Bursting potential of portable fire extinguishers at elevated temperatures

Tauno Andstén, Olavi Keski-Rahkonen, Jukka Myllymäki

Research output: Book/ReportReport

Abstract

Pressurised powder and water based extinguishers have traditionally not been equipped with safety devices against an incidental rise of the internal pressure. Such safety devices have, on the other hand, always been mandatory for carbon dioxide and halon extinguishers. Dissenting opinions have always been raised, particularly by ministries responsibly for technical safety issues and by pressure vessel authorities. The Finnish Ministry of the Interior requested VTT already in the 1980's a to carry out a study on the behaviour of pressurised portable fire extinguishers without safety devices when subjected to fire. In the present study, a set of equations for calculation of the pressure development inside a closed extinguisher as a function of temperature has been derived based on basic physical chemistry. The influence of the geometry of the extinguisher body on the strength of the cylinder has been calculated by applying equations for strength calculations related to internal pressure of pressure vessels. By combining the yield stress of steel with the temperature dependence of the strength of the extinguisher body a diagram has been designed showing the maximum allowed pressure as a function of the dimensions of the extinguisher. Three methods have been applied for determining the decomposition pressure of the fire extinguishing media as a function of temperature. Measurements of pressure vs. temperature showed a good correspondence with the presented theory. The total pressure build-up in the extinguisher could be explained as the sum of the partial pressures of the propellant and the thermally decomposing extinguishing media. This study does not consider the question on the necessity of safety devices of portable fire extinguishers. Pressurised powder and water based extinguishers have traditionally not been equipped with safety devices against an incidental rise of the internal pressure. Such safety devices have, on the other hand, always been mandatory for carbon dioxide and halon extinguishers. Dissenting opinions have always been raised, particularly by ministries responsibly for technical safety issues and by pressure vessel authorities. The Finnish Ministry of the Interior requested VTT already in the 1980's a to carry out a study on the behaviour of pressurised portable fire extinguishers without safety devices when subjected to fire. In the present study, a set of equations for calculation of the pressure development inside a closed extinguisher as a function of temperature has been derived based on basic physical chemistry. The influence of the geometry of the extinguisher body on the strength of the cylinder has been calculated by applying equations for strength calculations related to internal pressure of pressure vessels. By combining the yield stress of steel with the temperature dependence of the strength of the extinguisher body a diagram has been designed showing the maximum allowed pressure as a function of the dimensions of the extinguisher. Three methods have been applied for determining the decomposition pressure of the fire extinguishing media as a function of temperature. Measurements of pressure vs. temperature showed a good correspondence with the presented theory. The total pressure build-up in the extinguisher could be explained as the sum of the partial pressures of the propellant and the thermally decomposing extinguishing media. This study does not consider the question on the necessity of safety devices of portable fire extinguishers.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages44
ISBN (Print)951-38-6153-8
Publication statusPublished - 2003
MoE publication typeD4 Published development or research report or study

Publication series

SeriesVTT Tiedotteita - Research Notes
Number2200
ISSN1235-0605

Fingerprint

Fire extinguishers
Safety devices
Temperature
Pressure vessels
Fires
Halon
Physical chemistry
Propellants
Partial pressure
Yield stress
Carbon dioxide
Decomposition
Powders
Geometry
Steel

Keywords

  • portable fire extinguishers
  • high temperature
  • safety devices
  • risks
  • models
  • fire safety

Cite this

Andstén, T., Keski-Rahkonen, O., & Myllymäki, J. (2003). Bursting potential of portable fire extinguishers at elevated temperatures. Espoo: VTT Technical Research Centre of Finland. VTT Tiedotteita - Research Notes, No. 2200
Andstén, Tauno ; Keski-Rahkonen, Olavi ; Myllymäki, Jukka. / Bursting potential of portable fire extinguishers at elevated temperatures. Espoo : VTT Technical Research Centre of Finland, 2003. 44 p. (VTT Tiedotteita - Research Notes; No. 2200).
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Andstén, T, Keski-Rahkonen, O & Myllymäki, J 2003, Bursting potential of portable fire extinguishers at elevated temperatures. VTT Tiedotteita - Research Notes, no. 2200, VTT Technical Research Centre of Finland, Espoo.

Bursting potential of portable fire extinguishers at elevated temperatures. / Andstén, Tauno; Keski-Rahkonen, Olavi; Myllymäki, Jukka.

Espoo : VTT Technical Research Centre of Finland, 2003. 44 p. (VTT Tiedotteita - Research Notes; No. 2200).

Research output: Book/ReportReport

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N2 - Pressurised powder and water based extinguishers have traditionally not been equipped with safety devices against an incidental rise of the internal pressure. Such safety devices have, on the other hand, always been mandatory for carbon dioxide and halon extinguishers. Dissenting opinions have always been raised, particularly by ministries responsibly for technical safety issues and by pressure vessel authorities. The Finnish Ministry of the Interior requested VTT already in the 1980's a to carry out a study on the behaviour of pressurised portable fire extinguishers without safety devices when subjected to fire. In the present study, a set of equations for calculation of the pressure development inside a closed extinguisher as a function of temperature has been derived based on basic physical chemistry. The influence of the geometry of the extinguisher body on the strength of the cylinder has been calculated by applying equations for strength calculations related to internal pressure of pressure vessels. By combining the yield stress of steel with the temperature dependence of the strength of the extinguisher body a diagram has been designed showing the maximum allowed pressure as a function of the dimensions of the extinguisher. Three methods have been applied for determining the decomposition pressure of the fire extinguishing media as a function of temperature. Measurements of pressure vs. temperature showed a good correspondence with the presented theory. The total pressure build-up in the extinguisher could be explained as the sum of the partial pressures of the propellant and the thermally decomposing extinguishing media. This study does not consider the question on the necessity of safety devices of portable fire extinguishers. Pressurised powder and water based extinguishers have traditionally not been equipped with safety devices against an incidental rise of the internal pressure. Such safety devices have, on the other hand, always been mandatory for carbon dioxide and halon extinguishers. Dissenting opinions have always been raised, particularly by ministries responsibly for technical safety issues and by pressure vessel authorities. The Finnish Ministry of the Interior requested VTT already in the 1980's a to carry out a study on the behaviour of pressurised portable fire extinguishers without safety devices when subjected to fire. In the present study, a set of equations for calculation of the pressure development inside a closed extinguisher as a function of temperature has been derived based on basic physical chemistry. The influence of the geometry of the extinguisher body on the strength of the cylinder has been calculated by applying equations for strength calculations related to internal pressure of pressure vessels. By combining the yield stress of steel with the temperature dependence of the strength of the extinguisher body a diagram has been designed showing the maximum allowed pressure as a function of the dimensions of the extinguisher. Three methods have been applied for determining the decomposition pressure of the fire extinguishing media as a function of temperature. Measurements of pressure vs. temperature showed a good correspondence with the presented theory. The total pressure build-up in the extinguisher could be explained as the sum of the partial pressures of the propellant and the thermally decomposing extinguishing media. This study does not consider the question on the necessity of safety devices of portable fire extinguishers.

AB - Pressurised powder and water based extinguishers have traditionally not been equipped with safety devices against an incidental rise of the internal pressure. Such safety devices have, on the other hand, always been mandatory for carbon dioxide and halon extinguishers. Dissenting opinions have always been raised, particularly by ministries responsibly for technical safety issues and by pressure vessel authorities. The Finnish Ministry of the Interior requested VTT already in the 1980's a to carry out a study on the behaviour of pressurised portable fire extinguishers without safety devices when subjected to fire. In the present study, a set of equations for calculation of the pressure development inside a closed extinguisher as a function of temperature has been derived based on basic physical chemistry. The influence of the geometry of the extinguisher body on the strength of the cylinder has been calculated by applying equations for strength calculations related to internal pressure of pressure vessels. By combining the yield stress of steel with the temperature dependence of the strength of the extinguisher body a diagram has been designed showing the maximum allowed pressure as a function of the dimensions of the extinguisher. Three methods have been applied for determining the decomposition pressure of the fire extinguishing media as a function of temperature. Measurements of pressure vs. temperature showed a good correspondence with the presented theory. The total pressure build-up in the extinguisher could be explained as the sum of the partial pressures of the propellant and the thermally decomposing extinguishing media. This study does not consider the question on the necessity of safety devices of portable fire extinguishers. Pressurised powder and water based extinguishers have traditionally not been equipped with safety devices against an incidental rise of the internal pressure. Such safety devices have, on the other hand, always been mandatory for carbon dioxide and halon extinguishers. Dissenting opinions have always been raised, particularly by ministries responsibly for technical safety issues and by pressure vessel authorities. The Finnish Ministry of the Interior requested VTT already in the 1980's a to carry out a study on the behaviour of pressurised portable fire extinguishers without safety devices when subjected to fire. In the present study, a set of equations for calculation of the pressure development inside a closed extinguisher as a function of temperature has been derived based on basic physical chemistry. The influence of the geometry of the extinguisher body on the strength of the cylinder has been calculated by applying equations for strength calculations related to internal pressure of pressure vessels. By combining the yield stress of steel with the temperature dependence of the strength of the extinguisher body a diagram has been designed showing the maximum allowed pressure as a function of the dimensions of the extinguisher. Three methods have been applied for determining the decomposition pressure of the fire extinguishing media as a function of temperature. Measurements of pressure vs. temperature showed a good correspondence with the presented theory. The total pressure build-up in the extinguisher could be explained as the sum of the partial pressures of the propellant and the thermally decomposing extinguishing media. This study does not consider the question on the necessity of safety devices of portable fire extinguishers.

KW - portable fire extinguishers

KW - high temperature

KW - safety devices

KW - risks

KW - models

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T3 - VTT Tiedotteita - Research Notes

BT - Bursting potential of portable fire extinguishers at elevated temperatures

PB - VTT Technical Research Centre of Finland

CY - Espoo

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Andstén T, Keski-Rahkonen O, Myllymäki J. Bursting potential of portable fire extinguishers at elevated temperatures. Espoo: VTT Technical Research Centre of Finland, 2003. 44 p. (VTT Tiedotteita - Research Notes; No. 2200).