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Evaluation of the possibilities of substituting potent greenhouse gases (HFCs, PFCs and SF6) 4 Application of PFC substances and their substitution possibilities
PFC substances are perfluorocarbons, i.e. substances developed on the basis of simple hydrocarbons where all hydrogen atoms have been replaced by fluoride atoms. It is substances like CF4, C2F6, C3F8, etc. Stable substances These substances are very stable and have thus a very long atmospheric life. They are at the same time very potent greenhouse gases. However, only small amounts of these substances are used in the Danish industry, and the main area of application is in refrigeration systems. There is a certain emission of PFC abroad in connection with production of aluminium, which is produced from aluminium oxide (alumina) in an electrolytic process. The PFC substances are only developed when a special effect occurs (i.e. the anode effect), in which the electric voltage grows fast by means of which PFC substances (CF4 and C2F6) are developed locally. The fluoride atoms come from cryolite (Na3AlF6) acting as a catalytic converter in the process. Norway and Iceland have in recent years done much to reduce development and emission of PFC substances. A great deal of the substance C6F14 is used abroad in the electronic industry.
Drop-in According to the analysis of the Danish Environmental Protection Agency, approx. 6.4 tons of C3F8 (R-218) was used in 1999 as refrigerant in a special mixture. The refrigerant is used as a "drop-in" substitute for CFC-12 in refrigeration systems. The consumption is stagnant and was approx. 8 tons in 1997. The refrigerant mixture is known under several terms, including Isceon 49 (R-413A) consisting of approx. 88% of HFC-134a, 9% of C3F8 and 3% of isobutane. According to Kølebranchens MiljøOrdning (KMO) (the Danish refrigeration industry's environment scheme), there are approx. 2,000 systems charged with R-413A in Denmark. The Danish Technological Institute has demonstrated that systems with Isceon 89 exist, which is a mixture of HFC-125 (86%), C3F8 (9%) and propane (5%). It is a refrigerant which has been developed as a "drop-in" substitute for R-13B1 and is used for low-temperature purposes (–40 to –50°C). New mixtures are emerging all the time, but the industry is very cautious about using refrigerant mixtures, as there is doubt about the concentration of the remaining mixture after leakage, and because it is not desired to transport more types of refrigerants than is strictly necessary in the service vans. Prolonged life The mixtures can be convenient to use if prolonged life is desired for a system, which originally was designed for CFC refrigerant. The only reason for using these mixtures is to prolong the life of old refrigeration systems. It is possible to avoid this application either by converting the refrigeration systems for HFC refrigerant or keep the systems tight until they have to be scrapped. 4.2 Other applications of PFC substancesA small amount of PFC substances are used for producing electronic and optical microchips in Denmark. This application is described in chapter 5. Moreover, an amount of PFC is used for cleansing of electronic components. The total amount of PFC used for cleansing electronics was approx. 1.5 tons of C3F8 in 1999. It can also be mentioned that a PFC substance has been tried to be sold abroad as a fire extinguishant as substitute for halons. This application of PFC is prohibited in Denmark (cf. section 3.3).
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