Hydrofan does not respect game speed settings, instead operating at constant rate. It takes roughly the same amount of real (out of game) time for it to "suck up" gas regardless of whether the game is running at slowest or fastest speed.
It seems that even the animation is affected somewhat: switching speed while looking at a hydrofan being operated may cause the dupe's animation not to match hydrofan's.
Steps to Reproduce
Use a hydrofan on slowest and fastest speed, record the time required for it to get full.
This issue has not been confirmed by a developer yet.