The essence of foam extinguishing system is also a kind of water fire-fighting facility. By mixing the foam proportioning device, the water and foam liquid are mixed according to the required ratio, and then the foam is generated by the foam device, and the foam is used to cover or burn the protected object to extinguish the fire. Compared with the water fire extinguishing system, it mainly consists of two parts, one is the foam proportion mixing device, and the other two is the foam generator.

泡沫滅火系統的滅火機理；

The extinguishing mechanism of foam extinguishing system.

泡沫滅火系統的滅火機理是隔氧窒息、輻射隔熱和吸熱冷卻。泡沫滅火系統主要用于撲滅水不溶性易燃液體和一般固體火災。滅火的原理是泡沫滅火劑水溶液通過化學和物理作用充入大量氣體(CQ、空氣)，然后形成無數小氣泡，覆蓋在燃燒物表面，使燃燒物與空氣隔絕，阻擋火焰的熱輻射，從而形成滅火能力。同時，泡沫在滅火過程中沉淀液體，可以冷卻燃燒。加熱產生的蒸汽還能降低燃燒物附近的氧氣濃度，也能起到更好的滅火效果。

The extinguishing mechanism of foam extinguishing system is oxygen isolation, radiation insulation and endothermic cooling. Foam extinguishing system is mainly used to extinguish water insoluble flammable liquids and general solid fires. The principle of fire extinguishing is that the foam extinguishing agent water is filled with large quantities of gas (CQ, air) through chemical and physical action, and then forms numerous small bubbles, covering the surface of the combustion material, so that the combustion object is isolated from the air, blocking the thermal radiation of the flame, thus forming the ability of extinguishing fire. At the same time, the foam precipitates the liquid in the process of extinguishing, which can cool down and burn. The steam generated by heating can also reduce the oxygen concentration near the combustor and play a better fire extinguishing effect.

泡沫滅火系統有多種類型：固定式、半固定式和移動式根據安裝；的使用情況按泡沫噴射方式可分為液體噴射、液體噴射和泡沫噴射三種類型。根據泡沫的發泡次數，可分為低、中、高三種。那么它們的優缺點是什么呢？

There are many types of foam extinguishing systems: fixed, semi fixed and mobile according to installation. The use of foam spray can be divided into three types: liquid injection, liquid injection and foam injection. According to the times of foaming, it can be divided into low, medium and high. So what are their advantages and disadvantages?

液體噴射系統的優缺點；

Advantages and disadvantages of liquid injection system;

1.液體噴射泡沫滅火系統具有結構簡單、安裝，維護方便、易于調試、適用于多種泡沫液體的優點。

1. the liquid spray foam extinguishing system has the advantages of simple structure, easy installation, easy maintenance, and suitable for various foam liquids.

2.注液的缺點是泡沫發生器和一些管道容易被儲罐的燃燒和爆炸損壞，失去功能。該系統主要適用于油庫地面固定頂立式油罐、浮頂油罐、甲、乙、丙類液體儲罐等場所。

The disadvantage of the 2. injection is that the foam generator and some pipes are easily damaged by the combustion and explosion of the storage tanks and lose their functions. The system is mainly applicable to the ground fixed roof oil tank, floating roof oil tank, class A, B, C liquid storage tank and other places.

液體注射系統的優缺點：

Advantages and disadvantages of liquid injection system:

1.在液體下噴射時，噴嘴受到壓力的限制。為了保證滅火質量，一定要采用高背壓泡沫發生器。

1. When spraying under liquid, the nozzle is limited by pressure. In order to ensure the quality of fire suppression, high backpressure foam generator must be used.

2.缺點是液下噴射只能用于水不溶性液體火災，否則會影響泡沫質量和滅火效果。而且噴嘴容易腐蝕。液體噴射泡沫系統僅適用于水不溶性甲、乙、丙類液體的地面固定頂儲罐。不適用于水溶性甲、乙、丙類液體儲罐，也不適用于外浮頂和內浮頂儲罐。

The 2. drawback is that the liquid injection can only be used for water insoluble liquid fire, otherwise it will affect the quality of foam and the effect of fire extinguishing. And the nozzle is easy to corrode. The liquid ejection foam system is only applicable to ground fixed roof tanks for water insoluble class A, B and C liquids. It is not applicable to water-soluble class A, B and C liquid storage tanks, nor to external floating roof and internal floating roof storage tanks.

3.潛注的優點是油罐底部爆炸時不易損壞，從而提高了潛泡系統的安保性和油罐的儲量。滅火時，泡沫到達液體下的燃燒液面，不通過高溫火焰，減少泡沫的損失，提高滅火效果。當泡沫油箱從下部上升到燃燒液面時，油箱下部的冷油和上部的熱油會產生對流，起到冷卻作用，有助于滅火。而且可以不設置專門的泡沫管道，節省投資。

3. The advantage of submerged injection is that it is not easy to be damaged when the bottom of the oil tank explodes, which improves the security of the submerged bubble system and the storage of the oil tank. When the fire is extinguishing, the foam reaches the combustion liquid level under the liquid, and does not pass the high temperature flame, so as to reduce the loss of the foam and improve the extinguishing effect. When the foam tank rises from the bottom to the combustion level, the cold oil and the upper hot oil at the bottom of the tank will produce convection, which will play a cooling role and will help to extinguish the fire. Moreover, no special foam pipe can be set up to save investment.

一般情況下，宜采用低膨脹泡沫滅火系統撲滅易燃液體火災。所謂低膨脹泡沫是指膨脹率小于20倍的空氣泡沫。

Generally speaking, it is advisable to use low expansion foam extinguishing system to extinguish flammable liquid fires. The so-called low expansion foam refers to the expansion rate of less than 20 times the air foam.

低膨脹泡沫滅火系統的優缺點；

Advantages and disadvantages of low expansion foam fire extinguishing system;

(1)系統泡沫膨脹率小，泡沫密度高，因此泡沫基本不隨燃燒產生的熱氣流上升，適用于撲滅易燃液體火災；

(1) the foam expansion rate of the system is small and the density of the foam is high. Therefore, the foam does not rise with the heat flow generated by combustion, and is suitable for extinguishing the fire of flammable liquids.

(2)泡沫射流距離遠，射流高度大，適用于移動式泡沫滅火系統。

(2) the distance between foam jet and jet is very high, so it is suitable for mobile foam extinguishing system.

低膨脹泡沫系統不適用于以下情況：

The low expansion foam system does not apply to the following situations:

(1)通常不適合撲滅流動的易燃液體火災；

(1) Generally not suitable for extinguishing flowing flammable liquid fires;

(2)不應用于撲滅氣體火災、液化氣

(2) It shall not be used to extinguish gas fire and liquefied gas