What Is A Carbon Dioxide Fire Extinguishing System?

Mar 7, 2023 | news


Carbon dioxide is an extinguishing agent that can be used to fight many types of fires. Its fire extinguishing function is mainly to relatively reduce the oxygen content in the air, reduce the temperature of the burning material, and extinguish the flame.


Carbon dioxide is an inert gas, which has no destructive effect on most substances and can dissipate quickly after extinguishing a fire without leaving traces and is not poisonous. It is suitable for extinguishing fires of various flammable and flammable liquids and solid substances that are easily damaged by contamination by water, foam, and dry powder fire extinguishing agents. In addition, carbon dioxide is a non-conductive substance that can be used to fight fires in live equipment. At present, it has been widely used in many important places with fire hazards in the world. The International Organization for Standardization and industrialized countries such as the United States, the United Kingdom, Japan, and the former Soviet Union have all formulated design specifications or standards for carbon dioxide fire extinguishing systems. The use of a carbon dioxide fire extinguishing systems can protect books, archives, art, cultural relics, and other precious data warehouses; bulk liquid warehouses, computer rooms, communication rooms, power transformation and distribution rooms and other places can also be used to protect valuable instruments and equipment.
Rationally design the carbon dioxide fire extinguishing system to effectively protect the safety of people and property.

A carbon dioxide fire extinguishing system applies and does not apply

Carbon dioxide fire extinguishing systems can be used to extinguish the following fires:

  1. Gas fires where the gas source can be cut off before extinguishing the fire. the
  2. Liquid fires or meltable solid fires such as paraffin and asphalt. the
  3. Solid surface fires and some solid deep fires such as lint, fabric, paper, etc. the
  4. Electrical fire.

Carbon dioxide fire extinguishing systems shall not be used to extinguish the following fires:

  1. Chemical fires containing oxidants such as nitrocellulose and gunpowder. the
  2. Potassium, sodium, magnesium, titanium, zirconium, and other active metal fires. the
  3. Potassium hydride, sodium hydride, and other metal hydride fires. the
  4. The carbon dioxide flooding fire extinguishing system should not be used in places where people often stay.

General rules for the design of carbon dioxide fire extinguishing systems

  1. Carbon dioxide fire extinguishing system can be divided into total flooding fire extinguishing system and partial application fire extinguishing system according to the application method. The total flooding fire extinguishing system is used to extinguish the fire in the closed space; the local application fire extinguishing system is used to extinguish the non-deep fire of the specific protection object that does not need the closed space conditions. the
  2. The protection area using the total flooding fire extinguishing system shall meet the following requirements:
    ① For gas, liquid, electrical fires, and solid surface fires, the area of openings that cannot be automatically closed before carbon dioxide is sprayed should not exceed 3% of the total internal surface area of the protection zone, and the openings should not be located on the bottom. the
    ② For solid deep fires, openings other than pressure relief ports shall be automatically closed before carbon dioxide is discharged. the
    ③ The fire resistance rating of the enclosure structure, doors, and windows in the protection zone should not be lower than 0.50h, and the fire resistance rating of the suspended ceiling should not be lower than 0.25h; the allowable pressure of the enclosure structure, doors, and windows should not be less than 1200Pa. the
    ④ The ventilators used in the protected area and the fire dampers in the ventilation ducts should be automatically closed before carbon dioxide is sprayed. the
  3. The protected objects using the local application fire extinguishing system shall meet the following requirements:
    ①The air velocity around the protected object should not be greater than 3m/s. When necessary, wind protection measures should be taken. the
    ② Between the nozzle and the protected object, there should be no obstructions within the range of the spray angle of the nozzle. the
    ③ When the protected object is a flammable liquid, the distance from the liquid surface to the edge of the container shall not be less than 150mm. the
  4. Before or at the same time when starting to release carbon dioxide, the gas source of flammable and combustion-supporting gases must be cut off.
  5. The carbon dioxide storage capacity of the combined distribution system should not be less than the storage capacity of a protection zone or protected object with the largest required storage capacity. the
  6. When the combined distribution system protects 5 or more protected areas or protected objects, or cannot be restored within 48 hours, there should be a reserve amount of carbon dioxide, which should not be less than the storage capacity designed by the system. the
  7. For the high-pressure system and the low-pressure system with a separate reserve storage container, the reserve storage container should be connected to the system pipe network, and it should be able to switch to the main storage container.

Composition of carbon dioxide fire extinguishing system storage device



The storage device of the high-pressure system shall consist of storage containers, container valves, one-way valves, fire extinguishing agent leakage detection devices, and headers, etc., and shall meet the following requirements:

  1. The working pressure of the storage container should not be less than 15MPa, a pressure relief device should be installed on the storage container or container valve, and the pressure relief action pressure should be 19MPa±0.95MPa.
  2. The ambient temperature of the storage device should be 0°C to 49°C.
    The storage device of the low-pressure system shall consist of storage containers, container valves, safety pressure relief devices, pressure gauges, pressure alarm devices, and refrigeration devices, etc., and shall meet the following requirements:
  3. The design pressure of the storage container should not be less than 2.5MPa, and good heat insulation measures should be taken. At least two sets of safety pressure relief devices should be installed on the storage container, and the pressure relief action pressure should be 2.38MPa±0.12MPa.
  4. The high-pressure alarm pressure setting value of the storage device should be 2.2MPa, and the low-pressure alarm pressure setting value should be 1.8MPa.
  5. The container valve should be able to close automatically after the required amount of carbon dioxide is sprayed out.
  6. The storage device should be kept away from heat sources, and its location should be convenient for refilling. The ambient temperature should be -23°C ~ 49°C.
    The storage device should have a fire-extinguishing agent leakage detection function. When the loss of carbon dioxide filled in the storage container reaches 10% of its initial filling volume, it should be able to send out an audible and visual alarm signal and replenish it in time.
    The arrangement of storage devices should be convenient for inspection and maintenance and should avoid direct sunlight.

Select valves and nozzles

  1. In the combined distribution system, each protection area or protection object should be equipped with a selection valve. The selector valve should be set in the storage container room and should be easy to operate manually for easy inspection and maintenance. There should be a nameplate indicating the protection zone on the selector valve.
  2. The selector valve can be operated by electric, pneumatic, or mechanical operation. Select the working pressure of the valve: the high-pressure system should not be less than 12MPa, and the low-pressure system should not be less than 2.5MPa.
  3. When the system is started, the selection valve should be opened before or at the same time as the container valve of the carbon dioxide storage container; the selection valve that uses the fire extinguishing agent itself as the starting gas source to open is not subject to this limitation.
  4. The nozzle layout of the total flooding fire extinguishing system should make the carbon dioxide distribution even in the protection area, and the nozzle should be installed close to the ceiling or roof.
  5. For nozzles installed in places with dust or painting operations, a dust cover that does not affect the spraying effect should be added.

Pipes and accessories


High-pressure system piping and its accessories should be able to withstand the storage pressure of carbon dioxide at the highest ambient temperature; low-pressure system piping and its accessories should be able to withstand a pressure of 4.0MPa. And should meet the following requirements:

  1. Pipelines should be used in accordance with relevant regulations, and the inner and outer surfaces should be galvanized and anti-corrosion treated.
  2. In the environment that is corrosive to the galvanized layer, the pipeline can be made of stainless steel pipe, copper pipe or other corrosion-resistant materials.
  3. The flexible hose should be able to withstand the working pressure and temperature of the system, and stainless steel hose should be used.
    Anti-expansion and contraction measures should be taken in the pipe network of the low-pressure system.
    In places where explosions may occur, the pipe network should be hung and installed and anti-shake measures should be taken.
    Pipes can be threaded, flanged or welded. Pipes with a nominal diameter equal to or less than 80mm should be threaded; pipes with a nominal diameter greater than 80mm should be flanged.
    The carbon dioxide fire extinguishing agent delivery pipeline network should not use four-way pipe fittings for diversion.
    The closed pipe section between the valves in the pipe network should be equipped with a pressure relief device, and its pressure relief action pressure should be 15MPa±0.75MPa for the high-pressure system, and 2.38MPa±0.12MPa for the low-pressure system.

Control and operation of carbon dioxide fire extinguishing system

  1. The carbon dioxide fire extinguishing system should be equipped with three starting modes: automatic control, manual control, and mechanical emergency operation; when the locally applied fire extinguishing system is used in a protective place where there are often people, automatic control may not be provided.
  2. When fire detectors are used, the automatic control of the fire extinguishing system shall not start until two independent fire signals are received. According to the requirements of personnel evacuation, it is advisable to delay the start, but the delay time should not be greater than the 30s.
  3. The manual operation device should be located outside the protected area where it is easy to operate, and it should be able to complete all the operations of the system startup in one place. The manual operation device of the local application fire extinguishing system shall be located near the protected object.
  4. For the protective area protected by a total flooding fire extinguishing system, a manual and automatic conversion control device should be installed at the entrance; when someone is working, it should be placed in a manual control state.
  5. The power supply and automatic control of the carbon dioxide fire extinguishing system shall comply with the current international standards. When a pneumatic power source is used, the pressure and gas consumption required for system operation and control should be guaranteed.
  6. The power supply of the refrigeration device of the low-voltage system shall be a fire-fighting power supply, the refrigeration device shall be automatically controlled, and a manual operation device shall be provided.
  7. For places with an automatic fire alarm system, the action signals and related alarm signals, working status and control status of the carbon dioxide fire extinguishing system should be displayed on the fire alarm controller.

Safety requirements for carbon dioxide fire extinguishing systems

  1. Fire alarms should be installed in the protected area, and optical alarms can be added if necessary. Fire sound and light alarms should be installed at the entrance of the protection zone. The alarm time should not be less than the time required for the fire extinguishing process, and the alarm signal should be manually cut off.
  2. The protected area should have aisles and exits that can evacuate the people in the area within 30 seconds. At the evacuation walkways and exits, fire accident lighting and evacuation indication signs should be set up.
  3. Fire extinguishing system protection signs and carbon dioxide discharge indicator lights should be set at the entrance of the protection area.
  4. When the system pipeline is set in a place with combustible gas, steam, or explosive dust, it should be grounded against static electricity.
  5. The underground protection area and the above-ground protection area without windows or with a fixed sash should be equipped with mechanical ventilation devices.
  6. The door of the protected area should be opened in the direction of evacuation, and can be closed automatically; in any case, it should be able to be opened from the protected area.
  7. The obvious position at the entrance of the protected area where the fire extinguishing system is installed should be equipped with a special air respirator or oxygen respirator.