The fire extinguishing system is designed to test and study the compressed air foam fire extinguishing system. The composition and working principle of the Shanghai Fire Research Institute (200032) of the Ye Longchuan Public Security Department, and some application conclusions of this system have been obtained through experiments and the future research directions are proposed.

1 Overview In existing fire-extinguishing systems, air-foam fire-extinguishing systems have become more widely used and have played an important role in the actual fire-fighting process. However, existing air foam fire extinguishing systems also have some problems. First, the stability of the foam is not strong. Generally, the foaming time of the foam is only 3 min to 4 min. It is difficult to adhere to the surface of the fuel for a long time, and the fire extinguishing efficiency is also affected. Second, the foam is not high and is easily exposed to wind. Impact. Moreover, in areas with poor water resources, the general air-bubble fire-extinguishing system is also difficult to achieve its best performance due to the limitation of water volume.

Practice has proved that compressed air type A foam fire extinguishing system has many advantages, mainly reflected in the following aspects: a) saving fire water, improving water fire extinguishing efficiency b) easy to operate, reducing the physical effort of fire fighters c) The action of the compressed gas can appropriately increase the injection range. Because of the above advantages, since the 1990s, it has been unanimously recognized by the majority of fire departments.

2Compressed air A type foam fire extinguishing system composition and working principle In order to carry out research and test of compressed air foam fire extinguishing system, we specially developed two sets of test devices. One set is to establish a test bench for the ratio of compressed air to mixed liquid under different mixing ratios. The system is simple in composition and convenient in testing. The other is a complete compressed air Class A foam fire extinguishing system. The fire extinguishing system is mainly composed of four small systems: a) power system (including diesel engine, power take-off, drive shaft, etc.) b) water system (including water pump, water cannon, water pipeline, etc.) c) compressed air system (including compressor) , gas flow meters, gas lines, etc.) d) foam proportion mixing system (including foam liquid pump, control module, mixer, foam tank, etc.). See Figure 1.

The system works as follows: The diesel engine transmits power to the fire pump and air compressor through the power take-off and drives them to work. After the fire pump and air compressor work, the outlet pressure water of the fire pump flows through the flow meter, and the signal is transmitted to the control module. After the calculation and processing of the control module, a command signal is issued to control the motor speed of the foam pump, that is, to control the foam liquid. The pump outputs a certain flow of foam liquid into the water stream to achieve proportional mixing, and the mixing ratio can be adjusted by the control module (0.1 to 0.9). Compressed air is then injected into the mixture and the pressure and flow of the compressed air are adjusted by a manual valve. Compressed air-like foam is produced by mixing a mixture of compressed air and foam through a length of hose. Depending on the mixing ratio of the foaming liquid and the amount of compressed air injected, the compressed air type A foam can be classified into a wet foam and a dry foam.

3 Compressed air type A foam system test In order to test the working process of the compressed air foam fire extinguishing system and the relationship between the foam mixing ratio, the injection volume of compressed air and the foam performance, we conducted a series of tests using the test device: including different mixing The test of the foam performance is compared with the test of the dry foam and the wet foam. The test of the compressed air type A foam range and the water range is compared. Through the test, we obtained a series of test data () and the test conclusions related to this system.

Foam mixing ratio Mixture pressure Mixture flow Compressed gas pressure Compressed gas flow Foam stability time Compressed air/mixture Through experimental observation and analysis of test data, we have obtained some preliminary experience and conclusions of compressed air foam fire extinguishing system.

3. When the mixing ratio of the foam mixture is between 0.6 and 0.8, it is suitable to spray dry foam. The amount of air injected is generally about 10 times the amount of the foam mixture. The foam has good stability and the residence time on the vertical wall is more than 5 min, which can effectively protect the flame retardant.

3. The mixing ratio of the foam mixture is between 0.3 and 0.5, which is suitable for spraying wet foam. Moreover, the amount of air injected is generally about three times that of the foam mixture. The stability of this foam is not as good as dry foam, and the design of fire-fighting system design network-type fire automatic alarm system is discussed. Zuojian Shenzhen Fire Bureau (518049) Bao Jiayu Shenzhen Urban Construction Development (Group) Company (518028) along with social economy and With the rapid development of urban construction, more and more large-scale public buildings and community-style buildings are built. These buildings generally require a fire alarm system with complex system and large capacity. The network-type automatic fire alarm system is flexible in its system structure. The advantages of large capacity, centralized control, etc. have been widely applied. The network type fire automatic alarm system is the result of the rapid development of computer software and hardware technology and its in-depth application in fire alarm technology. Although the current technical standards for automatic fire alarms in China have no clear provisions on the network-type automatic fire alarm system, the main function of the system design and production is to extinguish Class A fires, and it is also the most compressed air type A foam fire extinguishing system. Important application.

3. 3 Compressed air type A foam, due to the boosting effect of compressed air, can significantly improve the injection range. In the test, when the jet flow rate was 0.1 L / s, the range of compressed air was more than three times higher than that without compressed air. At higher flow rates, the range can be increased by about 30 after adding compressed air.

3. 4 Squirting compressed air with a water gun Compared with a single-filled water-filled water column, the weight of the portable water-belt is obviously reduced and the operation is convenient.

3. 5 In addition to the advantages of high efficiency of extinguishing Class A fires, compressed air can also extinguish some Class B fires. In the test, we used a compressed air foam fire extinguishing system to extinguish the general oil pan fire, which also showed good fire extinguishing performance.

4 compressed air type A foam system needs to continue to study the content of the author believes that at least the following aspects of research.

4. 1 Study the relationship between the pressure of the injected compressed air and the pressure of the mixed liquid, and develop the hydraulic pressure and pressure pressure balancing valve according to the determined relationship to realize the automatic control and balance of the air compressor and the system.

4. 2 Further improve the quality of the compressor, reduce the volume and weight of the body, separator and cooler, bringing convenience to loading and engineering applications.

4. 3 Research and development of a control module that achieves a mixture of foam proportions.

4. 4 Further comparison test of compressed air type A foam and water fire extinguishing, quantitative analysis of the superiority of compressed air type A foam.

The selection of 200032 products in No. 601, Nanshan Road, Zhongshan, Shanghai, should still follow the principle requirements of the relevant national mandatory standards. The author combines the practice of his own fire building construction work to explore some problems that should be paid attention to in the design of network fire automatic alarm system.

1 System structure form problem 1. 1 Network centralized alarm controller setting problem Network type fire automatic alarm system is generally connected by multiple code transmission bus system fire alarm controller through network communication interface, and with a certain communication protocol Data exchange and information processing, its system structure is flexible and diverse, it is difficult to accurately divide several fixed modes, but no matter which mode, it should follow the "Fire Automatic Alarm System Design Specification" (GB 50 98) related system Principled requirements for formal design requirements. If the structure of the network-type automatic fire alarm system is distinguished by the roles and relationships between the nodes in the access network, the following two modes are common: one is the unowned network and the other is the main network. The status and role of the nodes in the main network are basically the same. There is no need to set the main control node in the network. The typical system structure is shown in Figure 1. The main network system has a master node, and its typical structure is shown in Figure 2. In the above two forms of network structure, the maximum number of nodes in the access network is determined by the technical parameters of the manufacturer. Each node of the unowned network and the non-master node with the main network can connect a certain number of basic components of the area automatic display, detectors, modules, alarm bells, etc., and form a subsystem separately. However, for the entire network system, it is necessary to set up a centralized alarm controller. Therefore, any node in the main network and the main control node with the main network should be able to display and record the alarm trigger in the entire network. Alarms or fault information of devices, modules, circuit cards, power supplies, etc., and can perform operation control such as mute and reset on the entire network, that is, have all functions as a centralized alarm controller in the network system.

1. 2 area display setting problem In the main network and the main network system, except for the main control node of the main network, the other nodes are formed as the centralized alarm controller with respect to the entire network. The subsystem is alert to multiple floors. Refer to Section 5.2.3 and Section 5.2.4 of the Design Code for Automatic Fire Alarm Systems. These subsystems shall be provided with a certain number of area displays. In some specific projects, it is often just a set of auxiliary displays in the fire center that the author thinks that for some floor plans, the layout is simple, and the number of detectors per floor is small, such as residential buildings.

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