Fire-Retardant Clothing Research in Combustion Laboratories

In this article, you’ll find a guide on the testing methods for fire-retardant protective clothing in combustion laboratories. You’ll also learn about the roles a combustion laboratory and a manikin system play in simulating a real burning environment. In a combustion lab, utilizing the data obtained, you can assess second and third-degree burns on the manikin’s surface and develop protective clothing with improved fire-retardant capabilities.

Fire-Retardant Clothing Research

The Importance of Fire-Retardant Clothing

The ability of humans to protect themselves from fire is an important sign of civilization’s progress. Fire-retardant protective clothing refers to clothing that can prevent itself from being ignited, flame burning, and smoking when in contact with fire and hot objects. In the fight against fire, firefighters are the most important force, and fire-retardant protective clothing is one of the most important pieces of protective equipment for firefighters. On the battlefield, high-performance fire-retardant protective clothing and equipment are a strong guarantee for individual survival and combat effectiveness. According to battlefield burn research reports, in the smoke-filled battlefield, the number of people burned by warfires accounts for about one-quarter of the total casualties. When a soldier has 11-30% of their total body area with second-degree burns or 10% with third-degree burns, they lose their combat effectiveness.

The Importance of assessing the actual burning environment and its impact on individuals

Scientifically evaluating and testing the protective performance of fire-retardant protective clothing and equipment is crucial for the rational design and selection of protective gear. When designing protective clothing, it is not comprehensive to solely pursue resistance. Bulky protective gear can hinder quick escape in a fire. Therefore, flexibility is also one of the key considerations for protective clothing. To achieve this, you need to assess the actual burning environment and its impact on human beings. Only when you know the actual burn conditions of human skin in different areas during a fire can you design protective clothing (military uniforms, fireproof suits, firefighter gear, and fire-retardant high-temperature workwear) that effectively guards against burns in each specific part. This way, you can combine optimal resistance and mobility in the protective gear.

The main testing methods for flame-retardant protective clothing

Vertical Flammability Test:

This test involves burning a 12-inch long fabric strip under a propane flame for 12 seconds, then removing the flame and measuring the after-flame time, flame-retardant time, and the char length of the fabric strip. This method directly measures the flame retardance of the material. However, it only indicates whether the tested fabric can withstand burning; it does not provide information on the fabric’s thermal resistance to flames or electric arcs, nor does it represent the material’s protective capability against skin burns in high-temperature environments.

TPP Test:

This test places a 6-inch square fabric sample under a total energy source of 2 cal/(cm².s) of convective and radiant heat and then records the time required to reach a second-degree burn. The TPP value is calculated by multiplying this time by the energy of the heat source in cal/(cm².s). The higher the TPP value, the greater the protective performance of the fabric against high-temperature and high-heat flames. This method is suitable for multi-layer thermal protective materials, and the TPP result is a key indicator of the garment’s thermal protection performance. However, the TPP value cannot provide a quantitative estimate of the predicted burn severity. The thermal protection performance of materials that ignite and burn cannot be accurately evaluated using TPP, as ongoing burning can cause additional damage.

Manikin Test in a Combustion Lab:

This involves a 6-inch tall human model made of special fiberglass, equipped with temperature sensors, dressed in fireproof clothing, and exposed to 2 cal/(cm².s) of heat from a propane flame thrower. A computer uses data from the temperature sensors to simulate the potential second and third-degree burn degrees and areas on human skin, providing a test report.

The Manikin Test technology is internationally recognized as the best objective evaluation of the overall thermal protection performance of clothing. It is at the forefront of interdisciplinary technologies combining clothing science, combustion engineering, and biophysics. The Manikin Test system can accurately perceive high-temperature heat flow in different postures and precisely predict skin burn severity. It also allows for the creation of highly realistic simulation environments for dangerous fire scenarios. The system can be used for evaluating and researching the fire-retardant performance of various protective gear like firefighting and military uniforms, speeding up the development cycle of new fire-retardant materials and equipment, and promoting the development of individual protective equipment. Additionally, the Manikin Test system in a combustion lab provides valuable data for biophysical research on human skin tissue burn analysis, and its use extends beyond military applications to the development of thermal protective fabrics, clothing, and other equipment in civilian contexts, playing a significant role in protecting against thermal injuries caused by fires and thermal radiation.

Burn Manikin Research History, Status, and Development Trends

The study of the Manikin Project originated in the 1960s. In 1962, the U.S. Navy, in conjunction with DuPont, developed the ‘THERMO-MAN’, a manikin used for burn testing. This manikin was controlled by a computer to conduct experiments, record data, analyze results, and create human body diagrams of the anterior and posterior burn areas and their extent. This essentially achieved the expected functionality of a burn manikin.

In the 1980s, the University of Minnesota also built a manikin for clothing flammability tests. This manikin was equipped with 44 thermocouple sensors to predict the extent and areas of skin burns by measuring temperature. The ignition method involved a set of gas flames igniting the lower edge of the test clothing worn by the manikin. However, this gas flame could not fully engulf the manikin, thus failing to simulate various sudden intense fires.

By the late 1980s, the University of Alberta in Canada successfully developed a manikin named ‘Pyroman’, equipped with 110 heat flux sensors on its surface. This manikin and the sudden burning flame system are similar to the U.S. military’s manikin system. Six burners installed around the manikin ignite, completely engulfing it in flames produced by propane gas. A computer-controlled data acquisition system records and stores data from the sensors, calculating potential skin damage, i.e., the percentages of second and third-degree burns relative to the total body area, and prints out the results.

Switzerland, Japan, and other countries have also developed second-generation ‘Firefighter Manikins’ that collect data closer to real battle conditions, simulating the special environment of firefighting operations and improving the accuracy of tests and experimental results.

 

Combustion Laboratory Testing System by DaRong

Darong Textile Instruments, a leader in the textile testing industry, has successfully developed and put into use:

Scope of Application:

The combustion testing system simulates a clothed human (manikin) in a burning flame, testing changes in the surface temperature of the manikin, and estimating potential second and third-degree burns and the total percentage of burn area, accurately predicting the degree of skin burns. In a high-fidelity simulated fire environment laboratory, the manikin testing system can conduct evaluations of the flame-retardant performance of various protective gear like firefighting and military uniforms and study influencing factors.

Relevant Standards:

ASTM F1930-2000

ISO 13506-2008

GB/T 23467-2009

Technical Parameters:

Combustion Lab System

The laboratory uses an integrated fireproof structure, made of metal frames and fire-retardant materials.

Effective size: 4×4×3m (requires at least 4m height and 50m² floor space).

Ventilation and exhaust system with a pre-designed fan that automatically adjusts airflow for ventilation and exhaust, ensuring indoor air and oxygen supply during tests and quickly expelling waste gas after combustion, followed by cooling air replenishment.

Combustion Generation and Safety Control System

Burners: 6 sets of 12 burners.

Gas delivery system with propane gas pipes, pressure regulating valves, valves, and pressure sensors for transporting gaseous propane to the ignition system and burner heads. This system provides a consistent heat flux density of at least 84KW/m², with a fuel delivery time error of ±0.1S.

The safety system includes gas detectors, door seal detectors, flame detectors, gas pressure monitoring, fire extinguishers, emergency stop devices, safety guide flames, residual gas treatment devices, and other necessary safety systems.

Manikin System

The manikin is modeled after an adult male with a height of 1.8 meters, including head, chest, back, abdomen, arms, hands, legs, feet, etc. The outer shell is made of non-metallic materials with excellent fire and thermal stability (customizable specifications).

Adjustable joints for various postures to meet specific testing needs (only for the DR666-40RC model).

Heat flux sensors are installed on the model surface to accurately test temperature changes. The DR666-40R model has 130 sensors, while the DR666-40RC model has 146 sensors (including independent head and hand test areas).

Computer-Controlled System and Application Software Platform

Utilizes in-house developed software for full computer control of the experiment process, with data collection and analysis completed automatically by the computer.

Result Assessment

The burn assessment module is designed to evaluate the extent and severity of burns caused by flames. The information about the changes in the surface temperature of the manikin over time, obtained from sensors, is input into the burn assessment model. After the burn assessment calculation, the burn score and the degree of burn severity are obtained. Combined with the digital human body model’s mapping, this results in a distribution map of second and third-degree burns on the surface of the manikin.

burn manikin

Conclusion:

The assessment of the degree of burns on different parts of the human body, conducted using a burning manikin in combustion laboratories, has played a milestone role in the development of fire-retardant protective clothing. The laboratory simulations of various real-world scenarios have provided invaluable data for research and development. You can imagine, that with the increasing prevalence and advancement of smart technologies, there will be a focus on developing intelligent protective equipment capable of automatic alerts and firefighting. In this context, combustion laboratories and burning manikins will take on even more significant responsibilities.

FAQ:

Q: When choosing a flame retardant testing method, what you need to consier?

A: First, the primary function of the protective clothing being developed must be taken into account. Additionally, the availability and cost of materials should be considered. The experimental site is also a necessary factor to consider. Based on these, the best method should be selected from three fire-retardant testing methods.

Q: Do combustion laboratories have other application scenarios?

A: They can also test the flame retardancy of buildings and furniture, as well as the development of fireproof materials other than clothing fabrics, such as fire extinguishing agents, fireproof coatings, and so on.

Related Resources

What is Fire-Retardant?

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