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Daimler balks at use of low GWP R-1234yf refrigerant, citing new internal safety findings; wants to continue using R-134a (updated)
25 September 2012
Daimler announced that findings from a new internal investigation have raised questions on the safe usage of R-1234yf as a replacement refrigerant in mobile air conditioning (MAC) systems. Due to the new findings of this study and the high safety demands at Mercedes-Benz, Daimler says that it will not use this chemical in its products. The company stated that it therefore wishes to continue to use R-134a refrigerant in its vehicles.
Over the last several years, the automotive industry has been tracking to replace the mobile air conditioning (MAC) refrigerant R-134a, which has a global warming potential (GWP) of 1,430, with the lower-GWP refrigerant R-1234yf (GWP = 4). In 2009, for example, a two-year Cooperative Research Program conducted through SAE International to investigate the safety and environmental performance of R-1234yf concluded that it could can be used as the global replacement refrigerant in MAC systems and could be safely accommodated through established industry standards and practices for vehicle design, engineering, manufacturing, and service. The report was the third SAE report to evaluate the new refrigerant. (Earlier post.)
Much of the momentum for the shift originally came from the EU’s directive on mobile air-conditioning systems (MACs), which aims to reduce emissions of specific fluorinated greenhouse gases in the air-conditioning systems fitted to passenger cars (vehicles of category M1) and light commercial vehicles (category N1, class 1).
The main objectives of the Directive are:
the control of leakage of fluorinated greenhouse gases with a global warming potential (GWP) higher than 150 in MACs; and
the prohibition from a certain date of MACs using those gases.
Beginning 21 June 2008 (12 months from the date of adoption of the test procedure) European automakers were unable to obtain a type approval for a new type of vehicle if it is fitted with MACs designed to contain fluorinated gases with a GWP higher than 150 leaking more than 40 grams per year (one evaporator systems) and 60 grams per year (dual evaporator systems). As from 21 June 2009 this also applied for all new vehicles having been type-approved in the past.
As of 1 January 2011, manufacturers have been unable to obtain a type approval for a new type of vehicle if it is fitted with these kinds of systems) and as from 1 January 2017 for all new vehicles. From that date on, new vehicles with these systems cannot be registered, sold and enter into service.
Honeywell, in collaboration with DuPont, developed HFO-1234yf in response to the directive.
Daimler acknowledged that up to now, the more climate-friendly chemical was set to be used worldwide in the automotive industry and was previously perceived to be safe. This was determined by numerous laboratory and crash tests carried out by international vehicle manufacturers and independent institutions.
Despite the multiple confirmations of non-critical results, however, Daimler carried out a series of additional tests on the new refrigerant as part of a new real-life test scenario developed in-house which goes above and beyond the legally prescribed requirements.
In the new real-life test scenario, the refrigerant is dynamically dispersed at high pressure near hot components of the test vehicle’s exhaust system. This corresponds to a serious head-on collision in which the refrigerant line is severed. The reproducible results demonstrate that refrigerant which is otherwise difficult to ignite under laboratory conditions can indeed prove to be flammable in a hot engine compartment. Similar tests of the current R-134a refrigerant did not result in ignition.
Daimler said it has already informed the relevant authorities of these facts and said will also make the results of this investigation available to all relevant associations as well as to other vehicle manufacturers.
With respect to the impact of the findings and the decision on Daimler in the context of the MAC directive, Daimler spokesperson Matthias Brock said that the company expects that it and the authorities will come to a mutual agreement.
Until further notice, the tried-and-tested R134a refrigerant is the technical alternative. In such a globalized world, there can really only be a single refrigerant which all vehicle manufacturers use. We will involve ourselves extensively in the international selection process. Together with our technology partners, we will be intensively looking at a long-term solution.—Matthias Brock
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