What is the maximum spacing permitted for an Extra Hazard hydraulically calculated system with a density less than 0.25 gpm/ft²?

In fire protection engineering, specifically for hydraulically calculated sprinkler systems, the maximum spacing between sprinklers is dictated by the hazard classification of the area being protected. For Extra Hazard classifications, which include environments with increased risks such as assembly areas or certain industrial applications, the design requirements are more stringent than those for Light or Ordinary Hazard areas.

When the density of water application is less than 0.25 gallons per minute per square foot (gpm/ft²), the maximum spacing allowed increases. The acceptable coverage provided by the sprinklers must ensure effective distribution and meet the system's hydraulic capabilities. In this case, the maximum spacing permitted for sprinklers in an Extra Hazard environment, when the density is at or below this threshold, is specifically limited to 15 feet between the sprinklers.

This spacing ensures that the water being discharged is appropriately targeted and overlaps sufficiently to maintain effective coverage over potentially hazardous materials or conditions. Thus, a maximum spacing of 15 feet aligns with the standards intended to provide adequate fire protection in such environments.