Walk through any Canadian factory, garage, or lab, and you’ll likely be surrounded by common flammable substances in workplaces. 

From the solvents used to clean tools to the fuels that power machinery, these materials are essential for getting the job done, but they also hide a dangerous potential for fire.

The risk is far from theoretical. Each year, fires caused by workplace flammable materials result in devastating losses. 

In Canada, workplace fires cause millions of dollars in property damage and, tragically, can lead to serious injuries and fatalities. What’s most alarming is that many of these incidents are preventable.

The reality is that a wide range of workplaces including warehouses, manufacturing plants, auto shops, and even offices, routinely store and use these hazardous materials without a full appreciation of the risks involved.

This guide exists to change that. We will highlight the 10 most common flammable substances you might encounter, explain what makes each one so dangerous, and provide clear, actionable best practices for their safe storage and handling. 

Knowing what you’re working with is the first step toward protecting your team and your business.

Understanding Flammable vs. Combustible Substances

Knowing the difference between flammable and combustible materials is critical for safe handling and storage. 

While often used interchangeably in everyday language, Occupational Safety and Health Administration (OSHA), Workplace Hazardous Materials Information System (WHMIS), and the National Fire Protection Association (NFPA) classifications draw a clear, scientific distinction based on a property called flashpoint.

Flashpoint is the lowest temperature at which a liquid gives off enough vapor to ignite in the air near its surface. It is the key property that determines how easily a material can start a fire.

Flammable substances have a low flashpoint, meaning they can ignite easily at normal working temperatures. They present an immediate and more severe fire risk.

Combustible substances have a higher flashpoint. They need to be heated up before they will ignite, making them less likely to cause a fire under typical conditions.

This classification directly informs storage requirements (e.g., the type of safety cabinet needed) and handling procedures to prevent catastrophic incidents.

Flammable vs. Combustible: A Quick Comparison

Top 10 Most Common Flammable Substances in Workplaces

From industrial plants to small auto shops, many Canadian workplaces contain materials that can easily ignite if handled improperly. 

Understanding these common substances (where they are found, their specific dangers, and how to manage them) is the foundation of fire prevention.

This list covers the most frequently encountered flammable liquids and gases, providing essential knowledge to keep your team safe and your facility compliant.

Gasoline

• What it is: A refined petroleum product used primarily as a fuel.
• Where it’s found: Vehicle maintenance bays, fleet refueling areas, generators, and landscaping equipment storage.
• Main hazards: Its vapors are highly flammable and can travel long distances to an ignition source, leading to flash fires or explosions. It also emits toxic fumes when burned.
• Safe handling tips: Store only in UL/ULC or CSA-approved safety cans, never in glass or unapproved plastic. Keep containers in a well-ventilated, dedicated storage area away from heat, sparks, and oxidizing agents.

Acetone

• What it is: A fast-evaporating solvent found in many industrial and commercial products.
• Where it’s found: Laboratories, paint and coating shops, cleaning supply closets, and beauty salons (as nail polish remover).
• Main hazards: It has an extremely low flashpoint, meaning its vapors can ignite at room temperature from something as small as a static spark.
• Safe handling tips: Keep containers tightly sealed when not in use. Use in well-ventilated areas or with local exhaust ventilation. Ground and bond containers during transfer to prevent static discharge.

Propane

• What it is: A liquefied petroleum gas (LPG) stored under pressure, commonly used as a fuel source.
• Where it’s found: Powering forklifts in warehouses, job site heaters in construction, torches in metalworking, and portable stoves.
• Main hazards: A leak can create an invisible cloud of gas that is highly explosive if it contacts an ignition source like a pilot light or spark. Tanks can also become projectiles if exposed to fire (BLEVE).
• Safe storage & handling tips: Always store cylinders upright and secured in a well-ventilated outdoor cage or designated area. Regularly inspect hoses and connectors for leaks using a soapy water solution. Never use or store propane cylinders indoors or in enclosed spaces.

Ethanol / Alcohol-Based Solutions

• What it is: A highly flammable alcohol found in many forms, from pure ethanol to industrial and consumer products.
• Where it’s found: Laboratories, cleaning agents, pharmaceuticals, and notably, large quantities of hand sanitizer stations in offices and facilities post-COVID.
• Main hazards: Ignites very easily with a low flashpoint. Vapors can accumulate and be ignited by even small ignition sources. Fires burn with a clean, often invisible flame.
• Safe storage & handling tips: Store in dedicated, well-ventilated, flame-resistant safety cabinets away from heat and oxidizers. Limit quantities in open work areas. Use non-sparking tools around large volumes.

Paints and Thinners

• What it is: A category of products containing volatile solvents that keep paints in liquid form and clean application tools.
• Where it’s found: Manufacturing plants, auto body shops, construction sites, maintenance departments, and even art studios.
• Main hazards: The solvents (e.g., mineral spirits, toluene, xylene) emit flammable vapors that are heavier than air and can travel along floors to distant ignition sources.
• Safe storage & handling tips: Keep all containers tightly sealed when not in use. Store in a well-ventilated, fire-rated storage cabinet designed for flammable liquids. Control all ignition sources (e.g., sparks, flames, hot surfaces) in areas where these materials are used or stored.

Hydrogen

• What it is: A colorless, odorless, and extremely light gas that is highly reactive.
• Where it’s found: Research laboratories, petroleum refineries, chemical processing plants, and in the production and storage of hydrogen fuel cells and batteries.
• Main hazards: It has an extremely wide flammability range in air, meaning it can ignite easily and explosively. Its flame is nearly invisible, making the fire very difficult to see. It can also cause embrittlement of some metals.
• Safe storage & handling tips: Store cylinders in a secure, upright position in a well-ventilated, dedicated area, preferably outdoors. Use specialized leak detection sensors and explosion-proof electrical fixtures. Strictly control ignition sources and use appropriate PPE.

Methane / Natural Gas

• What it is: The primary component of natural gas, a fossil fuel used for heating and power generation.
• Where it’s found: Power generation facilities, industrial heating processes, commercial kitchens, and buildings with natural gas heating systems.
• Main hazards: It is highly flammable and can form explosive mixtures in air. Leaks in confined spaces like utility rooms or basements pose a severe explosion risk. It is also an asphyxiant in high concentrations.
• Safe storage & handling tips: Ensure proper maintenance of pipelines, valves, and appliances. Install and regularly test methane/natural gas leak detectors. Ensure excellent ventilation in areas where gas is used. Have clear emergency shut-down procedures.

Aerosol Sprays

• What it is: Consumer and industrial products dispensed by a pressurized propellant, many of which are flammable.
• Where it’s found: Everywhere in workplaces; includes office supplies like air dusters, maintenance products like lubricants and paints, and cleaning supplies.
• Main hazards: The product itself is often flammable, and the propellant (e.g., butane, propane) is highly flammable. The can is pressurized, which can explode if heated or punctured.
• Safe storage & handling tips: Store in a cool, dry place away from heat sources, sunlight, and potential puncture hazards. Do not use near open flames, sparks, or hot surfaces. Follow manufacturer instructions for disposal; never incinerate or crush empty cans.

LPG (Liquefied Petroleum Gas)

• What it is: A mixture of flammable hydrocarbon gases, primarily propane and butane, stored as a liquid under pressure in cylinders or tanks.
• Where it’s found: Commonly used for cooking in commercial kitchens (restaurants, hospitals), as a fuel for industrial heating, and for welding and cutting (oxy-propane) in metal fabrication shops.
• Main hazards: Leaking LPG vapor is heavier than air, meaning it pools at ground level in low-ventilation areas, creating an invisible and explosive hazard that can be ignited by a distant pilot light or electrical spark.
• Safe storage & handling tips: Always store cylinders upright in a well-ventilated, secure outdoor cage away from building entry points. Use only hoses and regulators designed for LPG and regularly inspect them for damage. Ensure clear signage and prohibit ignition sources in storage and use areas.

Cleaning Solvents

• What it is: A broad category of liquid products used for degreasing, stripping, and cleaning surfaces. Many contain volatile organic compounds (VOCs) like alcohols, ketones, and petroleum distillates.
• Where it’s found: Nearly universal; found in manufacturing for parts cleaning, in healthcare for equipment sterilization, in automotive shops, and in general office and facility cleaning closets.
• Main hazards: These solvents emit flammable vapors at room temperature. Their widespread and common use can lead to complacency, increasing the risk of ignition from sparks, static electricity, or hot surfaces.
• Safe storage & handling tips: Clearly label all containers with their contents and hazards. Store in approved, dedicated fireproof safety cabinets. Ensure good ventilation during use and keep containers tightly sealed. Use the smallest amount necessary for the task.

Safe Storage and Handling of Flammable Substances

Proper storage and handling of flammable materials are legal requirements under OSHA standards and Canada’s Workplace Hazardous Materials Information System (WHMIS). 

These regulations are designed to prevent fires, explosions, and exposure to hazardous vapors by controlling how these substances are stored, used, and managed in the workplace. 

Failure to comply can result in severe penalties, but more importantly, it puts lives at risk.

Key requirements and best practices include:

• Fire-Resistant Cabinets: Flammable liquids must be stored in CSA/ULC-approved safety cabinets designed to contain fires and prevent the spread of flames. Cabinets should be clearly labeled "Flammable - Keep Fire Away."
• Spill Control: Areas where flammables are stored or used must have spill containment measures, such as drip trays or secondary containment pallets. Spill kits specifically designed for chemical and solvent spills must be readily accessible.
• Grounding and Bonding: When transferring flammable liquids from large containers to smaller ones, grounding and bonding cables must be used to prevent static electricity discharge, which can ignite vapors.
• Ventilation: Storage areas must be well-ventilated to prevent the accumulation of flammable vapors. This is often achieved through mechanical ventilation systems.
• No-Smoking Zones: Strictly enforce designated no-smoking zones away from storage and handling areas, with clear signage.
• Ignition Source Control: Keep flammables far away from potential ignition sources, including open flames, sparks, hot surfaces, electrical equipment, and static electricity.

Flammable Storage Checklist

Compliance and Fire Safety Standards

Following the regulatory standards is essential for any Canadian workplace handling flammable materials. Compliance isn’t just about avoiding fines; it’s about creating a culture of safety that prevents disasters. 

Key frameworks provide the blueprint for managing these hazards effectively, ensuring everyone from the warehouse floor to the executive office understands the risks and protocols.

Summarized Key Frameworks

• OSHA 1910 Subpart H – Hazardous Materials: This U.S. standard is often referenced as a best practice and aligns with many Canadian principles. It specifically outlines requirements for the storage, handling, and use of hazardous materials, including flammable and combustible liquids. It covers everything from container design and ventilation to emergency planning and employee training.
• WHMIS/GHS Chemical Classification: Canada’s Workplace Hazardous Materials Information System (WHMIS), which incorporates the Globally Harmonized System (GHS), is the cornerstone of chemical safety. It mandates standardized labeling (including pictograms like the flame symbol for flammables) and the preparation of Safety Data Sheets (SDS) to communicate hazards clearly to workers.
• NFPA Fire Diamond System: The National Fire Protection Association's (NFPA) 704 rating system, known as the "fire diamond," is a quick visual hazard identification tool used on containers and storage areas. It uses color-coded sections (Health-Blue, Flammability-Red, Instability-Yellow) and numbers (0-4) to indicate the severity of hazards, helping firefighters and workers assess risks at a glance.

The Importance of Training and SDS Management

Simply having rules is not enough. Fire safety training workers is a non-negotiable requirement.

Employees must be able to read labels and SDS documents, understand the specific hazards of the materials they work with, and know how to use a fire extinguisher accurately. This is where Fire Extinguisher Training can be useful. 

Furthermore, updating Safety Data Sheets (SDS) is a critical, ongoing duty. It contains essential information on first-aid measures, handling, storage, and physical and chemical properties that inform safe work practices and emergency response. 

Preventing Fires and Protecting Workers

Preventing a fire is always better than fighting one. A proactive approach to safety, centered on hazard control and preparedness, is the most effective way to protect your workforce and facility from the dangers of flammable materials. 

This involves a combination of engineering controls, administrative actions, and the right personal protective equipment (PPE) to create multiple layers of defense.

Proactive Measures for Fire Prevention

• Fire Risk Assessments: Conduct regular and thorough assessments to identify all potential ignition sources (e.g., electrical equipment, static electricity, hot work) and ensure flammable materials are stored and used away from them. This is a foundational step for any safety program.
• Installing Proper Ventilation: Use mechanical ventilation systems, like local exhaust vents, in storage and use areas to prevent the accumulation of flammable vapors. Proper airflow is critical to maintaining a safe atmosphere and reducing the risk of explosion.
• Emergency Drills and Evacuation Plans: Develop and practice clear emergency action plans specific to flammable liquid or gas fires. Ensure all workers know evacuation routes, assembly points, and how to activate alarm systems. Regular fire drills build muscle memory for a calm and effective response during a real crisis.
• Personal Protective Equipment (PPE): Equip workers with the appropriate PPE to create a final barrier against hazards. This includes:
• Chemical-resistant gloves and safety goggles to protect against splashes.
• Fire-resistant (FR) clothing to protect against flash fires, especially when handling highly flammable liquids or gases.

Using the Correct Fire Extinguishers

Not all fire extinguishers work on all types of fires. Using the wrong type can be dangerous and ineffective. For flammable liquids and gases, you must use a Class B fire extinguisher. 

These are designed to smother the fire by interrupting the chemical chain reaction and preventing oxygen from fueling the flames.

Look for the "B" on the label. Many extinguishers are multipurpose (e.g., ABC dry chemical), which are also effective on Class B fires.

Ensure that extinguishers are easily accessible, regularly inspected, and that employees are trained on how to use them safely.

Frequently Asked Questions

What are the most common flammable substances at work?

Common substances include gasoline, acetone, propane, ethanol (in cleaners and hand sanitizers), aerosol sprays, and solvents like paint thinner. These are frequently found in maintenance shops, labs, warehouses, and even offices.

What’s the difference between flammable and combustible?

Flammable materials ignite more easily, with a flashpoint below 37.8°C (100°F), like acetone. Combustible materials have a higher flashpoint (above 37.8°C but below 93.3°C), like diesel fuel, and require more heat to ignite.

How should flammable liquids be stored in offices vs. factories?

In offices, store small quantities like hand sanitizer or cleaning sprays in cool, ventilated areas away from heat. In factories, use approved flammable storage cabinets with proper ventilation, spill containment, and clear signage.

What safety equipment is required for handling flammables?

Required equipment includes fire-resistant storage cabinets, spill kits, Class B fire extinguishers, and PPE like chemical-resistant gloves and safety goggles. Grounding and bonding tools are also essential for transferring liquids.

What training should workers have for fire risks?

Workers need training on identifying flammable materials, safe handling and storage procedures, reading SDS labels, and using fire extinguishers. Regular emergency drills for evacuation and response are also critical.

Can hand sanitizers cause workplace fires?

Yes, alcohol-based hand sanitizers are highly flammable, especially in large quantities. They should be stored away from heat sources and open flames, and used in well-ventilated areas to prevent vapor buildup.

Conclusion

Recognizing and properly managing common flammable substances in workplaces is a non-negotiable aspect of operational safety. 

From everyday items like gasoline, solvents, and aerosol sprays to industrial gases like propane and hydrogen, these materials are present in many work environments and carry significant risk if mishandled.

The key to fire prevention lies in a diligent approach: understanding the properties of these substances, storing them correctly in approved containers and cabinets, and adhering to strict WHMIS and OSHA standards. However, compliance alone is not enough. 

Continuous, effective training ensures every team member can identify hazards and respond appropriately in an emergency.

Ultimately, fire safety must be treated as an ongoing commitment. By promoting a culture of awareness and responsibility, employers can protect their people, their assets, and their community from preventable disasters.