Relationship Between Flame Length and Fireline Intensity

Estimating flame length from fireline intensity

The following equations can be used to estimate fireline intensity from flame length:

where:

• L = flame length (m)
• I = fireline intensity (kW/m)

The last equation is often simplified for field use as:

The results of this simplified equation are within 20% accuracy of actual fireline intensity (Chandler et al. 1983), which is generally adequate considering it is difficult to estimate flame length to better than 20% accuracy (DeBano and others 1998). Numerous observations of flame length (minimum, maximum, and mode- or most frequently occurring flame length) should be considered with these equations (Wade 1986).

Estimating flame length from fireline intensity

Relationship between fireline intensity, ambient temperature, and scorch height

The following equations can be used to estimate flame length from fireline intensity:

where:

• L = flame length (m)
• I = fireline intensity (kW/m)

For crown fires, half of the mean canopy height should be added to L.