Chemistry:R-469A

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Short description: Refrigerant mixture

R-469A is the name given to a refrigerant mixture. It is made up of 35% carbon dioxide (R-744), 32,5 % Difluoromethane (R-32) und 32,5 % Pentafluoroethane (R-125).

History

The mixture was developed by TU Dresden and Weiss Technik (a member of the Schunk Group of companies).[1] Starting point for the development was the restriction in use of the refrigerant Fluoroform (R-23) by EU regulation 517/2014 [2] on fluorinated greenhouse gases. At this time, R-23 was the refrigerant used most often to achieve temperatures of up to –70 °C. Since 2014 R-23 has only been allowed to be used in new refrigerating equipment and devices within the context of transitional regulations. This has led to a significant shortage of the quantity available, among other things, and an enormous increase in price.[3]

The aim of the project was to develop a new refrigerant for temperatures down to –70 °C which fulfils the requirements of the EU regulation and is not combustible or toxic. In 2019 the mixture was registered with ASHRAE for the assignment of an R-number, which was allocated in the same year.[4]

Properties

Properties Value[5]
Composition

35% R-744 (CO2)
32,5 % R-32 (CH2F2)
32,5 % R-125 (C2HF5)

average molar mass [g/mol 59,1
Bubble point [°C] −78,5
Dew point [°C] −61,5

R-469A is a chemically stable, transparent and odourless gas mixture.[6] Since it is non-toxic and non-combustible, it has been graded in safety group A1. The global warming potential (GWP) ) of R-469A is 1357 and thus less than 10% of the value for R-23 (GWP 14800[2]). Thanks to the low GWP value it fulfils the requirements of EU regulation 517/2014 on refrigerants for new systems even without the certificate of exemption otherwise necessary. Systems using the refrigerant R-469A up to 3.6 kg filling quantity are exempt from the Leak test in accordance with EU regulation 517/2014.[7]

Use

R-469A is used in test chambers for climate simulation which reach low temperatures of up to –70 °C. It is used as a substitute for R-23. The properties of R-469A with a view to cooling rate, thermal compensation or air distribution are almost identical to those of R-23. This makes the test results of systems using the two refrigerants directly comparable.[8]

Trade names

  • WT69

Individual references