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Combustion & Flammability Calculator

NFPA 68 NFPA 69 API 521

Calculation Mode:
Look up flammability limits and calculate stoichiometric air for a single component

Pure Component

Operating Conditions

Β°F
LEL/UEL vary with temperature
psia
Standard: 14.696 psia. UEL increases at elevated pressure.

Engineering Basis

Le Chatelier's Mixing Rule
1/LEL_mix = Ξ£(y_i / LEL_i)

Calculates flammability limits for gas mixtures from pure component limits weighted by mole fractions.

Stoichiometric Combustion
Cβ‚™Hβ‚˜ + (n + m/4)Oβ‚‚ β†’ nCOβ‚‚ + (m/2)Hβ‚‚O

Complete combustion requires exact oxygen ratio. Excess air ensures complete burn.

Common Flammability Limits

Methane5.0 – 15.0%
Ethane3.0 – 12.4%
Propane2.1 – 9.5%
Hydrogen4.0 – 75.0%
Hβ‚‚S4.0 – 44.0%

Frequently Asked Questions

What does the Combustion & Flammability Calculator do?

It calculates flammability limits (LEL/UEL), stoichiometric air requirements, adiabatic flame temperature, and combustion products for hydrocarbon mixtures per NFPA 68/69.

What are LEL and UEL?

LEL (Lower Explosive Limit) and UEL (Upper Explosive Limit) define the concentration range in which a gas-air mixture is flammable.

What standards does this flammability calculator follow?

The calculator follows NFPA 68 and NFPA 69 standards for combustion and flammability analysis of natural gas and hydrocarbon mixtures.