What is the difference between Standard and Environmental Grade Gases? 

Linde mixtures are grouped into two basic categories, environmental and standard. Please refer to the table on our Gas Composition page for complete specifications of all available grades. 

Environmental Grades

Environmental Grades have been developed to meet the stringent requirements of specific environmental applications such as EPA Protocols, I&M (Inspection and Maintenance) emission standards, and mixtures requiring NIST Traceability. In all cases, specifications have been developed to meet industry standards or, in some cases, to meet regulatory requirements.

When EPA Protocols are not necessary, but NIST traceability is desired, Linde’s master grades provide the highest degree of accuracy and confidence for your most demanding applications. These mixtures are prepared gravimetrically on high precisions, electronic balances or with state-of-the-art dynamic blenders.
The accuracy from these methods generally exceed the accuracy of most analytical instruments. Linde produces three grades within the Master category; Primary, Certified, and Dynamic-Blend. The minor component(s) are analyzed and certified by Linde and are traceable to NIST reference material.


Standard Grades

For general purposes, Linde’s standard grades are available as Primary and Certified. These analyzed standards are typically used for high volume applications where the blending precision and accuracy of the Master grade is not required. Standard grade mixtures are prepared using gravimetric, volumetric, or partial pressure methods. As in the Master grades, the minor component(s) are analyzed and certified. The economical Non-Certified grade is suitable for applications that do not require analytical certification.

If your requirements call for specifications that fall outside of those defined by Linde’s various grades, a custom standard will include the exact specifications you need.