fire mechanism

Enroll in a class at the local university.

Heptafluoropropane (FM-200) suppresses fire by both physical and chemical means. When you say "reaction" I assume you are referring to the "chain breaking" ability of this compound. It does indeed break the chain of combustion, and hence the demise of the fire triangle and the birth of the fire tetrahedron years ago.

yes i mean chain breaking............and i need the equation for free radical that used in the reaction .

I don't know what you mean by "I need the equation". The combustion process is not fully understood. Neither is the process by which chain breaking occurs. The most likely theory is that oxygen must be "activated" for use by the fire. The cross section, however, of the fluorine molecule is large enough to capture the electrons created during the ionization of hydro-carbon molecules that would otherwise create O2 for combustion, thereby inhibiting the combustion process. There certainly is no equation for any of this theoretical shtuff.