A new EPDM rubber compound dedicated to R744 refrigerant

Hutchinson has developed an elastomer compound specially designed to meet the sealing needs of components used for heat pump applications in electric vehicles using the R744 refrigerant (valves, compressors, etc.).

Co-design and validation

The development of this innovative material was made possible thanks to the expertise of our teams in the formulation of elastomer materials and a close collaboration with the Volkswagen Group and a major thermal management equipment manufacturer. In addition to laboratory tests, functional validations were carried out with expert appraisal of the parts, confirming the technical solution with the EPDM 8EP3411 compound. Sealing solutions made with this EPDM are used in series production on vehicles equipped with the MEB platform, such as ID.3.

Thermal performance

Compared with traditional EPDM materials, this elastomer compound offers enhanced thermal performance with a temperature range from -40 to +165°C, corresponding to the optimum operating temperatures for heat pumps running on R744.

High-pressure resistance

A complete re-engineering of existing solutions enabled us to meet the new specifications. The 80 Shore A hardness makes it suitable for high-pressure applications of up to 130 bar. The seal environment still needs to be designed to limit extrusion gaps. The development teams are currently working on an elastomer with a hardness of 90 Shore A for the most extreme pressure conditions.

Resistance to Explosive Decompression (RGD – Rapid Gas Decompression)

Resistance to explosive decompression is a critical characteristic for elastomers to avoid physical degradation of seals (cracking, crazing, bubbles, etc.). Specific tests were carried out to reach the final formulation. 8EP3411 complies with the Norsok M710 standard: Rating 0, confirming the absence of defects after exposure.

A solution for the future

Already used in heat pump systems on buses and trains, and in industrial air conditioning systems such as supermarket refrigeration systems, environmental and now legislative constraints are likely to increase the use of R744 more widely in industrial applications such as residential heat pumps.

The planned end to the internal combustion engine vehicles in Europe in 2035, combined with environmental issues (PFAS, GWP, etc.), also make R744 a serious option for becoming the standard refrigerant for automotive applications in Europe.