Low Heat-Flux Measurements: Some Precautions.
Low Heat-Flux Measurements: Some Precautions.
(1218 K)
Robertson, A. F.; Ohlemiller, T. J.
NIST SP 971; August 2001.
NIST SP 971: "Collected Reports and Publications by the
National Institute of Standards and Technology on Heat
Flux Gage Calibration and Usage.", 2001.
Fire Safety Journal, Vol. 25, No. 2, 109-124, September
1995.
Available from:
For More Information on NIST SP 971 visit: WEBSITE:
http://www.bfrl.nist.gov/866/heatflux/index.htm
Keywords:
heat flux; experiments; sensors; fluxmeters; hot
surfaces
Abstract:
Simple experiments are described for the purpose of
illustrating measurement errors and their avoidance
during use of Gardon or Schmidt-Boelter total heat flux
sensors. These errors can assume serious proportions of
the observed signal at flux levels below about 15 kW/m2.
They result from two sources, both a consequence of the
flux gage's temperature relative to its surroundings:
firstly, convective heating of the gage by the boundary
layer from hot surfaces surrounding it and second, heat
exchange with the ambient environment by radiation and
convection. Some proposals are made for standardizing
measurement methods, but it seems unlikely that errors
in measurement can be completely eliminated. It thus
becomes important for users of experimentally derived
data to understand the limitations which may existin the
data reported.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899