Is it permissible to penetrate the wall of an x-purged electrical control cabinet with pneumatic lines, either plastic hose or metal tubing?
And if so, how must the cabinet be sealed at the pneumatic line penetration?
Thanks
Do you understand the difference between purging and pressurizing? Type X, whether purging or pressurizing, is a nightmare if done properly. Have you consulted NFPA 496; especially Chapters 4, 5, and 6? (They aren't that long and are worth the study.)
To answer your initial question, the enclosure may be penetrated with either plastic or metal lines if the airflow is maintained properly.
You may find if you are actually
purging the enclosure, you may not want to seal around the line at all. Remember, you are trying to
evacuate hazardous materials. Of course, for Class II, there should be no source of dust inside the panel in the first place. Raceway entires must be sealed to prevent transmitting volitiles into the raceway system.
For a
pressurized panel, sealing around the lines may be beneficial; however, all you are required to do is maintain pressure and sealing may not be required if the pressurizing system is strong enough. You could even protect the raceways if you chose to. See NEC Section 501.15(A)(2). I don't generally recommend ommitting raceway seals, mostly because there's no way to determine if the pressurizing system is adequate.
