Research into the fire properties of wood products most frequently used in construction.
Maciulaitis, Romualdas ; Praniauskas, Vladas ; Yakovlev, Grigory 等
Introduction
In the modern global industry, wood has become very popular, thus
its shortage is a growing problem. As many countries, including
Lithuania, use wood in constructions, importance of this material must
be taken into consideration. A wide choice of application options
results in growing demand and requirements for the range of these
products.
Fire safety is one of the main requirements set for buildings.
Another important condition is to ensure that in case of fire, wood
products would cause as low threat to civil population and fire-fighters
as possible (Hakkarainen 2002; Frangi et al. 2009). This goal can be
accomplished by using products, the fire properties of which limit the
speed of fire propagation (Richardson, Batista 2001). When assessing
products in terms of fire safety, it is also important to perform all
the required tests exposing products to various heat flows and assess
the heat release rate, decomposition (pyrolysis) of products and
toxicity of substances emitted in the course of fire, including the
amount of emitted smoke (Nyderis, Maciulaitis 1999; White 2000; Bednarek
et al. 2009; Sauciuvenas, Griskevicius 2009).
Heat release rate, which is considered to be an important fire
property, is highly significant for fire propagation. This statement is
substantiated by the fact that fire temperature, which predetermines the
propagation speed of fire itself depends on heat release rate and
combustion time (Babrauskas, Peacock 1992; Wladyka-Przybylak 1997;
Mouritz et al.2006; Filipczak et al. 2005).
Due to high temperatures, the combustion process is the main factor
destroying materials and structures. This is the reason why even wooden
structures should be made resistant to fire (Bednarek, Kaliszuk-Wietecka
2007; Chow, C. L., Chow, W. K. 2009).
Wooden structures are usually protected with the help of
impregnation with fire retardant solutions; however, incorrectly
selected impregnator may result in dramatic consequences in case of
fire. Flammable substances contained in impregnators may accelerate fire
propagation even further (BridZiuviene, Lugauskas 2003; Poika 2008;
Praniauskas, Maciulaitis 2010; Pereyra, Giudice 2009). Instead of
extinguishing a small seat of fire, the fire-fighting team would have to
extinguish the whole building enveloped in flames. Most importantly, a
building should not be constructed using a lot of flammable materials,
but rather substances that could arrest and limit fire propagation
(Babrauskas 2005; Wang et al. 2007; Chou et al. 2009). Fire-resistance
enhancing materials used for the protection of wood and wood products
act as a firewall arresting fire propagation, extending fire resistance
and improving the durability of structures in general (Draizdeil 1998;
Maciulaitis, Praniauskas 2010).
It must also be noted that the combustion of large-molecular
substances causes the emission of extensive amounts of carbon dioxide
(C[O.sub.2]). C[O.sub.2] is the final product of carbon oxidation.
C[O.sub.2] is a colourless gas with sour odour and flavour,
approximately 1.5 times heavier than air. C[O.sub.2] forces people to
breathe more frequently, this way leading to a greater intake of toxic
combustion products.
It causes vasodilatation as well as changes in blood pH and
increased content of adrenaline in blood. Pursuant to the available
data, it can be stated that in case of a short-term exposure to
C[O.sub.2] (15 minutes), the permissible concentration is 1.5% (Zukas et
al. 2007).
The purpose of our study is to determine the impact of impregnated
and non-impregnated (with fire retardant solution BAK-1) wood on fire
propagation.
1. Materials tested and test methodology
The tests were performed with non-impregnated boards and boards
impregnated with fire retardant solution BAK-1: 24 mm thick wood
particle boards (WPB) and oriented strand boards (OSBs) of different
thickness (6 mm, 10 mm, 15 mm and 18 mm). Five samples for both
impregnated and non-impregnated wood products of each board type were
prepared.
Fire hazard tests were carried out in accordance with the
requirements of the standards LST ISO 5657:1999 (Fig. 1) and LST EN
13823:2010 (Fig. 2).
In accordance with the standard LST ISO 5657:1999, samples were cut
out from test boards maintaining their real thickness (150 x 150 mm).
Then, a frame wrapped in aluminium foil was prepared. It was placed on
one side of the sample while exposing only a circular opening to a heat
flow (the heat flow is radiated by a spiral heated up to a certain
temperature). Then, while exposing the sample to selected heat flows,
the time to ignition (TTI) of the test boards was determined with the
help of a stopwatch.
[FIGURE 1 OMITTED]
[FIGURE 2 OMITTED]
In accordance with the standard LST EN 13823:2010, the sample was
made of two parts with dimensions 1500 x 495 mm and 1500 x 1000 mm
(height x width) and exposed to the flame of the burner equipped at the
bottom of the corner. Flame was obtained by combusting propane gas with
a heat capacity of (30.7 [+ or -] 2.0) kW supplied through a sandbox.
The duration of the test was 25 minutes. However, during the first 5
minutes, an auxiliary burner was burned. It was equipped father from the
sample, and the sample was not directly exposed to the flame. By means
of the auxiliary burner, only the heat capacity and smoke formation of
the burner were measured; therefore, the programme evaluated the heat
capacity and smoke formation of the burner itself as well as provided
only the test results of the sample once the sample was exposed to the
flame of the main burner. The sample was exposed to the flame of the
main burner for 20 minutes. The following operating parameters were
obtained: heat formation, smoke formation, lateral flame spread and fall
of flaming droplets and particles.
In order to summarise the test results, the average values of the
obtained indicators were used.
2. Test results and discussion
First of all, non-impregnated products were tested in order to
determine the ignition point. It was determined that at the heat flow of
10 kW/[m.sub.2] (380[degrees]C and 20 kW/[m.sub.2] (500[degrees]C
products did not ignite but charred. This might have happened because in
order to initiate flame combustion, a certain concentration of volatile
products (emission from the sample at the time of thermal decomposition
when it is exposed to heat flows) and oxygen should be reached. However,
in this case, under the exposure to smaller heat flows, a sufficient
quantity of volatile products and concentration of the mix (of volatile
products and oxygen) necessary for flame combustion was not reached.
Therefore, only charring of the board and emission of volatile products
without flame combustion proceeded. The test wood products that did not
ignite after 900 seconds was terminated (see Table 1).
Ignition was obtained only at the heat flow of 30 kW/[m.sup.2]
(590[degrees]C. When gradually increasing the heat flow, the time to
ignition decreased correspondingly as concentration of volatile products
and oxygen necessary for flame combustion was reached faster.
However, it is possible to suggest that the ignition of neither WPB
or OSB depends on the board thickness or the difference is minimal. The
data presented in Table 1 prove that a thicker board may ignite faster
than a thinner one. This may be influenced by additives used in board
production and their concentration on the board surface because in case
of a higher concentration of additives on the board surface, the
concentration of volatile products and oxygen required for flame
combustion may be reached faster or slower (White 2000; Richardson,
Batista 2001; Morkevicsius, Papreckis 2004).
Table 2 presents the results of combustibility tests of impregnated
wood products and average times to ignition.
The results of the tests with impregnated products are presented
starting from 35 kW/[m.sup.2] (620 [degrees]C) because the samples did
not ignite when exposed to lower heat flows. Furthermore, the 24-mm
thick WPB did not ignite even at 35 kW/[m.sup.2] (620 [degrees]C). It
can be explained by the fact that when boards are covered with BAK-1
fire retardant solution and exposed to heat flows, it absorbed salts
intumesce, forming an additional protective layer (see Fig. 3) over the
board surface exposed to the heat flow, which retains a part of the heat
flow. As a result, the board surface is heated to a lesser degree and
the amount of emitted volatile pyrolysis products is smaller.
Most frequently, differences were observed when exposing 6 mm OSB
and WPB to 35 kW/[m.sup.2] (620 [degrees]C) heat flow. After
impregnation with fire retardant solution BAK-1, the ignition time of
OSB extended by approximately 13 seconds, while WPB withstood the test
and did not ignite.
[FIGURE 3 OMITTED]
When increasing the temperature, fire retardant provides worse
protection against the impact of fire: the time differs from that of
non-impregnated samples increasingly less and that difference amounts to
2-3 seconds on average. Therefore, it can be presumed that the impact of
fire retardant is not as effective when increasing the temperature. When
the heat flow of 50 kW/[m.sup.2] (700 [degrees]C) is reached, the
results of impregnated products were similar to those of non-impregnated
products; therefore, fire retardant becomes less effective at high
temperatures. This might be explained by the fact that when exposed to
high heat flows, the additional protective layer forming of the absorbed
salts of the fire retardant arrests the heat flow; however, the heat
flow that reaches the board surface is still sufficient for a
concentration of the mix of pyrolysis gases and oxygen required for
flame combustion.
[FIGURE 4 OMITTED]
[FIGURE 5 OMITTED]
On the other hand, OSB absorbs fire retardant solution differently,
and one place of the board absorbs more salts, while another absorbs
less. It can be observed after the test from the quantity of additional
intumesced coating (Fig. 4).
The best result was achieved with WPB, which did not ignite at the
heat flow of 35 kW/[m.sup.2] (620 C) for as many as 23 minutes and more.
The sample charred, although there was no flame, and it continued to
smoulder. However, under the heat flow above 40 kW/[m.sup.2] (650
[degrees]C), fire retardant almost failed to protect WPB.
WPBs, 24 mm thick, and OSBs, 6 mm, were selected for further tests
in accordance with the standard LST EN 13823:2010.
As may be seen from Figure 5, as soon as WPB was exposed to the
flame of the main burner, the heat release rate immediately began to
increase and the maximum heat release rate ([HRR.sub.max]) was reached
after approximately 160 seconds. The heat release rate is the most
important fire property, which influences fire propagation speed and its
physical and chemical properties (Mouritz et al. 2006). The change time
of the [HRR.sub.max] value has a particular importance: the shorter it
is, the greater is the hazard for humans because if high temperatures
are reached quickly, fire propagates faster blocking evacuation ways.
When [HRR.sub.max] is reached, heat release decreases as a result of the
carbon layer, which inhibits the emission of flammable gases
(Praniauskas et al. 2010). The decrease occurs gradually, and no heat
surges as a result of the formation of cracks in the carbon layer are
observed. The test was terminated in approximately 1500 seconds.
According to FIGRA 0.2 MJ (the maximum relation between heat release
rate and duration) equals to 615.7 [W/s], and the flammability class
established according to LST EN 13501-1:2007 + A1:2010 standard is D
(>250 [W/s] and [less than or equal to] 750 [W/s]).
[FIGURE 6 OMITTED]
Figure 6 presents the curve of the test of reaction of 2-mm-thick
WPB impregnated with BAK-1 fire retardant solution to fire. The highest
value of the relation of the heat release rate and duration FIGRA =
249.6 W/s. All the heat released from the sample during 600 s from the
beginning of the exposure to the flame of the main burner [THR.sub.600]
= 13.7 MJ. The total amount of heat released THR = 22 MJ. Within 10
minutes from the beginning of the exposure of the sample to the main
burner, approximately 62% of the total heat emission was released, and
approximately 38% of the total heat emission was released during the
remaining 10 minutes. The HR[R.sub.max] (HRR-Prod.) during the test was
reached in approximately 4 minutes, after the sample was exposed to the
flame of the main burner. In this case, the curves of HRR and FIGRA are
very similar to those of WPB; however, they differ by values of these
parameters. After WPB was impregnated with the fire retardant BAK-1
solution, the values of its parameters decreased as a result of the
additional fire retardant protection.
According to the results obtained during the test, the WPB
impregnated with BAK-1 fire retardant solution according LST EN
13501-1:2007+A1:2010 is 120 W/s and [less than or equal to] 250 W/s and
classified in C flammability class.
It was noticed that the amount of smoke released from a 24-mm-thick
WPB is nearly three times greater than that released from a
non-impregnated board. It can be explained by the interaction between
the fire retardant and a board as well as partial pyrolysis (Table 3).
The test with a non-impregnated OSB was terminated because of rapid
ignition. Sharp increase in the heat release rate is demonstrated in
Figure 7. The test reached the maximum values and was terminated in
approximately 200 seconds from the start of exposure of the sample to
the main burner. The image of the sample at the time of the test and
later is presented in Figure 8. Figure 7 shows that at the time of the
termination of the test as FIGRA0.2 MJ [W/s] ~ 3000.
A 6-mm-thick OSB impregnated with BAK-1 fire retardant solution
showed better results (Fig. 9) than a similar non-impregnated board
(Fig. 7), with the test of the latter having been terminated because of
high parameters that exceeded all criteria. The maximum relationship
between the heat release rate and the duration FIGRA=555.5 W/s. The
total amount of heat released from the sample within 600 s from the
beginning of exposure to the flame of the main burner [THR.sub.600] =
20.8 MJ. The total amount of heat released THR = 22 MJ. Approximately
94% of the total heat was released within 10 minutes from the beginning
of exposure of the flame of the main burner and around 6% was released
within the remaining 10 minutes. This might have happened because after
the first 10 minutes, the sample became burned through at the place
where it was exposed to the flame and was no longer exposed to the
flame. The [HRR.sub.max] (HRR-Prod.) during the test was reached in
approximately 5 minutes after the sample was exposed to the flame of the
main burner (Fig. 9). According to the results obtained during the test,
the OSB impregnated with BAK-1 fire retardant solution is classified in
D flammability class.
[FIGURE 7 OMITTED]
[FIGURE 8 OMITTED]
[FIGURE 9 OMITTED]
Even after terminating the test on the basis of the values of
SMOGRA, it can be concluded that smoke release rate decreased after
impregnating the OSB with fire retardant solution. Therefore, the impact
of the fire retardant is absolutely positive in this case (Table 4).
[FIGURE 10 OMITTED]
Analysis of the emission of C[O.sub.2] determined during the tests
shows that the amount of C[o.sub.2] emitted from wooden boards
impregnated with BAK-1 fire retardant solution was lower than that from
non-impregnated ones. C[o.sub.2] emission from non-impregnated OSB and
WPB started to increase rapidly almost from the beginning of the test,
as soon as the sample was exposed to the flame of the main burner. In
the case of non-impregnated WPB, a C[o.sub.2] concentration limit of
almost 1.3% was reached, while in the case of OSB, the hazardous
C[o.sub.2] concentration limit of 1.5% was exceeded (Zukas et al. 2007)
(Fig. 10). Impregnated OSB reached a C[o.sub.2] concentration limit of
approximately 2.2%, and in the case of non-impregnated OSB, the
C[o.sub.2] concentration limit was as high as 9% (Fig. 10). Therefore,
fire retardant solution not only worsens the combustion properties of
wood but also decreases the amount of C[o.sub.2] emission. As a result,
there is a greater possibility to save lives as well as wealth.
The results of the tests performed in accordance with the standard
LST ISO 5657:1999 were processed statistically in order to derive
equations for forecasting the time to ignition. Three parameters were
selected to derive the equations: TTI (time [S]), board thickness
(thickness [mm]) and heat flow (Q [kW/[m.sup.2]]) to which the sample
was exposed.
On the basis of regression analysis, it was established that the
results obtained from the tests of non-impregnated and impregnated OSB
(6, 10, 15 and 18 mm thick) and WPB (24 mm thick) were the most suitable
to forecast the time to ignition. Since the correlation coefficients R
of the first (R=0.97826) and second (R=0.98049) equation for
non-impregnated boards were close to one, and the correlation
coefficients R of the third (R = 0.99216) and fourth (R=0.99415)
equation for impregnated boards were also close to one, it can be
concluded that the selected equation model with a turning point is
correct, and there is a high interdependence between the parameters
(Rudskiene, Kulvietiene 1995; Borovikov 1998; Kleinbaum et al. 1998).
Therefore, the following empirical equations can be used for the
forecasting of time to ignition of non-impregnated (1) and (2) and
impregnated (3) and (4) OSB and WPB:
[y.sub.1] = (52.128 - 0.683[x.sub.1])*([y.sub.1] [less than or
equal to] 45.276) + (201.774 - 3.818[x.sub.1])*([y.sup.1] > 45.276);
(1)
[y.sub.2] = (60.725 - 0.762[x.sup.1] - 0.434[x.sub.2])*([y.sup.2]
[less than or equal to] 45.276) + (196.62 - 3.818[x.sub.1] -
0.421[x.sub.2])*([y.sub.2] > 45.276); (2)
[y.sub.3] = (74.334 - 1.137[x.sub.1])*([y.sub.3] [less than or
equal to] 34.74) + (299.813 - 6.416[x.sub.1])*([y.sub.3] > 34.74);
(3)
[y.sub.4] = (75.430 - 1.106[x.sub.1] - 0.177[x.sub.2])*([y.sub.4]
[less than or equal to] 34.74) + (265.634 - 5.268[x.sub.1] -
0.488[x.sub.2])*([y.sub.4] > 34.739), (4)
where: [y.sub.1,2,3,4]-time to ignition [s]; [x.sub.1]-power of the
superficial heat flow to which the sample was exposed [kW/[m.sup.2]];
[x.sub.2]-thickness of OSB or WPB [mm];
*([y.sup.1,2] [less than or equal to] 45.27589) means that the
equation is applicable when time to ignition > 45.27589 [s]. As
demonstrated in Table 1, this equation is applicable when samples are
exposed to heat flow power >40 [kW/[m.sup.2]]; *([y.sub.1,2] >
45.27589) means that the equation is applicable when time to ignition
>45.27589 [s]. As suggested in Table 1, this equation is applicable
when samples are exposed to heat flow power [less than or equal to] 40
[kW/[m.sup.2]]; *([y.sub.3,4] [less than or equal to] 34.73916) means
that the equation is applicable when time to ignition [less than or
equal to] 34.73916 [s]. As demonstrated in Table 1, this equation is
applicable when samples are exposed to heat flow power >40
[kW/[m.sup.2]], and the equation is applicable to WPB when samples are
exposed to heat flow power >45 [kW/[m.sup.2]]; *([y.sub.3,4] >
34.73916)-means that the equation is applicable when time to ignition
>34.73916 [s]. As suggested in Table 1, this equation is applicable
when samples are exposed to heat flow power < 40 [kW/[m.sup.2]], and
the equation is applicable to WPB when samples are exposed to heat flow
power < 45 [kW/[m.sup.2]].
Tables 5 and 6 present the forecasted TTI values calculated in
accordance with the Eqns (1)-(4) as well as the actual average TTI
values for impregnated and non-impregnated OSB and WPB. As the obtained
results suggest, TTI values can be forecasted promptly and accurately
enough in accordance with the Eqns (1) and (3). However, slightly more
accurate results can be obtained when forecasting uses the Eqns (2) and
(4).
Conclusions
The TTI of OSB and WPB when exposed to a heat flow with powers
exceeding 35 kW/[m.sup.2] almost does not change compared to similar
non-impregnated samples.
When exposed to a heat flow with power of 35 kW/[m.sup.2], some WPB
samples did not ignite but rather charred. Therefore, it is recommended
to use WPB impregnated with fire retardant.
The [HRR.sub.max] (HRR) values (i.e. the highest amount of heat
released during combustion) for all samples was reached after
approximately 160 seconds after ignition. It is a very short period of
time, which would pose danger to human life in case of real fire.
The best fire resistance properties were demonstrated by WPB
impregnated with fire retardant solution, the fire growth rate (FIGRA)
and the entire amount of heat released of which were almost 2.5 times
lower than that of a non-impregnated board.
Fire retardant solution not only worsens the combustion properties
of wood and increases the flammability class but also decreases the
amount of C[o.sub.2] emission.
Prompt forecasting of the TTI (s) can be made according to the heat
flow (Q, kW/[m.sup.2]) to which the sample is exposed and more accurate
forecasting is possible once its thickness (D, mm) is also taken into
consideration. The aforementioned indicators are sufficient for making
rather accurate forecasting and deciding on the combustibility of OSB
and WPB.
doi: 10.3846/13923730.2013.810169
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powlok peczniejacych do drewna w zaleznosci od zastosowanych
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wood swell, depending on the used modifiers]. PhD thesis. Institute of
Natural Fibres, Poznari, Poland. 80 p. (in Polish).
Zukas, A.; Macsiulaitis, R.; Ssukys, R. 2007. Statybos produktu
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products]: Mokomoji knyga. Vilnius: Technika. 112 p. (in Lithuanian).
Romualdas MACIULAITIS (a), Vladas PRANIAUSKAS (b), Grigory YAKOVLEV
(c)
(a) Department of Building Materials, Vilnius Gediminas Technical
University, Sauletekio al. 11, LT-10223 Vilnius, Lithuania
(b) Fire Research Centre of the Fire and Rescue Department under
the Ministry of the Interior, Svitrigailos g. 18, LT-03223 Vilnius,
Lithuania
(c) Department of Building Materials, Kalashnikov Izhevsk State
Technical University Studencheskaia Str. 7, Izhevsk 426069, Russia
Received 21 Aug. 2012; accepted 16 Apr. 2013
Corresponding author: Vladas Praniauskas
E-mail: vladas.praniauskas@vpgt.lt
Romualdas MACIULAITIS. Prof. Doctor Habil of Technological
Sciences. He works at Department of Building Materials of Vilnius
Gediminas Technical University (VGTU). Research interests: development
of building materials and analysis of their characteristics.
Vladas PRANIAUSKAS. Doctor of Technological Sciences. He works at
the Fire Research Centre of the Fire and Rescue Department under the
Ministry of the Interior (PAGD prie VRM GTC). Research interests: fire
resistance and flammability research of building materials.
Grigory YAKOVLEV. Prof. Doctor Habil of Building Materials. He
works as head of Department of Building Materials in Kalashnikov Izhevsk
State Technical University (Kalashnikov IzhGTU). Research interests:
nanotechnology for green and sustainable construction.
Table 1. The average moisture content and the TTI of
non-impregnated wood products exposed to heat flows
of different capacities (temperature)
Average values of the TTI (s)
Indicators OSB (6 mm) OSB (10 mm)
Moisture content, (%) 8 6
30 kW/[m.sup.2] (590 [degrees]C) 93.11 74.54
35 kW/[m.sup.2] (620 [degrees]C) 65.34 67.01
40 kW/[m.sup.2] (650 [degrees]C) 26.45 28.34
45 kW/[m.sup.2] (675 [degrees]C) 24.43 21.58
50 kW/[m.sup.2] (700 [degrees]C) 19.15 17.64
Average values of the TTI (s)
Indicators OSB (15 mm) OSB (18 mm)
Moisture content, (%) 8 8
30 kW/[m.sup.2] (590 [degrees]C) 87.34 93.98
35 kW/[m.sup.2] (620 [degrees]C) 69.14 71.18
40 kW/[m.sup.2] (650 [degrees]C) 24.11 19.81
45 kW/[m.sup.2] (675 [degrees]C) 22.11 18.7
50 kW/[m.sup.2] (700 [degrees]C) 16.48 15.55
Average values of the TTI (s)
Indicators WPB (24 mm)
Moisture content, (%) 6
30 kW/[m.sup.2] (590 [degrees]C) 87.47
35 kW/[m.sup.2] (620 [degrees]C) 68.11
40 kW/[m.sup.2] (650 [degrees]C) 32.11
45 kW/[m.sup.2] (675 [degrees]C) 19.11
50 kW/[m.sup.2] (700 [degrees]C) 15.01
Table 2. The average moisture content and the TTI of impregnated
wood products exposed to heat flows of different capacities
(temperature)
Average values of the
indicators of samples (s)
Indicators OSB (6 mm) OSB (10 mm)
Moisture content (%) 8 8
35 kW/[m.sup.2] (620 [degrees]C) 78.52 75.8
40 kW/[m.sup.2] (650 [degrees]C) 29.63 28.2
45 kW/[m.sup.2] (675 [degrees]C) 27.52 22.27
50 kW/[m.sup.2] (700 [degrees]C) 18.39 18.81
Average values of the
indicators of samples (s)
Indicators OSB (15 mm) OSB (18 mm)
Moisture content (%) 6 8
35 kW/[m.sup.2] (620 [degrees]C) 74.65 72.11
40 kW/[m.sup.2] (650 [degrees]C) 27.84 27.18
45 kW/[m.sup.2] (675 [degrees]C) 23.11 24.11
50 kW/[m.sup.2] (700 [degrees]C) 17.89 16.87
Average values of the
indicators of samples (s)
Indicators WPB (24 mm)
Moisture content (%) 8
35 kW/[m.sup.2] (620 [degrees]C) -
40 kW/[m.sup.2] (650 [degrees]C) 41.19
45 kW/[m.sup.2] (675 [degrees]C) 22.20
50 kW/[m.sup.2] (700 [degrees]C) 13.91
Table 3. Smoke release values of impregnated and
non-impregnated WPB
Smokiness Non-impregnated Impregnated WPB
parameter WPB (24 mm) (24 mm)
SMOGRA 7.8 19.5
TS[P.sup.600] 43.6 96.9
TSP 165 180
SMOGRA-smoke growth rate. The maximum value of the
relationship between the rate and duration of smoke formation
from the sample) [[cm.sup.2]/[s.sup.2]];
TS[P.sub.600]-the total quantity of smoke forming from the sample
within 600 s (300 s [less than or equal to] t [less than or equal to]
900 s) from the beginning of exposure of the flame of the main
burner [[m.sup.2]];
TSP-the total quantity of smoke forming from the sample [[m.sup.2]];
FIGRA-fire growth rate. The maximum relationship between
HRR and duration [W/s].
Table 4. Smoke release values of impregnated and non-
impregnated (before terminating the test) OSBs.
Smokiness Non-impregnated Impregnated OSB
parameter OSB (6 mm) (6 mm)
SMOGRA 82 36.1
TS[P.sub.600] - 176.5
TSP - 220
Table 5. Actual and forecasted values of TTI for non-impregnated
OSB and WPB
Non-impregnated OSB and WPB
Actual TTI value (s)
Q,
kW/ OSB OSB OSB OSB WPB
[m.sup.2] (6 mm) (10 mm) (15 mm) (18 mm) (24 mm)
30 93.1 74.5 87.3 94.0 87.5
35 65.3 67.0 69.1 71.2 68.1
40 26.5 28.3 24.1 19.8 32.1
45 24.4 21.6 22.1 18.7 19.1
50 19.2 17.6 16.5 15.6 15.0
Non-impregnated OSB and WPB
TTI according to
the Eqn (1), (s)
OSB (6 mm);
OSB (10 mm);
Q, OSB (15 mm);
kW/ OSB (18 mm);
[m.sup.2] WPB (24 mm)
30 87.23
35 68.14
40 24.81
45 21.39
50 17.98
Non-impregnated OSB and WPB
TTI according to the Eqn (2), (s)
Q,
kW/
[m.sup.2] OSB OSB OSB OSB WPB
(6 mm) (10 mm) (15 mm) (18 mm) (24 mm)
30 79.55 77.87 75.77 74.5 71.98
35 60.46 58.78 56.68 55.41 52.89
40 27.64 25.91 23.74 22.43 19.83
45 23.83 22.1 19.93 18.62 16.02
50 20.02 18.29 16.12 14.81 12.21
Table 6. Actual and forecasted values of TTI for impregnated OSB and WPB
Impregnated OSB and WPB
Actual TTI value (s)
Q,
kW/ OSB OSB OSB OSB WPB
[m.sup.2] (6 mm) 10 mm (15 mm) (18 mm) (24 mm)
35 78.5 75.8 74.7 72.1 -
40 29.6 28.2 27.8 27.2 41.2
45 27.5 22.3 23.1 24.1 22.2
50 18.4 18.8 17.9 16.9 13.9
Impregnated OSB and WPB
TTI according to
the Eqn (3), (s)
OSB (6 mm);
OSB (10 mm);
Q, OSB (15 mm);
kW/ OSB (18 mm);
[m.sup.2] WPB (24 mm)
35 75.25
40 28.85 (OSB);
43.17 (WPB)
45 23.17
50 17.48
Impregnated OSB and WPB
TTI according to the Eqn (4), (s)
Q,
kW/ OSB OSB OSB OSB WPB
[m.sup.2] (6 mm) (10 mm) (15 mm) (18 mm) (24 mm)
35 84,18 76.37 73.93 72.47 -
40 30.13 29.42 28.54 28.00 43.2
45 24.67 23.89 23.01 22.47 21.41
50 19.07 18.36 17.48 16.94 15.88
