Comparing Techniques for Estimating Flame Temperature of Prescribed Fires

Fire Ecology

Table 6 Estimated cost, time for deployment, detail, precision, and accuracy of data, and typical uses of 7 techniques for estimating fire temperature, heat output, or fire severity. Infrared cameras, while not included in this study, are included here for comparison purposes.

Time for Detail Precision Accuracy
Measuring technique	Cost per unit	Reusable	deployment	of data	of data	of max temp	Typical uses ^d
Post-burn assessments	none	n/a	30 s	low	mod.	n/a	Fire severity, spatial heterogeneity
Fuel loading	none	n/a	1 m	low	poor-mod.	n/a	Heat output
Calorimeters	$0.1-1	yes	2–3 m	low	poor	n/a	Heat output, spatial heterogeneity
Pyrometers	$0.5-1	no	4–5 m	mod.	mod.	low-mod.^a	Maximum temperature, spatial heterogeneity
Thermocouples/Hobo dataloggers	$100-125	yes	10–15 m	high	high	mod.-high^b	Average and maximum temperature, rate of spread spatial heterogeneity
Thermocouples/Standard datalogger	$2,500 (36 TC)	yes	10–15 m	″	″	″	Average and maximum temperature, rate of spread
Infrared cameras	$15,000–50,000	yes	2–3 m	very high	high	high^c	Average and maximum temperature, rate of spread spatial heterogeneity

^aVaries according to pyrometer material and subject to observer bias.
^bDepends on thermocouple thickness and type (shielded-aspirated thermocouples are most accurate in flames).
^cOnly measures surface temperatures of objects, not flames. Accuracy dependent on knowing emissivity of objects and is affected by RH (including water vapor in smoke).
^dTypical uses are subject to the device limitations noted in this study. For example thermocouples are typically used to estimate “maximum temperature”, although reported values indicate the device temperature and generally underestimate true maximums.