Discussion and Countermeasures on fire protection

Discussion and Countermeasures on fire-fighting problems in coating workshop (Part 2)

3.2 views on the use of CO2 automatic fire extinguishing system

3.2.1 applicability

CO2 automatic fire extinguishing system has obvious applicability for extinguishing flammable and explosive gas fires, and does not leave stains after extinguishing, so it plays a unique role in the protection of places with potential gas fires and valuable equipment. However, Article 3 of code for design of CO2 automatic fire extinguishing system (GB) l.2. Article 1 stipulates that the protection area of the fixed total submerged CO2 fire extinguishing system should be a basically enclosed space. Before CO2 is sprayed, the opening area on its side wall that cannot be closed is less than 3% of the surface area of the protection area, and there should be no opening at the bottom. The inlet and outlet of workpieces set at both ends of the paint booth are generally impossible to be closed due to production needs and the limitation of transportation mode. Although its area is less than 3% of the total surface area, it is difficult to control the loss of CO2 at the opening in case of fire, so it is difficult to ensure the fire extinguishing concentration of CO2. In terms of the structure of the equipment itself, no matter the water curtain, water spinning spray booth or Wenshi spray booth, due to its characteristics of requiring forced ventilation and open circulating water supply, there are large openings at the bottom of the equipment, which cannot form the basic enclosed space required by the CO2 fire extinguishing system to extinguish the fire, which is actually contrary to the requirements of the design code of CO2 fire extinguishing system. Therefore, CO2 fire extinguishing system is not very suitable for paint booth fire. If CO2 automatic fire extinguishing system is to be set in the paint booth, necessary measures should be taken. In case of fire and before CO2 emission, the bottom of the equipment can be closed

3.2.2 economy

co2 automatic fire extinguishing system device, because of its special performance, complex control and high pressure requirements, from materials, processing technology to installation and commissioning must meet strict technical standards, so the cost is much higher than that of general fire extinguishing system. Among the coating lines that have been built in China, the total cost of a CO2 fire extinguishing system on the motorcycle coating line (including installation, commissioning and personnel training) is about 400000 ~ 500000 yuan; The total cost of a set of CO2 fire extinguishing system on the automobile coating line is about 80 ~ 10 yuan, and the emission is also lower than 0 million yuan. The tensile strength of the expanded polystyrene board perpendicular to the board surface is about 5 times the price of the automatic sprinkler system of the same scale, which is a great burden for domestic enterprises

3.3 reliability

co2 fire extinguishing system's refilling, daily maintenance and other costs are much higher than other fire extinguishing systems. There have been many instances in China that due to management and operation reasons, the CO2 fire extinguishing system malfunctioned in the absence of fire, the CO2 gas in the system was sprayed out, the CO2 was refilled and the accessories were replaced, resulting in economic losses of several 100000 yuan. Therefore, the coating workshop should be equipped with special fire safety management personnel, who can ensure the normal operation of the CO2 fire extinguishing system after strict professional technical training, and timely detect and stop the misoperation of the system in case of false alarm

2. To sum up, CO2 fire extinguishing system is used for the fire-fighting equipment in the whole room of the paint booth, which is not the best choice in terms of necessity, practicality and economy. It is suggested that CO2 automatic fire extinguishing system, automatic sprinkler system, water spray system and portable fire extinguisher system should be selected according to the nature, investment and resources of the fire in the paint booth and the opinions of the local fire department. Mobile fire extinguishers can be used in some small paint spraying rooms with low production load

3.4 fire protection of automatic spraying equipment

with the substantial improvement of surface coating quality requirements and production output, the application of automatic spraying technology is becoming more and more common. New large-scale coating lines are equipped with automatic spraying equipment in the paint booth. This kind of equipment has high degree of automation, complex control, most of which rely on imports and are expensive. Therefore, the fire protection of automatic spraying equipment can not be ignored

at present, the international fire protection for automatic spraying equipment is to configure an independent CO2 local application system attached to the spraying equipment, which is connected to the inlet of the automatic spray gun (cup). In case of fire, it will automatically switch according to the alarm signal, and the spray gun (cup) will automatically spray CO2 gas to cover the automatic spraying equipment and isolate the air, so as to achieve the purpose of protecting the automatic spraying equipment. This set of CO2 supply system is only connected with the automatic spraying equipment, and does not have a horizontal connection with the overall fire-fighting facilities in the paint booth. It has strong independence and does not affect the selection of the type of fire-fighting system in the paint booth

3.5 fire protection in paint storage and mixing room

in paint storage room and mixing room, generally only paint materials and solvents of 1 ~ 2D are stored. Due to many combustibles, poor ventilation or poor management, a large number of volatile solvents and vapors in the room may cause explosion and fire due to electrostatic ignition or other sparks. Therefore, the focus of fire and explosion prevention in the coating workshop is in the paint storage room and paint mixing room

in addition to setting fire hydrants in accordance with the general requirements of the building code, it takes time and fire extinguishers for the team to be confident in this new process. In addition, it must also set up an automatic combustible gas concentration alarm system and a separate automatic fire extinguishing device. Considering the reasons of cost, automatic sprinkler system can also be selected

source: China steel drum packaging