In the specified time, spray the designed amount of heptafluoropropane fire extinguishing agent into the protection area, and make it evenly fill the entire protected area, and maintain an appropriate concentration during the immersion time, cut off the combustion chain in the molecule, and at the same time, heptafluoropropane will be quickly removed The liquid turns into a gaseous state and absorbs a lot of heat to reduce the ambient temperature around the protection zone and the burning material, thereby quickly extinguishing the fire. In the underground space of the subway, this gas fire extinguishing system is mainly used in important electromechanical equipment rooms. Its typical protection areas include environmental control electric control room, station control room, signal equipment room, automatic fare collection (AFC) machine room, communication equipment room, and substation equipment room, etc.

　　Heptafluoropropane HFC-227EA fire extinguishing process:

　　When a fire occurs in the protection area, the fire detector sends out a fire signal, and the alarm and fire extinguishing controller sends out a sound and light signal and simultaneously sends out a linkage command to close the interlocking equipment. After a delay time (adjustable within the 30s), a fire extinguishing command is issued and the start valve is opened The starting gas is released, and the starting gas opens the corresponding selection valve and container valve (bottle head valve) through the starting pipeline to release the extinguishing agent and implement the fire extinguishing.