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Paint shop fire protection system solution

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In recent years, with the rapid development of China's economy, the most advanced level of painting technology and equipment has mushroomed in China. However, there is no uniform basis for the classification of fire protection grades in the relevant workshops in the country and the configuration of fire protection systems in the workshop. In order to make the paint shop safe and economical, not only meet the relevant fire codes, but also save investment, it is necessary to study and analyze the characteristics of the production process of the paint shop and fire hazards, and then determine the fire hazard category and then set the fire protection system. .


    1. Classification of fire risk in paint shop

    The coating production process is very complicated and the fire hazards of different processes are quite different. Paint booths and paint deployment storage rooms are classified as Category A and B because of the use or storage of Class A and B flammable materials. The pre-processing, electrophoresis, puttying and other processes that account for a large proportion of the workshop area are all operated in a water-based environment and are basically free of fire hazards and are classified as “E” production. If the overall fire risk of the workshop is classified as Class A and Class B, according to the “Building Design Fire Protection Code” GBJ16-87 requirements, the fire-resistant rating of the plant must be Class I or Class II, and most of the painting workshops are generally used light steel. Structural buildings, which are not in line with the requirements. Therefore, a reasonable determination of the overall production category of the paint shop is the primary issue related to the economy, application, and production safety of the workshop.

    Article 3.1.1 of the "Construction Regulations" stipulates that: For the paint (paint) workshop, "when the closed spray painting process is adopted, the negative pressure shall be maintained in the closed spray paint room, and the paint section shall be provided with a flammable gas concentration alarm system or automatic explosion suppression. When the ratio of the paintwork section to the fireproof partition is not more than 20%, the workshop can be determined as D. At present, most of the new paint production lines use special paint spraying equipment, such as water curtains, hydro-spinners and venturi spray booths. All of them are steel-enclosed equipment. The air-supply and exhaust systems are readily available. Indoors can be adjusted to maintain the negative pressure and are large. Most are equipped with a flammable gas concentration alarm system. At the same time, the total area of the entire workshop, including painting, leveling, drying, and paint deployment and storage, shall not exceed 20% of the fireproof partition area. All of the above conditions have met the requirements of Article 3.1.1 of the "Building Regulations." Therefore, the fire risk of the paint shop is determined according to the D & C class.

    Article 3.1.1 of the "Building Regulations" also states: "In the factory or laboratory, a small amount of inflammable and explosive (type A and B) dangerous goods shall be taken into account. After all of its volatilization is permeated in the entire plant or laboratory, the air Whether the mixing ratio is lower than 5% of the lower explosive limit, and the lower one can be determined not according to Class A and B fire hazards." The most commonly used solvent in the painting process is xylene, which has a flash point of less than 28°C, is a Class A flammable and explosive product, has an explosion limit of 1%, and a vapor density of 3.68 kg/m3. According to calculations, the mass concentration of xylene gas in the air is 2210 mg/m3 when the lower explosion limit is 5%. In other words, according to the provisions of the provisions of the provisions of the provisions, when the concentration of xylene in the factory is lower than 2210mg/m3, the fire risk of the plant may not be determined in accordance with Class A and B.

    According to the provisions of GB 6514-95, the maximum permissible mass concentration of xylene in the air is 100 mg/m 3 under normal production conditions at the coating work site. When spread throughout the entire plant, the sum of the area of the coating equipment is calculated as 20% of the workshop area. The xylene vapor concentration in the entire workshop was 20 mg/m3, which was far below the judgement value (2210 mg/m3). Therefore, in summary, the overall fire risk of the paint shop is determined by D-type.


    2, the choice of fire extinguishing system

    At present, it has become a trend to set up a CO2 automatic fire extinguishing and fire fighting system in the painting room of a painting line, but some experts and scholars have different opinions on this. Some opinions do not support the use of a CO2 automatic fire extinguishing system. The following discussion is necessary. Appropriate opinions are given after analyzing the applicability and economy.

    “Building Regulations” Section 3.1.1 is the only provision in the current fire protection code that places a safety requirement on the painting and painting section. However, this note only requires that a flammable gas concentration alarm system or an automatic explosion suppression system be set on the painted part, and no automatic fire extinguishing is provided. System regulations. However, the frequent occurrence of fires in recent years, especially on May 16, 1995 when fire broke out in the painting shop of Liuzhou Miniature Automobile Factory, has warned people that the safety of painting lines is worthy of attention. There are no provisions in the legal provisions but it does not mean that there is no safety hazard in the spraying line.

    For solid surface fires, a variety of fire suppression systems can be selected, such as automatic sprinkler systems, water spray systems, dry powder systems, foam fire suppression systems, and CO2 automatic fire suppression systems. According to the investment situation and local fire department requirements, the design selection situation is not the same. Automatic spray, spray and foam fire extinguishing are suitable for spray booth fires, but these methods require fast matching after the matching water tank, pump room and water spray. Diversion and restoration of basic facilities such as production, some new factories can consider this approach. If dry powder fire extinguishing systems are available, there are few domestic manufacturers of large-scale dry powder fire extinguishing equipment, and high system cost is also a problem.

    The CO2 automatic fire extinguishing system extinguishes flammable and explosive gas fires has its obvious applicability, and does not leave any stains after fire extinguishing. Therefore, it has a unique role in the protection of places where there are gas fire hazards and valuable equipment. However, Article 3.l.2.1 of the Code for Design of CO2 Automatic Fire Extinguishing Systems (GB50193-93) stipulates that the protected area of the fixed full-submerged CO2 fire extinguishing system should be a basic enclosed space, before the CO2 is sprayed. The area of the wall that cannot be closed is less than 3% of the surface area of the guard area, and there should be no openings at the bottom.

    Domestic articles have pointed out that “the workpiece entry and exit at both ends of the paint booth are generally impossible to close because of the production needs and the transportation methods. Although the area is less than 3% of the total surface area, it is difficult to control the opening CO2 in the event of a fire. It is difficult to ensure the CO2 extinguishing concentration due to the amount of bleed, and from the standpoint of the structure of the equipment itself, the spray booth requires a forced air discharge and an open circulation water supply, and there is a large area opening at the bottom of the equipment, and a CO2 fire extinguishing system cannot be formed. The basic enclosure required to extinguish a fire is in fact inconsistent with the requirements of the CO2 fire extinguishing system design code. Therefore, the CO2 fire extinguishing system is not suitable for spray booth fires."

    The above content is from the CO2 flooding fire control design method to see this problem, the conclusion is not unfair, but from the local fire suppression design method has different results: a whole spray line is generally there is a The loss problem does exist, but we can design the CO2 unit independent fire extinguishing design with the “CO2 partial fire extinguishing design method” at both ends of the exit room. The dosage is more than the total flooding method, but it does not hurt the overall situation; or The CO2 combinative distribution of fire extinguishing design can be designed with the "CO2 partial fire extinguishing design method" for each section of the room. This problem can also be solved. As for the opening formed by the delivery of exhaust air, spray line manufacturers can be required to install an electric fire damper to solve this problem. Therefore, the CO2 fire extinguishing system is not applied to the entire spraying line and cannot be realized as a fundamental technical obstacle and can be effectively used.

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3. Fire protection for paint storage and paint transfer

     In the paint storage room and the paint lacquer room, due to the large amount of combustible materials, poor ventilation, or poor management, a large amount of solvents and vapors that volatilize in the room may cause explosions due to static electricity or other sparks. Therefore, the focus of fire and explosion protection in the paint shop is in paint deposit rooms and paint booths. The room must be equipped with an automatic flammable gas alarm system and an automatic fire extinguishing device. Fire hazards are classified as Class A and Class B. The fire resistance rating of the maintenance structure should be Class I or Class II. This article seems to be somewhat different from the above-mentioned “The Dangerousness of the Fire-Fighting Workshop is Qualitatively D-Moided.” In fact, we all know that this room is the most dangerous. Why should we stick to the rules? There is nothing wrong with doing a small amount of Class A or Class B buildings in Ding E buildings. Safety first! Life is first!

4, the choice of detection equipment

    The fire detection in the painting section is to perform different fire detection methods for different workpieces. If a production line is used for painting on steel components, fire detection can use two fixed-temperature detectors to detect it, because combustibles do not generate large amounts of smoke. Unchecked, but ambient temperature detectors for leveling and drying are prone to high temperatures. The instrument temperature stick should be used to measure the room temperature from time to time. In fact, this method is due to frequent occurrence of 60°C in the drying room and flow environment during inspection or shutdown. Above the high temperatures or higher, point-type or linear detectors currently on the market are subject to great restrictions in terms of both material and temperature detection range; if the production line is painted on flammable components, fire detection can be performed at a constant temperature and all the way. Smoke detectors to detect, because the smoldering stage will produce a lot of smoke, to detect the speed of the fire must precede the temperature, but the constant temperature detector for leveling and drying room should also use the instrument temperature stick, as the high temperature area of the current market for smoke detection Some of the above products can also be achieved, which is a bit high in terms of cost.


Address: RM. 1103, Lihe Building, NO.59 Suli Road, Suzhou, Jiangsu, China

Tel:13862166059

Email:sales@licornechina.com

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