Types of Grades Available

EPA Protocol Gases
EPA Protocol Gases are manufactured and analytically certified in strict accordance with the most recent EPA traceability guideline document entitled “EPA Traceability Protocol for Assay and Certification of Gaseous Standards”. The majority of EPA Protocol mixtures are certified to a +/- 1% overall uncertainty guarantee, except where limited by the higher uncertainty of the NIST Standard Reference Materials (SRMs) or NIST Traceable Reference Materials (NTRMs). All analytical certifications are performed under completely interference-free conditions. Maximum allowable shelf life is guaranteed. Documentation fully conforms to the requirements of the EPA Protocol program, in compliance with the Clean Air Act.

Traceability Standards
Traceability Standards are calibration mixtures, which are analytically certified directly against either NIST SRMs or
NTRMs, within a comprehensive quality system. The analytical testing process is based upon the EPA Protocol document, including triad analysis, comprehensive instrumentation characterization, and statistical data analysis. This results in a +/- 1% overall uncertainty (accuracy) with direct traceability to NIST Reference Materials.

Precision Blends
Precision Blends are developed to satisfy customer requirements for “zero blend tolerance” mixtures. These blends are manufactured by dynamically mixing the mixture components in real time while monitoring the composition using continuous analytical monitoring. Minor adjustments are made as needed during the blending process to assure the final mixture is statistically identical to the requested composition, as shown through careful analysis.

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Primary Standards
Primary Standards, often referred to as NIST Traceable By Weight Mixtures, should be used when your application
demands the highest mixture accuracy and reliability. Primary Standards are produced gravimetrically on sophisticated high-load, high-sensitivity scales, with statistically measured precision and accuracy. These weighing systems are stringently calibrated with NIST Class S weights, in accordance with ISO procedures. Gravimetric blending offers the closest tolerance available, often better than available through laboratory testing. A dual verification of mixture accuracy is also performed by routine quality control analysis on instrumentation
calibration.

Certified Standards
Certified Standards, sometimes referred to as working standards, are analyzed calibration mixtures used routinely in science and industry. For the majority of applications, the tolerance of a Certified Standard is acceptable. These standards are generally prepared either by partial pressure or gravimetrically. Certification of the standard is performed through quality control analysis on instrumentation calibrated.