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Speaker 1: Welcome to Brainstuff from house stuff works dot com where

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Speaker 1: smart happens. Hi. I'm Marshall Brain with today's question. What

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Speaker 1: do those big diamond shaped signs with red, yellow, and

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Speaker 1: blue squares on the mean when you see them on

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Speaker 1: the sides of buildings. You see these signs on any

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Speaker 1: building that contains hazardous chemicals. The sign is called an

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Speaker 1: nfp A panel. N f p A stands for the

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Speaker 1: National Fire Protection Association. The idea behind these signs is

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Speaker 1: to give firefighters some sort of advanced notice on what

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Speaker 1: they're getting themselves into when they arrive at the scene

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Speaker 1: of a fire. When there's a house fire, firefighters have

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Speaker 1: a pretty good idea of what they're in for, but

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Speaker 1: if there's a fire at a warehouse in an industrial park,

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Speaker 1: it is very hard to know what chemicals might be

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Speaker 1: stored there. The n f p A panel is a

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Speaker 1: clear indication of what sort of dangers might lie inside.

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Speaker 1: The panel has four different areas. The red area is

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Speaker 1: the fire hazard area, the blue is the health hazard area,

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Speaker 1: the yellow is the reactivity area, and the white is

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Speaker 1: a specific hazard area. The numbers in the first three

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Speaker 1: areas range from zero to four, with zero signifying no hazard,

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Speaker 1: and four signifying a severe hazard. For example, in the

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Speaker 1: reactivity area, zero means stable, one means unstable if heated,

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Speaker 1: two means a violent chemical, three means shock or heat

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Speaker 1: may detonate, and four means may detonate on its own.

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Speaker 1: In the fire hazard area, the numbers indicate the flash point.

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Speaker 1: Zero means it won't burn, one means it will burn

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Speaker 1: above two hundred degrees, two means it will burn below

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Speaker 1: two hundred degrees, three means it will burn below one degrees,

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Speaker 1: and four means it will burn below seventy four degrees fahrenheit.

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Speaker 1: Concrete is an example of a class zero fire hazard.

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Speaker 1: It won't burn paper and wood, or class one. In

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Speaker 1: the health hazard area, zero means no hazard, one means

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Speaker 1: slightly hazard as, two means hazardous, three means extremely hazardous,

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Speaker 1: and four means deadly. In the specific hazard area, which

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Speaker 1: is the white square at the bottom of the diamond,

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Speaker 1: you'll see things like O X Y or oxy for oxidizer,

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Speaker 1: acid for acids, a O K for alkali, cr for corrosive.

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Speaker 1: You may also see a W with a bar through

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Speaker 1: it meaning use no water, or a radiation hazard symbol

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Speaker 1: for radioactive materials now you can drive around your neighborhood

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Speaker 1: and get a glimpse into what is stored in all

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Speaker 1: those buildings. Do you have any ideas or suggestions for

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Speaker 1: this podcast? If so, please send me an email at

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Speaker 1: podcast at how stuff works dot com. For more on

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Speaker 1: this and thousands of other topics, go to how stuff

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Speaker 1: works dot com and be sure to check out the

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Speaker 1: brain stuff blog on the how stuffworks dot com home page.