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Temperature Uncertainties for Bare-Bead and Aspirated Thermocouple Measurements in Fire Environments.


pdf icon Temperature Uncertainties for Bare-Bead and Aspirated Thermocouple Measurements in Fire Environments. (1027 K)
Pitts, W. M.; Braun, E.; Peacock, R. D.; Mitler, H. E.; Johnsson, E. L.; Reneke, P. A.; Blevins, L. G.

Thermal Measurements: The Foundation of Fire Standards. American Society for Testing and Materials (ASTM). Proceedings. ASTM STP 1427. December 3, 2001, Dallas, TX, American Society for Testing and Materials, West Conshohocken, PA, Gritzo, L. A.; Alvares, N. J. Editor(s), 3-15 pp, 2003 AND U.S./Japan Government Cooperative Program on Natural Resources (UJNR). Fire Research and Safety. 14th Joint Panel Meeting. Proceedings. May 28-June 3, 1998, Tsukuba, Japan, 240-247 pp, 1998, 2003.

Keywords:

fire research; fire science; fire suppression; aspirated thermocouples; enclosures; fire tests; measurement uncertainties; temperature measurements; thermocouples

Abstract:

Temperature measurements have been made for natural-gas and heptane fires in a reduced-scale enclosure using a variety of bare-bead and aspirated thermocouples in order to characterize the uncertainties. The focus is the role of radiative heat transfer and the effects of finite time response on the measurements. The findings show that significant errors are possible for all thermocouples considered. Aspirated thermocouples reduce, but do not eliminate, such uncertainties. An alternate approach, use of several bare-bead thermocouples with extrapolation to zero diameter, is not easily implemented in the time-varying temperature environments characteristic of fires.