水是最便宜,最常用的灭火剂,因为它能吸收很多热量和蒸发大量水蒸汽冲淡空气中的氧气,故而灭火效果很好。但是,水较重,对汽油、煤油、香蕉水等重量较轻,又不与水相溶的液体,就不能用水扑救,因为这类液体能浮在水面上继续烧,并随水流散,扩大烧火面积。水能导电,在电源未断前不宜扑救电气火灾。水又能与许多物质起化学反应,如钾、钠、电行、镁粉、锌粉、铝粉、过氧化钠、过氧化钾等遇水会自燃、加剧燃烧或发热等。如钾、钠遇水燃烧,电石与水反应生成可燃气体乙炔。高温的金属和溶化的物质也不能用水施救,因为水会迅速的气化,产生很大的压力,爆炸伤人。此外,水遇高热的金 Water is the cheapest and most commonly used extinguishing agent because it absorbs a lot of heat and evaporates a lot of water vapor to dilute the oxygen in the air so that the fire extinguishing effect works well. However, heavier water, on gasoline, kerosene, banana water and other lighter, but not water-soluble liquid, you can not use water fight, because these liquids can float on the water to continue burning, and with the water dispersed, expanding Burning fire area. Water can be conductive, should not put out electrical fire before the power is off. Water and chemical reactions with many substances, such as potassium, sodium, electricity, magnesium, zinc, aluminum, sodium peroxide, potassium peroxide and other water will spontaneous combustion, increased combustion or fever. Such as potassium, sodium water combustion, calcium carbide and water react to generate combustible gas acetylene. High-temperature metals and dissolved substances can not be rescued by water as the water evaporates rapidly, creating significant stress and blasting it. In addition, water meets hot gold