If fire is prematurely extinguished, a fog stream of at least ______ GPM may dissipate the cloud of unburned gas.

If fire is prematurely extinguished, a fog stream of at least ______ GPM may dissipate the cloud of unburned gas.

• A. 50 GPM
• B. 200 GPM
• C. 100 GPM
• D. 25 GPM

Answer: (C)

Dissipating a cloud of unburned gas relies on cooling and diluting the vapor with a fine spray from a fog nozzle. When a fire is prematurely extinguished, unburned fuel can linger as a vapor cloud that remains capable of reigniting. A fog stream with enough flow rate creates a curtain of tiny water droplets that contact the vapor, cooling it and mixing it with air. This dilution reduces the vapor concentration and lowers the risk of ignition. The minimum flow rate needed for this effect is about 100 GPM, which provides enough droplets and momentum to reach and disrupt the vapor cloud. Lower flows don’t deliver enough cooling and dilution, while higher flows (like 200 GPM) may be used in larger spaces but aren’t required in all cases to achieve dissipation.

Dissipating a cloud of unburned gas relies on cooling and diluting the vapor with a fine spray from a fog nozzle. When a fire is prematurely extinguished, unburned fuel can linger as a vapor cloud that remains capable of reigniting. A fog stream with enough flow rate creates a curtain of tiny water droplets that contact the vapor, cooling it and mixing it with air. This dilution reduces the vapor concentration and lowers the risk of ignition. The minimum flow rate needed for this effect is about 100 GPM, which provides enough droplets and momentum to reach and disrupt the vapor cloud. Lower flows don’t deliver enough cooling and dilution, while higher flows (like 200 GPM) may be used in larger spaces but aren’t required in all cases to achieve dissipation.