Most fog nozzles are designed to operate at ______ psi.

Most fog nozzles are designed to operate at ______ psi.

• A. 80 psi
• B. 100 psi
• C. 120 psi
• D. 140 psi

Answer: (B)

Fog nozzles rely on a specific operating pressure to create the fine mist that absorbs heat efficiently. About 100 psi provides the best balance between the amount of water flowing and the droplet size needed for effective cooling, shielding, and visibility. At this pressure the nozzle produces a dense fog without excessive recoil, making it practical for typical fire suppression. If the pressure is much lower, the spray becomes coarser and cooling is less effective; if the pressure is much higher, droplets become finer and more water or force is required, with diminishing returns and more strain on the system. So, 100 psi is the standard operating pressure.

Fog nozzles rely on a specific operating pressure to create the fine mist that absorbs heat efficiently. About 100 psi provides the best balance between the amount of water flowing and the droplet size needed for effective cooling, shielding, and visibility. At this pressure the nozzle produces a dense fog without excessive recoil, making it practical for typical fire suppression. If the pressure is much lower, the spray becomes coarser and cooling is less effective; if the pressure is much higher, droplets become finer and more water or force is required, with diminishing returns and more strain on the system. So, 100 psi is the standard operating pressure.