The Difference Between Flammable and Combustible

In workplace health and safety, understanding the difference between flammable and combustible substances is crucial. These terms refer to the fire hazard levels of various materials and help guide safe handling, storage, and usage practices. This blog explains the differences between flammable and combustible substances, offers examples, and provides essential tips for ensuring safety in the workplace.

What is the Difference Between Flammable and Combustible?

Flammable and combustible are both terms used to describe a material’s potential to catch fire, but there are important distinctions based on the temperature at which each substance can ignite. The terms are often defined according to flash points, which is the lowest temperature at which a substance produces enough vapour to ignite.

• Flammable substances: These have a lower flash point, generally below 37.8°C (100°F), and can ignite easily at room temperature.
• Combustible substances: These have a higher flash point, typically between 37.8°C (100°F) and 93.3°C (200°F), and require more heat to ignite.

Why Does the Difference Matter in the Workplace?

In the workplace, knowing whether a substance is flammable or combustible helps in assessing risks, choosing proper storage, and implementing suitable fire prevention measures. Flammable substances present a higher risk of catching fire even at lower temperatures, making them more dangerous than combustible materials in typical work environments. However, both types can lead to fires and explosions if not managed carefully.

Characteristics of Flammable Substances

Flammable substances have flash points at or below 37.8°C (100°F). These materials can ignite easily from sparks, friction, or exposure to even a minimal heat source. Common examples include:

• Petrol (Gasoline): A widely used fuel with a flash point of around -43°C (-45°F).
• Acetone: Often used as a solvent in industrial settings, with a flash point of -18°C (0°F).
• Ethanol: Common in laboratories and cleaning products, with a flash point of 13°C (55°F).

Because flammable substances can ignite at room temperature, it is essential to handle and store them with extreme care.

Safety Tips for Handling Flammable Substances

1. Store in Approved Containers: Always store flammable substances in certified, airtight containers to prevent vapours from escaping.
2. Label Properly: Use clear and accurate labelling on all containers holding flammable materials, and ensure these labels are easily visible.
3. Ventilate Work Areas: Flammable substances produce vapours that can ignite even with minimal exposure to an ignition source. Ensure proper ventilation to avoid vapour build-up.
4. Eliminate Ignition Sources: Keep flammable substances away from heat sources, open flames, electrical equipment, and static electricity.
5. Follow Proper Disposal Protocols: Dispose of flammable waste according to workplace protocols to prevent residual vapours from accumulating.

Characteristics of Combustible Substances

Combustible substances have a flash point between 37.8°C (100°F) and 93.3°C (200°F). They are less volatile than flammable substances but can still pose serious fire hazards, especially in high-heat environments. Examples of combustible materials include:

• Diesel Fuel: Often used in industrial equipment and generators, with a flash point between 52°C (126°F) and 96°C (205°F).
• Kerosene: Used for heating and lighting, with a flash point around 38°C (100°F).
• Mineral Oil: Commonly used in industrial machinery, with a flash point between 65°C (150°F) and 93°C (200°F).

While combustible substances require higher temperatures to ignite, they should still be stored and handled carefully to prevent fire risks.

Safety Tips for Handling Combustible Substances

1. Store in Cool, Well-Ventilated Areas: Keep combustible materials in cool, designated storage areas to reduce the risk of accidental ignition.
2. Use Non-Sparking Tools: When handling combustible liquids, use tools made from materials that don’t produce sparks, such as brass or plastic.
3. Keep Away from Heat Sources: Ensure combustible substances are stored far from heaters, furnaces, or machinery that generates heat.
4. Monitor Temperature: Avoid storing combustible substances in areas where temperatures may exceed their flash points, such as near direct sunlight or high-heat areas.
5. Follow Local and Industry Regulations: Different industries may have specific handling protocols for combustible substances to ensure safety. Always refer to local guidelines or regulatory bodies for compliance.

How to Identify Flammable and Combustible Substances in the Workplace

Most workplaces use a variety of chemicals and materials, each with distinct properties. Identifying whether a substance is flammable or combustible involves checking product labels, Safety Data Sheets (SDS), and other manufacturer information. The flash point, usually listed in the SDS, helps determine whether a substance is flammable or combustible.

Symbols to Look For

Chemical containers and storage units should be marked with clear hazard symbols, which may vary depending on regional standards. In the UK and EU, the following GHS (Globally Harmonised System) symbols are commonly used:

• Flammable symbol: A flame icon often accompanies materials that are highly flammable.
• Combustible warning: Though not always marked separately, combustible substances may have warning statements related to fire hazards.

Safe Storage Guidelines for Flammable and Combustible Substances

To minimise fire risks, flammable and combustible substances should be stored according to established fire safety guidelines. Here are key storage practices:

• Use Approved Storage Cabinets: Flammable and combustible materials should be stored in fire-resistant cabinets designed to contain any potential fire or explosion.
• Separate from Incompatible Substances: Certain chemicals can react with flammable or combustible substances, so store these materials away from oxidisers, acids, and other reactive chemicals.
• Limit Quantities on Site: Keep only the necessary amount of flammable or combustible materials on hand to reduce fire hazards. Larger quantities should be stored in secure, external storage facilities if possible.

The Role of Employers in Reducing Fire Hazards

Under the Health and Safety at Work Act 1974, employers have a duty of care to protect employees from fire risks, including those related to flammable and combustible substances. Employers can enhance workplace safety by:

• Providing Proper Training: Ensure that employees understand the differences between flammable and combustible substances and know how to handle, store, and dispose of each type safely.
• Conducting Regular Risk Assessments: Regularly assess the workplace for fire hazards, paying particular attention to storage areas for flammable and combustible materials.
• Maintaining Fire Safety Equipment: Fire extinguishers, alarms, and sprinklers should be installed and maintained to protect against potential fires.
• Updating Emergency Plans: Make sure employees know what to do in case of fire, including evacuation procedures and first aid protocols.

Conclusion

Understanding the difference between flammable and combustible substances is essential for maintaining a safe workplace. While flammable materials ignite easily at lower temperatures, combustible materials require more heat to catch fire. However, both types pose serious risks if mishandled. By implementing safe handling, storage, and training practices, workplaces can minimise these risks and protect employees from potential fire hazards.

Ensure your staff are suitably and sufficiently trained to enable them to understand safety measures and actions to take with our accredited Fire Safety Course.