Flame Penetration Test

Another measure of thermal stability is the limiting oxygen index (LOI). Polyimide 2080 has an LOI of 44% and a syntactic foam using the resin as the matrix has an LOI greater than 55%. The flame penetration test of the US Bureau of Mines is a severe test of thermal stability. A syntactic foam having a density of 0.27 g/an exhibited a flame penetration of 1.1 hr/in. Thermal conductivity of the foam is in the range of 0.38 to 0.46 Btu/hr-ft - F/in over a density range of 0.22 to 0.30 g/cta . 

Expanded thermosets are examined by the Flame Penetration Test developed by the US Bureau of Mines. A 1200 jet flame is directed at the geometric centre of a specimen, 150 mmx 150 mm, and the time is measured which is needed for the flame to penetrate the 25 mm thickness of the specimen, either in the horizontal (Fig. 3.64) or vertical position. ... 

In a fire, isocyanurate foams become charred on the surface and the carbonaceous layer protects the underlying bulk for a considerable time. A 25 mm thick slab of flame-retarded polyurethane foam burns through within 2 or 3 minutes when exposed to a jet flame at 1000 °C in the flame penetration test. A corresponding test piece of isocyanurate foam lasts 30 to 50 min in the same test (cf. Section 3.1.5.3). 

Endurance burn testing generally implies that the ignited gas mixture and flow rate are adjusted to give the worst-case heating (based on temperature observations on the protected side of the element surface), that the burn continues for a specified duration, and flame penetration does not occur. Continuous flame testing implies a gas... 

Chapter 24 Burn through test for thermal/acoustic insulation blankets used in the fuselage. This test uses the same type of oil burner as the one for seat cushions (Chapter 7), but the fuel flowrate is 378mL/min (6 gal/h) of gas flow for4min. The acceptance criteria are no flame penetration through the insulation blanket and a heat released by the insulation not exceeding 22.7 kW/m2. 

By the fire test it was recognized that the ability of fire endurance of a wooden door depended on the thickness of materials and the flame came out from panel inserted portion which was thinnest. The thickness of the carbonized layer was about 20mm after testing. From this point it was judged it was unnecessary to use fire retardant wood for thick door parts like a stile. Meanwhile it was necessary to improve the panel inserted portion to prevent flame penetration, because panels as door parts are constructed independently and the gaps of the panel inserted portions are extend more by shrinkage with wood combustion. 

This test also requires special equipment and generally consists of three parts a preliminary ignition test, a fire penetration test and a spread of flame test. The specimen is subjected to radiant heat and a vacuum is applied to one side to simulate service conditions. A specified flame is applied to the test piece for various durations and the time for the flame to penetrate, as well as the maximum distance of flame spread, are noted. Glowing, flaming or dripping on the underside of the specimen are also taken into consideration. Results are classified as follows ... 

This test is intended for materials used in the construction and finishing of buildings or structures. It is also specified where fire resistant elements are used to limit flame penetration such as in bulkheads and partitions in ships. 

Endurance Burn Under certain cou(itious, a successfully arrested flame may stabilize on the unprotected side of an arrester element. Should this condition not be corrected, the flame will eventually penetrate the arrester as the channels become hot. An endurance burn time can be determined by testing, which specifies that the arrester has withstood a stabilized flame without penetration for a given period. The test should address either the actual or worst-case geometry, since heat transfer to the element will depend on whether the flame stabilizes on the top, bottom, or horizontal face. In general, the endurance burn time identified by test should not be regarded as an accurate measure of the time available to take remedial action, since test conditions will not necessarily approximate the worst possible practical case. Temperature sensors may be incorporated at the arrester to indicate a stabilized flame condition and either alarm or initiate appropriate action, such as valve closure. 

More than coincidence is probably responsible for the easy penetration and deposition of the non durable (water soluble) flame retardant. The durable (nonwater soluble) flame retardants, restricted to surface deposition are not as effective. The results of the testing, using the stringent NFPA-701 test protocol, are summarized in Table VI. Once again, several conclusions can be made ... 

POLYURETHANE FOAM SHEETS OR BLOCKS. These are required to resist ignition source 5 (17 gram wood crib) of BS5852 Part 2 except that the flames may penetrate the full depth of the specimen and that the mass loss (due to burning and liquid residues falling from the test rig) shall not exceed 60 grams. 

Testing codes within the scenario of a fully developed fire are based on intermediate, large, or full-scale testing. Specimens are typically in the dimension of several square meters and often, real components such as building columns are tested, or the whole product in the case of gas bottles. Tests like the small-scale test furnace based on specimens of 500 mm x 500 mm are exceptions. Intensive flame application or the use of furnaces realizing standard time-temperature curves are used to simulate the characteristics of fully developed fires. Thus, in particular the heat impact of convection and the surface temperature are clearly greater than in the tests discussed earlier. The fire properties investigated are often resistance to fire, or the fire or temperature penetration. 

When electrolytic iron foil is immersed in concentrated solutions of jodium or potassium hydroxide for several weeks, and, after thorough cleaning, allowed to corrode in distilled water, the latter gradually becomes contaminated with traces of sodium or potassium salts, the bresence of which can be detected by the spectroscope or by the usual Bunsen flame test.6 Similar results have been obtained with lithium lydroxide, barium hydroxide, and with ammonia.7 It appears probable hat the alkali penetrates in minute quantities into the metal between he ferrite crystals, possibly in consequence of a certain amount of borosity in the intercrystalline cement. This theory is supported by he fact that iron which has been soaked in alkali invariably pits ... 

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