SAE collaborating with VDA on standards for CO₂ MAC

In reaction to the ongoing activities related to development of standards for CO₂ mobile air-conditioning by the German association of the automotive industry (VDA) in collaboration with the German Institute for Standardisation (DIN), SAE International has re-initiated its project on reviewing the standards for R744 MAC systems so as to satisfy the requirements set under the Significant New Alternatives Policy (SNAP) Programme of the US Environmental Protection Agency (EPA).

Release in June 2012, the final use conditions for CO₂ in MAC under SNAP relate to:

• CO₂ concentration limits - the ceiling limit of 4% or 40,000 ppm in the passenger breathing zone
• Record keeping requirements of tests performed by OEMs
• Requirements for high-pressure system warning label, compressor cut-off switch, unique fittings

SAE standards for R744 MAC under revision

The SAE committee will focus on reviewing and, where necessary, completing these standards for R744 MAC systems:

• J2683—refrigerant purity and container requirements
• J2769—service hoses, fittings, and couplers
• J2770—service standards
• J2771—refrigerant removal and recharging equipment
• J2772—measurement of refrigerant concentration in the cabin under leakage conditions
• J2773—risk analysis
• J2774—minimum performance for electronic leak detectors
• J2775—minimum requirements for ultraviolet (trace dye) leak detection
• J2842—design criteria for evaporators
• J2845—technician training for service and containment of refrigerants

The standard J639 that sets safety requirements, including a flame symbol label to warn of flammability of refrigerants applies also to MAC. However, because R744 is not flammable, cars so equipped would not be required to have the warning symbol and notice on the underhood J639 label.

DIN specifications to be published for comments in spring 2014

The DIN specifications for standardising the components of CO₂ MAC are expected to be published in spring 2014 and experts, including the members of the SAE’s Committee will have two months to submit comments.

Within the VDA working group several car manufacturers (Daimler, Volkswagen, BMW and others) are collaborating on development of standards, while each is responsible for individual parts of the system.

While the German Institute for Standardisation (DIN) uses a three-year time frame for review, SAE's standard review period is five years. SAE ICCSC standards for air-conditioning are generally performance-related, whereas DIN’s are more construction-related.