What is the density maximum for an extra hazard system classified as having a density less than .25?

The correct choice reflects the understanding of density requirements for extra hazard classification in fire sprinkler systems. An extra hazard system is designed for areas where flammable materials are present, and therefore, it has specific requirements related to the maximum spacing of sprinklers and the minimum density of water applied.

For an extra hazard system with a density of less than .25, the code specifies that the area of coverage for each sprinkler at this density can go up to a maximum of 130 square feet. This means that when spacing sprinklers in an area designated as extra hazard, one sprinkler can adequately protect up to 130 square feet when the density of water application is less than .25 gallons per minute per square foot.

Understanding these parameters is crucial in designing effective fire protection systems tailored to the specific risks presented in extra hazard environments. The effective functioning of these systems relies not just on water flow but also on the correct spacing of sprinklers to ensure comprehensive coverage.