storage of small tanks of hydrogen and acetylene

I am designing an out building that has three walls and the fourth wall is open to the air. This building will have small tanks that will have welding gases stored. this will be a small building, 10x14. 9 foot ceiling. i am trying to determine the hazardous classification. These tanks will only be stored at this location, not used or filled. this leads me to believe that there will not be any gases outside of the tanks that would warrant a classification for the building. Any ideas to support or not support? There will not be any fans or ventilation of any sort; only light fixtures in the building.


Staff member
Mission Viejo, CA
Professional Electrical Engineer
I have been discouraging site members from recommending specific hazardous classification envelopes for various installations for some time now. It is too much like assisting DIYers. I refer you back to don_resqcapt19's answer to your previous inquiry. Electrical hazardous area classifications should be done by someone qualified to do so and familiar with the installation (and it should be properly documented). There are too many variables to consider to give a quick answer.

Not being "… used or filled", building configuration, and ventilation are indeed significant considerations; however, I recommend reviewing NFPA 497 [2021Edition], Figures 5.10.8(a) and (b), and their associated texts for some other relevant considerations. If you really care to dig deep, you might consider NFPA 2 and NFPA 50A and B.

A good source to ask for assistance might be the site's insurance company.