All, i was reading an article the other day about how to approach storage design, and while it was very helpful I think it may have the wrong answer to it's example problem. The only reason I'm asking is because I'm new to a lot of this and while i was following along with his steps I got a different answer. Can anyone let me know if I'm looking at this correct?

I linked to the article if you want to read the whole thing, but the summary of his example was....

Group A Plastics, cartoned, non expanded. Palletized on open grates, no shelving.
Double Row storage
20feet high
30foot ceiling height
25.2k ESFR

https://www.pmengineer.com/articles/91278-tips-on-...

By these parameters, the chart i was looking at states that 15psi is the minimum operating pressure. He lists it in his article as 20psi. I'm really just looking for guidance and to see if I am missing some component, so any help would be appreciated.