The Flame Height Calculator is a valuable tool used in fire safety engineering, combustion research, and industrial hazard analysis. It estimates the vertical length of a flame above the source of combustion, based on the heat release rate and the diameter of the flame source.
Understanding flame height is crucial in designing safe fire protection systems, assessing fire risks, and developing fire-resistant structures. It helps professionals ensure compliance with safety standards and predict potential fire behavior in various environments like buildings, factories, or outdoor settings.
formula of Flame Height Calculator
Where:
L = Flame height above the base of the fire (in meters)
Q̇ = Heat release rate of the fire (in kilowatts)
D = Diameter of the fire source or burner (in meters)
To calculate Q̇ if it is not given:
Q̇ = ṁ × ΔH_c
Where:
ṁ = Mass burning rate of fuel (kg/s)
ΔH_c = Heat of combustion of the fuel (kJ/kg)
Then:
Q̇ (kW) = Q̇ (kJ/s)
This equation assumes vertical open flames and is most accurate for circular fuel sources. It is commonly used in fire dynamics simulation and safety code assessments.
Reference Table for Fire Safety and Flame Measurements
| Fuel Type | Heat of Combustion (ΔH_c, kJ/kg) | Example Use | Notes |
|---|---|---|---|
| Gasoline | 44,000 | Vehicle fires, spills | High energy, spreads quickly |
| Propane | 46,400 | Industrial burners, BBQs | Requires contained ignition |
| Wood (dry) | 18,000 | Campfires, structure fires | Variable moisture affects value |
| Diesel | 45,300 | Transport and machinery | Slower ignition, steady burn |
| Methane (natural gas) | 50,000 | Residential, industrial | Efficient combustion, clean burn |
This table helps estimate Q̇ values when planning or investigating different fire scenarios.
Example of Flame Height Calculator
Suppose you are evaluating the flame height of a propane burner in a lab setting. You are given:
- Heat release rate (Q̇) = 1500 kW
- Diameter of the burner (D) = 0.5 meters
Use the formula:
Flame Height = 0.23 × (1500)^(2/5) − 1.02 × 0.5
First, calculate the exponent:
1500^(2/5) ≈ 29.74
Then:
L = 0.23 × 29.74 − 0.51
L ≈ 6.84 meters
So, the flame height is approximately 6.84 meters.
Most Common FAQs
Flame height indicates how far fire can reach vertically. It's crucial for determining safe distances, selecting fire-resistant materials, and designing ventilation or suppression systems in both indoor and outdoor environments.
Yes, but you must adjust the heat of combustion value based on the specific fuel. Standard fuels like gasoline, wood, or propane have well-documented ΔH_c values which should be used for accurate results.
Excluding the diameter can result in inaccurate flame height predictions. The diameter affects how the flame behaves and distributes its energy, so it is essential for precise safety calculations.