この火災区分は、米国ではK級、ヨーロッパとオーストラリアではF級と呼ばれ、植物油、動物性脂肪、グリースなどの可燃性調理油脂が原因となります。これらの火災は非常に高温で燃焼するため、水をかけると蒸気爆発（沸騰）を起こして燃えているグリースが拡散する恐れがあり、極めて危険です。そのため、専用の湿式化学消火器が主な消火方法となります。
K級火災／F級火災：調理用媒体
1998
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The creation of a separate class for cooking media fires was driven by changes in the food service industry. Modern, highly efficient deep-fat fryers heat cooking oils to sustained temperatures at or above their autoignition point. It was discovered that traditional dry chemical (Class B) extinguishers could extinguish the flame, but the oil would often re-ignite because it remained above its autoignition temperature. A new approach was needed.
The solution was the wet chemical agent, typically an aqueous solution of potassium acetate, potassium carbonate, or potassium citrate. When applied to burning cooking oil, this agent performs two functions. First, the water content has a cooling effect, lowering the temperature of the oil below its autoignition point. Second, the potassium salts react with the hot grease in a process called saponification. This chemical reaction creates a thick, soapy foam layer on the surface of the oil. This foam blanket effectively smothers the fire by cutting off the oxygen supply and prevents flammable vapors from escaping, thus preventing re-ignition.
The danger of using water on a grease fire is a key aspect of this class. Because oil is hotter than water’s boiling point, any water introduced instantly flashes to steam, expanding in volume by a factor of about 1,700. This rapid expansion ejects the burning oil from the pan, creating a large fireball and spreading the fire dramatically.
UNESCO Nomenclature: 3305
化学工学
タイプ
化学プロセス
混乱
増分
使用法
広く普及している
前駆物質
- the proliferation of high-efficiency deep-fat fryers in commercial kitchens
- an observed high rate of re-ignition in cooking fires when using traditional class b extinguishers
- a scientific understanding of the saponification chemical reaction
- high incidence of severe fires and injuries in the restaurant industry
アプリケーション
- automatic fire suppression systems installed in commercial kitchen ventilation hoods
- design of wet chemical portable fire extinguishers for restaurants and food processing plants
- fire safety education for culinary students and home cooks
- building code requirements for commercial cooking operations
- development of cooking oils with higher smoke points and reduced flammability
特許:
NA
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Related to: class K fire, class F fire, grease fire, cooking oil, wet chemical extinguisher, saponification, kitchen safety, boilover, deep fryer, NFPA.
歴史的背景
K級火災／F級火災：調理用媒体
（日付が不明または関連性がない場合、例えば「流体力学」などでは、その注目すべき出現時期の概算値が提示されます。）
