Clean agent FS 49 C2 is an environmentally engineered, human safe, fast acting Clean Agent fire extinguishing gas for gaseous fire suppression installed in a suited fire suppression system.  The gas consists of tetrafluoroethane, pentafluoroethane and carbon dioxide.
FS 49 C2  maintains breathable concentrations of oxygen in the air. It can extinguish a fire with less danger to people in the room at extinguishing concentrations in contrast to pure carbon dioxide based fire suppression system that is deadly to humans when released in extinguishing amounts. 
The gas was initially called Halotron II B/FS49C2.