Wood cribs

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. 

Source No.l gas flame No.5 wood cribs No.7 wood cribs specifier... 

Figure 9.18 Burning rate correlation for wood cribs according to Heskestad [23] with student data [24]...

Figure 11.11 Compartment thermal effect on burning rate for wood cribs and pool fire...

Fully developed fire studies have been performed over a range of fuel loadings and ventilation conditions, but primarily at scales smaller than for normal rooms. Also the fuels have been idealized as wood cribs or liquid or plastic pool fires. The results have not been fully generalized. The strength of the dimensionless theoretical implication of Equation (11.38) suggests that, for a given fuel, the fully developed, ventilation-limited fire should have dependences as... 

Law developed a correlation for the extensive Conseil International du Batiment (CIB) test series [17] involving wood cribs that covered most of the compartment floor [26], The test series also addressed the effect of compartment shape by varying its width (W) and depth (D). The correlation for the maximum temperature was given as... 

The CIB tests consisted of compartments with heights ranging from 0.5, 1.0 and 1.5 m with dimension ratios of D/H, W/H, H/H coded as data sets 211, 121, 221 and 441. A total of 321 experiments were conducted in still air conditions. The wood crib fuel loading ranged from 10 to 40 kg/m2 with stick spacing to stick thickness ratios of 1 and 3. The data are plotted in Figures 11.17 and 11.19. The compartment surface area, A, excludes the floor area in the plot variables. 

An alternative plotting format was used by Bullen and Thomas [6] for the mass loss rate, which shows the effect of fuel type in Figure 11.18. These data include an extensive compilation by Harmathy [27] for wood crib fuels (including the CIB data). Here the fuel area is included, but the compartment area is omitted. This shows the lack of... 

For the fully developed fire, various correlations have sought to portray the temperature in these fires in order to predict the impact on structures. Chapter 11 highlights the CIB work on wood cribs and the corresponding correlation by Law [19]. It is instructive... 

Croce, R A., Modeling of vented enclosure fires, Part 1. Quasi-steady wood-crib source fires, FMRCJ.I.7A0R5.G0, Factory Mutual Research, Norwood, Massachusetts, July 1978. 

Plywood walls, wood cribs, cellulosic ceiling tile Non-FR chair, TV cabinets, cables, etc. 

The second, more empirical path, is marked by the development of larger scale test methods that are meant to simulate potential "real world" or actual exposure conditions. Examples of such test methods are room fire tests in which actual pieces of furniture are placed in 8 x8 xl2 room-size enclosures and exposed to fire sources ranging from multiple sheets of newspaper or waste baskets in full conflagration to even larger sources such as 20 lb. and 25 lb. wood cribs. 

For simulation, a rectangular compartment of 80 m long, 10m wide, 8 m high with opening at one end is considered. A section of the compartment is shown in Fig. 5 (half section of a symmetric compartment is shown). As the fire source a burning wood cribs is considered for this study of fire environment inside the compartment. The volume of the fire source is taken to be 9 m (3 m X 3 m X 1 m). The source is located 24 m from open end of the compartment, i.e. left portal. The heat release rate curve, as shown in Fig. 6 is taken from experimental results measured by Ingason et al. (1994) [19] on a wood crib fire imder natural ventilation condition as mentioned therein. 

Figure 6. Heat release rate for wood cribs fire.

Scandinavia Nordtest NT Fire 004. The test is designed to measure the ability of floor covering to resist fire spread and smoke development, a flaming wood crib is placed on a 1000x400 mm specimen. After 15 seconds the blower and suction fans are switched on to give a specified airflow. Highest classification... 

It has proved difficult to determine any correlation between the test result of the various national procedures [53]. Because of this, the experts of TC92 of the International Standards Organisation (ISO) have undertaken the development of a test procedure to characterise independently ignitability, flame spread, rates of heat release, and other fire-related parameters [54-56]. Worldwide efforts continue to correlate laboratory tests to real-life fires [57]. Examples of such programmes are the corner test programme carried out by Factory Mutual and the corrugated metal tool deck [58] trials [59, 60] carried out by TNO. The corner test has been used to determine the fire behaviour of rigid foam materials when exposed to severe wood crib fire. 

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