Evaluation of thermal protection performance of civil fireproof clothing based on burning dummyRelease time: 2016-07-26 13:54
At present, scholars at home and abroad have conducted a lot of research on test methods and prediction models of thermal protection performance of fire protection clothing [5-7]. Although traditional textile flame retardant experiments and TPP experiments can evaluate the thermal protection performance of fabrics, they cannot reflect clothing and clothing. The fire resistance of the package as a whole and the degree of protection that can be provided to the wearer, because it ignores the cutting, design and other additional functions of the clothing manufacturing process [8-9]. An objective and comprehensive evaluation of thermal protective clothing should be as realistic as possible Ground simulation of the actual situation of the human body wearing protective clothing in the fire field . The combustion dummy test method uses dummy placed in a fire field environment that can control the heat flow, burning time and flame distribution, and predicts that the human skin will reach the second degree and The location and degree of third-degree burns, so as to evaluate the overall thermal protection performance of clothing. Its biggest feature is that it can quickly, accurately and repeatably simulate the heat exchange between the human body, clothing and the environment under flash conditions . In the 1960s, burning dummy was used to evaluate various thermal protective clothing.In China, the development of the burning dummy system was relatively late. Vertical combustion method and TPP test method to evaluate the thermal protective performance fabrics, restricted the research and development of thermal protective clothing to some extent.
Civil fire protection clothing plays an important role in national fire safety, and excellent thermal protection performance is one of its most important functions. Based on the "Donghua Fireman" combustion dummy system of the Functional Protective Clothing Research Center of Donghua University, this article is for civilian use The overall thermal protection performance of fire protection clothing was evaluated.The effects of factors other than fabrics such as clothing design and structure, and heat shrinkage deformation of the clothing surface on thermal protection performance were analyzed. Relevant factors provide the basis for the optimal design of fire-resistant clothing.
1.1 Samples The test clothing used in this experiment is three sets of civil fireproof clothing of the same material and material produced by an enterprise. The clothing is a long coat, stand collar, and sleeves. A safety belt is provided for easy escape. The outer fabric of the fire protection clothing is aramid 1313, the thermal insulation layer uses thermal insulation cotton, and the TPP value of the fabric combination is 33.8, which is greater than the thermal protection value specified by industry standards. The finished product specifications of the three sets of fire protection clothing are as follows: Table 1.
1.2 Experimental method The test instrument is the "Donghua Fireman" combustion system of Donghua University's Functional Protective Clothing Research Center. This system fully meets the relevant technical indicators of the evaluation of combustion dummy systems such as ISO13506, ASTMF1930. The size of the dummy body is in China. Adult male standard body shape, with 135 heat flow sensors covering the body, head, hands, feet and other parts.It can be used not only for the evaluation of thermal protective clothing, but also for the evaluation of a complete set of thermal protective equipment such as helmets, gloves, and fire boots. Need; In addition, the burning dummy is also equipped with shoulders, elbows, hips, knees and ankles, as well as rotation and sliding systems, which can simulate various postures and activities of the human body .
In the experiment, a fire dummy wearing a fireproof clothing was placed in a laboratory simulated combustion environment and exposed for a certain period of time. 135 thermal sensors distributed on the dummy measured and calculated through the measured clothing and transmitted to various parts of the human body surface. Heat and temperature, predict the human body burns, and evaluate the thermal protection performance of the clothing. The test conditions for the three sets of fire protection clothing are shown in Table 2. Before the experiment, the average heat flow was calibrated to achieve the standard of 84 ± 2kW / m2, The standard deviation is controlled within 21kW / m2. In the experiment, the burning process is recorded by video, and the real-time changes of the clothing during the burning process are observed. The dressing combustion test scene is shown in Figure 1.
In order to quantify the apparent change of clothing after burning, the size of key parts such as collar, body, sleeves of fire protection clothing before and after burning was measured with a soft ruler, and a 5mm diameter circular stamp was stamped on the clothing corresponding to the dummy heat flow sensor. .The seal has imprints in four directions: vertical, horizontal, oblique, and right oblique. After measuring the change in the length of the imprint in each direction after burning, the shrinkage of the clothing in all directions can be obtained. The calculation method of the shrinkage α is shown below. : α = (L-L1) / L × 100% where: L is the length of the mark before burning, cm; L1 is the length of the mark after burning, cm.
Results and discussion
2.1 Evaluation results of the degree of skin burnThe test results of the burning dummy showed that wearing the No. 1 and No. 2 fireproof clothing did not reach the burn level on the dummy surface, while wearing the No. 3 fireproof clothing, a large degree and range of burns appeared on the dummy surface The distribution of burns is shown in Figure 2. The total surface area of the dummy is 1.816m2. When wearing No. 3 clothing, the total ratio of burns on the surface of the dummy is 62.6%, of which the ratio of third-degree burns is 28.0% and the ratio of second-degree burns It was 34.6% (first-degree burns were not included in the burn area statistics). The most severe burns were concentrated in the hips, chest, back, thighs, calves, and head. There was almost no burn on the knee joint covered by the coincident foot cover.
Compared with the test conditions of 3 sets of clothing, the No. 3 fireproof clothing burned for 6s in an environment where 12 flamethrowers work together, and the burning time and area of the flame are significantly larger than the No. 1 and No. 2 clothing. In addition, the wide hem makes the flames It quickly climbed into the clothing, and the flame continued to burn for nearly 10 seconds before extinguishing on the inner surface of the clothing with relatively poor flame retardancy, which caused a large degree of burn on the body surface of the burning dummy when wearing the No. 3 fireproof clothing in the experiment. After using the provincial road to reduce the opening of the hem of No. 1 and No. 2 fire protection clothing, the flames did not penetrate into the fire protection clothing, and the fire protection clothing did not continue to burn. Therefore, the openings in key parts of the clothing were reduced, and the inner material of the clothing was improved. The flame retardant performance is more conducive to improving its thermal protection efficiency. In addition, it is observed that the reflective belt of the clothing chest continues to burn and melt more seriously. Although the clothing meets the relevant requirements in the TPP test, the performance of the reflective belt is not This also shows that the thermal protection performance of clothing is not only related to the performance of the fabric, the style and structure design of clothing, clothing accessories and accessories such as buttons, Velcro, reflective tape, and clothing The use environment is also important to the overall thermal protection performance of the protective clothing.
2.2 Heat shrinkage deformation of clothing
After the burning test of No. 3 garment, obvious shrinkage occurred, and holes appeared in many places, exposing the thermal insulation layer. Because the No. 3 fireproof clothing was severely damaged after burning, it was impossible to accurately measure the size of the key parts of the garment after the burning test. When analyzing the shrinkage deformation of the surface of the clothing after burning, it is mainly aimed at the fireproof clothing of No. 1 and No. 2. According to Table 3, for the clothing of No. 1 and No. 2, the shrinkage of each part of the body after burning is generally greater than the shrinkage of each part of the sleeve. The most shrinkable part of the body is the hip width, which is about 11cm on average, followed by the waist width, and the shrinkage gradually decreases from the hip to the chest. In addition, the total length of the body's longitudinal contraction is also larger, reaching about 7cm. The shrinkage of the outer collar of the No. 1 garment reached 8 cm, which was significantly larger than the shrinkage of the outer collar of the No. 2 garment, which may be related to the experiment in which the No. 1 fireproof clothing was equipped with a fireproof mask. The outer wall of the mask fits tightly, which increases the area where the neutral collar contacts the flame in the combustion experiment. The variance analysis of the size shrinkage of key parts of the No. 1 and No. 2 garments found no significant difference between them, p> 0.05.1 And number 2 The two garments with the same material, style and size are not different.The difference in the shrinkage rate of the garments is not significant, indicating that the heat distribution of the two combustions is consistent, the experimental results are stable, and the repeatability is strong.
According to formula (1), calculate the shrinkage rate of each seal on the garment in the four directions of vertical, horizontal, oblique, and right oblique, and then take the average to obtain the shrinkage rate of the corresponding sensor site on the garment, and its distribution is shown in Figure 3. It can be seen that the frontal shrinkage rate is more than 5% more than the back, and the severely deformed part of the front is lower than the back.The main deformation area on the front is 3cm from the hip line to the knee, and the main deformation area on the back is chest. It is about 3cm below the hip line, which may be related to the distribution of the air layer under the clothing and the amount of heat flow obtained at the part when the dummy is standing. Both the front and back sides of the garment have the largest contraction in the abdomen and hips, and the contraction rate is 15% ~ 20 Take the deformation of the seal on the abdominal hip of the left piece of clothing as an example, the deformation rate of the seal in all directions is obtained, as shown in Table 4. According to the statistical analysis results of SPSS16.0, the same seal part is in the horizontal and vertical directions. There is no significant difference in the deformation rate with the oblique direction, p> 0.05, which indicates that for this experimental clothing, the same part of the experimental clothing shrinks evenly in different directions.
In summary, in the burning dummy test, the main deformation range of the fireproof clothing No. 1 and No. 2 is from the chest to the knee area, and the most severely deformed part is the abdominal hip. The deformation not only affects the structural size of the clothing but also destroys the clothing The integrity of the clothing will reduce the protective ability of the clothing to the human body. When the clothing continues to be exposed to flames, the probability of burns in the area from the dummy's chest to the knee will increase significantly, so the shrinkage and deformation of the clothing surface will also affect the clothing to a certain extent Thermal protection performance.
3. Conclusions <br /> This article uses a combustion dummy to evaluate the overall thermal protection performance of civil fire protection clothing. The results show that the thermal protection performance of clothing depends not only on the thermal protection performance of the fabric, but also on the style and design of the clothing and the accessories. The performance and the environment in which the garment is used are closely related. When wearing the No. 3 garment, the total burn area of the dummy reached 62.6%, and the second- and third-degree burns were concentrated in the abdomen, hips, back and thighs. Numbers 1 and 2 After the hem of the clothing was closed, the flame did not penetrate into the clothing and caused continuous burning. Reducing the openings in key parts of the clothing was more conducive to improving the thermal protection performance of the clothing.
The combustion dummy can be used to quantitatively evaluate the overall thermal protection performance of clothing, predict the location and degree of human skin's second and third degree burns, and the shrinkage deformation of the clothing surface can also reflect the thermal protection effectiveness of clothing to a certain extent. In the test of clothing No. 2 and No. 2, the surface of the dummy was not predicted to be burned, but the chest to sub-knee area showed a large shrinkage deformation, and the abdomen and hips even reached 15% to 20%. Explore the heat shrinkage mechanism of clothing surface and its heat resistance under high temperature The effect of protective performance is of great significance for the research of clothing thermal protection performance.
More about: Burning Dummy
- What are the precautions for purchasing flame retardant fabrics?
- Car safety crash test dummy unemployed
- Human body 3D scanning technology attracts members into the gym
- Interpretation of the characteristics of the spine of a colliding dummy
- Black technology! 3D body scanner can be used for measuring body
- Apple vs. WeChat-Chinese Internet companies
Previous: Previous: Application scope of 3D scanner