What is a Fire Point

In fire safety, knowing when a material can ignite isn’t enough—knowing when it can sustain combustion is where true safety lies. That’s where the fire point comes into play. Unlike the more commonly referenced flash point, the fire point determines when a flammable liquid becomes a true fire hazard, capable of maintaining a flame once ignited.

If you’ve ever wondered why certain substances keep burning after being set alight while others quickly extinguish, the answer lies in this crucial physical property. Whether you’re storing flammable liquids in your workshop or assessing risk in an industrial facility, understanding the fire point can be the difference between containment and catastrophe.

In this article, we’ll break down what fire point means, how it’s measured, how it compares to flash point, and why it matters in real-world fire safety. We’ll use relatable scenarios, real-life examples, and safety tips to ensure you grasp the full picture.

What is a Fire Point? A Simple Yet Critical Definition

Fire point is the lowest temperature at which a substance—notably a flammable liquid—produces enough vapors to sustain combustion for at least five seconds after ignition. In other words, it’s not just about catching fire—it’s about staying on fire.

Here’s a simple way to understand it:

• Flash Point: The liquid gives off vapors that ignite, but the flame goes out quickly unless the heat source is maintained.

• Fire Point: The liquid gives off enough vapors to keep burning on its own after the ignition source is removed.

Real-Life Analogy

Imagine you’re lighting a barbecue. You pour lighter fluid on the charcoal and strike a match. At a certain moment, the vapors ignite briefly and flare up—this is the flash point. But unless the fire continues burning on its own, it hasn’t reached the fire point.

Once the charcoal starts burning steadily and the flames stay alive without your match, you’ve hit the fire point.

Key Fire Point Characteristics

• Always slightly higher than the flash point (usually by 5–40°C)

• Indicates sustained fire risk

• Varies between substances; for example:

  • Diesel: Flash point ~52°C, Fire point ~65°C

  • Kerosene: Flash point ~38°C, Fire point ~47°C

Why This Matters

In fire safety and hazard classification, the fire point provides a more realistic picture of danger. It shows when a flammable liquid becomes self-sustaining, making it a critical metric for storing, transporting, and using such materials.

Citation: NFPA 30 – Flammable and Combustible Liquids Code; ASTM D92 – Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester

How Is Fire Point Measured? The Science Behind the Safety

Measuring fire point isn’t just about watching for flames—it’s a carefully controlled process using standardized equipment, such as the Cleveland Open Cup Tester (COC).

The Cleveland Open Cup Method

This widely accepted test involves:

1. Place a sample of the liquid in a metal container.

2. Gradually heating it at a controlled rate (e.g., 5–6°C per minute).

3. Applying a small test flame at set intervals (typically every 2°C).

4. Observing the vapors to see if they ignite and sustain a flame for at least 5 seconds.

Only when the sample continues to burn without the flame being held over it is the fire point recorded.

Application Scenario

In chemical manufacturing, understanding the fire point helps determine safe storage temperatures. For instance, if a flammable solvent has a fire point of 60°C, keeping it in environments exceeding that temperature poses significant fire hazards.

Many industries rely on Material Safety Data Sheets (MSDS), which include both flash and fire points. Workers, safety managers, and engineers use this data to plan:

• Ventilation needs

• Safe transport protocols

• Fire suppression readiness

Citation: ASTM International. “ASTM D92 – Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester”

Flash Point vs Fire Point: Why the Distinction Matters

One of the biggest misconceptions in fire safety is confusing flash point with fire point. Though closely related, these two have distinct safety implications.

Workplace Example

Let’s say you’re storing mineral oil. It has a flash point of 160°C and a fire point of 200°C. If an ambient heat source raises the temperature above 200°C, you’re at risk of an uncontrollable fire, not just a flash.

That’s why fire safety protocols—such as setting upper thermal limits—must be based on fire point, not flash point alone.

Pro Insight: In fire investigations, distinguishing between flash and fire points helps determine how a fire started and why it continued to burn.

Real-Life Applications of Fire Point in Industries

Understanding fire point isn’t limited to laboratories or technical manuals—it plays a crucial role in real-world settings across many industries.

1. Petroleum Industry

• Refineries use fire point data to separate highly flammable liquids from those with safer profiles.

• Transport regulations depend on the fire point to classify liquids as:

  • Flammable (fire point < 60°C)

  • Combustible (fire point > 60°C)

2. Paint and Coating Industry

Paint thinners, lacquers, and solvents often have low fire points. Proper ventilation, spark-proof tools, and grounding become mandatory safety protocols based on fire point data.

3. Food Processing Facilities

Even cooking oils can become hazardous. Canola oil, for example, has:

• Flash point: ~327°C

• Fire point: ~360°C

Industrial fryers need temperature control systems to ensure oils never reach fire point.

4. Construction Sites and Workshops

Power tools and heat sources can easily raise flammable liquids to their fire point. Safety training must include:

• Recognizing fire point hazards

• Using correct fire extinguishers (e.g., Class B for flammable liquids)

Case Study: In a 2021 incident at a chemical plant, failure to monitor fire point data led to an explosion after vapors ignited during maintenance. The investigation found that fire point awareness could have prevented the incident.

Fire Point and Fire Prevention: Practical Safety Guidelines

To prevent fires caused by liquids reaching their fire point, implement the following safety practices:

1. Temperature Control

Maintain liquid storage areas below fire point temperatures using:

• Climate-controlled environments

• Insulated storage units

• Fire-resistant enclosures

2. Proper Ventilation

Vapors accumulate faster in enclosed spaces. Ensure:

• Continuous airflow

• Exhaust systems in enclosed areas

• Fume hoods were applicable

3. Use of Fire Point Data in Risk Assessments

Fire Risk Assessments (FRA) should:

• Include the fire point data of all chemicals

• Categorize substances based on their hazard level

• Guide decisions on PPE, extinguishers, and emergency planning

4. Fire Safety Training

Ensure staff understand:

• Difference between flash and fire point

• Actions to take when dealing with heated liquids

• How to store and handle flammable materials safely

Fire Safety Tip: Always refer to the Safety Data Sheet (SDS) of any chemical you’re handling. Fire point is often listed under Section 9: Physical and Chemical Properties.

Frequently Asked Questions (FAQs) About Fire Point

Is the fire point always listed on safety labels?

Not always. While flash point is more commonly displayed due to regulations, fire point is usually found in the technical datasheets or SDS.

Can a material have a flash point but no fire point?

Yes. Some substances can ignite briefly but can’t sustain a flame unless vapor production increases, meaning no fire point under normal conditions.

Are fire point and autoignition temperature the same?

No. Autoignition temperature is when a substance ignites without an external flame. Fire point requires an ignition source, but once lit, the material sustains combustion.

What fire extinguisher is best for fire point-related fires?

For flammable liquid fires (where fire point is a concern), use a Class B extinguisher, such as:

• Foam (AFFF)

• Dry Powder (ABC)

• CO₂ (for electrical risk scenarios too)

Final Thoughts: Why Fire Point Knowledge Saves Lives

Understanding the fire point isn’t just for engineers—it’s for anyone handling flammable materials. Whether you’re managing fuels, cooking oils, or solvents, the fire point tells you when a material turns dangerous.

By integrating fire point knowledge into fire safety planning, you go beyond compliance—you actively reduce risk. From the laboratory to the loading dock, from the warehouse to the workshop, fire point awareness is a cornerstone of modern fire prevention.

Author’s Note: As a certified Fire Safety Consultant, I’ve conducted countless hazard assessments where the lack of fire point understanding led to improper storage and fire incidents. My advice? Always respect the data—and let science guide your safety decisions.