Get fluid throughput

[ljdp]

Is there a way to get fluid throughput on an entity with a fluidbox, such as the offshore-pump?

I've tried getting the delta of the fluid amount with the fluid amount on the last tick but that does not work. Once a pump reaches an amount of 10 it stays at 10 from tick to tick.
Also, setting the amount back to 0 once it reach 10 causes it to rapidly shoot to 10 again.