NFPA 704 instability quadrant

The right quadrant rating reactivity.

Also known as: Yellow quadrant fire diamond, Instability rating

Engineering & technicalSafety & hazardStandard profile

Meanings

The right quadrant of the NFPA diamond, carrying a figure from zero to four rating the material's instability.

Officially standardisedVerified fact
Rates a material's instability, from zero to four, on the NFPA diamond.
Contexts: Public information
Officially standardisedVerified fact
Was renamed from reactivity to instability, so older placards and newer ones use different words for the same quadrant and the same figure.
Contexts: Public information

The right of four small diamonds, filled with a distinguishing colour and carrying a single digit.

IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard, but only a single source has been found so far.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

NFPA 704, Standard System for the Identification of the Hazards of Materials
National Fire Protection Association · retrieved 2026-08-25
The standard defining the four-quadrant hazard diamond used on fixed installations in the United States. Cited for what each quadrant and rating means. Records are descriptive; they are not emergency response guidance and no record should be used to assess a hazard.

Last reviewed 2026-08-25

Meanings

The right quadrant of the NFPA diamond, carrying a figure from zero to four rating the material's instability.

Officially standardisedVerified fact

Rates a material's instability, from zero to four, on the NFPA diamond.

Officially standardisedVerified fact

Was renamed from reactivity to instability, so older placards and newer ones use different words for the same quadrant and the same figure.

Confidence

IdentityHigh confidence: High confidence because the identity is defined by a current official standard, but only a single source has been found so far.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is defined by a current official standard, but only a single source has been found so far.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but only a single source has been found so far.

Sources

NFPA 704, Standard System for the Identification of the Hazards of Materials
National Fire Protection Association · retrieved 2026-08-25
The standard defining the four-quadrant hazard diamond used on fixed installations in the United States. Cited for what each quadrant and rating means. Records are descriptive; they are not emergency response guidance and no record should be used to assess a hazard.

Last reviewed 2026-08-25