Case Study on the Rupture Morphology of a Copper Tube in an Air Conditioner Condenser After Fire
The new eco-friendly flammable refrigerant in air conditioners has resulted in an annual increase in fire incidents associated with these units. Fire investigators face significant challenges in identifying the causes of these fires. In this study, copper tube samples were extracted from various loc...
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| Format: | Article |
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MDPI AG
2025-04-01
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| Series: | Fire |
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| Online Access: | https://www.mdpi.com/2571-6255/8/4/145 |
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| author | Yunlong Ou Ming Fu Jing Zhang Wenzhong Mi Changzheng Li Shouhai Chen Shoulei Zheng |
| author_facet | Yunlong Ou Ming Fu Jing Zhang Wenzhong Mi Changzheng Li Shouhai Chen Shoulei Zheng |
| author_sort | Yunlong Ou |
| collection | DOAJ |
| description | The new eco-friendly flammable refrigerant in air conditioners has resulted in an annual increase in fire incidents associated with these units. Fire investigators face significant challenges in identifying the causes of these fires. In this study, copper tube samples were extracted from various locations of air conditioner condenser debris post fire. The morphology characteristics of the ruptured copper tubes formed by a high-temperature flame in fire and that formed by corrosion were analyzed, respectively. The findings indicate that the ruptures in the copper tubes of air conditioners may be classified into two types based on their origins: ruptures resulting from fire and ruptures resulting from corrosion. The ruptures in the copper tubes resulting from fire are associated with the presence of aluminum alloy fins. At elevated temperatures, the copper and aluminum atoms persist in diffusing and fracturing. A significant quantity of silver-white aluminum is present surrounding the ruptures, and distinct elemental layers may be seen in the cross-section. The corrosion-induced ruptures in the copper tubes are associated with ant nest corrosion. Despite the influence of high-temperature flame melting on surface corrosion pits, they will not entirely obscure the pits and the cross-section continues to exhibit the bifurcated structure characteristic of ant nest corrosion. This investigation demonstrates that corrosion of ant nests is the root cause of copper tube breakage obscured by flames. An investigation method for the refrigerant leakage air conditioning fire is proposed. The above findings can provide proof and method for air conditioning fire investigation. |
| format | Article |
| id | doaj-art-23eaadbf31e34d5ea616ca45b190db78 |
| institution | OA Journals |
| issn | 2571-6255 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Fire |
| spelling | doaj-art-23eaadbf31e34d5ea616ca45b190db782025-08-20T02:28:22ZengMDPI AGFire2571-62552025-04-018414510.3390/fire8040145Case Study on the Rupture Morphology of a Copper Tube in an Air Conditioner Condenser After FireYunlong Ou0Ming Fu1Jing Zhang2Wenzhong Mi3Changzheng Li4Shouhai Chen5Shoulei Zheng6School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, ChinaHefei Institute for Public Safety Research, Tsinghua University, Hefei 230601, ChinaHefei Institute for Public Safety Research, Tsinghua University, Hefei 230601, ChinaHefei Institute for Public Safety Research, Tsinghua University, Hefei 230601, ChinaHefei Institute for Public Safety Research, Tsinghua University, Hefei 230601, ChinaHisense Air Conditioning Co., Ltd., Tsingdao 266736, ChinaTsingdao Haier Home Life Service Co., Ltd., Tsingdao 266103, ChinaThe new eco-friendly flammable refrigerant in air conditioners has resulted in an annual increase in fire incidents associated with these units. Fire investigators face significant challenges in identifying the causes of these fires. In this study, copper tube samples were extracted from various locations of air conditioner condenser debris post fire. The morphology characteristics of the ruptured copper tubes formed by a high-temperature flame in fire and that formed by corrosion were analyzed, respectively. The findings indicate that the ruptures in the copper tubes of air conditioners may be classified into two types based on their origins: ruptures resulting from fire and ruptures resulting from corrosion. The ruptures in the copper tubes resulting from fire are associated with the presence of aluminum alloy fins. At elevated temperatures, the copper and aluminum atoms persist in diffusing and fracturing. A significant quantity of silver-white aluminum is present surrounding the ruptures, and distinct elemental layers may be seen in the cross-section. The corrosion-induced ruptures in the copper tubes are associated with ant nest corrosion. Despite the influence of high-temperature flame melting on surface corrosion pits, they will not entirely obscure the pits and the cross-section continues to exhibit the bifurcated structure characteristic of ant nest corrosion. This investigation demonstrates that corrosion of ant nests is the root cause of copper tube breakage obscured by flames. An investigation method for the refrigerant leakage air conditioning fire is proposed. The above findings can provide proof and method for air conditioning fire investigation.https://www.mdpi.com/2571-6255/8/4/145air conditioning firefire investigationinternal thread copper tubehigh temperaturecorrosionrupture morphology |
| spellingShingle | Yunlong Ou Ming Fu Jing Zhang Wenzhong Mi Changzheng Li Shouhai Chen Shoulei Zheng Case Study on the Rupture Morphology of a Copper Tube in an Air Conditioner Condenser After Fire Fire air conditioning fire fire investigation internal thread copper tube high temperature corrosion rupture morphology |
| title | Case Study on the Rupture Morphology of a Copper Tube in an Air Conditioner Condenser After Fire |
| title_full | Case Study on the Rupture Morphology of a Copper Tube in an Air Conditioner Condenser After Fire |
| title_fullStr | Case Study on the Rupture Morphology of a Copper Tube in an Air Conditioner Condenser After Fire |
| title_full_unstemmed | Case Study on the Rupture Morphology of a Copper Tube in an Air Conditioner Condenser After Fire |
| title_short | Case Study on the Rupture Morphology of a Copper Tube in an Air Conditioner Condenser After Fire |
| title_sort | case study on the rupture morphology of a copper tube in an air conditioner condenser after fire |
| topic | air conditioning fire fire investigation internal thread copper tube high temperature corrosion rupture morphology |
| url | https://www.mdpi.com/2571-6255/8/4/145 |
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