A类泡沫对液体火灾的防护效果及泡沫稳定机理研究

On the performance study of Class A foam for the purpose of liquid fire protection and the foam stability mechanism

A类泡沫是针对固体火灾的新型灭火技术产品,其采用正压式泡沫产生方式时的灭液体火性能有待准确评估。采用标准油盘火试验模型定量评价其用于非水溶性液体危险品的灭火防护效果,同时对压缩空气A类泡沫的泡沫性能及影响泡沫稳定性的因素进行评估,分析泡沫稳定机制。结果表明,正压式泡沫产生方式是提高A类泡沫稳定性的重要手段,而泡沫稳定性是影响其灭火防护效果的重要因素,混合比、发泡倍数与泡沫析液稳定性呈正比关系,而温度与泡沫析液稳定性呈反比关系,液膜的自我修复及气泡间的气体扩散是影响泡沫稳定性的微观机制。

The aim of this paper is to clarify the protection effect of Class A foam on the liquid fuel fire extinguishing power and its foam stability mechanism via the analysis of the fire extinguishing performance and its foam features. Class Afoam is known as a newproduct for fire safety protection, whose extinguishing performance on the liquid fuel fire is mainly given by the positive pressure foam generation mode. In this paper, we have done the assessment by doing standard 4.52 m2pool fire experiments, in which the fire protection for flammability hazardous liquid can be tested. The liquid fuel to be used for the test is rubber industrial solvent oil whose flowing rate of foam solution is 11.4 L/min. We have also investigated the foam property and the factors affecting the foam stability, such as the mixture ratio, expansion ratio and the drainage time （just 25% of thewhole process）. In addition, we have also analyzed the stability mechanism in accordance with the general principle of the surface chemistry. And, finally, we have proposed a conclusion in this paper, stating that the fire extinguishing performance level of Class A foam can reach Level IA, the highest level that the low expansion foam can reach in extinguishing the non-water soluble liquid fire. Since foaming stability is the most important factor which can affect fire safety protection, it is very important to improve the stability of Class A foam by studying howthe positive pressure foam is generated and study the factors influencing the drainage stability of Class A foam. To our knowledge, the higher the mixture ratio and expansion ratio, the more stable the drainage will be. On the contrary, the higherthe temperature, the less stable the drainage will be. Thus, the general drainage characteristics of Class A foam can be described and the drainage stability mechanism of the foam can be made clear. The liquid film’s sel-f repair and the gas diffusion between the bubbles is the micromechanism affecting the stability of Class Afoam. Therefore, the study in this area may lend us a hand to provide a theoretic guidance for the use of Class A foam for liquid hazard fire protection and promote the application of Class A foam.