In-rack fire protection sprinkler system

A fire protection sprinkler for protecting commodities stored between two solid horizontal barriers in a plurality of adjoining racks having a longitudinal flue space between the racks, the sprinkler comprising:

• a body having an inlet and an outlet defining an output orifice having a K-factor of at least about 11.2, the inlet constructed to a fluid supply to dispose the body in the vertical flue space;
• a seal cap sealing the output orifice;
• a frame extending from the body;
• a deflector supported by the frame;
• and
• a thermally responsive element supported between the seal cap and the frame;
• the thermally responsive element urging the seal cap sealing the output orifice in an inactivated condition,
• wherein when the storage height between the solid horizontal barriers is up to about 30 feet and the sprinkler is positioned between the stored commodities and the solid horizontal barrier in the vertical flue space, the sprinkler is constructed to protect stored commodities including Class I-IV hazards, Group A cartoned and exposed plastics (expanded and unexpanded), flammable liquids, tires, roll paper, and aerosols.