If the condensate pump is pumping out of a tank that is vented to atmosphere, then some of the steam will be lost to flashing. The amount of flash loss depends on the pressure upstream of the trap. 300 lb/hr is a conservative number.
The rated flow rate for the pump might be two times the steam load, however. This is the case when the pump is controlled on/off by level switches in the tank, so the pump is running at most 50% of the time.