Simple dust extractor question

[Gregor]

It is no use having a super duper HEPA filter if another seal in the vac is not as rigorous and spews particles all around.

Sure. Only that adding a pre-separator onto the hose neither changes any seals in the vac, nor can a pre-separator spew any particles as it'll always be at or below room pressure.

 

[Michael Kellough]

I can’t speak to “HEPA certification” but the goal of using more effective filtration is to prevent the redistribution of harmful particles into the environment via the machine’s exhaust. Even if the CT (or other) cyclone had a big crack in the side it would not reduce the effectiveness of the HEPA filter, just the efficiency of the vac. The CT cyclone is still at negative pressure while the vac is running so nothing will escape.