This question came across my desk last week…
If I want to measure the flow rate in the mold cooling system, should I measure the water coming IN the mold or the water going OUT of the mold?
Either is OK. Unless there is a leak, the IN and OUT flow rates should be the same.
Some companies will also check the flow of each water line (during initial mold testing) just to ensure there are no significant restrictions or imbalances.