Hydrant Design Flow vs Available Flow

I don't like the new update, which makes the available flow subject to a velocity constraint. In the previous version, the pressure constraint was on the hydrant flowing, while the design flow would consider the network pressure and pipes. They should go back to this original method to calculate available fire flow. Now there is hardly a difference between design and available flow! I believe the only difference is the available flow considers the connecting pipes while the design can consider domain pipes and connecting pipes