The best replacement for flow rate is pressure.

The best alternatives to flow rate are rated as following:
★★★★★  pressure
★★★  velocity
★★★  pipe size
★★★  viscosity
★★  pipe diameter
★★  pressure drop
★★  flow velocity
★  diameter
★  drip rate
★  mass flow rate
★  flow time
★  head
★  flow speed
★  flux
★  volumetric flow rate
★  head loss
★  flow rate
  differential pressure
  heat transfer
  volume flow rate
  drop rate
  air pressure
  3 4 copper pipe

Your alternative for flow rate is not listed? Suggest!
Speaking about flow rate, one probably shouldn't forget about head loss.

Other search terms related to flow rate and their ratings are:
★★★★★ head loss
★★★★ pressure drop
★★★ pipe size and pressure
You have in mind a companion for flow rate and it is not yet here? Propose!



Google Trends

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flow rate
pressure
velocity