The task of a cooling device is to deliver coolant with a given temperature and a given flow rate into a cooling system.
Within each cooling channel there is a pressure drop. The pressure drop depends not only on the flow rate.
Furthermore length and geometry of the cooling system play an important role in the occurring pressure.
The pump curve shows the maximum flow rate at a given pressure rate.
If the pressure drop in the cooling channel is higher than suggested in the pump curve, the flow rate will drop.
As actual value the flow rate is shown, which is the maximal possible for the given pressure.
In this case the cooling channel needs to be adjusted or another cooling device should be used.