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Status and management of extinguishing agent filling in gas fire extinguishing systems in China

Edit:Jiangsu Yongtai Fire Engineering Co., Ltd.UpDate:2019-12-06

Briefly describe the types of gas fire extinguishing agents currently used in China, and the causes of gas cylinder explosions in the application of gas fire extinguishing systems. The current status of gas fire extinguisher filling in China's gas fire extinguishing systems and the problems existing in gas fire extinguisher filling are introduced. Suggestions are made for regulating the filling of gas fire extinguishing systems and expectations for the management of fire extinguishing agent filling.

Gas fire extinguishing system is one of the four traditional fire extinguishing systems (spray fire extinguishing system, foam fire extinguishing system, dry powder fire extinguishing system, gas fire extinguishing system). The gas fire extinguishing agent is widely used in China because it is non-conductive, non-corrosive, and has no residue after release, and will not cause secondary pollution disasters to the environment. At present, the gas fire extinguishing agents used in our country mainly include heptafluoropropane, carbon dioxide, hexafluoropropane, trifluoromethane, trifluoromonobromomethane, IG-01 (argon), IG-100 (nitrogen), IG-55 (argon, nitrogen ), IG-541 (argon, nitrogen, carbon dioxide) and other 9 types. Among them, heptafluoropropane, carbon dioxide, and IG-541 are more commonly used. With the promotion and application of gas fire extinguishing systems, the market demand is increasing, and the number of gas fire extinguishing system production units has increased to more than 200. However, many problems have arisen in the production, use, maintenance and management of gas fire extinguishing systems. Especially in recent years, there have been many gas cylinder explosion accidents of gas fire extinguishing systems in engineering applications, making people question the safety of gas fire extinguishing systems. The causes of gas cylinder explosion accidents are related to factors such as the material of the container, the wall thickness, and the irrational treatment of the inner wall. Another main reason is related to the filling process of the gas fire extinguishing agent.

1. Status of gas fire extinguishing system filling

At present, there are more than 200 gas fire extinguishing system production units in China. According to survey statistics, nearly 90% of the fire extinguishing systems of heptafluoropropane, hexafluoropropane, trifluoromethane, and trifluoromonobromide fire extinguishing systems are filled by the production units themselves. Less than 10% is filled in a qualified gas filling unit; nearly 80% of the inert gas fire extinguishing system extinguishing agent is filled in a filling unit without such gas extinguishing agent filling qualification. Less than 20% filled in a qualified gas fire extinguishing agent filling unit.

China's gas fire extinguishing agent is a compulsory certification. However, there still exists a phenomenon that some fire extinguishing system production units and filling units filled gas fire extinguishing systems with gas fire extinguishing agents that have not obtained compulsory certification. Among them, the IG-541 fire extinguishing agent of the IG541 fire extinguishing system, which has repeatedly suffered gas cylinder explosion accidents, is common. There are currently no relevant standards and regulations regarding the filling of gas fire extinguishing agents in China. The published new version of TSGR00n6—2014 “Cylinder Safety Technical Supervision Regulations” clearly stipulates that “the materials, design and manufacture of gas cylinders for fire extinguishers shall be in accordance with this Regulation”, but the Regulations also do not specify whether the gas filling requirements are applicable. Fire cylinders. The current standards GB14194-2006 "Regulations for Filling Gas Cylinders" and (jBl4193-2009 "Regulations for Filling Liquefied Gas Cylinders" also mainly provide provisions for general-purpose gas filling. There is also no provision for gas fire extinguishing agents. In order to meet the quality requirements of the fire extinguishing agent for gas fire extinguishing systems and the needs of the filling market. Several domestic large-scale secondary industry gas filling units refer to the standards GB14194-2006 "Regulations for Filling Gas Cylinders" and GB14193- The 2009 "Liquefied Gas Cylinder Filling Regulations" and the relevant requirements of gas fire extinguishing systems and gas fire extinguishing agent product standards set the enterprise or local gas fire extinguishing system fire extinguishing agent filling standards, and obtained the gas issued by the local quality and technical supervision department Permit for filling fire extinguishing agents. However, there are still a considerable number of units that fill fire extinguishing agents for gas fire extinguishing systems. They do not refill according to the standard requirements, nor do they fill according to the relevant technical parameters of gas fire extinguishing system standards. Whether the agent is a compulsory certification product is not controlled, even to reduce the cost of doping other gas extinguishing agents when filling The gas fire extinguishing systems and fire safety performance of their performance are not guaranteed.

2. Existing problems with gas fire extinguishing system filling

The author visited some gas fire extinguishing system production units and gas fire extinguishing agent filling units, and found that there are many problems in the process of filling most gas fire extinguishing agents in China.

(1) Cylinders are not routinely inspected and inspected before the fire extinguishing agent is filled. Gas cylinders are containers that contain high-pressure gas. Due to manufacturing quality, use environment, and usage methods, the safety performance of gas cylinders may be reduced. Therefore, the regulations and standards such as TSGRO006-2014 "Cylinder Safety Technical Supervision Regulations", GB14194-2006 "Gas Cylinder Filling Regulations" and GB14193-2009 "Liquefied Gas Cylinder Filling Regulations" are all clearly required. Routine inspections and inspections must be performed before inflation. For example, check whether the gas cylinder is produced by a unit with a "special equipment manufacturing license", whether there is a supervision inspection mark, whether the cylinder bottle thread is complete, whether the cylinder is within the prescribed periodic inspection cycle, and whether the safety accessories of the cylinder are Complete other projects. To ensure the safe use of cylinders. Some gas fire extinguishing agent filling units did not perform the above inspections and inspections on gas cylinders, but directly filled the gas fire extinguishing agent. This also increases the safety hazards of the fire suppression system.

(2) The compatibility of the material of the cylinder, the mark of the filling medium name on the cylinder and the compliance with the nominal working pressure of the cylinder have not been verified. TSGRO006-2014 "Cylinder Safety Technical Supervision Regulations" put forward the following requirements related to gas filling for gas cylinders: First, the special requirements for gas cylinders, requiring the steel stamp of the cylinder to indicate the name of the gas or the chemical molecular formula. , Can not be filled with gas outside the cylinder steel mark, can not change the purpose of the cylinder at will; the second is the material compatibility requirements. It is required that all metal or non-metal gas cylinder materials (such as cylinder body, valve, sealing material, etc.) that are in contact with the containing gas should be compatible with the gas they are filled with. Third, the nominal working pressure of the gas cylinder is selected, and the regulations stipulate For a mixed gas consisting of compressed gas and low-pressure liquefied gas used in fire-fighting and fire-extinguishing systems, the nominal working pressure of the gas cylinder should not be less than the larger working pressure of the fire-extinguishing system at the corresponding temperature specified in the corresponding standard. But some gas fire extinguishing agent filling units ignore these requirements. Cylinder markings, material compatibility, and nominal working pressure compliance of the cylinders are not verified. As usual, the phenomenon of not paying attention to the compatibility of the gas cylinder material with the filled gas is filled with high pressure nitrogen and IG-541 fire extinguishing agent with carbon dioxide gas cylinders; 17.2 MPa IG-541 gas is filled with carbon dioxide gas cylinders with a nominal working pressure of 15 MPa Agent phenomenon is also quite common. Many gas cylinder explosions in recent years are related to this.

(3) The cylinders were not cleaned, dried, replaced, etc. before the fire extinguishing agent was filled. The industrial gas filling standard stipulates that whether the cylinder is filled or refilled, the cylinder should be cleaned, dried, replaced, etc., to remove impurities, moisture, residual gas, etc. before filling. However, many gas fire extinguishing system production units do not have or are unwilling to provide equipment for cleaning, drying, and replacing gas cylinders. Some even do not consider it necessary to perform these treatments. Instead, they directly fill the gas fire extinguishing agent, which often causes filling The water content of the fire extinguishing agent in the rear cylinder increases. Increase the probability of stress corrosion of the gas cylinder and even cause the gas cylinder to explode.

(4) No standard compliance check was performed on the filled gas fire extinguishing agent and pressurized nitrogen before filling. For example, the purity, impurity content of the gas fire extinguishing agent, and the moisture content and impurity content of nitrogen are not inspected before filling. Make the gas fire extinguishing agent purity and other indicators do not meet the requirements of the standard. It will seriously affect its fire extinguishing performance.

(5) The filling process of fire extinguishing agent and filling equipment are not strictly controlled. Many fire extinguishing system production and filling units have formulated the filling process and operation guidance documents, which do not specify the filling temperature of the fire extinguishing agent, regardless of the temperature difference between filling places throughout the year. The fire extinguishing agent filling and nitrogen pressurization are always performed at the same pressure value, and the gas fire extinguishing agent temperature-pressure curve is not used for filling. As a result, cylinders filled with fire extinguishing agents and nitrogen pressurization under low temperature conditions in winter will increase the temperature in the summer, and the pressure inside the cylinders will increase, causing the safety relief device on the cylinders or the main sealing diaphragm of the container valve to act. , Fire extinguishing agent was accidentally sprayed. Such an accident occurred in an underground project in Tianjin. In the mixed gas filling process operation guidance document. The filling sequence of various gas components is not determined according to the properties of each gas component of the mixed gas, and the key to replacing the filling configuration system pipeline with the gas to be filled before each gas component is not specified Process requirements. Large randomness. Causes the deviation of the filling ratio of each gas component. Can not meet the requirements of fire extinguishing agent standards.

The gas fire extinguishing system product standard specifies correspondingly large filling factors for cylinders with different nominal working pressures. Such as GB16669-2010 "General technical conditions for carbon dioxide fire extinguishing systems and components". The filling factor of carbon dioxide gas cylinders with a nominal working pressure of 15 MPa is 0.6 kg / m3. However, in the specific filling process, due to the unreasonable selection of the weighing weighing instrument used for filling, the weighing weighing instrument has not been verified according to the prescribed verification cycle, the weighing instrument has no over-load alarm, and the filling quantity Failure to perform bottle-by-bottle retests and other reasons resulted in underfilling and overfilling of fire extinguishing agents. For example, the explosion of a bottle group in the carbon dioxide fire extinguishing system in Jiangsu in 2007 was caused by an overfill of fire extinguishing agent.

(6) Fill and pressurize the fire extinguishing agent at the project site. Some engineering companies and gas fire extinguishing system production units are experiencing the phenomenon of filling fire extinguishing agents and nitrogen pressurization at the project site. On-site filling process is not standardized. Filling conditions cannot be guaranteed, and overfilling and overpressure of fire extinguishing agents occur from time to time. Hidden safety hazards for fire extinguishing system use.

3. Suggestions for regulating the filling of extinguishing agents for gas fire extinguishing systems

The following text is omitted.

4. Management recommendations

(1) Formulate the filling standard for gas fire extinguishing system as soon as possible, and the management department can issue the Gas Filling Permit for filling units of gas fire extinguishing system based on this standard.

(2) In the implementation details of the 3C certification of gas fire extinguishing equipment, the filling of fire extinguishing agents is included in a key process of factory quality assurance.

(3) Draft and formulate standards for periodic inspection and assessment of gas cylinders of gas fire extinguishing systems as soon as possible. Solve the problem that the gas fire extinguishing system currently in use is used for a long time without periodic inspection, the service life, and the basis of the inspection and determination of the gas cylinder before it is refilled with the gas fire extinguishing agent. So as to ensure the reliable and safe use of gas cylinders in gas fire extinguishing systems.