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This paper deals with the flammability of refrigerant gas in air, inside refrigeration systems and outside the systems when the refrigerant is leaked out. Vapour explosions from ammonia, hydrocarbons, CFC/HCFC/HFC and some other old refrigerants will be discussed referring to world-wide accident case studies. For ammonia, there are no known cases of explosions inside of a refrigeration system itself, and it would not be expected to happen unless a certain quantity of oxygen is brought in. Fire or a mild explosion can happen outside a system as a result of a large release. Ammonia fires will self-extinguish unless other flammable materials are present. Ammonia can only burn in a confined spaces unless very special circumstances exist, namely a continuing source of ignition and a correct equivalence ratio of ammonia and air. Ignition sources are known and can be avoided: (i) All electrical equipment shall have standard encapsulation (explosion-proof is not required). (ii) No open fires shall be in the areas around the engine room. (iii) All light sources (bulbs) shall have simple spray safe covers. Modern Safety Codes and Standards shall be used and obeyed and proper engine room ventilation prevents build up of flammable concentrations. Emergency response training should emphasise how to contain the release, eliminate sources of ignition, de-pressurize the system, and safely ventilate gases before entering for repair. The fluorocarbons are generally non-flammable. Some of these refrigerants having flammable properties are well defined and classified accordingly by ASHRAE 34. However, the refrigerants R22 and R134a, which are classified as non flammable, may cause severe thermal explosions under certain conditions, especially when they are mixed with air or oxygen (except for the small amount that occurs as normal contamination (ppm amount) in correctly handled refrigeration systems) or when they are exposed to increased pressure or temperature. Hydrocarbons (HC) are inflammable, and the risk of fire and/or explosions is the most critical risk associated with HC refrigerants. Nevertheless, HCs are used in domestic refrigerators and in mobile air conditioning, and the number of reported incidents with HCs is very small in relation to the large number of systems in operation. HCs cannot spontaneously explode inside a systems unless in presence of oxygen and an ignition source.
This paper deals with the flammability of refrigerant gas in air, inside refrigeration systems and outside the systems when the refrigerant is leaked out. Vapour explosions from ammonia, hydrocarbons, CFC/HCFC/HFC and some other old refrigerants will be discussed referring to world-wide accident case studies. For ammonia, there are no known cases of explosions inside of a refrigeration system itself, and it would not be expected to happen unless a certain quantity of oxygen is brought in. Fire or a mild explosion can happen outside a system as a result of a large release. Ammonia fires will self-extinguish unless other flammable materials are present. Ammonia can only burn in a confined spaces unless very special circumstances exist, namely a continuing source of ignition and a correct equivalence ratio of ammonia and air. Ignition sources are known and can be avoided: (i) All electrical equipment shall have standard encapsulation (explosion-proof is not required). (ii) No open fires shall be in the areas around the engine room. (iii) All light sources (bulbs) shall have simple spray safe covers. Modern Safety Codes and Standards shall be used and obeyed and proper engine room ventilation prevents build up of flammable concentrations. Emergency response training should emphasise how to contain the release, eliminate sources of ignition, de-pressurize the system, and safely ventilate gases before entering for repair. The fluorocarbons are generally non-flammable. Some of these refrigerants having flammable properties are well defined and classified accordingly by ASHRAE 34. However, the refrigerants R22 and R134a, which are classified as non flammable, may cause severe thermal explosions under certain conditions, especially when they are mixed with air or oxygen (except for the small amount that occurs as normal contamination (ppm amount) in correctly handled refrigeration systems) or when they are exposed to increased pressure or temperature. Hydrocarbons (HC) are inflammable, and the risk of fire and/or explosions is the most critical risk associated with HC refrigerants. Nevertheless, HCs are used in domestic refrigerators and in mobile air conditioning, and the number of reported incidents with HCs is very small in relation to the large number of systems in operation. HCs cannot spontaneously explode inside a systems unless in presence of oxygen and an ignition source.
Refrigerant vapour explosions
Explosion von Kältemitteldämpfen
Lindborg, A. (author)
2003
8 Seiten, 25 Quellen
Conference paper
English
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