Selecting Design Point from Density/Area Curves

In NFPA 13 (2016), for Standard Spray, Extended Coverage, and CMDA sprinklers, Density/Area curves are used to design fire sprinkler systems. For the following conditions, NFPA 13 provides design curves:
 
  – Light, Ordinary, and Extra Hazard occupancies where the hydraulic calculations               method is used
  – Miscellaneous and low-piled storage
  – Palletized, Solid-Piled, Bin Box, Shelf, or Back to Back Shelf storage of Class I to IV
  – Rack Storage of Class I to IV (with storage height Up to 25 ft)

This text aims to examine the advantages of each point of the curve.
As shown in the below figure that is extracted from the “Design criteria” window of “Sprinkler Design software”, NFPA 13 requires Curve “D” of Figure 16.2.1.3.2(a) for the following conditions:

  – Rack Type: Double Row, Open Rack
  – Commodity: Nonencapsulated Class I
  – Storage height: 12 to 20 ft
  – Aisle width: 4 ft
  – Ceiling Sprinklers: CMDA, Ordinary temperature
  – In Rack sprinklers Option: Selected