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Suppression
Several fire scenarios can happen when an IED or HEAT round penetrate an armored vehicle. Flammable vapors from ruptured hydraulic fluid pipes or fuel spray or spill from fuel tank leakage can be ignited by the high-energy source penetrating the vehicle and a fireball may be created. Ammunition and other energetic materials carried by the vehicle may catch fire and further explode.
There are several classic methods to extinguish/suppress a fireball propagating at high speed in a closed compartment (like the crew or engine areas in the combat vehicle) by eliminating one of the fire pyramid parameters - oxygen, fuel, heat or chemically interfering in the fire chain reactions. Additional mechanical methods like flame arresting or venting, removing the fuel source by blanketing or mechanical covers, removing the oxygen by providing an inert atmosphere, heat absorbing by various means and finally interfering with chemical agents, namely fire extinguishing agents either in the gaseous, liquid or dry powder forms. The limitation of most of these methods is speed of the fire suppression agent discharge, its homogeneous dispersion in the hazard volume and successful extinguishing. An additional important requirement is the minimal pressure increase inside the protected compartment due to the high speed extinguishing agent discharge.
Automatic explosion/suppression systems comprise either pressurized cylinders containing gaseous, liquid or powder extinguishing agent or non-pressurized gas generators (or hybrids) containing the suppressing agent and a minute propellant activator that propels the extinguishing agent. Both the discharge speed and dispersion pattern of the extinguishing agent are of critical importance to the successful suppression of the fireball and prevention of flame deflagration to detonation process.
The SAFE system comprises a special extinguishing cylinder with high-speed hermetically sealed valve mechanism that discharges the extinguishing agent within 5 milliseconds and disperses the agent homogeneously in less than 80 milliseconds over an angle of 360 degrees. The dispersion of the fire-extinguishing agent in the protected volume is direct, with no hoses, pipes or other interference to the free flow (that slow discharge). The broad cone of agent discharge (360 degrees) provides a most effective agent deployment at lowest possible pressure.
The above Fig. shows the dispersion pattern of two types of cylinders, one with a solenoid valve and another with a hermetically sealed valve.
In the sealed valve, an electrical signal, transmitted by the control, activates an electrical squib, which ruptures a disc to release the extinguishing agent. Through the deflector, the extinguishing agent is distributed to the various areas of the protected volume. The homogeneous discharge allows for a fast drop in discharge pressure at short distance thus posing no threat to the personnel and equipment nearby. The extinguishing agent can be a clean gaseous agent (Halon Alternative) super pressurized with dry Nitrogen, dry powder or a water agent that may contain some additives. A pressure switch, designed as an integrated part of the cylinder valve, enables the control to continuously monitor the cylinders status.
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