                               10 - 25 ppm           ± 20%         ± 2%
                                               25.1 - 9999 ppm       ± 10%         ± 2%
                                               1.0 - 49.9%           ± 5%          ± 2%
              Dynamic Blend      DM            1 - 99.9 ppm          Zero          ± 2%
              Master                           100 ppm - 49.9%       Zero          ± 1%
              Dynamic Blend      D             1 - 99.9 ppm          Zero          ± 5%
              Standard                         100 ppm - 49.9%       Zero          ± 2%
                 ST – Standard Grades
              Primary Standard   P             1 - 9.9 ppm           ± 10%         ± 0.1 ppm
                                               10 - 25 ppm           ± 10%         ± 1%
                                               25.1 - 9999 ppm       ± 5%          ± 1%
                                               0.1% - 49.9%          ± 2%          ± 1% or 0.02% abs*
              Certified Standard   C           1 - 99.9 ppm          ± 20%         ± 5%
                                               100 - 999 ppm         ± 10%         ± 2%
                                               0.1 - 49.9%           ± 5%          ± 2%
              Non-Certified      U             1 - 999 ppm           ± 20%         N/A
              Standard                         0.1 - 49.9%           ± 10%
              Custom Standard    Z             1 ppm - 49.9%         TBD           TBD
              *  Whichever is smaller.
              (1)   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.


                                                                       Blend Tolerance
                                                            s                                s
                                                                   Requested Concentration

              Example:    Relative     Absolute                               s  5.10%   5.20%
                          Value        Value
              Blend       ± 5% of minor    ± 0.25%
              Tolerance   component
              Analytical   ± 2% of minor    ± 0.10%     4.75%              5%     s         5.25%
              Uncertainty  component                                            Reported
                                                                               Concentration
                                                                               Certification
                                                                                Accuracy
     Section C – Mixtures
                                                                              s           s


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