Code of Desig n for Carbon Dioxide Fire Extinguishing System

Transcription

1 UDC NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA p GB Code of Desig n for Carbon Dioxide Fire Extinguishing System (2010 Edition) Issued on: December 21, 1993 Implemented on: August 1, 1994 Jointly Issued by Ministry of Housing and Urban-Rural Construction of the People's Republic of China General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China

2 Explanation of Revision In this partial revision, the standard is revised on the base of "Code of Design for Carbon Dioxide Fire Extinguishing System" GB (1999 Edition) by the Tianjin Fire Research Institute of Ministry of Public Security jointly with the related organizations in accordance with the requirements of the document "Notice on printing and distributing (Formulation and Revision planning (Batch 1) of Engineering Construction Standards in 2008)" (Jian Biao [2008] No. 102), issued by the Ministry of Housing and Urban-Rural Development. Form the implementation, the current "Code of Design for Carbon Dioxide Fire Extinguishing System" pays an important roles in regulating the design of carbon dioxide extinguishing system and guiding the application and development of carbon dioxide extinguishing systems in China. However, with the deepgoing application and research of carbon dioxide extinguishing system and the progressive development of the products, the standard has not been applicable to the application actuality and developing trend of carbon dioxide extinguishing system, and it is necessary to be revised partially. Since the implementation of the current "Code of Design for Carbon Dioxide Fire Extinguishing System" on March 1, 2000, carbon dioxide extinguishing system has been applied under a sound developing condition in domestic engineerings. During the application process, there are several accidents of carbon dioxide extinguishing system misuse and leak, which results in the atrophic technical application of carbon dioxide extinguishing system in the last few years, especially, in civilian construction engineerings. Currently, the main application are centred on the industrial construction projects in coating line, cement production line, iron and steel industry, power plant, etc., In this revision, the problems in actual technical applications of carbon dioxide extinguishing systems are summed up in the following aspects: Due to the occurrence of carbon dioxide misuse and leak, causing injure to people, it is necessary to regulate the safety measures and related requirements for restriction, related to carbon dioxide extinguishing system, in the working space where staffs often work or stay; 2 Because the products and accessories made by different manufacturers are diverse from each other in hydraulic equivalent loss length, the equivalent lengths of pipe accessories, determined according to the requirements of Appendix B in This code will be greatly different from the ones in practical situation; 3 The standard has not specified that mechanical air exhaust devices shall be arranged between storage containers, so leaks may be serious threat to the lives of staff in the rooms and rooms nearby; 4 The specific requirements are proposed in the shunt design of carbon dioxide gas transfer lined, for improving the pressure equalization of the pipe network. The articles underline in This code are ones revised. Chief drafting organization: Tianjin Fire Research Institute of Ministry of Public Security Participating organization: National Engineering research Center for fire Protection China National Center for Quality Supervision and Test of Fixed Firefighting Systems and Fire-resisting Building Components Nanjing Fire Protection Technology Co., Ltd.

3 Contents General Provision Term and Symbol Term Symbol System Design General Requirement Total Flooding Extinguishing System Total Flooding Extinguishing System Pipe Network Calculations System Component I Storage System Selector Valve and Nozzle Pipe and Accessory Control and Operation Safety Requirements Appendix A Material Factor, Design Concentration and Inhibition Time Appendix B Equivalent Length of Pipe Accessories Appendix C Pipe Pressure Sink Appendix D YValue and Z Value of Carbon Dioxide Appendix E Elevation Correction Factor Appendix F Nozzle Inlet Pressure and Unit Area Injection Rate Appendix G Explanation of Wording in This Code Appendix H Nozzle Equivalent Orifice Dimension Appendix J Specifications of Carbon Dioxide Fire Extinguishing System Pipes

4 1 General Provision This code is formulated with a view to reasonably designing carbon dioxide extinguishing system, reducing fire hazards, and protecting and the safety of people and property This code is applicable to the designs of carbon dioxide extinguishing systems arranged in new, rebuild and extended engineering and storage systems The design of carbon dioxide extinguishing system shall actively adopt new technique, process and equipment, and be of safety and application, state-of-the-art, and economic feasibility Carbon dioxide extinguishing systems may be used for extinguishing the following fires: Gas fire, which the gad source can be Cutting off before fire extinction Liquid fire or meltable solid (like paraffin and asphalt) fire Solid surface fire and solid deep-seated fire (like cotton wool, fabric and paper) Electric fire Carbon dioxide extinguishing systems must not be used for extinguishing the following fires: Fires of chemicals (like nitrocellulose and blasting powder) containing oxidants Fires of active metals like kalium, sodium, magnesium, titanium and zirconium Fires of metal hydrides like potassium hydride and sodium hydride. 1.0.SA Total flooding carbon dioxide extinguishing system shall not be applied at the places where staffs stay often The design of carbon dioxide extinguishing system, besides the requirements of this code, shall also meet the requirements of the current related national standards.

5 2 Term and Symbol 2.1 Term Total flooding extinguishing system Fire extinguishing system which can eject carbon dioxide of finite concentration into a protected area within a specified time, and fully fill the whole protected area with carbon dioxide Local application extinguishing system Fire extinguishing system which directly ejects carbon dioxide onto protected object at the design ejection rate; and lasts for a certain time Protected area Close space meeting the application conditions of a total flooding carbon dioxide extinguishing system; and protected by the system Combined distribution systems Fire extinguishing system in which a suit of carbon dioxide storage device is used to protect two or more protected areas/protected objects Flame extinguishing concentration Minimum volume percentage (in a mixture of air and carbon dioxide) of carbon dioxide required to extinguish a certain fire, under the atmosphere 101 kpa and at the specified temperature Inhibition time Time to keep the designed carbon dioxide concentration and extinguish solid deep-seated fire fully Pressure relief opening An opening arranged on the exterior wall or top of a protected area to discharge internal super pressure of the protected area Equivalent orifice area Converted orifice area of a standard nozzle with the water flow rate coefficient of Filling factor Ratio of the mass of carbon dioxide stored in high pressure system container and the container volume A Loading factor Ratio of the mass of liquid carbon dioxide stored in low-pressure system container and the container volume Material factor Reduction coefficient of the design carbon dioxide concentration of combustible substance corresponding to 34% carbon dioxide concentration. 2

6 Vv--Volume of a protected area; <p--nozzle setting angle Symbol of physical parameters Cp--Specific heat of pipe metal material; H-Carbon dioxide vaporization heat; K 1 --Area factor; K 2 --Volume factor; Kb--Material factor; Kd--Pipe diameter coefficient; Kh--High pressure correction factor; Km--Margin factor; M--Designed dosage of carbon dioxide; Mc--Storage volume of carbon dioxide; Mg--Mass of a pipe; M,--Residual amount of carbon dioxide in a pipe; Ms--Residual amount of carbon dioxide in a container; Mv--Evaporation amount of carbon dioxide in a pipe; Pi--Average pressure of the ;th pipe; Pi--Pressure of a node; P 1 --Permissible pressure intensity of fender structure; Q--Design flow of a pipe; Qi--Design flow of a single nozzle; Q 1 --Carbon-dioxide ejection rate; q 0 --Unit-area ejection rate of unit equivalent orifice; qv--ejection rate of unit volume; T 1 --Mean temperature of a pipe before carbon dioxide ejection; T 2 --Mean temperature of carbon dioxide; T--Ejection time; td--delay time; Y--Pressure factor; Z--Density factor; 4

7 3 System Design 3.1 General Requirement Carbon dioxide fire extinguishing system may be divided into total flooding extinguishing system and local application extinguishing system according to the application mode. Total flooding extinguishing system shall be used for extinguishing the fire in confined space; local application extinguishing system shall be used for extinguishing non-deep-seated fire of specific protected object in no confined space The protected area for which total flooding extinguishing system is adopted shall meet the following provisions: As for gas/liquid/electric fire and solid surface fire, the area of the opening which can not automatically shut off before carbon dioxide ejection shall not be greater than 3% the total internal surface area in protected area; in addition, the opening shall be arranged at bottom surface As for solid deep-seated fire, the opening except pressure relief opening shall automatically shut off before carbon dioxide ejection The fire endurance of fender structure, door and window in protected area shall not be less than 0.50h; the fire endurance of suspended ceiling shall not be less than 0.25h; and the permissible pressure of fender structure, door and window should not be less than 1200Pa The fire damper of fan and ventilation duct used in protected area shall automatically shut off before carbon dioxide ejection The protected area for which local application extinguishing system is adopted shall meet the following provisions: The speed of air flow rate around protected object should not be greater than 3m/s. If necessary, wind-shielding measures shall be taken Between nozzle and protected objects, no barrier shall exist within nozzle ejection angle If the protected object is flammable liquid, the distance from liquid level to container edge shall not be less than 150mm Before or when carbon dioxide discharge is started, gas supply of combustible and combustionsupporting gases must be shut off A The carbon dioxide storage of combined distribution system shall not be less than that of a protected area or protected object which needs maximal storage If combined distribution systeip protects 5 (or above) protected areas or protected objects, or if such system can not recover within 48h; standby carbon dioxide shall be endowed with and the standby carbon dioxide shall not be less than the storage designed for the system. For the low-pressure system for which standby storage container is arranged separately or highpressure system, standby storage container shall be connected with system pipe network and the storage container shall be an alternative for main storage container. 6

8 3.2 Total Flooding Extinguishing System The designed concentration of carbon dioxide shall neither be less than 1.7 times of flame extinguishing concentration nor less than 34%. The concentration of carbon dioxide for combustible substance may be designed according to the provisions in Appendix A of this code If there are two or above two combustible substances in protected area, the maximally designed carbon-dioxide concentration for combustible substance shall be adopted herein The designed dosage of carbon dioxide shall be calculated according to the following formula; ( ) ( ) ( ) Where M--Designed dosage of carbon dioxide (kg); Kb--Material factor; K1--Area factor (kg/m 2 ), 0.2kg/m 2 ; K1--Volume factor (kg/m 3 ), 0.7kg/m 3 ; A--Converted area (m 2 ): Av--Total area of protected-area medial surface, bottom surface and top surface (including the openings) (m 2 ) ; Ao--Opening total area (m 2 ) ; V--Net volume of protected area (m\ Vv--Protected area volume (m 3 ); Vg--Total volume of non-combustible and combustible-resistance substance in protected area (m 3 ) When the ambient temperature in protected area is greater than loo "C, carbon-dioxide designed dosage shall be added by 2% for per 5 "C increase in addition to the calculated one in Article of this code When the ambient temperature in protected area is less than -20"C, carbon-dioxide designed dosage shall be added by 2% for per 1 "C decrease in addition to the calculated one in Article of this code Pressure relief opening shall be arranged in the external wall of protected area. The height of such opening shall be greater than 2/3, protected-area clear height. If anti-explosion and pressure relief holes are arranged in protected area, pressure relief opening may not be arranged separately Pressure relief opening area may be calculated according to the follow"ing formula: ~ = Ji._ Fi (3.2.7) 7

9 Where Ax--Pressure relief opening area (m 2 ); Q 1 --Carbon-dioxide ejection rate (kg/min); Pi--Permissible pressure of fender structure (Pa) The carbon dioxide ejection time of total flooding extinguishing system shall not be greater than 1 min During extinguishing solid deep-seated fire, the ejection time shall not be greater than 7 min and carbon dioxide concentration shall be ensured be greater than 30% in the first 2 min The inhibition time for using carbon dioxide to extinguish solid deep-seated fire shall be adopted according to the provisions in Appendix A of this code (Deleted). 3.3 Total Flooding Extinguishing System 3.3.l Area method or volume method may be adopted to design local application extinguishing system. If ignition surface of protected object is comparatively flat and straight, area method should be adopted; if the ignition object is irregular substance, volume method shall be adopted Carbon-dioxide ejection time of local application extinguishing system shall be less than 0.5 min. For the fire of liquid and fusible solid whose burning point temperature is less than boiling temperature, carbon dioxide ejection time shall not be less than 1.5 min If area method is adopted for design, the following provisions shall be met: Vertical projection area of integral protected surface shall be taken as the calculated area of protected object For overhead nozzle, design flow rate and the corresponding square protection area shall be determined according to the distance from nozzle outlet to the protected object surface; protection area of groove-side nozzle shall be determined the design flow rate of nozzle selected in the design Overhead nozzle arrangement should be perpendicular to protected object surface and the aiming point shall be the center of nozzle protection area. If nozzle shall be arranged in perpendicular direction, the setting angle shall not be less than 45. Thereof, aiming point shall be inclined to nozzle installation position (Figure 3.3.3) and nozzle deviation from protection area center may be determined according to Table 3.3. Table 3.3 Nozzle Deviation Distance From Protection Area Center Nozzle setting angle Nozzle deviation distance from protection area center (m) Lb Lb-0.125Lb Lr0 Note: Lb is the side length of single-nozzle square protection area When nozzle is not perpendicularly arranged, design flow rate and protection area shall be the same with that of perpendicular arrangement Nozzle should be arranged and grouped according to nozzle square protection area with equal interval. In addition, nozzle arrangement shall cover the protected object completely. 8

10 4 Pipe Network Calculations Carbon dioxide fire extinguishing system may be divided into high-pressure system and lowpressure system according to the storage mode of fire extinguisher agent. Concerning with the startingpoint calculation pressure (absolute pressure) of pipe network, it shall be 5. l 7MPa for high-pressure system and 2.07MPa for low-pressure system Main pipe design flow rate shall be calculated according to the following formula; Q=MIT ( 4.0.2) Where Q--Design flow rate of a pipe (kg/min) Branch pipe design flow rate shall be calculated according to the following formula; (4.0.3) Where Ng--Amount of nozzles arranged on the downstream of computation branch pipe flow; Q 1 --Design flow rate of a single nozzle (kg/min) A Pipe inside diameter may be calculated according to the following formula: (4.0JA) Where D-Pipe inside diameter (mm); Kct--Pipe diameter factor, From 1.41~ Computational length of pipe segment shall be the sum of actual pipe length and pipe- accessory equivalent length. Pipe-accessory equivalent length data shall be such ones being approved by relevant state detection mechanisms; if the above data are not available, the data may be adopted according to Appendix B of this code Pipe pressure sink may be converted according to the following formula or be adopted according to Appendix C of this code D 525 Y Q = L+( D 125.Z) ( 4.0.5) Where D-Pipe inside diameter (min); L--Pipe calculation length (m); Y--Pressure factor (MPa: Kg/m 3 ), Shall be adopted according to Appendix D of this code; Z--Density factor, shall be adopted according to Appendix D of this code The value of pressure correction caused by flow height in pipe may be adopted according to Appendix E of this code. In addition the value of pressure correction shall take this pipe-segment terminal pressure into consideration. If terminal height is less than starting one, the value is positive; if terminal height is greater than the starting one, the value is negative. I I

11 1.4 for high-pressure system and 1.1 for low-pressure system; Mv--Amount of carbon dioxide evaporated in pipe (kg); 0 for high-pressure total flooding extinguishing system; T 2 --Mean temperature of carbon oxide ( C); 15.6 C for high-pressure system and-20.6 C for low-pressure system; H-Carbon dioxide vaporization heat (kj/kg); 150.7kJ/kg for high-pressure system and 276.3kJ/kg for low-pressure system; Ms--Residual amount of carbon dioxide in a container (kg); M..--Residual amount of carbon dioxide in a pipe (kg); 0 for high-pressure system; ~--Volume of the i 1 h pipe segment in a pipe network (m 3 ); Pi--Mean density of the carbon dioxide in ;th pipe segment (kg/m3); Pi--Average pressure of the ;th pipe (MPa); Pi-1--Node Pressure at the head end of ;th pipe segment (MPa); Pi--Node Pressure at the terminal end of ith pipe segment (MPa) Amount of storage container in high-pressure system may be calculated according to the following formula: N =Mc p av 0 (4.0.10) Where Np-Container amount; Mc--Storage amount; (kg); a--filling rate (kg/l); V 0 --Volume of a single storage container (L) Specification of low-pressure-factor storage container may be determined according to the storage amount of carbon dioxide. 13

12 5 System Component 5.1 Storage System The storage system of a high-pressure system shall consist of container, container valve, oneway valve and collecting pipe, and it shall meet the following requirements: The working pressure of a container shall not be less than15mpa. The pressure relief device shall be equipped on the container or container valve, and the pressure-relief actuating pressure hereof shall be 19±0.95MPa The filling factor of the carbon dioxide stored in a container shall meet the requirements of the current standard "Regulation of Safety Supervision for Gas Container" The ambient temperature of a storage system shall be lA The storage system of the low-pressure system shall consist of container, container valve, safe pressure relief device, pressure gage, pressure warning unit, refrigerating unit and etc., and it shall meet the following requirements: 5.1.lA.1 The container shall have a design pressure not less than 2.5MPa and it shall be equipped with favorable thermal insulation measures. At least two safe pressure relief devices shall be arranged on a container, and the pressure-relief actuating pressure shall be 2.3 8±0.12MPa. 5.1.lA.2 The set value of the high-pressure alarm pressure of the storage system shall be 2.2MPa, and the under pressure alarm pressure set value hereof shall be l.8mpa. 5.1.lA.3 The filling factor of the carbon dioxide in a container shall meet the requirements of the current national standard "Regulation of Safety Supervision for Pressure Vessel". 5.1.lA.4 amount. The container valve shall be closed automatically after ejecting the required carbon dioxide 5.1.lA.5 The storage system shall be kept away from heat, and the location shall be convenient for re-filling. The ambient temperature hereof should be 'C The carbon dioxide stored in a container shall meet the requirements of the current national standard "Fire Extinguishing Agent-Carbon Dioxide" (Deleted) I appreciate your letter so much. as for the issues proposed by you, we make a reply as: (Deleted) The location of the storage system shall be convenient to check and repair the device and keep the system from direct sunlight The storage system should be arranged dedicated container room. The storage system for local application extinguishing system shall be arranged in a fixed safe fence. The arrangement of dedicated container rooms shall meet the following requirements: It shall be close to the protected areas, and the exit hereof shall be accessed directly to outdoor evacuation runway. 14

13 The fire resistance rating hereof shall not be lower than Class II The room indoor shall be dry and well ventilated The container rooms without natural ventilation condition shall be arranged with mechanical air exhaust device, the air exit should be under O.Sm away from the surface elevation of the container room, and the exhaust port shall be opened outdoor. The normal air exhaust amount shall not be less than 4times/h according to the air change ratio. The accident air exhaust amount shall not be less than 8 times/h according to the air change ratio. 5.2 Selector Valve and Nozzle In a combined distribution system, a selector valve shall be arranged for each protected area or protected object. And the selector valve should be located close to the containers, and convenient for manual operation, examination and maintenance. The nameplate to indicate the protected area shall be arranged in the selector valve The selector valves may be controlled/operated in electrical, pneumatic or mechanical mode. The working pressure of a selector valve shall not be less than 12MPa for high- pressure system; 2.SMPa for low-pressure system Once system starts up, the selector valve shall be opened before the container valve movement or simultaneously; the selector valve, opened through the gas supply of fire extinguisher agent, may not be limited A The arrangement of nozzles for total flooding extinguishing system shall ensure the distribution uniformity of carbon dioxide in a protected area, and the nozzle shall be arranged close to ceiling or roof The nozzles arranged at the places with dust or spray paint operation shall be arranged with dust shield not affecting the ejecting effects. 5.3 Pipe and Accessory The pipe and its accessory for high-pressure system shall be capable of withstanding the carbon dioxide storage pressure under the maximal ambient temperature, and the ones for low-pressure system shall withstand the pressure 4.0MPa. The pipes and accessories shall meet the following requirements: The pipes shall meet the requirements of the current national standard "Seamless Steel Tubes for Liquid Service" GB 8163, and they shall be arranged with galvanization antiseptic treatment on internal and external surfaces. The specifications of the pipes may ne selected from Appendix J In the environment corrosive to zinc coating, the pipes may be made of stainless steel, copper, or other in corrodible material The hose with flexible joint must withstand the working pressure and temperature of the system, and it should be stainless steel flexible hose. 5.3.lA The measure to prevent expansion and shrinkage shall be adopted in the pipe network for low-pressure system. 15

14 6 Control and Operation The carbon dioxide extinguishing system shall be initiated by automatic control, manual control and mechanical emergency operation; when a local application extinguishing system is used at the place with often protection, automatic control may not be arranged When fire detectors are adopted, the automatic control of a fire extinguishing system shall be initiated after receiving two independent fire signals. According to the personal evacuation requirement, the automatic control should be initiated by delay, and the delay time shall not be longer than 30s Manual operation devices shall be arranged at the place of convenient operation outside of the protected area, and can realize all operation of system startup. The manual operation device for local application extinguishing system shall be arranged nearby the protected object A In a protected area protected by a total flooding extinguishing system, manual and automatic operation switching control device shall be arranged on the access point hereof; during the period of person working available, the control device shall be under the manual control state The power supply and automatic control for a carbon dioxide extinguishing system shall meet the relevant provisions of the current national standard "Code of the Design of Automatic Fire Alarm System". The pneumatic power supply, if adopted, shall ensure the pressure and gas supply required by the operation and control The power supply of the refrigerating unit for a low-pressure system shall be a fire control power supply, and the refrigerating unit shall be automatically controlled, and arranged with manual operation device. 6.0.SA At the places with or in a auto alarm system, the alarm signal, working state and control state related to the actuating signal of a carbon dioxide extinguishing system shall be indicated on the fire alarm controller. 17

15 7 Safety Requirements Fire acoustical alarm shall be arranged in protected areas; if necessary, visual alarm shall be arranged additionally. The visual alarm shall be arranged on the access point of protected areas. The alarm time should not be shorter than the time required by fire extinction process, and the warning signal can be canceled manually The protected areas shall have runways and exits that evacuate all personal away within 30s. And the fire lighting and evacuation indication signs shall be arranged on evacuation runways and exits Fire extinguishing system protection sign and carbon dioxide ejection indicator lamp shall be arranged on the access points of protected areas When the system pipes are arranged at the places with fuel gas, vapors or explosive dust, the electrostatic grounding shall be arranged Mechanical air exhaust devices shall be arranged in over-ground protected areas without window or permanent sash, and underground protected areas The doors of protected areas shall be open to the evacuation directions, and automatically closed; in any case, they can be opened on the inner side of the protected area Dedicated air breathing apparatus or oxygen breathing apparatus shall be arranged on obvious positions on the access point of the protected area equipped with fire extinguishing system. 18

16 Additional Information List of Chief Development Organization, Participating Organizations and Chief Drafting Staff of This Code Chief Development Organization: Tianjin Fire Research Institute of Ministry of Public Security Participating Organizations: Design & Research Institute of the Ministry of Machine-Building Industry Shanghai Merchant Ship Design & Research Institute Jiangsu Provincial Public Security Bureau Chief Drafting Staffs: Xu Bingyao, Xie Longde, Song Xudong, Liu Lina, Feng Xiuyuan, Liu Tianmu, Qian Guotai, Luo De' an, Ma Shaokui and Ma Heng 29