What Pressure to Use for Standpipe Flow Testing?

When doing a flow test for a 5-year on an automatic wet standpipe system in a building which has had significant additions over the years, which design pressure applies?

The original 8-story building and pump are from the early 1980's and was required to have a minimum residual 65-psi at the roof, flowing 750 gpm.

Fast forward to the most recent building attachment to the existing fire pump, and the code now requires a minimum of 100-psi at 750 gpm at the roof. 

Would these additions be considered separate zones and therefore be tested individually at their specific design requirement, or would they all be tested at the original design requirements?

The building is a healthcare facility and is inspected to NFPA 25-2011 per the Joint Commission requirements.

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