<Tr> <Th> </Th> <Td> Short exposure could cause serious temporary or moderate residual injury (e.g. liquid hydrogen, carbon monoxide, calcium hypochlorite, hexafluorosilicic acid) </Td> </Tr> <Tr> <Th> </Th> <Td> Very short exposure could cause death or major residual injury (e.g. hydrogen cyanide, phosgene, methyl isocyanate, hydrofluoric acid) </Td> </Tr> <Table> <Tr> <Th_colspan="2"> Instability / reactivity (yellow) </Th> </Tr> <Tr> <Th> 0 </Th> <Td> Normally stable, even under fire exposure conditions, and is not reactive with water (e.g. helium, N) </Td> </Tr> <Tr> <Th> </Th> <Td> Normally stable, but can become unstable at elevated temperatures and pressures (e.g. propene) </Td> </Tr> <Tr> <Th> </Th> <Td> Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water (e.g. white phosphorus, potassium, sodium) </Td> </Tr> <Tr> <Th> </Th> <Td> Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked (e.g. ammonium nitrate, caesium, hydrogen peroxide) </Td> </Tr> <Tr> <Th> </Th> <Td> Readily capable of detonation or explosive decomposition at normal temperatures and pressures (e.g. nitroglycerin, chlorine dioxide, nitrogen triiodide, chlorine trifluoride) </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Instability / reactivity (yellow) </Th> </Tr>

In the nfpa 704 system a 4 in the reactivity diamond indicates what type of hazard