Last Updated: 2026-10-16
Answer Capsule: NFPA diamond examples show how the four quadrants read on real chemicals. Gasoline is 1-3-0, sulfuric acid is 3-0-2 with a W symbol, chlorine gas is 4-0-0 with OX, and nitrogen is 0-0-0 with SA. Each number rates health (blue), flammability (red) and instability (yellow) from 0 to 4, and the white square holds one of three special symbols.
You know what the colors mean. You know 0 is low and 4 is severe. Then you stand in front of a real placard on a pool chemical room that reads 3-0-2-OX and you are not sure what to tell the new hire standing next to you.
Rating charts explain the rules. They do not show the rules applied to a drum of acetone or a bank of nitrogen cylinders, and that gap is where sign orders go wrong.
This post decodes twelve NFPA diamond examples pulled from the 50-chemical table Print Pro AZ uses to build placards. Each one gets three sentences: what the material is, what the numbers say, and what a responder does when they see it. Brent Hanke at Print Pro AZ picked the twelve that show up most often on order forms.
How Do You Read an NFPA Diamond Example?
You read an NFPA diamond example left to right, then top, then bottom: blue health, red flammability, yellow instability, white special hazard. Each colored square holds a number from 0 (no hazard) to 4 (severe) under the criteria in NFPA 704. The white square is blank or holds W with a line through it (water reactive), OX (oxidizer), or SA (simple asphyxiant gas).
Written out, a placard is health-flammability-instability plus the symbol, so 3-0-2-W means health 3, flammability 0, instability 2, water reactive. The full reading method is in the NFPA 704 diamond explained pillar.
Callout: Some chemicals below carry a star. That means suppliers commonly disagree on the rating, so use the SDS for your exact product and concentration. The number here is the common one, not the only correct one. Flash points and other properties are in the NIOSH Pocket Guide.
What Do Fuel and Solvent Placards Say?
Fuel and solvent placards carry a high red number and a low blue number, because the material burns easily but does not poison on brief contact.
1. Gasoline: 1-3-0
Gasoline is the fuel in the dispenser tank and the cans in the fleet shop. Health 1 means brief exposure irritates but leaves little lasting harm, flammability 3 means it ignites at normal temperature with a flash point near minus 45 F, and instability 0 means it is stable. A responder clears ignition sources and uses foam rather than a water stream on the fuel.
2. Diesel: 0-2-0 (star)
Diesel fills the generator day tank and the yard fuel skid. Health 0 and instability 0 are as low as they go, and flammability 2 means the fuel must be heated to ignite because its flash point is 125 F or higher. A responder treats it as combustible, cools any exposed tank, and worries far less about vapor than with gasoline.
Supplier note: some diesel SDS sheets rate health at 1 or 2, so the sign might read 1-2-0 or 2-2-0. Match your supplier's SDS.
3. Propane (LPG): 1-4-0 (star)
Propane feeds forklifts, roof heaters and the cylinder cage outside the warehouse. Health 1 is a minor irritant, flammability 4 is the top score because propane is a gas at room temperature with a boiling point of minus 44 F, and instability 0 means the gas itself is stable. A responder expects a leak to travel low and flash back, and cools tanks from a distance.
Supplier note: some propane SDS sheets rate health at 2, and the Print Pro AZ stock sign reads 2-4-0. Either can be correct for your product.
4. Acetone: 1-3-0
Acetone is the cleaning solvent in the paint booth and the lab. Health 1 means it irritates skin and eyes, flammability 3 comes from a flash point near minus 4 F, and instability 0 means it is stable. A responder kills ignition sources and uses alcohol-resistant foam because acetone mixes with water.
5. Ethanol: 2-3-0
Ethanol sits in the sanitizer stock, the brewery, and the lab solvent cabinet. Health 2 means intense or continued exposure can cause temporary incapacitation, flammability 3 comes from a flash point near 55 F, and instability 0 means it is stable. A responder treats it like acetone: no ignition sources and alcohol-resistant foam.
6. Acetylene: 0-4-3
Acetylene is the welding gas in the shop cylinder rack. Health 0 means no hazard beyond ordinary combustibles, flammability 4 is the top score for a flammable gas, and instability 3 means the gas can detonate if heated under confinement. A responder cools the cylinder from a distance and never moves one that has been in a fire.
Print the NFPA 704 Diamond Field Guide
A 2-page field card: how to read every quadrant, the three legal special symbols, sign size by viewing distance, and NFPA 704 ratings for 50 common chemicals with the matching part number. Print it and tape it inside the chemical room door.
The download link appears instantly. No spam, and you can unsubscribe anytime.
Need placards for a chemical room? Send your inventory, get a quote in one business day.
Attach your chemical inventory or SDS list. Print Pro AZ works out the room rating, prints the NFPA 704 placards on vinyl or aluminum, and ships the same week.
No commitment. A real person replies within one business day.
What Do Acid, Base and Oxidizer Placards Say?
Acid, base and oxidizer placards flip the pattern: high blue, zero or low red, and often a symbol in the white square. Here are five.
7. Sulfuric Acid, Concentrated: 3-0-2-W
Concentrated sulfuric acid is in the battery room, the water treatment plant and the metal finishing line. Health 3 means short exposure causes serious injury, flammability 0 means it will not burn, instability 2 means violent reaction with water, and the W with a line through it warns not to put water on it. A responder wears full splash protection, dikes the spill, and never sprays the material directly.
8. Hydrochloric (Muriatic) Acid: 3-0-0
Muriatic acid is the pool pH adjuster and the concrete cleaner on the loading dock. Health 3 means the fumes and liquid cause serious injury, and flammability 0 and instability 0 mean it will not burn or react violently. A responder uses breathing protection, dikes the spill, and knows fire is not the problem.
9. Sodium Hydroxide: 3-0-1
Sodium hydroxide, or caustic soda, runs through the CIP system and the drain cleaning stock. Health 3 means serious tissue damage on contact, flammability 0 means it will not burn, and instability 1 means it heats up when it meets water but stays stable. A responder wears splash protection, expects heat if water hits a concentrated spill, and treats it as a corrosive, not a fire.
10. Chlorine Gas: 4-0-0-OX
Chlorine gas feeds municipal water treatment and some large pool plants. Health 4 means a very short exposure can kill, flammability 0 means it does not burn, instability 0 means it is stable, and OX means it feeds a fire by supplying oxygen. A responder evacuates downwind, enters only with self-contained breathing apparatus, and keeps fuel and flame away from the leak.
11. Calcium Hypochlorite (Pool Shock): 3-0-2-OX
Calcium hypochlorite is the granular pool shock in the chemical room of every aquatic center. Health 3 means it burns skin and airways, flammability 0 means it does not burn on its own, instability 2 means it decomposes violently when heated, and OX means it feeds any nearby fire. A responder keeps it cool and away from acids and fuels, and expects it to speed up any fire that reaches it.
What Does a Gas Placard With SA Mean?
A gas placard with SA in the white square means the gas is a simple asphyxiant: it displaces oxygen in a closed space without being toxic. Here is the most common one.
12. Nitrogen: 0-0-0-SA
Nitrogen sits in cylinder banks for purging, blanketing and lab supply. Health 0, flammability 0 and instability 0 look harmless, but SA warns that a leak in a closed room can drop oxygen below a breathable level. A responder monitors oxygen before entry, ventilates the space, and treats a silent room as the danger sign.
Liquid nitrogen rates 3-0-0-SA because the cold injures on contact. Match the sign to the state of the product you store.
Which NFPA Diamond Example Fits Your Room?
The placard on your door matches the highest number in each color from any material inside, plus every special symbol present. It is worst case, not average. A room with sodium hydroxide (3-0-1), acetone (1-3-0) and a nitrogen bank (0-0-0-SA) posts 3-3-1-SA.
Here is a call Print Pro AZ gets every month. A pool operator wants a 3-0-0 placard because muriatic acid is the biggest drum in the room. The same room holds calcium hypochlorite, which brings instability 2 and OX, so the correct placard is 3-0-2-OX.
The NFPA 704 diamond signs collection covers the common ratings, and the sulfuric acid 3-0-2-W diamond sign is the most requested acid placard Print Pro AZ prints. For the full table of 50 chemicals with part numbers, grab the NFPA 704 Diamond Field Guide. Use the download form on this page.
Take the field guide with you
Everything in this article on one printable card: the rating scales, the white square symbols, placement rules, and 50 chemical ratings. Free to share with your crew.
The download link appears instantly. No spam, and you can unsubscribe anytime.
Ready to placard the building? Get a quote in one business day.
Tell us the rooms, tanks and chemicals. We handle the rest, from the composite rating to an aluminum placard the fire marshal can read from the street.
Start my quoteOr browse NFPA 704 diamond signs and order online.
Frequently Asked Questions
Why do two suppliers give different NFPA ratings for the same chemical?
The facility assigns the rating, and suppliers apply the criteria to different concentrations, blends and test data. Diesel, propane and methanol are common examples. Use the SDS for the exact product on your shelf, and if two products in one room differ, post the higher number.
What does W with a line through it mean?
It means the material reacts dangerously or unusually with water. Concentrated sulfuric acid, sodium metal and calcium carbide carry it. A responder will not put a water stream on it.
Does water need an NFPA diamond?
Water is 0-0-0 with no symbol. In a placarded building every rated room gets a diamond, because a missing diamond reads as a missing rating. A 0-0-0 sign tells the responder the room was checked and nothing hazardous is inside.
Conclusion
Twelve placards, three lessons. Fuels and solvents run high on red and low on blue, acids and bases run high on blue with a zero on red, and the white square is where the surprise lives. A starred chemical means suppliers disagree, so the SDS for your product wins.
Posting the right diamond the first time keeps you off the re-inspection list and gives the crew at the door a true picture of what is inside. Have a chemical list? Send us your chemical inventory and Print Pro AZ will return the full placard set with the composite ratings done. Questions? Call Brent at (602) 649-5305.
Sources
- NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency Response
- NIOSH Pocket Guide to Chemical Hazards
Brent Hanke | Print Pro AZ | (602) 649-5305 | b.hanke@printproaz.com
Brent Hanke is the founder of Print Pro AZ, supplying NEC-compliant labels to contractors across the country.