KR102496572B1 - Method for assessing smoke risk of combustible materials in fire - Google Patents

Abstract

The present invention is a method for evaluating the smoke risk due to combustion gas generation in the event of a fire of combustible materials. Through a test on the combustion gas generation of four types of wood test specimens used as construction materials and durable materials, the smoke of combustion gases generated from the test specimens It relates to a method for evaluating risk by evaluation indices of smoke performance index-II (SPI-II) and smoke growth index-II (SGI-II).

Description

Method for assessing smoke risk of combustible materials in fire}

The present invention is a method for evaluating the smoke hazard in the event of a fire of wood and combustible materials. Through a test on the combustion gas generation of cedar, spruce, lawang, and red pine wood, the smoke risk of combustion gas generated from a test piece is measured by the smoke performance index -II (smoke performance index-II; SPI-II) and smoke growth index-II (smoke growth index-II; SGI-II).

Due to its aesthetic appearance and excellent physical and chemical properties, wood is widely used as a building material for general homes and medium-sized residential buildings. However, it has a vulnerability to fire compared to other building materials.

Combustible materials such as wood also cause a lot of damage due to combustion gases and smoke generated during combustion. In particular, smoke accounts for the largest proportion of human casualties in the event of a fire.

Therefore, in order to compensate for the problem of the combustibility of these woods, laws and regulations based on fire performance are enacted and implemented domestically and abroad, and studies to predict the burning rate of wood are being actively conducted.

Looking at the prior art for this, Non-Patent Document 1 has selected and evaluated some of the heat and smoke characteristics of wood treated with flame retardant with ammonium monophosphate and boric acid, but there is a limit to evaluating only the heat release rate among thermal characteristics.

In addition, in Non-Patent Document 2, a cone calorimeter experiment was performed by comparing high heat flux and low heat flux by selecting wood, and the critical heat flux was calculated and displayed using an integral model.

Non-Patent Document 3 studied incandescence and thermal ignition of wood in the vertical direction when exposed to radiant heat in the wood grain direction or in the vertical direction using a cone calorimeter.

In Non-Patent Document 4, the cone calorimeter method most closely simulates the actual fire phenomenon, and most organic materials use the principle of oxygen consumption in which about 13.1 MJ of heat is released when 1 kg of oxygen is consumed during combustion. is based on

On the other hand, as conventional smoke measurement and expression methods, smoke production rate (SPR), total smoke emission rate (TSR), smoke extinction area (SEA) (Non-Patent Document 5), smoke A factor (smoke factor, SF) (Non-Patent Document 6) and the like are used as a measure of smoke generation.

However, conventional smoke generation scales and expressions such as those in Non-Patent Document 5 and Non-Patent Document 6 are limited methods, and are still insufficient to fully implement risk and quantitative evaluation of smoke generation, leaving much room for improvement.

Currently, to improve this, smoke performance index (SPI) and smoke growth index (SGI) are used (Patent Document 1), but they do not include the risk of heat, so formulas for comprehensive evaluation of smoke risk in case of fire need to expand.

With the recent increase in buildings using wood and the expansion of the use of polymer materials in high-tech industries such as automobiles, ships, and electrical appliances, a situation in which safety must be considered in the event of a fire is being expressed. A new evaluation measurement index to evaluate the risk of smoke generation And the provision of quantitative evaluation indicators is urgently required.

Registered Patent Publication No. 10-2059475

The proceedings of Wood & Fire Safety (part one), 101-110 (2000) Fire Saf. J. 36, 391-415 (2001) Proceedings Combust. Inst. 30, 2303-2310 (2005) Elsevier Applied Science Publisher, London, UK. (1986) ISO 5660-1, Reaction-to-fire tests-heat release, smoke production and mass loss rate-Part 1: heat release rate(cone calorimeter method) and smoke production rate(dynamic measurement), Genever, Switzerland 2015 A. W. Coaker, M. M. Hirschler, S. Shakir, C. L. Shoemaker, Flammability testing of new vinyl compounds with low flammability and low smoke release in cables, US Army Communications-Electronics Command, Cherry Hill, USA 643-654 (2006)

As a result of studying a method for solving the disadvantages of smoke risk evaluation of the prior art and supplementing the disadvantages of expression, the present inventors have expanded the formula for smoke by including the risk of heat in the prior art, It was completed as a method to increase more quantitative and precision.

Accordingly, an object of the present invention is to provide a novel evaluation measurement index and quantitative evaluation index to evaluate the risk of smoke generation.

In order to achieve the above object, the present invention provides a method for evaluating the smoke risk of combustible materials in case of fire performed by a computer system, the smoke performance index-II (SPI-II) of Equation 1 and the following Equation 2 Provided is a method for evaluating the smoke risk of combustible materials in case of fire, including determining the smoke risk of combustible materials in case of fire by one or more evaluation indexes selected from the smoke growth index-II (SGI-II) of.

[Equation 1]

(In Equation 1, TTI represents the ignition time of the combustible material, SPR _peak represents the secondary peak value of the smoke generation rate, and PHRR represents the maximum heat release rate.)

[Equation 2]

(In Equation 2, SPR _peak is the peak value of the smoke generation rate, PHRR is the maximum heat release rate, and Time to SPR _peak represents the time to reach the SPR _peak .)

In the present invention, smoke-related indexes and harmful gases are measured as combustion characteristics by an external radiant heat source using a cone calorimeter for wood, which is mainly used as a building material and interior material, and smoke performance index-II (SPI-II ) and smoke growth index-II (SGI-II) were developed to predict the fire risk in case of wood fire.

Therefore, the present invention has the advantage that it can be commercialized as a method for evaluating the smoke generation risk of wood, plastic, fiber, etc. in case of fire.

1 shows a heat release rate curve of a wood specimen at an external heat flux of 50 kW/m ² .
2 shows a smoke generation rate curve of a wood specimen at an external heat flux of 50 kW/m ² .
3 shows a CO concentration (ppm) curve of a wood specimen at an external heat flux of 50 kW/m ² .
4 shows a CO ₂ concentration (ppm) curve of a wood specimen at an external heat flux of 50 kW/m ² .

The present invention is a method for evaluating the smoke risk of combustible materials in case of fire performed by a computer system, the smoke performance index-II (SPI-II) of Equation 1 below and the smoke growth index-II (SGI-II) of Equation 2 below II) relates to a method for evaluating the smoke risk of combustible materials in case of fire, including the step of determining the smoke risk of combustible materials in case of fire by one or more evaluation indicators selected.

[Equation 1]

(In Equation 1, TTI represents the ignition time of the combustible material, SPR _peak represents the peak value of the smoke generation rate, and PHRR represents the maximum heat release rate.)

[Equation 2]

(In Equation 2, SPR _peak is the peak value of the smoke generation rate, PHRR is the maximum heat release rate, and Time to SPR _peak represents the time to reach the SPR _peak .)

In case of fire, the non-thermal hazards of combustible materials are smoke, odor, corrosion, and toxicity. It is known that about 75-80% of the fire damage caused by these non-thermal hazards is due to oxygen deficiency and inhalation of smoke and toxic gases, etc., rather than direct exposure to flame.

Combustion of wood is known to be an important source of toxic emissions of some toxic substances, such as carbon monoxide (CO), volatile organic compounds (VOCs) and polycyclic aromatics hydrocarbons (PAHs), all of which are incomplete. A product of combustion, polycyclic aromatic hydrocarbons have been widely studied since they were found to be carcinogenic compounds.

The smoke performance index-II of Equation 1 is a result of implementing smoke hazard evaluation in consideration of three variables, the maximum smoke generation rate, ignition time, and maximum heat release rate, in order to be more quantitative and precise.

The smoke performance index (SPI) of Patent Document 1 is defined as a value obtained by dividing TTI by SPR _peak , and the smoke performance index-II is equal to the value obtained by dividing this smoke performance index by the maximum heat release rate. That is, SPI-II is defined as a value divided by multiplying TTI by SPR _peak and PHRR.

In the smoke hazard evaluation method of combustible materials in case of fire of the present invention, the larger the smoke performance index-II (SPI-II) value in Equation 1, the higher the smoke safety, and the smoke performance index-II (SPI-II) It can be judged that smoke safety decreases as the value decreases.

Since this correlates with the fire performance index (FPI) of wood and the time of flashover, it is understood that as the FPI value increases, fire safety also increases, as does fire safety.

The smoke growth index-II (SGI-II) of Equation 2 is more quantitative and more accurate by using three variables, the maximum smoke generation rate, the time to reach the maximum smoke generation rate, and the maximum heat release rate. This is the result of implementing the smoke hazard assessment in consideration of

The smoke growth index (SGI) of Patent Document 1 is defined as a value obtained by dividing the SPR _peak by the time to reach the SPR _peak , and the smoke growth index-II (SGI-II) is obtained by multiplying the smoke growth index by the maximum heat release rate. equal to the value That is, SGI-II is defined as a value obtained by dividing the product of SPR _peak and PHRR by Time to SPR _peak (time to reach SPR _peak ).

In the smoke risk evaluation method of combustible materials in case of fire of the present invention, the larger the smoke growth index-II (SGI-II) value in Equation 2, the higher the smoke risk, and the smoke growth index-II (SGI-II) value It can be judged that the smaller this is, the lower the risk of smoke.

It is predicted that the higher the SGI-II value, the shorter the time to reach the SPR _peak , and the higher the smoke hazard of the material. This goes hand in hand with the increased risk of fire.

In the smoke risk evaluation method of the combustible material in case of fire of the present invention, the PHRR firstly selects the secondary peak value, which is a severe condition, and secondarily, the primary peak value is selected according to the fire pattern of the combustible material You can choose.

Meanwhile, in the smoke hazard evaluation method of combustible materials in case of fire of the present invention, the PHRR may select a primary peak value according to a fire pattern of combustible materials.

In the smoke hazard evaluation method of the combustible material in case of fire of the present invention, the Time to SPR _peak firstly selects the time to reach the second peak value, which is a severe condition, and secondarily the fire pattern of the combustible material Depending on , the time to reach the first peak value can be selected.

Meanwhile, in the smoke hazard evaluation method of the combustible material in case of fire of the present invention, the time to reach the first peak value may be selected as the Time to SPR _peak according to the fire pattern of the combustible material.

In the method for evaluating smoke risk of combustible materials in case of fire of the present invention, the combustible material may be at least one selected from wood, plastic, and fiber, but is not limited thereto.

In the smoke risk evaluation method of the combustible material in case of fire of the present invention, the combustible material may include flame retardancy or be treated with a flame retardant material.

In the fire hazard evaluation method of the combustible material of the present invention, the flame retardant material may include a boron compound, but is not limited thereto.

The boron compound may be at least one selected from the group consisting of boric acid and ammonium pentaborate, but is not limited thereto.

Hereinafter, the present invention will be described in detail through examples. However, these examples are only for explaining the present invention in detail, and the scope of the present invention is not limited by these examples.

<Example>

Conventional building materials and durable materials have suffered great damage to human life due to the generation of toxic gases harmful to the human body and damage to smoke during a fire. Therefore, it was judged that continuous research on the combustion characteristics and fire risk characteristics of various wood and combustible materials was necessary, and the fire risk characteristics of wood were evaluated for some wood materials.

In this embodiment, Japanese ceda, spruce, Lauan, and red pine wood, which are mainly used as building and interior materials, are measured by an external radiant heat source using a cone calorimeter. Smoke related index and harmful gases are measured as combustion characteristics, and new factors such as smoke performance index-II (SPI-II) and smoke growth index-II (SGI-II) are developed. An evaluation index was developed to predict the fire risk in case of wood fire.

<Example 1> Heat release rate (HRR)

The heat release rate controls the characteristics of fire, represents the contribution to the occurrence of fire, and is an important measurement for combustion modeling. The heat release rate is the size of an instantaneous amount of heat generated per sample surface area, and is a factor that best represents the risk of burning of a material.

The main combustion characteristic measured during the test is the heat release rate. If a building material with a low heat release rate is used, a combustion suppression effect can be expected in the event of a fire. Flame combustion with a high rate of heat release causes the fire area to grow and develop, which determines the intensity of the fire.

Table 1 below shows the combustion properties of wood specimens.

1 shows a heat release rate curve of a wood specimen at an external heat flux of 50 kW/m ² , and the heat release rate shows a tendency to suddenly increase and then decrease when all specimens are ignited. During the combustion period, two peaks appear in common: the first peak appears in the first stage of combustion, and the second peak appears before the fire is extinguished.

The first peak occurs before char formation close to the combustion surface. After the first peak, a tendency to decrease was observed in the middle part because the charcoal layer initially formed served as an insulating layer through the thickness and the sample gradually burned due to the insulating effect.

The second peak occurs when the thermal wave reaches the back insulating layer, and due to this back effect, heat is accumulated and a lot of heat is released at the same time.

The peak heat release rate (HRR _peak ) is the size of the instantaneous amount of heat generated per sample surface area, and is the factor that can best represent the combustion hazard of a material. The second maximum heat release characteristics of the four types of wood were 150.49 kW/m ² for cedar, 201.19 kW/m ² for spruce, 248.96 kW/m ² for red pine, and 277.45 kW/m ² for Nawang, respectively. was high.

Nawang showed the highest HRR _{2nd - peak} value, and it was found that the mass loss rate was high at some point, so it burned very quickly, and the momentary combustion risk was also high. The HRR _2nd-peak value tended to increase in proportion to the average density.

In the evaluation of the risk in the early stage of fire, Nawang showed the greatest risk even in the HRR _{1st -peak} area, and cedar appeared to be the least dangerous wood. The higher the average density in the HRR _{2nd -peak} region, the higher the heat accumulation, so the fire risk was higher.

<Example 2> Smoke production

The smoke generation rate over time (SPR) is calculated as the product of the volumetric flow rate of smoke in the exhaust duct and the damping coefficient.

Figure 2 shows the smoke generation rate curve of the wood specimen at an external heat flux of 50 kW/m ² , and the smoke generation rate of cedar showed two peaks at 15 seconds and 275 seconds.

This agrees well with the pyrolysis fraction of most woods. This is a result of the cracking of the wood and the sudden release of combustion gases as more of the surface is exposed to the fire.

The second smoke generation rate (SPR _{2nd -peak} ) of red pine was the highest at 0.0372 m ² /s, which is understood because red pine itself contains a large amount of volatile organic matter. It was 77.1% higher than the second smoke generation rate (SPR _{2nd -peak} ) of cedar, 0.0210 m ² /s, which is understood to be partially related to the volume density of the test piece and the instantaneous smoke production rate of the test piece in the early stage of the fire. .

In this regard, the time to reach the first smoke generation rate was measured as 15 to 25 seconds. Subsequently, the time to reach the secondary smoke generation speed was 275 to 325 seconds, and the time to reach the smoke generation speed was delayed. It is believed that this is because the combustion suppression effect increased as charcoal was generated during combustion.

Since the charcoal formed by burning the test piece has a lower thermal conductivity than wood, it hinders heat penetration into the lower part of the wood. This is considered to have resulted in delaying the burning time because the thermal resistance between the pyrolysis shear and the wood surface exposed to the heat flux increases as the amount of charcoal increases.

The data used, the ignition time and the maximum value of the initial peak of the heat release rate, characterize the fire hazard of the material. In addition, the risk of smoke is expected to be the same. Therefore, in order to predict the smoke safety of combustibles, the inventors devised a smoke performance index (SPI) and previously announced it as Equation 3 below (Patent Document 1 and Appl . Chem . Eng . 29, 670-676). (2018)).

[Equation 3]

The above formula considers two variables, the maximum smoke generation rate and ignition time, in order to evaluate the smoke performance index. However, in the present invention, in order to be more quantitative and precise, the smoke hazard evaluation was implemented by considering the three variables of maximum smoke generation rate, ignition time, and maximum heat release rate.

Therefore, a new smoke performance index-II (SPI-II) is devised and applied. The equation for obtaining the SPI-II is shown in Equation 4 below.

[Equation 4]

That is, SPI-II is defined as a value obtained by dividing SPI by PHRR. Since the fire performance index (FPI) of wood is correlated with the flashover time, just as fire stability increases as the FPI value increases, Smoke safety is also understood to increase.

Equation 4 is understood as a more quantitative and precise expression than previously announced Equation 3. In the present invention, the value of the smoke generation rate is the most severe condition, and the second maximum smoke generation rate (SPR _{2nd -peak} ) value is applied, and the maximum heat release rate (PHRR, kW/m ² ) is also the second peak value (HRR _{2nd -peak)} was applied.

However, for combustible materials including liquid plastics, the first maximum smoke generation rate (SPR _{1st -peak} ) during the combustion process is applied. In the case of the maximum heat release rate (PHRR, kW/m ² ), similarly, the first maximum heat release rate (HRR _{1st -peak} ) value during the combustion process is applied to combustible materials including liquid plastics.

As shown in Table 2 below, the SPI-II of red pine was the lowest at 0.97 s ² /kW, whereas the SPI-II of cedar, spruce, and Nawang was 1.27 to 2.09 s ² /kW, which was 1.31 to 2.15 higher than that of red pine. twice as high

The fire hazard by SPI-II is spruce. Cedar, Nawang, and red pine increased in order. This means that wood containing volatile organic substances, such as red pine, has a low SPI-II, and thus has a high fire risk. In addition, the second heat release rate (HRR _{2nd_peak} ) was applied in the same sense as above for heat release.

In addition, the present inventors have previously reported a smoke growth index (SGI) capable of predicting the smoke hazard of combustible materials as shown in Equation 5 below (Patent Document 1 and Appl . Chem . Eng . 29, 670). -676 (2018)).

[Equation 5]

Equation 5 considers two variables, the maximum smoke generation rate and the time required to reach the maximum smoke generation rate, in order to evaluate the smoke growth index. However, in the present invention, in order to be more quantitative and precise, the smoke hazard evaluation was implemented in consideration of three variables: the maximum smoke generation rate, the time to reach the maximum smoke generation rate, and the maximum heat release rate.

Therefore, as shown in Equation 6 below, a new smoke growth index (SG-II) equation is devised and applied.

[Equation 6]

That is, SGI-II is defined as a value obtained by multiplying SGI by PHRR. The higher the SGI value, the shorter the time to reach the SPR _peak , and it is predicted that the smoke hazard of the material increases, which coincides with the increase of the fire hazard.

Here, the time to reach the second maximum smoke generation speed (TSPR _2nd _ _peak ) was applied in the same way as the calculation of SPI-II. However, as in the case of SPI-II, for combustibles including liquid plastics, the first maximum smoke generation rate (SPR _1st-peak ) and the time to reach it (Time to SPR _{1st _peak} ) are applied during the combustion process.

In addition, in the case of the maximum heat release rate (PHRR, kW/m ² ), similarly, the first maximum heat release rate (1st _- HRR _peak ) is applied to combustible materials including liquid plastic during the combustion process.

At a heat flux of 50 kW/m ² , as shown in FIG. 2 and Table 3 below, SGI-II of cedar was the lowest at 0.011 m ² /s ² . However, spruce, lawang, and red pine had 1.18 to 2.27 times higher than cedar.

The fire risk caused by SGI-II increased in the order of cedar, spruce, lawang, and red pine. In particular, red pine showed the highest SGI-II, and showed a similar tendency to the results obtained from SPI-II.

Therefore, it was found that the higher the value of SGI-II, the higher the fire risk and the lower the fire stability of the wood and combustibles tested in the present invention.

SPI-II and SGI-II are values obtained by calculating using measured data, and can be seen as comprehensive evaluations to determine the smoke safety of materials in cone calorimeter experiments.

<Example 3> Carbon monoxide and carbon dioxide concentration

Carbon monoxide (CO) is a product of incomplete combustion of volatile substances between the wood and the flame. An increase in the heat release rate, which is one measure of the rate of thermal decomposition of volatiles, can be explained by an accompanying increase in the production of CO gas.

CO _mean of Nawang among the test pieces shown in Figure 3 The concentration was 133 ppm, which was 2.3 times higher than the _mean CO concentration of 57 ppm of spruce. As such, all test specimens were found to produce 1.14 to 2.66 times fatal toxicity compared to 50 ppm, which is the permissible exposure limits (PEL) of the US occupational safety and health administration (OSHA).

CO _{2 mean} As shown in FIG. 4, the concentration was 993 to 1626 ppm for all test pieces. It is judged that complete combustion occurs more than incomplete combustion.

These results were lower than the OSHA acceptance criteria (PEL) of 5000 ppm. This is expected to be less likely to cause hyperventilation caused by stimulating the human body's respiration. According to the Mine safety and health administration (MSHA), carbon dioxide causes simple suffocation and is a potential inhalation toxicant.

Although described with reference to the preferred embodiments of the present invention as described above, those skilled in the art with ordinary knowledge in the technical field of the present invention can find this within the scope not departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that various modifications and variations may be made to the invention.

Claims (10)

In the smoke hazard evaluation method of combustible materials in case of fire performed by a computer system,
Determining the smoke risk of combustible materials in case of fire by one or more evaluation indexes selected from the smoke performance index-II (SPI-II) of Equation 1 below and the smoke growth index-II (SGI-II) of Equation 2 below A method for evaluating the smoke hazard of combustible materials in case of fire, comprising the steps of:
[Equation 1]

(In Equation 1, TTI represents the ignition time of the combustible material, SPR _peak represents the peak value of the smoke generation rate, and PHRR represents the maximum heat release rate.)
[Equation 2]

(In Equation 2, SPR _peak is the peak value of the smoke generation rate, PHRR is the maximum heat release rate, and Time to SPR _peak represents the time to reach the SPR _peak .) The method of claim 1, wherein the smoke safety increases as the smoke performance index-II (SPI-II) value of Equation 1 increases, and the smoke safety decreases as the smoke performance index-II (SPI-II) value decreases. A method for evaluating the smoke risk of combustible materials in case of fire, characterized in that it is determined as The method of claim 1, wherein the larger the smoke growth index-II (SGI-II) value of Equation 2, the higher the smoke risk, and the smaller the smoke growth index-II (SGI-II) value is, the lower the smoke risk. A method for evaluating the smoke risk of combustible materials in case of fire, characterized in that for determining. The method of claim 1, wherein the PHRR preferentially selects the second peak value of the maximum heat release rate, which is a severe condition, and selects the first peak value of the maximum heat release rate when the combustible material is liquid plastic,
The first peak value is a value that appears at the first stage, when the peak value of the heat release rate over time during combustion is at the beginning of the fire, and the second peak value is the second peak value when the peak value of the heat release rate over time during combustion is before the fire is extinguished. A method for evaluating smoke risk of combustible materials in case of fire, characterized in that the value appears in the second step. The method of claim 1, wherein the PHRR selects the first peak value of the maximum heat release rate when the inflammable material is liquid plastic, and the first peak value is the peak value of the heat release rate over time during combustion is the initial fire A method for evaluating smoke risk of combustible materials in case of fire, characterized in that the value appears in the first step. The method of claim 1, wherein the time to SPR _peak is to preferentially select the time to reach the second peak value of the smoke generation rate, which is a severe condition, but when the combustible material is liquid plastic, the first peak value of the smoke generation rate Choose the time to reach
The primary peak value is a value that appears at the first stage, when the peak value of the smoke generation rate over time during combustion is the initial stage of the fire, and the secondary peak value is the peak value of the smoke generation rate over time during combustion before the fire is extinguished. A method for evaluating smoke risk of combustible materials in case of fire, characterized in that the value appears in the second step before. The method of claim 1, wherein the Time to SPR _peak selects a time to reach a first peak value of a smoke generation rate when the inflammable material is a liquid plastic, and the first peak value is smoke generation according to time during combustion A method for evaluating smoke risk of combustible materials in case of fire, characterized in that the peak value of the speed is the value that appears in the first stage, which is the initial stage of fire. The method of claim 1, wherein the combustible material is at least one selected from wood, plastic and fiber. The method of claim 1, wherein the combustible material includes flame retardancy or is treated with a flame retardant material. 10. The method of claim 9, wherein the flame retardant material comprises a boron compound.

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