The goal of the research project that they were reviewing, was to develop cost effective sprinkler system design criteria for rack storage for exposed expanded group A plastics, because there wasn't any at all beforehand. Group A plastics are included in mattresses, food containers and some furniture. They are challenging to protect because they create a fast developing fire with high heat release and fire travel is rapid in both horizontal and vertical directions. 188 inches of water/hour would be needed to stop this fast developing fire with high heat release - and if you compare that to some of the worst hurricanes, they produce around 8 inches or water/hour, so tons of water is needed to stop these fires.
Protection criteria was tested in order to make revisions and additions to NFPA 13. Experiments were reviewed through the presentation today that were used to create 40 ft design criteria. Provisions that were developed from results include 8 ft minimum aisle width, 40 ft maximum ceiling height, 35 ft maximum storage height, 60psi design pressure on K=25.2 pendant sprinklers and more.
This research was conducted as part of Fire Protection Research Foundation project, and so a summary of all research findings and full reports can be found on their website. You can also find subsequent research on 30 ft ceiling height storage space and the findings on that in the same place.