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Environmental

Product Summary

Environmental Grades Standard Grades
Praxair’s North American Specialty Gases sales, technical When NIST traceability is not required, Praxair’s standard
support and production teams will provide you with the grades are available to meet your working gas requirements.
right information and products for all your environmental In addition to Primary, Certified and Non-Certified
applications.
Standards, Praxair’s unique Custom Standard allows
Our extensive product offering includes: you to specify the exact blend tolerance and analytical
■ NIST Traceable Reference Materials (NTRM) – uncertainty for the mixture.
Certified by the National Institute of Standards and ■ Primary Standard – Highly accurate mixtures prepared
Technology (NIST) and accepted by the Environmental gravimetrically on high-precision electronic balances.
Protection Agency (EPA), as the highest accuracy These standards are analyzed against Praxair Primary
standards commercially available. These standards Laboratory Standards (PPLS) and named to a gravime-
are the regulatory equivalent to NIST’s Standard trically generated concentration.
Reference Materials (SRMs). NTRMS are made using ■ Certified Standard – These routine calibration mixtures
the same components and are within the are prepared by either gravimetric, volumetric or partial
analytical range of NIST SRMs. pressure methods. These standards are analyzed
■ EPA Protocols – These gas mixtures are used for the against Praxair Primary Laboratory Standards (PPLS).
calibration and audit of Continuous Emission Monitors ■ Non-Certified – Mixtures are prepared by the same
(CEMs). Praxair EPA Protocols are NIST traceable with methods and the same care used for Certified Standard
a ±1% accuracy and produced in accordance with the
latest EPA specifications found in document – Grades. Analyses are not reported.
EPA 600/R-12/531 Rev. 5/2012. ■ Custom – Mixtures prepared to the exact blend
■ Primary Master – High accuracy mixtures prepared tolerance and analytical uncertainty requested.
gravimetrically on electronic high precision scales.
These standards are analyzed and named against
NIST traceable reference materials.
■ Certified Master – These routine calibration mixtures
are prepared by either gravimetric, volumetric or partial
pressure methods and analyzed against NIST traceable
reference materials. Environmental
■ Dynamic-Blend Master – These zero blend tolerance
mixtures are prepared on an instrument based dynamic
blending system. All master gases are analyzed and
named against NIST, SRM or NTRMs. Replication for
any number of cylinders can be produced with identical
concentrations.
■ Dynamic-Blend Standard – These mixtures are
prepared similarly to the Dynamic Blend Master.
Certification of the mixtures is based on process
accuracy and Praxair Primary Laboratory Standards
(PPLS).

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