Combustible vs Flammable: Uncover the Differences for Enhanced Industrial Safety

man standing beside a truck filled with gas cylinders that can be flammable

In the world of industrial safety, the terms 'combustible' and 'flammable' are often used interchangeably. However, understanding the distinction between these two categories of materials is a crucial aspect of maintaining safety in workplaces dealing with hazardous substances. This article delves into what makes a material flammable vs combustible, highlighting why this knowledge is essential for professionals in various industries. By comprehending these differences, we can implement more effective safety measures, reducing the risk of accidents and ensuring a safer working environment.

What Makes a Material Flammable vs Combustible?

A flammable material is one that ignites easily and burns rapidly. This is typically determined by a low flash point, the lowest temperature at which a liquid can form an ignitable mixture in air. Flammable materials can catch fire under almost all temperature conditions. Examples include gasoline, alcohol, and certain types of solvents.

Combustible materials, on the other hand, require higher temperatures to ignite. Their flash points are typically above room temperature, making them less likely to spontaneously ignite under normal working conditions. Common combustible materials found in industrial settings include diesel fuel and certain oils.

Understanding the flammability of a substance is critical in industrial settings for several reasons. It influences how the substance is stored, handled, and disposed of. For instance, flammable materials require special storage containers to prevent accidental ignition. The way these materials are labeled is also governed by regulatory standards, ensuring that workers are aware of the potential hazards.

Breaking Down the Differences: Combustible vs Flammable

Flash Points: The Defining Factor

The primary factor that distinguishes a combustible vs flammable material is its flash point. Flammable materials have a flash point below 100 degrees Fahrenheit (37.8 degrees Celsius). This means they can catch fire at relatively low temperatures, making them more hazardous in terms of fire risk. In contrast, combustible materials have higher flash points, generally above 100 degrees Fahrenheit, implying that they require more heat to ignite.

OSHA and NFPA Standards

Both the Occupational Safety and Health Administration (OSHA) and the National Fire Protection Association (NFPA) provide guidelines and classifications for flammable and combustible materials. OSHA, under its Hazard Communication Standard (29 CFR 1910.1200), categorizes these materials based on their flash points and boiling points. This classification helps in determining the necessary safety measures and precautions required in the workplace.

The NFPA, through its NFPA 30: Flammable and Combustible Liquids Code, offers a comprehensive guide on how to safely store, handle, and use these materials. According to NFPA 30, flammable liquids are classified into four categories, with Class IA being the most hazardous (flash point <73°F and boiling point <100°F) and Class IC being the least hazardous within the flammable category (flash point ≥73°F and <100°F). Combustible liquids are divided into two classes, Class II (flash point ≥100°F and <140°F) and Class III, which is further subdivided into Class IIIA (flash point ≥140°F and <200°F) and Class IIIB (flash point ≥200°F).

Practical Implications in Industrial Settings

These classifications have direct implications on how industries manage these substances. For flammable materials, strict controls are required due to their low flash points. This includes using explosion-proof equipment, implementing stringent storage requirements, and ensuring proper ventilation. For combustible materials, while the risk of spontaneous ignition is lower, it is still crucial to adhere to safe handling practices. This includes maintaining proper storage temperatures and avoiding exposure to high heat sources.

Aspect Flammable Materials Combustible Materials
Definition Materials that ignite easily and burn rapidly. Materials that require higher temperatures to ignite.
Flash Point Below 100 degrees Fahrenheit (37.8 degrees Celsius). At or above 100 degrees Fahrenheit (37.8 degrees Celsius).
Ignition Ease Can ignite at almost all temperature conditions. Less likely to ignite spontaneously at normal temperatures.
Examples Gasoline, alcohol, certain solvents. Diesel fuel, certain oils.
Storage Requirements Require special containers and storage areas with fire suppression. Require safe storage, but less stringent than flammable materials.
Handling Precautions Need for grounding and bonding during transfer, explosion-proof equipment. Precautions against high heat sources, spill control measures.

Handling and Safety Protocols

Safety Measures for Flammable Materials

Flammable materials, due to their low flash points, require vigilant handling and storage procedures. Here are key safety measures:

  • Proper Storage: Flammable materials should be stored in approved, clearly labeled containers away from ignition sources. Storage areas must be equipped with fire suppression systems.
  • Use of Safety Equipment: Workers handling flammable materials should use personal protective equipment (PPE), including flame-resistant clothing, safety goggles, and gloves.
  • Grounding and Bonding: When transferring flammable liquids, grounding and bonding procedures must be followed to prevent static electricity buildup, which could lead to sparks.
  • Adequate Ventilation: Ensure sufficient ventilation in areas where flammable materials are used or stored to disperse vapors and reduce the risk of ignition.

Safety Measures for Combustible Materials

While combustible materials are less volatile than flammable materials, they still pose significant risks and require appropriate safety measures:

  • Temperature Control: Store combustible materials in areas where temperatures are consistently below their flash points.
  • Spill Prevention and Control: Implement procedures to quickly and safely manage spills, including having appropriate spill containment materials on hand.
  • Training and Emergency Preparedness: Employees should be trained in the proper handling of combustible materials and emergency response procedures.

Regulatory Compliance

Both OSHA and NFPA provide comprehensive guidelines for the safe handling of these materials. For instance, OSHA's 29 CFR 1910.106 outlines specific requirements for the storage and handling of flammable and combustible liquids, emphasizing the design and construction of storage containers and rooms. Similarly, NFPA codes, like NFPA 30, provide detailed guidelines on the storage, handling, and use of these materials.

Advancements in Handling Flammable and Combustible Liquids

The handling of flammable and combustible liquids in industrial settings has seen significant advancements, thanks to technological innovation and a growing emphasis on safety. These developments not only enhance the safety of these materials but also streamline their management, contributing to more efficient and secure industrial operations.

Innovative Safety Equipment

  • Automated Monitoring Systems: Modern facilities are increasingly adopting automated systems that monitor temperature, vapor levels, and potential leaks. These systems can provide real-time alerts, allowing for swift action to prevent accidents.
  • Advanced Fire Suppression Systems: Fire suppression technology has evolved to include systems that can detect and extinguish fires more quickly and effectively, specifically designed for areas where flammable and combustible liquids are stored or used.

Improved Container and Storage Solutions

  • Smart Storage Containers: The latest containers for flammable and combustible liquids are designed with integrated sensors that monitor internal conditions and alert staff of potential hazards, like temperature fluctuations or leaks.
  • Enhanced Material Design: Research into new materials has led to the development of containers and storage facilities that are more resistant to corrosion and breaches, reducing the risk of leaks and spills.

Training and Simulation Tools

  • Virtual Reality (VR) Training: VR technology is being used to train employees in safely handling flammable and combustible liquids. These simulations provide a realistic yet risk-free environment to practice response strategies for various scenarios.
  • E-learning Platforms: Digital learning tools offer accessible and comprehensive training modules on safety protocols, regulatory compliance, and best practices in handling hazardous materials.

Regulatory Compliance Software

Compliance management software has become an essential tool for industries. These programs help in tracking and ensuring compliance with OSHA, NFPA, and other relevant safety standards, simplifying the complex task of regulatory adherence.


Is combustion the same as flammable?

Combustion is a chemical process of burning, where a substance reacts with oxygen to produce heat and light. Flammable, on the other hand, describes a material's ability to ignite easily and burn quickly. While all flammable substances can undergo combustion, not all combustion involves flammable materials (as some require higher temperatures to burn).

Is gasoline flammable or combustible?

Gasoline is classified as a flammable liquid. This is because it has a low flash point and can vaporize quickly at room temperature, making it easy to ignite.

Is paper flammable or combustible?

Paper is generally considered a flammable solid because it can catch fire relatively easily and burn quickly under normal conditions.

What is the difference between flammable vs combustible temperatures?

The difference lies in the flash points of the materials. Flammable materials have a flash point below 100 degrees Fahrenheit (37.8 degrees Celsius), meaning they can ignite at lower temperatures. Combustible materials have flash points at or above 100 degrees Fahrenheit, requiring higher temperatures to ignite.

What is the difference between a flammable solid and a combustible solid?

A flammable solid is a material that can ignite easily and burn rapidly with a flame, like paper or dry leaves. A combustible solid, while still burnable, does not ignite as easily and generally requires higher temperatures to burn. An example would be certain types of wood or coal, which need more heat to start burning compared to flammable solids.

The material provided in this article is for general information purposes only. It is not intended to replace professional/legal advice or substitute government regulations, industry standards, or other requirements specific to any business/activity. While we made sure to provide accurate and reliable information, we make no representation that the details or sources are up-to-date, complete or remain available. Readers should consult with an industrial safety expert, qualified professional, or attorney for any specific concerns and questions.


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Author: Herbert Post

Born in the Philadelphia area and raised in Houston by a family who was predominately employed in heavy manufacturing. Herb took a liking to factory processes and later safety compliance where he has spent the last 13 years facilitating best practices and teaching updated regulations. He is married with two children and a St Bernard named Jose. Herb is a self-described compliance geek. When he isn’t studying safety reports and regulatory interpretations he enjoys racquetball and watching his favorite football team, the Dallas Cowboys.