Mercedes-Benz Independent Study Finds New Refrigerant to Be Dangerous
In real-life test scenarios, the new refrigerant is flammable when in a head-on collision unlike the previous R134a refrigerant
by Jim Davis | 25 September 2012
Daimler has provided relevant authorities with the findings of an investigation which raises questions on the safe usage of the new internationally recognised R1234yf refrigerant. Up to now, the 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 multiple confirmations of non-critical results, 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 to hot components of the test vehicle’s exhaust system. This corresponds to a serious head-on collision in which the refrigerant line is severed and the reproducible results demonstrate that the 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 R134a refrigerant did not result in ignition.
Due to the new findings of this study and the high safety demands at Mercedes-Benz, this chemical will not be used in its products. The company therefore wishes to continue to use the proven and safe R134a refrigerant in its vehicles.
Daimler has already informed the relevant authorities of these facts and will also make the results of this investigation available to all relevant associations as well as to other vehicle manufacturers.
For those of you unfamiliar with R1234yf refrigerant, it is a hydrofluoroolefin with the formula CH2=CFCF3. It has been proposed as a replacement for R-134a as a refrigerant in automobile air conditioners.
HFO-1234yf is the first in a new class of refrigerants acquiring a global warming potential (GWP) rating 335 times less than that of R-134a (but still 4 times higher than the alternative substitute R-744) and an atmospheric lifetime of about 400 times shorter. It was developed to meet the European directive 2006/40/EC that went into effect in 2011 requiring that all new car platforms for sale in Europe use a refrigerant in its AC system with a GWP below 150.
HFO-1234yf, which has a GWP of 4, could be used as a “near drop-in replacement” for R-134a, the current product used in automobile AC systems, which has a GWP of 1430. This means that automakers would not have to make significant modifications in assembly lines or in vehicle system designs to accommodate the product. HFO-1234yf has the lowest switching cost for automakers among the currently proposed alternatives, although the initial cost of the product is much higher than that of R134a. The product could be handled in repair shops in the same way as R-134a, although it would require different, specialized equipment to perform the service. One of the reasons for that is the mild flammability of HFO-1234yf. Another issue affecting the compatibility between HFO-1234yf and R-134a-based systems is the choice of lubricating oil.Current oil is showing signs of damage to plastic, aluminium and issues with health, mouth dryness, rash, sore throat among others affects.
Shortly after confirmation from automakers that HFO-1234yf would be adopted as a replacement of R134a automotive air-conditioning refrigerant, Honeywell and DuPont announced that they will jointly build a manufacturing facility to produce HFO-1234yf which is in operation now. Although others claim to be able to make and sell HFO-1234yf, Honeywell and DuPont hold most or all of the patents registered for HFO-1234yf.
On July 23, 2010, General Motors announced that it will introduce HFO-1234yf in 2013 Chevrolet, Buick, GMC and Cadillac models in the U.S.
Although the product is classified slightly flammable by ASHRAE, several years of testing by SAE proved that the product could not be ignited under conditions normally experienced by a vehicle. In addition several independent authorities evaluated the safety of the product in vehicles and some of them concluded that it was as safe to use as R134a, the product in use in cars today. In the atmosphere, HFO-1234yf degrades to trifluoroacetic acid, which is a mildly phytotoxic strong organic acid with no known degradation mechanism in water. In case of fire it can release highly corrosive and toxic hydrogen fluoride.