File talk:NFPA704-444-W-OXY.jpg

For categorization and reference purposes, any information about which substance this sign is actually warning against would be, I am sure, appreciated. Arlo Barnes (talk) 22:21, 16 February 2011 (UTC)[reply]

It might not be a single substance, but the aggregate rating of multiple substances. This is allowed by law, and it is mandatory in many cases. Basically, it works like this; if you have one chemical that rates 2 for health, 3 for flammability and 4 for reactivity, and another chemical stored in the same location that rates a 4 for health, 3 for flammability and 2 for reactivity, the combined score would be 4, 3, 4. Add another chemical with a 4 in the flammability category, and the aggregate is raised to 4, 4, 4. 24.19.253.41 (talk) 19:12, 18 July 2011 (UTC)[reply]