Deflagration vs Detonation Visualizations

🔥 Deflagration vs 💥 Detonation

Visualizing the two fundamental types of explosions

Explosions come in two main varieties: deflagrations and detonations. While both involve rapid energy release, they differ dramatically in their propagation mechanisms, speeds, and destructive potential. This visualization demonstrates the key differences between these two explosion types.

Deflagration: The "Slower" Explosion

  • Flame front moves subsonically (slower than sound)
  • Propagates through heat transfer
  • Example: Flash fire in a dust collector
  • Pressure buildup is more gradual
  • Typical flame speed: 1-10 meters per second

🔍 Expert Commentary

Deflagrations are often what we see in industrial accidents involving combustible dust or vapor clouds. While they move "slower" than detonations, they can still be devastating if confined, as pressure builds up with nowhere to go. Most accidental gas and dust explosions begin as deflagrations.

Detonation: The Real Boom

  • Flame front moves supersonically (faster than sound)
  • Shock waves compress and ignite the mixture ahead of the flame front
  • Example: High explosives like TNT
  • Creates powerful shock waves
  • Typical detonation velocity: 1,500-9,000 meters per second

🔍 Expert Commentary

The key difference with detonations is the shock wave. This compression wave is so powerful it can ignite material ahead of the flame front, creating a self-sustaining reaction that moves incredibly fast. This is why high explosives are so destructive - the energy release is nearly instantaneous.

Explosion Simulation Lab

🚀 Explosion Simulation Lab

Explore how different materials behave during an explosion

Welcome to the Explosion Simulation Lab! Here you can explore how different materials behave during an explosion. Select a material, adjust the quantity and confinement parameters, and watch the dynamic simulation unfold. The lab provides real-time data on peak pressure, flame speed, and damage radius based on your inputs.

Select Material

Adjust Parameters

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Peak Pressure: 0 kPa
Flame Speed: 0 m/s
Damage Radius: 0 m

Methane (CH4)

  • LFL: 5.0% by volume
  • UFL: 15.0% by volume
  • Flame Speed: 0.4 m/s (deflagration)
  • Energy Density: 55.5 MJ/kg

🔍 Expert Commentary

Methane is the primary component of natural gas. Its explosions typically manifest as deflagrations, but in confined spaces with the right mixture, they can be devastating. The 2010 Upper Big Branch mine disaster was caused by a methane explosion that transitioned to a coal dust explosion.

Hydrogen (H2)

  • LFL: 4.0% by volume
  • UFL: 75.0% by volume
  • Flame Speed: 2.7 m/s (deflagration)
  • Energy Density: 142 MJ/kg

🔍 Expert Commentary

Hydrogen has an extremely wide flammable range and high energy density, making it both versatile as a fuel and dangerous as an explosion hazard. Its small molecule size means it can leak through tiny openings and accumulate in unexpected places. The Hindenburg disaster is perhaps the most famous hydrogen explosion.

Propane (C3H8)

  • LFL: 2.1% by volume
  • UFL: 9.5% by volume
  • Flame Speed: 0.5 m/s (deflagration)
  • Energy Density: 50.3 MJ/kg

🔍 Expert Commentary

Propane is heavier than air, which means it can accumulate in low-lying areas, creating invisible pools of explosive gas. This property makes propane leaks particularly dangerous in basements and other confined spaces. The 2013 Tavares, Florida propane plant explosion is an example of propane's destructive potential.

TNT (Trinitrotoluene)

  • Detonation Velocity: 6,900 m/s
  • Energy Release: 4.184 MJ/kg
  • Reaction Type: Detonation
  • Blast Pressure: High shock wave production

🔍 Expert Commentary

TNT is the standard against which all explosives are measured. Unlike the gases in this comparison, TNT doesn't need oxygen from the air to explode - it contains its own oxidizer. This makes it capable of detonation rather than deflagration, producing supersonic shock waves that cause devastating damage.

Flammable Range Explorer

🔥 Flammable Range Explorer

This interactive tool helps you understand how different fuel–air mixtures behave and whether they are too lean, flammable, or too rich to ignite.



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📘 Learn About Fuel–Air Concentration

What Is Fuel–Air Concentration?

Fuel–air concentration is the percentage of vaporized fuel in air. Only within a specific range—called the flammable range—can combustion or explosion occur.

Too Lean vs. Too Rich

Too Lean: Not enough fuel. The mixture won't ignite.

Too Rich: Too much fuel. There isn't enough oxygen to burn it.

Flammable Range: The sweet spot between lean and rich. Combustion is possible here.

What Affects LFL and UFL?
  • Temperature: Warmer conditions increase vaporization and widen the range.
  • Pressure: More pressure = more molecules = easier ignition.
  • Oxygen Concentration: More oxygen widens the flammable range.
  • Inert Gases: Suppress combustion by absorbing heat and reducing reactivity.
  • Fuel Type: Each fuel has its own LFL and UFL. Examples:
    • Methane: 5%–15%
    • Hydrogen: 4%–75%
    • Propane: 2.1%–9.5%
    • Acetylene: 2.5%–81%
Real-World Behavior

A fuel leak might begin too rich to ignite, become flammable as it mixes with air, and then too lean as it continues to disperse.

Analogy: Making Tea

Think of making tea:

  • Too little tea = too weak (too lean)
  • Just right = flavorful (flammable)
  • Too much tea = undrinkable sludge (too rich)