Note:

This calculator determines the flammable range, helping assess the safe concentration limits of gases or vapors to prevent fire hazards.

The Flammable Range is the range of fuel-to-air concentration within which a gas or vapor can ignite.

It is determined by two key limits:

• Lower Flammable Limit (LFL): The minimum concentration of a gas or vapor in air that can sustain combustion.
• Upper Flammable Limit (UFL): The maximum concentration beyond which the mixture is too rich to burn.

If the gas concentration falls **below the LFL**, there isn’t enough fuel to sustain combustion. If it is **above the UFL**, there is too much fuel and not enough oxygen for combustion to occur.

Examples of Flammability Limits (in air)

Fuel	LFL (%)	UFL (%)
Methane	5.0	15.0
Propane	2.1	9.5
Ethylene	2.7	12.0
Hydrogen	4.0	75.0
Methanol	6.0	36.0
Acetylene	2.5	100.0

The flammable range is calculated as the **difference between UFL and LFL**. Enter the LFL and UFL values above and click Calculate Range to determine the flammable range.