Hot Water Pipe Sizing

Hi guys,will you clarify me on the following for office building hot water pipe sizing. For same Fixture Unit Value, ASHRAE Modified Hunters Curve and Internation Plumbing Code,APPENDIX-E (Table E103.3(3) give different flow rates causing different pipe sizes. For example, for a fixture unit value of 140,ASHRAE Modified Hunters Curve indicates flow rate of 20 gpm (for Office Building) while International Plumbing Code,APPENDIX-E (Table E103.3(3) indicates flow rate of 52.5 gpm. Which flow rate (gpm) to use for hot water pipe sizing?