Fire safety isn’t just about avoiding open flames. It’s also about knowing what burns and how quickly it does. Flammable and combustible materials both catch fire, but they do so differently. But what exactly are the differences between flammability and combustibility? 

This guide breaks down what makes something flammable or combustible, what factors affect their fire risk, and how to store them properly. 

What Is Flammability?

Flammability is how easily something catches fire and burns. Some materials ignite quickly, while others take more effort. That’s why we classify them as flammable, highly flammable, or non-flammable.

Scientists do fire tests to figure out a material’s flammability. These tests help set safety rules for buildings, workplaces, and transportation. For example, storing gasoline requires more precautions than storing vegetable oil.

The Globally Harmonized System of Classification and Labeling of Chemicals (GHS) is an international system that ranks flammable liquids into four categories based on their flash point and boiling point. This system helps industries and workers handle materials safely.

Plus, different organizations have their ways of classifying flammability. The National Fire Protection Association (NFPA) and the Occupational Safety and Health Administration (OSHA) have guidelines for storing flammable items.

Testing for flammability can also be done on a small scale in labs. These tests are usually cheaper and faster. 

Factors Affecting Flammability

Things don’t catch fire the same way. Some materials ignite instantly, while others resist burning. Here are the factors affecting an item’s flammability:

Chemical Composition

What something is made of affects how easily it burns. Hydrocarbons like gasoline are highly flammable, while others are not.

Physical State

Gases and fine dust particles catch fire more easily than solid blocks of material. Liquids with low boiling points also produce more flammable vapors.

Vapor Pressure

Liquids that evaporate quickly (like alcohol) release more vapors. This increases the chances of ignition. The higher the vapor pressure, the greater the fire risk.

Surface Area

A material with a larger surface area (like wood shavings or misted fuel) catches fire faster than a solid block because more of it is exposed to oxygen.

Temperature

Heat speeds up evaporation and combustion. Higher temperatures mean materials reach their flashpoint faster, making them more flammable.

Oxygen Concentration

Fires need oxygen, a component of the fire triangle. More oxygen in the air means faster and more intense burning, while less oxygen makes ignition harder.

Ignition Sources

Flames, sparks, or static electricity can start a fire. The stronger the ignition source, the easier it is for materials to catch fire.

Atmospheric Composition

Other gases in the air (like carbon dioxide or nitrogen) can dilute oxygen levels and reduce flammability.

Material Thickness

Thinner materials ignite faster, while thicker ones take longer. Some may even self-extinguish.

Auto-Ignition Temperature

Some materials can catch fire on their own if they get hot enough, even without a spark or flame.

Flash Point

This is the lowest temperature at which a liquid releases enough vapor to ignite. A lower flash point means higher flammability.

Examples of Flammable Materials

Some everyday items are more flammable than you might think. Here are the most common examples of flammable materials:

1. Cleaning Products

Many cleaning products contain flammable chemicals, such as alcohol, ammonia, or acetone. These ingredients evaporate quickly and release flammable fumes. They can ignite when exposed to an open flame, a spark, or a hot surface.

2. Aerosol Cans

Hairspray, air fresheners, and spray paints contain flammable propellants. Since they’re stored under pressure, high heat can make them explode. Even spraying near an open flame can create a dangerous fireball.

3. Alcohol-Based Products

Rubbing alcohol, hand sanitizers, and perfumes contain ethanol or isopropyl alcohol, which catches fire easily. Since these liquids evaporate fast, their vapors can ignite even without direct contact with a flame. 

4. Paper 

Stacks of paper, newspapers, and cardboard burn quickly. They can ignite from a small spark, especially when stored near heat sources like space heaters, overloaded outlets, or faulty wiring.

5. Fabric and Upholstery

Curtains, carpets, and office chairs are often made of synthetic fibers that burn fast. They can catch fire when exposed to an open flame, cigarette, or faulty wiring. The fire can also spread in minutes. 

6. Gasoline

Gasoline is highly volatile, so it evaporates quickly and creates flammable vapors. A single spark can ignite these vapors, making it extremely dangerous to store near heat, flames, or even static electricity.

7. Solvents 

Oil-based paints, paint thinners, and industrial solvents contain chemicals that release flammable fumes. Poor ventilation increases the risk of vapor buildup, which can ignite easily. 

8. Liquefied Petroleum Gas (LPG)

LPG tanks contain pressurized, highly flammable gases like propane and butane. A tiny leak can start a Class B fire if exposed to sparks, open flames, or static electricity.

How to Store Flammable Items

Storing flammable items properly can prevent fires and keep your space safe. Whether at home or work, following proper storage guidelines reduces accidents. Here’s how to store flammable items the right way:

1. Use Approved Containers

Not all containers are safe for flammable materials. Always store them in approved, fire-resistant containers made of metal or specially designed plastic. Never use regular plastic bottles or glass jars because they can crack, leak, or react with the chemicals inside.

2. Keep Them in a Cool, Dry Place

Heat and flammable items don’t mix. Store them in a cool, dry area, away from direct sunlight, heaters, and other heat sources. Remember, temperature changes can cause flammable vapors to build up.

3. Put Them in a Well-Ventilated Area

Flammable liquids release fumes that are dangerous in confined spaces. Keep them in a well-ventilated storage area to prevent vapor buildup. If possible, use a storage room with proper exhaust systems to keep the air clean and reduce fire risks.

4. Store Them Away from Ignition Sources

Sparks, flames, and electrical equipment can ignite flammable materials. Store them far from open flames, electrical outlets, and power tools. 

5. Label Everything Clearly

Accidents happen when you don’t know what you’re handling. Label all containers with clear, visible warnings and fire hazard symbols. Plus, make sure everyone who has access to the storage area understands what’s inside and how to handle it safely.

6. Use Fireproof Storage Cabinets

Fireproof storage cabinets are a must for workplaces or homes with many flammable materials. These cabinets help contain fires if something ignites inside. 

7. Store Only What You Need

Don’t store excessive amounts of flammable materials. Keep only what you regularly use and dispose of old or unnecessary chemicals properly. Doing this reduces fire risk and makes storage easier.

8. Separate Incompatible Materials

Some flammable items react dangerously when mixed. Keep different types of chemicals separate and follow specific guidelines for each one. For example, storing flammable liquids near oxidizers can lead to explosions.

What Is Combustibility?

Combustibility refers to a material’s ability to catch fire and burn. However, unlike flammable materials, it needs to be heated to a certain temperature before it ignites. This temperature, known as the flash point, determines how easily a substance can start burning. For example, if you drop a match into a pool of diesel fuel, it won’t catch fire immediately. However, if the diesel is heated enough, it will produce vapors that ignite.

Experts do tests to measure combustibility. These tests help set safety rules for buildings, workplaces, and storage facilities. Many materials are combustible, including solids like wood and liquids like oil and grease. While combustible materials don’t ignite as easily as flammable ones, they’re still fire hazards.

Organizations like the NFPA (National Fire Protection Association) and OSHA (Occupational Safety and Health Administration) have strict guidelines for the safe handling and storage of combustible materials. Buildings also use fire-resistant materials to minimize risks,  while workplaces that deal with combustible substances must follow fire safety regulations. 

In some cases, materials can catch fire on their own. This process is called spontaneous combustion.  It happens when heat builds up from chemical reactions, such as when oily rags are left in a pile and slowly heat up until they ignite. 

Factors Affecting Combustibility

Combustibility isn’t just about whether something burns. It’s about how easily and quickly it happens. Here are the factors affecting a material’s combustibility:

Chemical Composition

What a material is made of determines how easily it burns. Some substances, like wood and paper, contain compounds that ignite easily. Others, like metals, don’t combust easily. The presence of fuels like hydrocarbons or oxidizers can also influence how a material reacts to heat.

Surface Area

The more surface area a material has, the easier it is to catch fire. For example, fine powder or thin shavings will ignite much faster than a solid block of the same material. This is why sawdust is more combustible than a wooden log.

Oxygen 

Fire needs oxygen to burn. The more oxygen available, the easier and faster combustion happens. 

Temperature

Higher temperatures lower the ignition point of materials. When exposed to extreme heat, some substances release vapors that ignite. 

Humidity

Moisture in the air or within a material can affect combustibility. High humidity makes materials harder to burn since water absorbs heat and slows down ignition. On the other hand, dry conditions increase the risk of fire.

Flash Point

This is the lowest temperature at which a material releases enough vapors to ignite when exposed to a spark or flame. Materials with lower flash points burn more easily and are considered more hazardous.

Vapor Pressure

Liquids with high vapor pressure evaporate quickly. This can lead to lower flash points and make combustion easier. 

Examples of Combustible Materials

Knowing which materials are combustible helps with fire safety and prevention. Here are some everyday items that can pose a fire risk.

1. Cooking Oil and Grease

Cooking oil and grease don’t ignite as quickly as gasoline, but they can still catch fire at high temperatures. They can overheat and start a fire when left unattended on a hot stove or oven. Since water doesn’t put out grease fires, using the wrong extinguisher can make things worse. Find out what extinguisher to use for kitchen fires here. You can also use fire blankets on grease fires.

2. Plastic

Contrary to popular belief, plastic is classified as an ordinary combustible. Many household items, like plastic containers and decor, can melt and release toxic fumes before catching fire. 

3. Fabric

Some natural and synthetic fabrics are combustible, especially if they’re untreated. Cotton and polyester can catch fire if exposed to heat or open flames. Some synthetics even melt before igniting. Loose, flowing fabrics like curtains and bedding burn even faster.

4. Wood

Dry wood, lumber, and plywood are highly combustible. Sawdust is even more dangerous because it has a larger surface area and can ignite easily. Wood can catch fire from sparks, faulty wiring, or prolonged heat exposure in homes and construction sites. 

5. Diesel

Diesel fuel doesn’t ignite as easily as gasoline, but it will burn when heated enough. It produces vapors that can catch fire under the right conditions. Since diesel is widely used in trucks, generators, and industrial machinery, safe storage and handling are crucial.

How to Store Combustible Items

Storing combustible items the right way helps prevent fires and accidents. Whether at home, in a workshop, or at a business, following safe storage practices keeps everyone protected. Here’s how to store combustible items properly:

1. Choose the Right Storage Area

Keep combustible materials in a cool, dry place. Avoid basements or enclosed spaces where heat and vapors can build up. Remember, a well-ventilated storage area helps prevent dangerous fumes from accumulating.

2. Use Proper Containers

Store combustibles in sealed, non-reactive containers. Don’t use flimsy plastic or paper packaging that can easily catch fire. Use leak-proof metal or approved plastic containers with tight-fitting lids when storing combustible liquids.

3. Put Them Away from Ignition Sources

Sparks, flames, and electrical equipment can quickly ignite combustible items. Store them far from candles, lighters, matches, power tools, electrical outlets, and other heat sources. 

4. Label Everything Clearly

Mislabeling or not labeling containers can lead to accidents. Clearly mark all combustible items with hazard labels and safety instructions. Then, keep a list of stored materials so you know what’s on hand and where it’s located.

5. Avoid Overcrowding

Don’t stack combustible items too close together. Keep them organized and easy to access so they don’t get knocked over or damaged. Leaving space between items also improves airflow and reduces heat buildup.

6. Separate from Flammables 

Combustible materials should not be stored near flammable liquids, corrosive chemicals, or oxidizers. Certain chemicals can react and cause fires or explosions when mixed. Always check safety guidelines to ensure materials are stored correctly.

7. Use Fireproof Cabinets for High-Risk Items

Workplaces or storage areas with large amounts of combustibles should use fire-resistant cabinets or storage rooms. They help contain fires if something ignites and protect combustibles from external hazards.

Combustible vs. Flammable: Understanding the Differences

Both flammable and combustible materials can catch fire, but there are differences in how they do. Here’s a detailed look at the differences between combustible and flammable items:

Ignition Temperature

Flammable items ignite at lower temperatures, making them riskier to store and handle. On the other hand, combustibles need higher temperatures to catch fire. As a result, they’re less likely to ignite under normal conditions. However, they’re still fire hazards.

Flash Point

Flammables have flash points below 100°F (37.8°C). They produce enough vapors to ignite at lower temperatures. On the other hand, combustibles have flash points between 100°F (37.8°C) and 200°F (93.3°C), so they need more heat to release enough vapors for ignition.

Common Uses 

Flammable materials include fuels, solvents, and chemicals used in industries like automotive, painting, and cleaning. They have a higher risk of sudden ignition. On the other hand, combustible materials include oils and wood. They’re commonly used in construction, manufacturing, and household settings. Fires develop slower but can be intense.

Fire Risk

High-risk environments include gas stations, labs, and chemical plants where ignition sources are common. On the other hand, combustibles are usually found in warehouses, workshops, and storage areas where prolonged heat exposure can lead to fire.

Safe Storage and Handling

Flammables should be stored in well-ventilated areas, away from open flames, sparks, and direct sunlight. You should also store combustibles away from heat sources.

Here’s a table showing the key differences between flammable and combustible materials:

Why It Matters

Understanding the distinction between flammable and combustible materials helps prevent fires. Proper handling, storage, and awareness reduce risks in workplaces and homes, making environments safer.

How to Prevent Fires Due to Flammable and Combustible Items

A small flame can turn into a major fire in as fast as 30 seconds. The good news? A few smart precautions can significantly reduce the risk. Here’s how to keep your home or workplace safe:

1. Store the Items Properly

Flammable and combustible materials should be kept in proper storage areas. Use fireproof cabinets for chemicals, fuels, and solvents. Keep them away from heat sources, open flames, and direct sunlight. You should also store liquids in sealed containers to prevent vapor buildup.

2. Control Heat and Ignition Sources

Keep flammable materials away from open flames, sparks, and electrical equipment. You also shouldn’t smoke near these items. Regularly check your electrical wiring as well because faulty wires can spark and ignite flammable vapors. Plus, proper ventilation is needed to prevent buildup if working with combustible dust.

3. Handle Them With Care

Always follow safety instructions when using flammable liquids or gases. Use only the amount needed, and seal containers immediately after use. If you need to transfer flammable liquids, do so in well-ventilated areas. Use grounded, non-sparking tools to prevent static electricity from igniting fumes as well.

4. Use Fire-Resistant Containers

Store flammable liquids in approved, fire-resistant containers for extra safety. Label all containers clearly to avoid mix-ups. Never transfer flammable substances into regular plastic or glass bottles not designed for them.

5. Have Proper Ventilation

Good airflow is essential when handling flammable materials. Fumes from gasoline, paint thinner, and other substances can accumulate and ignite with a small flame or spark. Use exhaust fans in areas where vapors can build up, and always work in open or well-ventilated spaces.

6. Have Fire Prevention Tools Nearby 

Make sure smoke detectors and sprinkler systems are installed. Keep fire sprays, fire blankets, and fire extinguishers near areas where flammable materials are stored. Plus, make sure your family members or employees know how to use them in case of an emergency.

Fire blankets and fire extinguishers are effective fire safety tools. However, there are differences that you should be aware of. 

For one, fire extinguishers are heavier than fire blankets. They also leave a mess, while fire blankets don’t. Plus, fire blankets are easier to use and don’t require training. Fire extinguishers are also harder to store since they are bulky. On the other hand, fire blankets can be hung on walls. 

Unlike fire extinguishers, Prepared Hero’s fire blanket doesn’t expire. You can reuse it as many times as you want as long as it’s not damaged. Plus, you can use it to save someone on fire.

Here’s a table summarizing the differences between Prepared Hero’s fire blanket and a regular fire extinguisher:

Don’t have the budget for a fire extinguisher? No problem!

While fire extinguishers help a lot, they can be expensive, heavy, and hard to store. The residue from the fire extinguisher may also be hard to clean up. 

Use a fire spray if you want a more affordable, lightweight, and convenient way to put out a fire in seconds. The Hero Fire Spray will help you deal with minor fire accidents and stop them before they turn into bigger disasters. 

Plus, Prepared Hero’s fire spray is biodegradable and non-toxic. Unlike a fire extinguisher, you can safely use it around your family and pets. It’s also eco-friendly, so you’re taking part in saving the environment.

Here’s a table summarizing the differences between Prepared Hero’s fire spray and a regular fire extinguisher:

7. Train and Educate

Everyone in the workplace or home should understand fire hazards and prevention methods. Train employees on proper handling, storage, and disposal of flammable materials. Regular safety drills reinforce fire prevention and emergency response strategies.

8. Dispose of Waste Properly

Oily rags, chemical-soaked cloths, and empty containers can be fire hazards. Dispose of them in metal, self-closing containers designed for hazardous waste. Never throw flammable waste in regular trash bins.

Is Flammability a Physical or Chemical Property?

Flammability is a chemical property because it describes how a substance reacts when exposed to fire. When something burns, it undergoes a chemical change. As a result, it becomes new substances like ash, carbon dioxide, and water vapor. You can’t test flammability without actually burning the material, which means the substance is permanently altered.

Chemical properties describe how a material reacts with other substances. Flammability falls into this category, along with things like reactivity and corrosion resistance. On the other hand, physical properties, like color, melting point, and density, can be observed without changing what the substance is. For example, melting ice turns it into water, but it's still water. Burning wood, however, turns it into something different.

A good way to remember this is that if testing the property changes the substance permanently, it’s a chemical property. Since burning something creates new materials, flammability is clearly a chemical property, not a physical one.

What Is Flammability Testing?

Flammability testing checks how easily a material catches fire, how fast it burns, and how much smoke it produces. It’s an important safety process used in industries like textiles, electronics, construction, and consumer products. The goal is to make sure materials meet fire safety standards and don’t pose risks. 

Testing methods vary depending on the material. The Vertical Flame Test is commonly used for fabrics. During this test, a sample is exposed to a flame, and the burn time and damage are measured. The Horizontal Flame Test is used for plastics and other materials to determine how fast flames spread. 

In addition, cigarette and match tests check if furniture and upholstery can resist ignition from small flames. Flash point testing finds the lowest temperature at which a liquid’s vapors can ignite. These tests help manufacturers select safer materials, comply with regulations, and prevent fire-related accidents. In short, flammability tests play a crucial role in protecting lives and property.

Is Combustibility a Physical or Chemical Property?

Combustibility is a chemical property because it describes how a substance reacts when exposed to heat and oxygen. When something burns, it goes through a chemical reaction. This produces substances like carbon dioxide, water, and ash. You can’t test combustibility without actually burning the material, which permanently changes its composition.

Chemical properties describe how a material reacts and changes. Combustibility fits into this category, along with flammability and reactivity. In contrast, physical properties, like color and volume, can be observed without changing what the substance is. For example, melting wax turns it into liquid wax, but it’s still wax. However, if wax burns, it becomes carbon dioxide and water vapor. This means it went through a chemical change.

Since combustion results in new materials, combustibility is clearly a chemical property, not a physical one.

What Is Combustibility Testing?

Combustibility testing checks how easily a material catches fire, burns, and contributes to flame spread. It’s important for safety and regulatory compliance, especially in industries dealing with construction materials and combustible dust. These tests help identify fire hazards and make sure materials meet safety standards before use. 

In particular, the ASTM E136 test measures how a material reacts to extreme heat using a vertical tube furnace at 750°C. On the other hand, the NFPA 259 test evaluates the heat a material releases before and after exposure to fire. For industries dealing with dust and powders, the Go/No-Go Test determines if a substance can ignite. 

Other tests, like the Burn Rate/Fire Train Test, check how fast a material burns. Meanwhile, the Minimum Ignition Energy Test determines the smallest energy spark needed to ignite a dust cloud. Additional tests determine the minimum temperature required to ignite a dust layer or cloud and the severity of a dust explosion. 

By conducting these tests, industries can choose safer materials, reduce fire risks, and comply with regulations. These protect workers, buildings, and products from potential fires.

Conclusion

Knowing the difference between flammable and combustible materials helps you stay safe at home and work. Flammable materials ignite easily, while combustible ones need more heat. However, both are dangerous if not handled properly. 

Following proper storage, labeling, and safety guidelines reduces risks and prevents accidents. Whether you're dealing with cleaning products, fuels, or household plastics,  some caution goes a long way. 

Do you want reliable, easy-to-use, and affordable tools to put out small fires before they spread? Check out Prepared Hero’s fire prevention tools here, and get up to 51% off on certain items. Stay prepared, hero!