Manufacturing and Processes

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A strict blend of adherence and expertise

There is a lot more to the EPA protocol gases you use than your average calibration gas mixture. As part of the Airgas Specialty Gases offering, our EPA protocols are on spec, all the time. To ensure your operation maintains compliance, our EPA protocol gases are manufactured leveraging Airgas’ technical expertise and a strict adherence to traceability.

Blending processes and technologies

All Airgas EPA protocol gases are made in strict accordance with the EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards (certified to ±1%) using our advanced filling systems and gas cylinder treatment processes.

  • AcuGrav®

    Think differently about what you used to expect in terms of gas mixture precision and consistency—because our labs have it down to a science with AcuGrav®. Our patented filling system eliminates human error by providing automated, multi-component gas blending that delivers precise and consistent gas mixtures, cylinder to cylinder and batch to batch.


    Know exactly what’s in your gas with automated FTIR analysis. AutoFTIR® validates gas blend components and concentrations for high-precision gas mixtures such as EPA protocol gases. This analysis references all components of a sample against a known standard to identify the precise composition of your gas.

    Automated lab packs

    Lab pack data acquisition systems eliminate your concerns about human error with data entry, interpretation and transcription of results.


    When it comes to your EPA protocol gases, getting exactly what you ordered is critical. ACUBLENDTM uses high resolution, real-time analyzers to blend, mix, compress and analyze gas mixtures in a single operation using either gas or liquid phase minor components. Because ACUBLEND is so tightly controlled, zero blend tolerance results in receiving exactly the concentration you ordered. Gas mixtures are completely homogeneous from top to bottom within the cylinder, from cylinder to cylinder, and even from batch to batch, improving accuracy and dependability, and eliminating the need for recalibration due to variations in mixture concentrations.

Standard and custom EPA protocol gases

Sometimes your application calls for a custom approach—and we can help. Airgas offers a wide variety of EPA protocol gases as standard. We have a proven track record of blending stable and accurate gases. When you have difficult components or a tricky preparation process, tap into our technical database to create custom or quasi-protocols.

SRM-contracted provider

National Institute of Standards and Technology (NIST) trusts Airgas to provide Standard Reference Materials (SRMs) for calibration gas mixtures that serve as the basis for production of all EPA protocol gases used for calibrating emissions monitoring equipment.


Talk to an Airgas specialist about achieving cleaner air, regulatory compliance and more.


Talk to an Airgas specialist about achieving cleaner air, regulatory compliance and more.

EPA Protocol Gas Verification Program (PGVP) participant

Airgas is a registered participant in the EPA’s Protocol Gas Verification Program (PGVP) for stationary source monitoring. This check and balance system helps gas manufacturers stay on track to provide the most accurate EPA protocol gases that ensure regulatory compliance throughout the industry.

Airgas PGVP-certified production sites

EPA protocol gases shelf life and certification periods

Certification periods for EPA protocol gases have been established by EPA in accordance with the May 2012 “EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards.”

GMAC standards

Sometimes EPA protocol gases are not available or approved to comply with EPA regulations governing the monitoring of certain emissions. In the case of hydrogen chloride monitoring at stationary sources, there is a regulatory void caused by the absence of EPA protocol gases. Airgas is the only provider of GMACS (Gas Manufacturer’s Alternative Certified Standards) HCl solutions that fill this void. Below illustrates the traceability and certification scheme for GMACS from Airgas. GMACS monitor emissions subject to compliance under the following EPA regulations:

  • 40 CFR Part 63 Subpart LLL (Portland Cement MACT)
  • 40 CFR Part 63 Subpart UUUUU (Utility MACT)
  • 40 CFR Part 63 Subpart DDDDD
  • 40 CFR Part 60 Subparts CCCC and DDDD

Airgas primary certification scheme for HCI standards