Manufacturing industries rely on various chemical substances to keep production running efficiently. However, some of these chemicals are flammable and require careful storage and handling. If not managed properly, even a small spark or a simple oversight can trigger a fire or explosion, putting people and property at serious risk. 

Flammable substances are materials that can catch fire easily, and many of them are commonly used in manufacturing operations. While not all of these substances are extremely flammable, some pose higher risks than others. The Occupational Safety and Health Administration (OSHA) classifies these high-risk substances as “most flammable” based on their flashpoints and boiling points. But how do you identify these materials and ensure they are handled safely? 

To make things easier, we’ve created a simple guide that highlights some of the most flammable chemicals used in manufacturing. This guide also explains the potential risks associated with these materials and outlines essential safety measures to help you protect your facility, employees, and operations. 

 

What are Flammable Substances? 

Flammable substances are materials that can catch fire quickly when exposed to heat, flames, or sparks. Such substances can be liquids, gases, or solids. These substances are commonly used in manufacturing processes for cleaning, as fuel sources, or as essential components in production. Some manufacturing facilities regularly use highly flammable substances such as alcohol, gasoline, and propane for cleaning, fueling, or production processes.  

 

Definition of Flammable Liquids According to OSHA 

 

Source Link: https://www.osha.gov/sites/default/files/training-library_TrngandMatlsLib_FlammableLiquids.pdf 

 

According to OSHA (Occupational Safety and Health Administration), a flammable liquid is any liquid that can catch fire easily. OSHA defines a flammable liquid as one that can release enough vapor to catch fire at or below 199.4 °F (93 °C), which is called its flashpoint. 

To make handling safer and easier, OSHA groups flammable liquids into four categories. These categories are based on how easily the liquids can catch fire and their boiling points. 

 

 Category 1: Most Flammable 

  • Flashpoint below 73.4 °F (23 °C) 
  • Boiling point at or below 95 °F (35 °C) 
  • Extremely easy to ignite 

 

Category 2: Highly Flammable 

  • Flashpoint below 73.4 °F (23 °C) 
  • Boiling point above 95 °F (35 °C) 
  • Still very flammable, but slightly less volatile than Category 1 

 

Category 3: Moderately Flammable 

  • Flashpoint between 73.4 °F and 140 °F (23 °C to 60 °C) 
  • If a liquid has a flashpoint above 100 °F (37.8 °C), it is usually less flammable. However, if it is heated to within 30 °F of its flashpoint, it becomes more dangerous. In that case, it must be handled with extra care—just like a highly flammable Category 3 liquid. 

 

Category 4: Slightly Flammable 

  • Flashpoint above 140 °F and up to 199.4 °F (60 °C to 93 °C) 
  • If heated to within 30 °F of the flashpoint, treat it as a Category 3 liquid for safety 

 

Most Flammable Substances 

Some substances catch fire much more easily than others. These are known as the most flammable substances. They have very low flashpoints, which means even a small amount of heat or spark can cause them to ignite. 

In manufacturing, these substances are often used for cleaning, fueling machines, or in the production process. Because they can be so dangerous, it’s important to know which chemicals are highly flammable, how they’re used, and how to handle them safely. 

 

List of Most Flammable Substances Used in Manufacturing 

Here are some of the most flammable substances found in factories and industrial settings: 

  1. Diethyl Ether

  • Flashpoint: -49 °F (-45 °C) 
  • Boiling Point: 94.8 °F (34.9 °C) 
  • Usage:
    Used as a solvent in pharmaceutical manufacturing and chemical synthesis. 
  • Risks:
    Highly volatile and extremely flammable. Vapors can form explosive mixtures with air and travel to ignition sources. 

        ✅Safe Handling Methods: 

  • Always store in tightly sealed containers away from heat or sparks. 
  • Use only in well-ventilated areas. 
  • Ground and bond containers when transferring. 
  • Use protective gear like chemical-resistant gloves and safety goggles.

 

  1. Acetaldehyde

  • Flashpoint: -38 °F (-39 °C) 
  • Boiling Point: 69 °F (20.8 °C) 
  • Usage:
    Used in the production of perfumes, plastics, and dyes. 
  • Risks:
    Extremely flammable. Also, vapors may cause respiratory irritation and are also considered a potential carcinogen. 

        ✅Safe Handling Methods: 

  • Always work with the substance inside explosion-proof fume hoods.  
  • Avoid direct contact with your skin or eyes—use proper protective equipment. 
  • Store the chemical in a dedicated flammable storage cabinet. 
  • Keep it away from oxidizers and heat sources.  

 

  1. Propylene Oxide

  • Flashpoint: -35 °F (-37 °C) 
  • Boiling Point: 95 °F (35 °C) 
  • Usage:
    Used as a sterilizing agent and intermediate in chemical manufacturing. 
  • Risks:
    Extremely flammable and classified as a probable human carcinogen. It can also cause respiratory and skin irritation. 

      ✅ Safe Handling Methods: 

  • Keep away from ignition sources. 
  • Use in controlled, ventilated environments. 
  • If there’s a chance of exposure, wear a respirator along with full personal protective equipment (PPE). 

 

  1. Ethyl Chloride

  • Flashpoint: -58 °F (-50 °C) 
  • Boiling Point: 54 °F (12 °C) 
  • Usage:
    Used as a local anesthetic and in refrigeration. 
  • Risks:
    Forms explosive vapor-air mixtures. May affect the nervous system and can cause dizziness or unconsciousness. 

      ✅ Safe Handling Methods: 

  • Use tools that are spark-proof to prevent ignition. 
  • Always ensure proper grounding and bonding when handling the substance to reduce the risk of static discharge. 
  • Avoid breathing in vapors for extended periods to protect your health. 

 

  1. Pentane

  • Flashpoint: -57°F  
  • Boiling Point: 97 °F (36 °C) 
  • Usage:
    Used as a blowing agent in foam production and as a solvent in labs. 
  • Risks:
    Vapors are heavier than air and can travel along surfaces to distant ignition points. Causes respiratory and skin irritation. 

       ✅ Safe Handling Methods: 

  • Store the substance safely in designated flammable liquid storage cabinets to minimize fire hazards. 
  • Make sure the storage area is well-ventilated and equipped with reliable leak detection systems.    
  • Always wear flame-resistant personal protective equipment (PPE).  

 

Conclusion 

Flammable chemicals play a vital role in many manufacturing processes, but they also pose significant risks if not handled properly. Identifying hazardous substances, understanding their applications, and following strict safety protocols are essential to preventing accidents and protecting lives. 

To keep the workplace safe, manufacturers need to take chemical safety seriously. This means storing chemicals properly, training workers well, and using reliable SDS (Safety Data Sheet) management software to stay informed and follow safety rules. In the end, safety starts with being aware and taking the right steps.