Abstract: A water and inert gas fire suppression system (10), and method for extinguishing a fire in a protected space are provided with a simple and inexpensive freeze protection mechanism. To prevent the water, or other liquid fire extinguishing agent, entrained in the inert gas flow from freezing during transport through the inert gas distribution network (15, 15a, 15b, 17, 19) a secondary liquid is introduced into the inert gas flow and then removed from the inert gas flow upstream of the discharge of the two-phase water and inert gas flow into the space being protected. The inert gas is heated by means of the thermal inertia (TI) of the secondary liquid, which may be excess amount of water or an amount of another liquid having a thermal inertia (TI) at least equal to that of water.

Abstract: A fire extinguishing or explosion suppression device comprises a chamber and a nozzle. The nozzle defines a discharge pathway from the chamber. The chamber has an inlet for pressure-driven introduction of a liquid into the chamber. The chamber is shaped so that a gas contained in the chamber before the introduction of the liquid is entrained into the liquid during the pressure driven introduction of the liquid such that a mixture of the liquid and the gas is discharged through the nozzle to create a mist for extinguishing a fire or suppression of an explosion. After the gas has been discharged from the chamber, the nozzle produces a spray having a core of larger liquid droplets with the core being surrounded by smaller liquid droplets.