VENT STACK AND FIRE FIGHTING (SNUFFING) SYSTEM
FIRE FIGHTING (SNUFFING) SYSTEM
The rapid snuffing of a vent is often required as a safety measure (usually for accidental ignition of the vent). It is normal to inject the extinguisher into the gas flow inside the vent stack. As snuffing agent Carbon Dioxide (CO2) is normally utilized. The extinguishing action of carbon dioxide happens by suffocating the fire, diluting the percentage of oxygen contained in the air and by cooling action provoked by the rapid expansion of gas. The CO2 is contained in cylinders installed on racks, remotely or manually activated, which discharges the CO2 inside the vent stack via special nozzles. The quantity of CO2 required to avoid the accidental ignition of the vented gas is normally 3,5 per volume of gas (obviously depend of the venting gas composition). To minimize the quantity of CO2, it is necessary to inject the inert via special nozzles in order to create a ball of inert gas between the possible flame and the incoming gas. Presence of flame in a vent system is normally detected via thermocouple located on vent tip. The thermocouple signals are run back to the snuffing system control panel where temperature switches are used to initiate the CO2 rapid discharge (it is important to consider that the velocity of CO2 at the exit of the bottles is on a range of 1Kg/sec).