Systems and methods of low clearance storage fire protection

A fire protection system, comprising:

• a plurality of parallel fluid supply pipes disposed beneath a ceiling of a storage occupancy;
• and
• a plurality of fluid distribution devices coupled to the fluid supply pipes to define four fluid distribution devices;
• the plurality of fluid distribution devices each having an outlet and a deflector, each outlet to direct a fluid from the fluid supply pipes to the respective deflector, the deflector including a central region and an arcuate annulus region that has a first portion circumscribed about a sprinkler axis to define a first diameter, a second portion circumscribed about the sprinkler axis to define a second diameter, and an outermost discontinuous peripheral edge to define a maximum diameter, a ratio of the second diameter-to-the first diameter that ranges from 2:1 to 3.5:1, the central region and the maximum diameter being axially spaced apart to define a maximum depth of the deflector, a ratio of the second diameter-to-maximum deflector depth ranging from 3:1 to 6:1, the deflector to deflect the fluid in a spray pattern;
• and
• the plurality of fluid distribution devices configured to generate a spray pattern that defines a rectangular area of fluid distribution below the fluid distribution devices, the rectangular area having a first pair of edges extending parallel to the fluid supply pipes and a second pair of edge extending perpendicular to the first edge, the rectangular area including a first zone of fluid distribution of a 4 ft.×4 ft. area centered in the rectangular area, the first zone having a fluid density that is at least 3% of a total fluid density.

A method of low clearance coverage fire protection of rack storage with a clearance of no more than 5 ft., the method comprising:

• obtaining a plurality of upright fire protection sprinklers, each sprinkler having:
• a body with an internal passageway axially extending along a sprinkler axis;
• a deflector disposed about at least a portion of the body and centered along the central axis with an internal deflecting surface circumscribed about the sprinkler axis, the internal deflecting surface having a central region, a peripheral region and an arcuate annulus region between the central region and the peripheral region, the central region being a planar surface disposed perpendicular to the sprinkler axis, the peripheral region having a plurality of spaced apart planar surfaces each angled outwardly with respect to the sprinkler axis to define a maximum diameter of the deflector circumscribed about the sprinkler axis;
• and
• providing the plurality of upright fire protection sprinklers for coupling to a network of fluid supply pipes in a spaced apart arrangement, the plurality of sprinklers defining a distribution density of 0.55 gpm/sq. ft. at a minimum operating pressure.

A method of providing and qualifying a sprinkler for low clearance fire protection, the method comprising:

• locating the sprinkler in an upright orientation above a floor, the sprinkler having a body and a deflector coaxially aligned along a sprinkler axis;
• generating a first fluid distribution below the deflector having a total fluid density of at least 15 gpm/sq. ft. in a first gridded area with a first edge and a second edge perpendicular to the first edge, the intersection of the first and second edges being disposed along the sprinkler axis, with at least 3% of the total fluid density in a first zone of the first gridded area;
• and
• generating a second fluid distribution greater than the first fluid distribution below the deflector having a total fluid density of at least 12 gpm/sq. ft. in a second gridded area with a first edge and a second edge perpendicular to the first edge, the intersection of the first and second edges being disposed along the sprinkler axis, with at least 35% of the total fluid density in a first zone of the second gridded area.