Identification and brief toxicological assessment of combustion products of the refrigerant HFO-1234yf.
This study aims to identify chemical reaction products upon combustion of the new freon HFO-1234yf intended for mobile air-conditioning systems. It also summarize possible negative health effects of the identified gases. The experiment was performed with controlled combustion of HFO-1234yf in a dynamic laboratory setup at two different air-to-freon mixtures. The chemicals were detected by means of GC-MS, FTIR, and Draeger tubes. Twenty-five chemicals were identified and emission factors were determined as mass of the emission product per supplied HFO-1234yf. The major detected components were unburned HFO-1234yf (220-480 mg/g), carbonyl difluoride (170-360 mg/g), carbon dioxide (120-320 mg/g) and hydrogen fluoride (70-240 mg/g).
Both carbonyl difluoride and hydrogen fluoride are strongly corrosive to tissues such as skin, eyes and the respiratory tract. Carbonyl difluoride is highly reactive with water and decomposes into hydrogen fluoride and carbon dioxide upon contact with humid air, eyes or mucus in the respiratory tract. Hydrogen fluoride can penetrate tissues and exposure to hydrogen fluoride may induce hypocalcaemia by binding to calcium. At lower levels, carbon monoxide (5-80 mg/g) was detected. Inhalation may lead to cellular hypoxia since carbon monoxide has a higher affinity to haemoglobin as compared to oxygen. In addition, a number of fluorinated hydrocarbons were detected at considerably lower levels. The majority of these are not acutely toxic to humans.
In this study, we found that HFO-1234yf required a hot surface to sustain fire. We consider the risk of fire of HFO-1234yf to be low. However, in situations with burning vehicles the temperature will possibly reach levels that ignite HFO-1234yf. The intended use for this report is to serve for automotive industry, rescue services, and other stakeholders to take the correct choices when implementing new technology of the refrigerant and to increase awareness for those who may come into contact with fire products.
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