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A. Rabiei et al.
by enhancing the thermal resistance where the S-S CMF is in contact with the instrumented steel plate. The combination of all of the above factors results in a temperature
resistant material with sufficient thermal insulating performance that is expected to
meet the torch fire test requirements with a 15.2 mm thick layer of S-S CMF.
The effect of the surface emissivity on the heat transfer of the S-S CMF can be
quantified if the heat flux from the jet can be partitioned into its convective and
radiative components. The S-S CMF is fabricated of mostly 316L stainless steel
and has a significant surface roughness if the pores on the surface are opened upon
grinding or machining prior to testing. The S-S CMF was previously measured to have
a surface emissivity of 0.60-0.13 with the average value being approximately 0.15 for
temperatures about 500°C [17]. However, since the S-S CMF exposed to significantly
greater than 500°C during the jet fire test, a surface emissivity measurement at higher
temperatures up to 1200°C must be conducted on S-S CMF before an extensive
analysis of its thermal performance can be concluded. This is the subject of our
current studies that will be reported later on. Once the surface emissivity of the S-S
CMF at the torch fire temperature conditions are established, the percentage of the
torch fire energy into the material can be calculated and correlated to the excellent
thermal insulating performance of the material in the torch fire testing.
The results of the current two tests along with the prior simulated pool fire testing
[17, 18] indicate the potential of lightweight S-S CMF panels to be used in the
structure of next-generation tank cars with more protection against fire. To complete
the full-scale test requirements of CFR Part 179 App. B, panels of 122 × 122 cm
dimensions will need to be tested against the torch fire exposure in duplicate.
Conclusions
1. A reduced-scale torch fire test was developed in general accordance with 49
CFR 179, Appendix B to screen the thermal protection performance of small,
30.2 cm × 30.2 cm S-S CMF panels.
2. The jet fire used in the test setup was demonstrated to meet the gas temperature
and velocity requirements stated in the test specification.
3. In addition, a calibration test was performed with the instrumented steel plate
only (no sample), and the exposure was sufficient to result in the required
temperature rise of the steel plate.
4. Two tests were successfully performed on the S-S CMF panels of two different
thicknesses. It was determined that a 1.52 cm (0.60 in) thick panel with
seven layers of hollow spheres within its thickness provides adequate thermal
protection to meet the torch fire test requirements in 49 CFR 179, Appendix B.
5. However, reducing the thickness to 1.36 cm (0.54 in.) or six layers of hollow
spheres within the thickness of the panel resulted in more heat transmission
through the panel causing the panel to not meet the temperature rise limit by
only a few degrees.
A. Rabiei et al.
by enhancing the thermal resistance where the S-S CMF is in contact with the instrumented steel plate. The combination of all of the above factors results in a temperature
resistant material with sufficient thermal insulating performance that is expected to
meet the torch fire test requirements with a 15.2 mm thick layer of S-S CMF.
The effect of the surface emissivity on the heat transfer of the S-S CMF can be
quantified if the heat flux from the jet can be partitioned into its convective and
radiative components. The S-S CMF is fabricated of mostly 316L stainless steel
and has a significant surface roughness if the pores on the surface are opened upon
grinding or machining prior to testing. The S-S CMF was previously measured to have
a surface emissivity of 0.60-0.13 with the average value being approximately 0.15 for
temperatures about 500°C [17]. However, since the S-S CMF exposed to significantly
greater than 500°C during the jet fire test, a surface emissivity measurement at higher
temperatures up to 1200°C must be conducted on S-S CMF before an extensive
analysis of its thermal performance can be concluded. This is the subject of our
current studies that will be reported later on. Once the surface emissivity of the S-S
CMF at the torch fire temperature conditions are established, the percentage of the
torch fire energy into the material can be calculated and correlated to the excellent
thermal insulating performance of the material in the torch fire testing.
The results of the current two tests along with the prior simulated pool fire testing
[17, 18] indicate the potential of lightweight S-S CMF panels to be used in the
structure of next-generation tank cars with more protection against fire. To complete
the full-scale test requirements of CFR Part 179 App. B, panels of 122 × 122 cm
dimensions will need to be tested against the torch fire exposure in duplicate.
Conclusions
1. A reduced-scale torch fire test was developed in general accordance with 49
CFR 179, Appendix B to screen the thermal protection performance of small,
30.2 cm × 30.2 cm S-S CMF panels.
2. The jet fire used in the test setup was demonstrated to meet the gas temperature
and velocity requirements stated in the test specification.
3. In addition, a calibration test was performed with the instrumented steel plate
only (no sample), and the exposure was sufficient to result in the required
temperature rise of the steel plate.
4. Two tests were successfully performed on the S-S CMF panels of two different
thicknesses. It was determined that a 1.52 cm (0.60 in) thick panel with
seven layers of hollow spheres within its thickness provides adequate thermal
protection to meet the torch fire test requirements in 49 CFR 179, Appendix B.
5. However, reducing the thickness to 1.36 cm (0.54 in.) or six layers of hollow
spheres within the thickness of the panel resulted in more heat transmission
through the panel causing the panel to not meet the temperature rise limit by
only a few degrees.