Which one should you choose: carbon dioxide or heptafluoropropane?

　　Sevenfluoropropane has long dominated the gas-based fire suppression market thanks to its unique product features—high efficiency, cleanliness, zero pollution, and abundant supply. These are just a few of its key advantages. Meanwhile, carbon dioxide also holds an irreplaceable position in gas-based fire suppression systems. So, what exactly are the differences between the two? This article will provide you with a thorough and informative explanation.

　　Let me first introduce the carbon dioxide fire suppression system.

　　The fire-extinguishing principle of carbon dioxide systems: Gaseous carbon dioxide is liquefied under high pressure or low temperatures. When discharged, the gas rapidly expands in volume while absorbing significant amounts of heat, thereby reducing the temperature in the fire area or protected zone. Simultaneously, the high concentration of CO₂ gas dilutes the oxygen level within the protected space, effectively suffocating the fire and achieving an extinguishing effect.

　　Advantages of carbon dioxide fire extinguishers and fire suppression systems: Since carbon dioxide can be easily liquefied, it is simple to fill and store, making the manufacturing process relatively straightforward. Additionally, it is cost-effective. When used for firefighting, carbon dioxide does not contaminate the fire scene and poses no corrosive or damaging effects on protected objects within the safeguarded area. Not only can it effectively extinguish Class A, B, and C fires, but at high concentrations, it can even tackle deep-seated solid-material fires. As a result, it proves particularly effective in protecting areas where water-based or foam-based extinguishing agents fall short.

　　Of course, carbon dioxide fire suppression systems also have their unavoidable drawbacks: Since CO2 extinguishing agents require a concentration of 34% to 75% to effectively put out fires, the system must store and transport the gas in liquid form. Typically, two types of systems are used—high-pressure systems that store CO2 under high pressure, and low-pressure systems that rely on cryogenic storage at lower temperatures. In high-pressure storage systems, a large number of cylinder banks is often needed for practical applications, occupying significant space in the storage room. Moreover, the high pressure levels impose strict temperature requirements on the storage environment. During summer months, special attention must be paid to the risk of cylinder explosions caused by rising storage temperatures. Therefore, during system design, it’s generally recommended that the storage room avoid direct sunlight exposure. Additionally, high-pressure CO2 fire suppression systems depend on high-pressure nitrogen gas to activate the automatic start-up sequence. This results in a higher number of auxiliary components, increasing both the initial investment costs and the complexity of maintenance. Over time, these additional parts can also raise the likelihood of system failures, making upkeep more challenging. On top of this, due to the high-pressure storage method, annual leakage rates typically reach around 5%, making it particularly difficult to maintain proper pressure throughout the year. Furthermore, as CO2 transitions from its liquid state to gas, it easily forms "dry ice," which sublimates directly into a gaseous state. During this sublimation process, the gas expands dramatically—increasing in volume by tens of thousands of times—which can severely damage the delivery pipelines. Such expansion may lead to cold embrittlement and eventual pipe rupture, posing serious risks of injury or destruction to personnel and protected areas. Adding to these concerns, the rapid expansion of CO2 during release can also generate static electricity, potentially igniting nearby flammable materials. Lastly, because the design concentration of CO2 is relatively high, there’s an added risk that individuals trapped within the protected area might suffer from asphyxiation if they fail to evacuate safely in time. In summary, while carbon dioxide fire suppression systems offer effective protection for certain applications, their limitations—including long discharge times (up to 60 seconds), complex maintenance needs, and potential hazards like dry-ice formation and static electricity—make them unsuitable for environments where people frequently stay or work.

　　The emergence of heptafluoropropane made it the ideal replacement for Halon fire extinguishers at the time—it poses no threat to the ozone layer, with an ODP (Ozone Depletion Potential) of zero. However, it has a significant greenhouse effect. Despite its superior firefighting efficiency and an extremely well-established market presence, heptafluoropropane has remained difficult to replace entirely—until now, with the advent of perfluoroacetone. Yet, while perfluoroacetone shows promise, it is still relatively immature in the market and has not yet fully eclipsed heptafluoropropane's dominance.

　　The fire-extinguishing principle of heptafluoropropane: The mechanism of the heptafluoropropane fire suppression system is very similar to that of halon-based extinguishing agents, falling under the category of chemical fire suppression. It works by thermally decomposing the extinguishing agent to generate fluorine-containing free radicals, which then interact in the gas phase with H, OH⁻, and O₂⁻ active free radicals—species that typically participate in chain reactions during combustion—thereby inhibiting the chemical reactions essential for sustaining the fire and effectively putting out the blaze.

　　The advantages of the heptafluoropropane fire suppression system: This system boasts powerful and rapid fire-extinguishing efficiency, delivering quick results with excellent performance. It requires a low extinguishing concentration—nearly matching that of its predecessor, the Halon 1301 system—and features an exceptionally fast discharge time, completing the spray within just 8 to 10 seconds for swift fire suppression.