The NFPA fire diamond provides a quick reference for hazards associated with a chemical. The numerical rating in each quadrant of the diamond provides a general evaluation of the material's hazardous properties
Take a look at the Genium Saftey Information Database link for specific examples of NFPA symbols
Blue - Health Hazard
0 = Normal Material
1 = Slight Hazard
2 = Moderately Hazardous
3 = Extremely Hazardous
4 = Deadly
Red - Flammability (flash points)
0 = Will not burn
1 = above 200 degrees Fahrenheit
2 = Between 100-200 degrees Fahrenheit
3 = Below 100 degrees Fahrenheit
4 = Flash point below 73 degrees Fahrenheit
Yellow - Reactivity
0 = Stable
1 = Unstable if heated
2 = Violent chemical change
3 = Shock or heat may detonate
4 = Rapidly capable of detonation or explosion
White - Specific Hazard
ACID-acid
ALK-alkali
COR-corrosive
OX-oxidizer
P-polymerization
W with a line through it - Use no water
Additional Symbols for Plackards and Warning Labels:
Explosive
Flammable
Acute Toxicity
Corrosive