Water Mist and Gaseous Clean Agents Suppress by Different Mechanisms
Where water damage or residue is unacceptable, two suppression families compete, and they act differently. A water mist system forces water through fine nozzles into droplets of tens of micrometres; the enormous surface area evaporates quickly, absorbing heat and displacing oxygen locally with steam, so it extinguishes with a small fraction of the water a sprinkler uses and leaves little residue. A gaseous clean agent floods the whole enclosure instead: inert-gas blends such as nitrogen and argon mixtures suppress by lowering oxygen concentration to a level that will not support flaming but still supports a person briefly, while chemical agents such as the fluoroketone commonly sold as Novec 1230 and the halocarbon HFC-227ea absorb heat and interrupt flame chemistry. The mechanism dictates the requirement. A clean agent needs a sealed enclosure to hold a design concentration, so a leaky room or an open door defeats it, and it acts once. Water mist tolerates openings and keeps working while water lasts. After this Concept you can match a suppression mechanism to a room and say which one an unsealed enclosure rules out.
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Where water damage or residue is unacceptable, two suppression families compete, and they act differently. A water mist system forces water through fine nozzles into droplets of tens of micrometres; the enormous surface area evaporates quickly, absorbing heat and displacing oxygen locally with steam, so it extinguishes with a small fraction of the water a sprinkler uses and leaves little residue. A gaseous clean agent floods the whole enclosure instead: inert-gas blends such as nitrogen and argon mixtures suppress by lowering oxygen concentration to a level that will not support flaming but still supports a person briefly, while chemical agents such as the fluoroketone commonly sold as Novec 1230 and the halocarbon HFC-227ea absorb heat and interrupt flame chemistry. The mechanism dictates the requirement. A clean agent needs a sealed enclosure to hold a design concentration, so a leaky room or an open door defeats it, and it acts once. Water mist tolerates openings and keeps working while water lasts. After this Concept you can match a suppression mechanism to a room and say which one an unsealed enclosure rules out.
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