Great question and can never get a real good answer if one exist..
What can be done to solve issues of grease exiting out of a exhaust hood in a commercial kitchen?
Some restaurants have no grease issues while many others do.
Come things I have to check are filter at hood installed properly, motor speed and belt size any thing else or a common issue?
One case in particular is a restaurant with about a 70 foot horizontal run with atleast one 90 degree turn and they still have some greasing coming out the end and it drips right into a parking lot. So that want to try to resolve the issue. Most guys just say that's just the way it is and not much you can do but I have seen plenty of units with no grease coming out.