WaterGems fire flow analysis gives the flow at points to bring the pressure down to 20 psi or the flow which will reduce the pressure elsewhere to 20 psi, whichever flow is least. That analysis predicts what flows can be potentially extracted from a system with a large tap and a jockey pump--often flows much higher than what can be obtained through a pumper truck and fire hydrant. My concern is people (including engineers) run your fire analysis and think that they can get that fire flow through a fire truck attached to a fire hydrant.