Which term describes a fire stream that can move large amounts of air and disrupt the thermal balance?

• A. Fog Stream
• B. Smooth Bore
• C. Straight Stream
• D. Direct Attack

Answer: (A)

Fog streams are designed to move large amounts of air and disrupt the thermal balance in a fire area. This happens because adjustable fog nozzles break water into a fine mist and entrain a lot of surrounding air. The tiny droplets have a large surface area and evaporate quickly, absorbing a lot of heat and cooling the hot gasses. That rapid cooling, combined with the air mixing, pushes hot gases and smoke away from the fire, helps control the environment, and improves visibility for crews.

Smooth bore and straight streams deliver solid jets with less air entrainment, focusing water delivery but not creating the same air movement and cooling effect. Direct attack is a tactic describing applying water to the flame, not the type of stream itself.