Traditionally, most fog nozzles operate at which nozzle pressure?

Fog nozzles are designed to produce a spray pattern that can effectively cool and smother fires while also providing thermal protection for firefighters. The traditional operating pressure for most fog nozzles is set at 100 psi (690 kPa). Operating at this pressure allows the nozzle to create fine water droplets that can maximize surface area and enhance the cooling effect on the fire, making extinguishment more effective.

When set to this pressure, the fog nozzle achieves a balance between the required reach of the water stream and the desired size of the droplets. At higher pressures, the fog pattern becomes more aggressive and can deliver water over greater distances, while still maintaining the fine mist necessary for efficient performance. This is crucial in firefighting scenarios where controlling heat and visibility is essential for both fire suppression and firefighter safety.

The other pressures listed, while they may be used in different contexts or configurations, do not represent the traditional standard for fog nozzles specifically. Each of these pressures has its applications, but they are not typical for fog nozzles operating traditionally in firefighting practices.