1 General Provisions
1.0.1 This standard is formulated with a view to reasonably designing carbon dioxide extinguishing system, reducing fire hazards, and protecting and the safety of people and property.
1.0.2 This standard is applicable to the designs of carbon dioxide extinguishing systems arranged in new, rebuild and extended engineering and storage systems.
1.0.3 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.
1.0.4 Carbon dioxide extinguishing systems may be used for extinguishing the following fires:
1.0.4.1 Gas fire, which the gad source can be cutted off before fire extinction
1.0.4.2 Liquid fire or meltable solid (like paraffin and asphalt) fire
1.0.4.3 Solid surface fire and solid deepseated fire (like cotton wool, fabric and paper)
1.0.4.4 Electric fire
1.0.5 Carbon dioxide extinguishing systems must not be used for extinguishing the following fires:
1.0.5.1 Fires of chemicals (like nitrocellulose and blasting powder) containing oxidants
1.0.5.2 Fires of active metals like kalium, sodium, magnesium, titanium and zirconium
1.0.5.3 Fires of metal hydrides like potassium hydride and sodium hydride
1.0.5A Total flooding carbon dioxide extinguishing system shall not be applied at the places where staffs stay often.
1.0.6 The design of carbon dioxide extinguishing system, besides the requirements of this standard, shall also meet the requirements of the current related national standards.
2 Term and Symbol
2.1 Term
2.1.1 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.
2.1.2 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.
2.1.3 Protected area
Close spece meeting the application conditions of a total flooding carbon dioxide extinguishing system; and protected by the system.
2.1.4 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.
2.1.5 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.
2.1.6 Inhibition time
Time to keep the designed carbon dioxide concentration and extinguish solid deepseated fire fully.
2.1.7 Pressure relief opening
An opening arranged on the exterior wall or top of a protected area to discharge internal superpressure of the protected area.
2.1.8 Equivalent orifice area
Converted orifice area of a standard nozzle with the water flow rate coefficient of 0.98.
2.1.9 Filling factor
Ratio of the mass of carbon dioxide stored in high pressure system container and the container volume.
2.1.9A Loading factor
Ratio of the mass of liquid carbon dioxide stored in low-pressure system container and the container volume.
2.1.10 Material factor
Reduction coefficient of the design carbon dioxide concentration of combustible substance corresponding to 34 % carbon dioxide concentration.
2.1.11 High-pressure system
Carbon dioxide extinguishing system which the fire extinguisher agent is stored at ordinary temperature.
2.1.12 Low-pressure system
Carbon dioxide extinguishing system which the fire extinguisher agent is stored at the low temperature of -18 ℃~ -20 ℃.
2.1.13 Equilibrlum flow
Two-phase flow uniformly mixed with gas phase and liquid phase.
2.2 Symbol
2.2.1 Symbol of geometric parameters
A -Converted area;
A0 -Total area of an opening;
AP -Area of actual enclosure, like solid wall, arranged in presumptive closed hood;
At -Side enclosure area of presumptive closed hood;
Av -The total area of protected-area medial surface, bottom surface and top surface (including the openings) of a protected area;
Ax -Pressure relief opening area;
D -Inside diameter of a pipe;
F -Equivalent orifice area of a nozzle;
L -Computational length of a pipe;
Lb -Side length of the square pretective area of a single nozzle;
Lp -Deviation distance of aiming point from nozzle protection area center;
N -Nozzle amount;;
Ng -Amount of nozzles arranged on the downstream of computation branch pipe flow;
Np -Amount of containers in high-pressure system;
V -Net volume of a protected area;
V0 -Volume of a single storage containner;
Vd -Volume of a pipe;
Vg -The total volume of non-combustible and combustible-resistance substance in a protected area;
Vi -Volume of the ith pipe segment in a pipe network;
V1 -Calculation volume of protected object;
Vv -Volume of a protected area;
Φ -Nozzle setting angle;
2.2.2 Symbol of physical parameters ：
Cp -Specific heat of pipe metal material;
H -Carbon dioxide vaporization heat;
K1 -Area factor;
K2 -Volume factor;
Kb -Material factor;
Kd -Pipe diameter coefficient;
Kh -Highpressure correction factor;
Km -Margin factor;
M -Designed dosage of carbon dioxide;
Mc -Storage volume of carbon dioxide;
Mg -Mass of a pipe;
Mr -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 ith pipe;
Pj -Pressure of a node;
Pt -Permissible pressure intensity of fender structure;
Q -Design flow of a pipe;
Qi -Design flow of a single nozzle;
Qt -Carbon-dioxide ejection rate;
q0 -Unit-area ejection rate of unit equivalent orifice;
qv -Ejection rate of unit volume;
T1 -Mean temperature of a pipe before carbon dioxide ejection;
T2 -Mean temperature of carbon dioxide;
T -Ejection time;
td -Delay time;
Y -Pressure factor;
Z -Density factor;
A -Filling factor;
ρi -Mean density of the carbon dioxide in ith pipe segment .
3 System Design
3.1 General Provisions
3.1.1 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-deepseated fire of specific protected object in no confined space.
3.1.2 The protected area for which total flooding extinguishing system is adopted shall meet the following provisions;
3.1.2.1 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.
3.1.2.1 As for solid deepseated fire, the opening except pressure relief opening shall automatically shut off before carbon dioxide ejection.
3.1.2.3 The fire endurance of fender structure, door and window in protected area shall not be less than 0.50 hours; the fire endurance of suspended ceiling shall not be less than 0.25 hours; and the permissible pressure of fender structure, door and window should not be less than 1200Pa.
3.1.2.4 The fire damper of fan and ventilation duct used in protected area shall automatically shut off before carbon dioxide ejection.
3.1.3 The protected area for which local application extinguishing system is adopted shall meet the following provisions;
3.1.3.1 The speed of air flow rate around protected object should not be greater than 3m/s. If necessary, wind-shielding measures shall be taken.
3.1.3.2 Between nozzle and protected objects, no barrier shall exist within nozzle ejection angle.
3.1.3.3 If the protected object is flammable liquid, the distance from liquid level to container edge shall not be less than 150mm.
3.1.4 Before or when carbon dioxide discharge is started, gas supply of combustible and combustion-supporting gases must be shut off.
3.1.4A 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.
3.1.5 If combined distribution system protects 5 (or above) protected areas or protected objects, or if such system can not recover within 48 hours; 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 high-pressure system, standby storage container shall be connected with system pipe network and the storage container shall be an alternative for main storage container.
3.2 Total Flooding Extinguishing System
3.2.1 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 Annex A of this code.
3.2.2 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.
3.2.3 The designed dosage of carbon dioxide shall be calculated according to the following formula;
M=Kb(K1A+K2V) (3.2.3-l)
A=Av+30A0 (3.2.3-2)
V=Vv-Vg (3.2.3-3)
Where, M——Designed dosage of carbon dioxide (Kg);
Kb——Material factor;
K1——Area factor (kg/m2), 0.2kg/m2;
K2——Volume factor (kg/m3), 0.7kg/m3;
A——Converted area (m2):
Av——Total area of protected-area medial surface, bottom surface and top surface (including the openings) (m2);
A0——Opening total area (m2);
V——Net volume of protected area (m3);
Vv——Protected area volume (m3):
Vg——Total volume of non-combustible and combustible-resistance substance in protected area (m3);
3.2.4 When the ambient temperature in protected area is greater than 100℃, carbon-dioxide designed dosage shall be added by 2 % for per 5℃ increase in addition to the calculated one in Article 3.2.3 of this code.
3.2.5 When the ambient temperature in protected area is less than -20℃, carbon-dioxide designed dosage shall be added by 2 % for per 1℃ decrease in addition to the calculated one in Article 3.2.3 of this code.
3.2.6 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.
3.2.7 Pressure relief opening area may be calculated according to the following formula:
(3.2.7)
Where, Ax——Pressure relief opening area (m2);
Qt——Carbon-dioxide ejection rate (Kg/min);
Pt——Permissible pressure of fender structure (Pa);
3.2.8 The carbon dioxide ejection time of total flooding extinguishing system shall not be greater than 1 minute. During extinguishing solid deepseated fire, the ejection time shall not be greater than 7 minutes and carbon dioxide concentration shall be ensured be greater than 30% in the first 2 minutes.
3.2.9 The inhibition time for using carbon dioxide to extinguish solid deepseated fire shall be adopted according to the provisions in Annex A of this code.
3.2.10 (deleted)
1 General Provisions
2 Term and Symbol
2.1 Term
2.2 Symbol
3 System Design
3.1 General Provisions
3.2 Total Flooding Extinguishing System
3.3 Total Flooding Extinguishing System
4 Pipe Network Calculations
5 System Component
5.1 Storage system
5.2 Selector valve and nozzle
5.3 Pipe and Accessory
6 Control and Operation
7 Safety Requirements
Annex A Material Factor, Design Concentration and Inhibition Time
Annex B Equivalent Length of Pipe Accessories
Annex C Pipe Pressure Sink
Annex D Y Value and Z Value of Carbon Dioxide
Annex E Elevation Correction Factor
Annex F Nozzle Inlet Pressure and Unit Area Injection Rate
Annex G Explanation of Wording in this Code
Annex H Nozzle Equivalent Orifice Dimension
Annex J Specifications of Carbon Dioxide Fire Extinguishing System Pipes
