Purge selected categories

I need to purge periodically Revit design models, but I don't want to remove all unused elements. I need to keep many elements like tags, pipe types, duct types, etc. in the mechanical model, because they are defined in the model by the company standard. But I want to delete all Families which people load for Mechanical Equipment, Pipe Accessories, Duct accessories, etc. They contribute the most to the models file size.

It would be nice if and application "Purge Categories" can be created. There I could select the categories I want to purge from the project. In fact, this setting will be applicable to all mechanical models. I would make a template, and voilà!