NFPA 704 Fire Diamond Rating Criteria Reference Table
The NFPA 704 diamond is the colored four-part sign on tank farms, drum storage rooms and building entrances that tells emergency responders how bad a material is at a glance. This table lists what each 0 to 4 number means so operators and EHS staff can read or assign a diamond without hunting for the standard.
| Diamond field | Hazard | Rating | Summary of criteria |
|---|---|---|---|
Blue (left) | Health | 4 | Very short exposure could cause death or major residual injury, even with prompt medical care. |
Blue (left) | Health | 3 | Short exposure could cause serious temporary or residual injury. |
Blue (left) | Health | 2 | Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. |
Blue (left) | Health | 1 | Exposure would cause irritation with only minor residual injury. |
Blue (left) | Health | 0 | Exposure under fire conditions offers no hazard beyond that of ordinary combustible material. |
Red (top) | Flammability | 4 | Rapidly or completely vaporizes at normal pressure and temperature, or burns readily. Flash point below 22.8 C (73 F) and boiling point below 37.8 C (100 F). |
Red (top) | Flammability | 3 | Liquids and solids that can ignite under almost all ambient conditions. Flash point below 37.8 C (100 F) not meeting rating 4. |
Red (top) | Flammability | 2 | Must be moderately heated or exposed to relatively high ambient temperature before ignition. Flash point at or above 37.8 C (100 F) and not above 93.4 C (200 F). |
Red (top) | Flammability | 1 | Must be preheated before ignition can occur. Flash point above 93.4 C (200 F). |
Red (top) | Flammability | 0 | Will not burn under typical fire conditions. |
Yellow (right) | Instability | 4 | Readily capable of detonation or explosive decomposition at normal temperatures and pressures. |
Yellow (right) | Instability | 3 | Capable of detonation or explosive decomposition but requires a strong initiating source, heating under confinement, or reacts explosively with water. |
Yellow (right) | Instability | 2 | Normally unstable and readily undergoes violent chemical change, but does not detonate. May react violently with water or form potentially explosive mixtures. |
Yellow (right) | Instability | 1 | Normally stable but can become unstable at elevated temperatures and pressures. |
Yellow (right) | Instability | 0 | Normally stable, even under fire exposure, and not reactive with water. |
White (bottom) | Special: W with bar | W | Reacts with water in an unusual or dangerous manner. Do not use water-based extinguishing. |
White (bottom) | Special: oxidizer | OX | Material is an oxidizer and can intensify a fire. |
White (bottom) | Special: simple asphyxiant | SA | Simple asphyxiant gas, limited to nitrogen, helium, neon, argon, krypton and xenon. |
This table summarizes the structure of NFPA 704 ratings for quick reference. NFPA 704 is a copyrighted standard: consult the current edition for the full wording, and assign ratings to specific products from the SDS and your own hazard review.
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How to use the table
Use the search box to filter by color, hazard name or rating. Blue is the health hazard on the left, red is flammability at the top, yellow is instability (called reactivity in older editions) on the right, and white at the bottom holds special symbols. To check a label, read the three numbers from the sign, then find the matching rows. To assign one, start from the SDS and the physical properties, then match the flash point and boiling point to the red field criteria.
- Filter by 'Flammability' to see the flash point cut-offs
- Export to Excel to build a tank and room labeling register
- Print the PDF as a quick reference for new operators
How flammability ratings follow flash point
Red ratings are driven by flash point and boiling point. A liquid with a flash point under 22.8 C and a boiling point under 37.8 C, such as diethyl ether, rates 4. Acetone, toluene and most common solvents flash below 37.8 C and rate 3. Combustible liquids that flash between 37.8 C and 93.4 C rate 2, and heavier liquids such as glycol rate 1. Always use closed cup flash point values from the SDS, and remember that a mixture rates as its worst credible hazard, not an average.
Common mistakes
The diamond is a fire-response signal, not a complete hazard communication. It does not replace GHS labels, which cover chronic and environmental hazards, and the two systems use opposite scales: GHS category 1 is the most severe, while NFPA 4 is the most severe. Another frequent error is reusing a pure-material rating for a solution or a heated process stream. Ratings are meant for the material as stored, so a hot or concentrated stream may need its own review.
- Do not copy GHS category numbers into the diamond
- Re-rate dilutions and blends instead of assuming the neat rating
- Check which edition your site and local fire authority follow
Frequently Asked Questions
What do the colors on the NFPA 704 diamond mean?
Blue is the health hazard, red is flammability, yellow is instability or reactivity, and white is for special notices such as OX for oxidizer or W with a bar for water reactive. Each colored field carries a number from 0 for minimal hazard to 4 for severe hazard.
Is NFPA 704 the same as the GHS pictograms?
No. NFPA 704 is a quick emergency-response sign for fixed facilities, while GHS labels and pictograms are the hazard communication system for containers and workplaces. They use different scales, so a GHS category cannot be copied directly into a diamond.
Who assigns the NFPA 704 rating?
NFPA 704 does not publish ratings for individual chemicals. The facility owner or a competent person assigns them from SDS data and the standard criteria, and the local fire authority may review them. Some suppliers print suggested ratings but they are not authoritative.
Does the diamond go on every container?
It is intended for fixed locations such as buildings, rooms, tanks and storage areas, not for shipping packages. Transport uses DOT or UN placards instead, and individual containers carry GHS labels. Many plants use both at storage sites.
If your labels, SDS data and ERP item masters all live in different places, Netray can help you pull hazard data into one controlled register that stays in sync with your inventory.
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