Re: Revised hydraulic calcs.
It depends on a few things:
1. Are these changes in the sprinkler system in the most remote design area, those 9-12 heads they calculate for the 1500 part of .10/1500? If not a few feet of pipe and few heads should not matter. Remember the closer you get the riser the better the flow and more pressure you will have.
2. What is the safety cushion in the original calculations? Was it 2 psi or 80 psi? If 2 psi do you really thing the job went in exactly as the plans indicated, do you think they did not have to add an extra elbows or a few tees, or a few feet of pipe?
3. If it is a high rise building were the calculations done for the 30th floor and the renovations are on the 1st floor? Sometimes I will get one set of calculations saying this is worse case. If on the 1st floor we will have a lot more psi available then the 30th floor.
4. IF the occupancy is the same i.e. light hazard to light hazard, less of a concern. If it is light hazard to ordinary hazard, now you have a whole bunch of issues, head spacing, higher density etc etc.
5. If you have a pressure reducer valve (PRV) on the floor control valve what is it set at and do they need to change that too?
Oh what fun....
Hope this helps.