What is the difference between a master stream and an attack line in terms of flow and purpose?

• A. Attack lines deliver higher flow than master streams.
• B. Master stream devices deliver high flow for large-area fires.
• C. Attack lines are smaller-diameter lines used for interior or direct attack with controlled flows.
• D. Master stream devices deliver high flow for large-area fires; attack lines are smaller-diameter lines used for interior or direct attack with controlled flows.

Answer: (D)

The essential idea is matching water flow to the task: master streams deliver a large volume of water to suppress a large fire from a distance or safe position, while attack lines provide a smaller, more controllable flow for a direct, interior attack. Master stream devices are designed to deliver high flow to rapidly knock down flames and protect exposures over a wide area. Attack lines, being smaller-diameter hoses, are used up close to the fire to apply water directly at the origin or along the path of the fire with careful control. The best description combines both: master streams deliver high flow for large-area fires; attack lines are smaller-diameter lines used for interior or direct attack with controlled flows.