Flammability Research Articles

Modified lignin-based intumescent flame Retardant's effect on flame retardancy, mechanical and electrical properties of HDPE material for cable sheathing

High-density polyethylene (HDPE) is a commonly used material for cable sheathing, which is a flammable material. To ensure the safe transportation of electrical energy, it is necessary to enhance the flame-retardant properties of HDPE materials. In this work, ammonium polyphosphate (APP) with lignin (Lig) is used as an intumescent flame retardant, and the flame retardant properties of APP/Lig for HDPE with different ratios are analyzed. It is found that with 3/1 ratio of APP and Lig under 30 wt%, the best flame-retardant performance is achieved. To further improve its properties, chemical modification of Lig with hexachlorocyclotriphosphazene (HCCP) is conducted to introduce nitrogen and phosphorus, obtaining NP-Lig. Flame retardant, mechanical and electrical properties are tested for the prepared material. The flame retardant tests show that the LOI of HDPE is increased from 23.8 to 28.2 by the addition of APP/NP-Lig, compared to that of APP/Lig. Mechanical tests show that replacing Lig with NP-Lig slightly increases the tensile strength and elongation at break of HDPE. Electrical tests show that APP/NP-Lig flame retardant maintains the electrical properties of HDPE under the industry standards.

Investigation of flashover occurrence criterion based on thermal equilibrium theory

Flashover is the rapid transition to a state of total surface involvement in a fire of combustible material within an enclosure fire, which is the most serious and fatal event in building fires. Although previous studies have provided quantitative and qualitative standards for flashover, the criteria of flashover were normally based on the independent measurement of experimental parameters and phenomena rather than the underlying physical reasons, resulting in a lack of mutual relationships between these criteria and the inability to reflect physical mechanisms. Moreover, the flashover criteria vary for different compartment fire fuels, which directly affects the calculation of compartment fire theory. This work was performed to provide a unified principle on the criteria of flashover based on the thermal equilibrium theory. The critical conditions for flashover are quantitatively developed by establishing a partial differential equation for the energy generation rate and energy loss rate with respect to the temperature inside the compartment. Moreover, based on the partial differential equation, inequalities were established for the relationship between the temperature of the hot gas and the heat flux of the floor at the onset of flashover, which was validated by the compartment experiment data. It was found that due to differences in emissivity and net heat transfer rate, at the onset of flashover, the hot gas temperature and the radiation heat flux at the floor were different for different fuels, and a high hot gas temperature does not necessarily indicate a high radiation heat flux at the floor.

Portable Mass Spectrometry for On-site Detection of Hazardous Volatile Organic Compounds via Robotic Extractive Sampling.

Various hazardous volatile organic compounds (VOCs) are frequently released into environments during accidental events that cause many hazards to ecosystems and humans. Therefore, rapid, sensitive, and on-site detection of hazardous VOCs is crucial to understand their compositions, characteristics, and distributions in complex environments. However, manual handling of hazardous VOCs remains a challenging task, because of the inaccessible environments and health risk. In this work, we designed a quadruped robotic sampler to reach different complex environments for capturing trace hazardous VOCs using a needle trap device (NTD) by remote manipulation. The captured samples were rapidly identified by portable mass spectrometry (MS) within minutes. Rapid detection of various hazardous VOCs including toxicants, chemical warfare agents, and burning materials from different environments was successfully achieved using this robot-MS system. On-site detection of 83 typical hazardous VOCs was examined. Acceptable analytical performances including low detection limits (at subng/mL level), good reproducibility (relative standard deviation (RSD) < 20%, n = 6), excellent quantitative ability (R2 > 0.99), and detection speed (within minutes) were also obtained. Our results show that the robot-MS system has excellent performance including safety, controllability, applicability, and robustness under dangerous chemical conditions.

Innovative coating of cotton textile fabrics for integrating outstanding flame hazard safety, UV protection, tensile strength strengthening and antibacterial properties

A rational green synthesis method was developed to produce sustainable nanocoatings for cotton fabrics that are flame retardant, strengthened, antibacterial, and UV protective. The nanocoatings were created using silica nanoparticles with an average size of 73.2 nm derived from rice husk (RH-SNP). These nanoparticles were adorned with ZnONPs with an average size of 7.6 nm, which were reduced and capped with molokhia extract made from molokhia stems by-products. The ultimate nanocomposite was evenly distributed in a chitosan solution using ultrasonication. The mass ratio of RH-SNP in the nanocoating was adjusted and fine-tuned for optimization. The coated cotton fabrics were analyzed using spectroscopic and microscopic techniques. The flammability of cotton fabrics treated with sustainable coatings was assessed. The coated fabrics exhibited significantly greater flame retardancy, achieving a zero burning rate compared to 110 mm/min for the untreated one. The enhanced flame-retardant properties were a result of the combined flame-retardant effects of RH-SNP and molokhia stem extract, along with decorated ZnONPs, which created a more robust protective char layer. The coated cotton's antibacterial characteristics showed significant inhibition of bacterial growth, resulting in a 10 mm distinct inhibition zone, while pure cotton had no inhibition zone. Additionally, the coated cotton fabrics had exceptional UV shielding properties with a UPF rating of 167.8, which was more than fourth the value of the uncoated fabric. The tensile strength and elongation of the cotton fabrics were enhanced after applying a sustainable nanocoating, indicating a beneficial effect on tensile strength. Furthermore, the coated fabrics exhibited exceptional durability characteristics.

Enhanced thermal conductivity of CS/BN/Ti3O5 coatings to promote electron transport for ultra-sensitive fire sensing

Intelligent fire warning system is a crucial protective equipment reduce fire hazards. A recent increasing concern is the development of sensitive fire warning materials that can be integrated with combustible materials to provide real-time alarms in the fire. However, current research on improving the sensitivity of fire warning sensors based on temperature-resistance response focuses on constructing continuous conductive networks. The effect of the heat transfer process is ignored, which limits the further improvement of alarm sensitivity. Here, we developed a strategy to improve thermal conductivity. Based on the chitosan (CS) conductive network in Ti3O5-based fire sensing system, aminated 2D h-BN nanosheets with high temperature resistance and ultrahigh in-plane thermal conductivity were further introduced. The h-BN improves the thermal conductivity of the fire warning coating from 1.43 W/m·K to 2.29 W/m·K. Intelligent fire warning sensors with ultra-sensitivity (1.16 s), low response temperature (170 °C), duration time (12 min) and durability (100 cycles) were successfully prepared by improving thermal conductivity to rapidly transfer heat to Ti3O5, which leads to a rapid decrease in resistance as the core mechanism. This work proposed an ingenious strategy for the construction of high fire safety and thermal conduction fireproof coatings, which revealed enticing prospects in the field of intelligent coatings.

Assessment of a staged and inclined hopper-air injection in enhancing low-NOx combustion and establishing a safe hopper environment for a large-scale arch-fired furnace

In response to the high NO x emissions and hopper overheating problem of a 600-MWe arch-fired furnace, a staged arch-firing framework (SAF) with an upper/lower staged hopper-air pattern was proposed to replace the original low-NO x technique. With implementing such a staged hopper-air configuration to enhance air staging and reduce the downward flame penetration, it was required to (i) affirm the SAF's effectiveness related to the mentioned problems and (ii) assess the upper hopper-air (UHA) angle effect for obtaining a reasonable UHA angle. Accordingly, the in-furnace flow, combustion, and NO x generation were respectively investigated under five UHA angles of θ = 0°, 20°, 30°, 35°, and 40°. Meanwhile, real-furnace tests and simulations in the original furnace were conducted to make comparisons with the SAF furnace. As θ increased, the flame penetration progressively deepened. The primary hopper-air function in favoring char combustion and overall combustion performance first strengthened and then weakened, while the production of CO and NO and combustible matter in fly ash first dropped and then ascended. The setup with θ = 35° demonstrated the most favorable low-NO x performance, exhibiting NO x levels of about 600 mg/m3 (O2 = 6%) and combustible matter of about 5% in fly ash. A comparison before and after the SAF application indicates that, despite reducing downward flame penetration, the SAF bolstered primary combustion and increased air utilization to facilitate char combustion in the hopper and the burnout zone. Consequently, a further 33.5% NO x reduction was achieved, along with slight burnout improvement and notably reduced hopper temperatures.

Utilizing Waste Materials to Enhance Crop Production: A Review

Waste management is a crucial aspect of modern societies, encompassing various activities to ensure the safe and effective disposal of waste materials. It can be classified as hazardous waste, electronic trash (e-waste), industrial waste, and municipal solid waste (MSW). Sustainable waste management practices aim to reduce environmental impact while protecting public health. Urbanization leads to increased residential water consumption, however reusing wastewater for non-potable applications like agriculture can be cost-effective. The overall costs of delivering wastewater for agricultural reuse, including treatment, storage, and transportation, are less the total costs of safe environmental disposal alternatives. Drainage may also be a source of macronutrients (nitrogen, phosphorus, and potassium), which reduces the cost of wastewater for agricultural reuse. The adoption of these principles could lead to a 48% reduction in global greenhouse gas emissions by 2030. The management of hazardous waste, including toxic, flammable, corrosive, or reactive materials, is also a significant concern. In order to safeguard public health and stop the spread of infectious illnesses, animal manure management is crucial. The global generation of construction and demolition waste is expected to double by 2025, with the majority generated in Asia. Sustainable waste management practices are necessary to ensure public health and the environment.

Evaluation of exterior wall cavity fires using an intermediate scale test method

AbstractCavities form an integral part of many external wall systems (EWSs). Numerous external wall fires worldwide have been primarily due to combustible exterior cladding. However, the Grenfell Tower and Knowsley Heights fire incidents (in the UK) are examples where wall cavity materials have impacted fire spread. Wall cavity materials are typically regulated by small‐scale fire test methods which do not necessarily represent the actual fire conditions that can exist within wall cavities. This experimental study proposes an intermediate‐scale test (IST) protocol to examine cavity wall fire behaviour. This protocol is a modified version of the FM Global Cavity Fire Test method (within the FM 4411‐2020 series). The study examines a broad range of cavity materials including sarking, polyester insulation, phenolic foam, PIR, and EPS. A low‐intensity (6–8 kW) and high‐intensity (~80 kW) ignition sources were used to represent two types of cavity fire scenarios. These two fire sizes were shown to differentiate reaction to fire behaviour between these materials and explore the “tipping point” in resulting fire behaviour (which may lie between these two intensities). This proposed cavity fire test protocol provides a suitable “elevated fire risk assessment tool” for combustible cavity materials.

Emissions of Benzо(a)pyrene and Carbon Monoxide from Forest Fires as a Source of Atmospheric Pollution in Cities of the Irkutsk Region

An assessment is made of the release of benz(a)pyrene (B(a)P) and accompanying toxic products of incomplete combustion – carbon monoxide and soot – from forest fires as a source of atmospheric air pollution in cities in the Irkutsk region. Mass gross emissions, t/year, averaged for 2014–2020. of the studied substances in all 33 districts of the Irkutsk region were calculated. The dependences of gross emissions B(a)P are establishedDepends on the indicators of forest fires: the amount, area, mass of burnt plant materials, gross emissions of carbon monoxide and soot. The conclusion is made about the pollution of the atmospheric air of cities with carcinogenic B(a)P and toxic carbon monoxide from forest fire emissions.

A novel unmanned aerial vehicle driven real-time situation awareness for fire accidents in chemical tank farms

A large number of flammable hazardous materials are stored in chemical tank farms, where fire-induced domino accidents can be easily triggered. In this study, a novel real-time fire situation awareness (FSA) approach based on UAV is proposed to capture spatio-temporal evolution characteristics and predict development trends of fire accidents. Firstly, fire images are acquired by UAV, and the key parameters of fire are extracted in real time based on YOLOv8 network. Then, the thermal radiation and impact on surrounding equipment are predicted by combining LSTM network, solid flame model and improved probit model. The proposed method is verified by small-scale tank fire experiments, which demonstrate its superiority in terms of physical consistency and prediction accuracy. The results show that the mean absolute percentage error (MAPE) of fire parameter extraction is not higher than 5.43%, the MAPE of thermal radiation prediction is not higher than 25%, and the dynamic time to failure (dttf) for the model tank at different location is predicted. This work has the potential to provide a novel solution for real-time assessment of fire size and trend prediction to support firefighting, emergency rescue and decision making in fire accident scenarios.

Fire Dynamics and Evacuation Simulation Study on the Library Adapting BIPV Based on the Experimental Data of a Cone Calorimeter

A building integrated photovoltaic (BIPV) system can function as a solar cell and as a building exterior material. As some of its components are made of combustible materials, it is necessary to evaluate the risk of fire. In this study, the risk of fire before and after BIPV installation was compared through fire simulation using the PyroSim program. Prior to the simulation, a BIPV combustion characteristic database was established via a cone calorimeter experiment with a BIPV system panel, and the results were analyzed through a fire simulation using these experimental values as input values. The fire risk evaluation confirmed that when BIPV was installed, the fire propagation due to vertical diffusion was fast. Additionally, the amount of heat and smoke emitted increased, resulting in an increase in the risk of fire by 54.94% based on the center of the building at 805 s. Therefore, it is expected that the results of this study will contribute to securing the reliability of evacuation and manual measures for people in BIPV-installed buildings as well as improve fire safety.

Dynamic Data-driven Research on Forest Fire Behavior Overview

In recent years, under the combined effects of climate change and El Niño, extreme weather has been occurring frequently, and natural disasters of all kinds have been increasing. Forest fire is the first of the three major natural disasters in forests, to reduce the possibility of starting forest fires, reduce the damage caused by forest fire disasters, as well as to predict the development trend of forest fires and fight them scientifically, we should systematically and scientifically grasp the law of forest fire occurrence and development. This paper analyses the various influencing factors affecting the behavior of forest fires and classifies meteorological factors and the moisture content of combustible materials as dynamic factors, and topographical factors and other factors of combustible materials except moisture content as slow-change factors. The research on dynamic data-driven forest fire behavior in recent years is reviewed, the advantages of dynamic data-driven technology for simulating fires are analyzed, the constraints of the technology are indicated, and the future development trend is shown.

3PL Fire and Safety Hazard Assessment and Mitigation

3PL facilities, handling high volumes of goods, face unique fire and safety risks. This abstract explores assessing and mitigating these hazards. Common fire hazards include flammable materials, electrical issues, and improper storage. Safety hazards encompass slips, falls, and misuse of machinery. Assessment techniques involve inspections, reviewing safety data sheets, and analyzing incidents. Mitigation strategies focus on fire safety plans, proper storage, electrical safety, and employee training. The abstract emphasizes preventative maintenance and a culture of safety for a safer 3PL environment.

Improving fire safety of thermoplastic poly(ether ester) elastomer by black phosphorus nanosheets and aluminum diethylphosphinate system

AbstractThermoplastic poly(ether ester) elastomer (TPEE) is a highly flammable material with severe melt‐dropping, which greatly limits its range of applications. Here, black phosphorus nanosheets (BPs) and aluminum diethylphosphinate (ADP) were used to improve the fire safety of TPEE for the first time. Results demonstrated that ADP/BPs as a synergistic combination exhibits good dispersity and excellent flame retardancy, also has minimal negative effects on the mechanical performances of the TPEE composites. By comparing TPEE/ADP‐22 and TPEE/ADP‐10/BPs‐4, the introduction of BPs significantly reduced the addition of ADP while keeping the material at the higher vertical burning grade, ~54.5% reduction in ADP usage. Compared with neat TPEE, TPEE/ADP‐10/BPs‐4 fulfilled V‐0 level, avoided dripping, and the limiting oxygen index value increased to 34.0%. Moreover, TPEE/ADP‐10/BPs‐4 performed the best in cone calorimetry test, both the peak heat release rate and total heat release reduced the largest, by 44.2% and 25.3%, respectively. The detailed studies of the flame‐retardant mechanism found that ADP/BPs showed the fire‐retardant impact of the condensed phase and gaseous phase. This work expands BPs in the flame‐retardant application and could facilitate to prepare the anti‐dripping flame‐resistant TPEE.Highlights BPs as an efficient flame retardant were added into TPEE for the first time. ADP/BPs as a synergistic combination has an excellent fire‐retardant effect. The introduction of BPs significantly reduced the addition of ADP. TPEE/ADP‐10/BPs‐4 showed the highest FPI and the lowest FGI. ADP/BPs has lowest negative effects on the mechanical performances of matrix.

Integrating Real-Time Meteorological Conditions into a Novel Fire Spread Model for Grasslands

Accurate comprehension of grassland fires is imperative for maintaining ecological stability. In this study, we propose a novel fire model that incorporates real-time meteorological conditions. Our methodology integrates key meteorological factors including relative humidity, temperature, degree of solidification of combustible materials, and wind speed. These factors are embedded into a comprehensive function that determines both the downwind and upwind spreading speeds of the fire. Additionally, the model accommodates fire spread in the absence of wind by incorporating the direction perpendicular to the wind, with wind speed set to zero. By precisely determining wind speed, the model enables real-time calculation of fire spread speeds in all directions. Under stable wind conditions, the fire spread area typically adopts an elliptical shape. Leveraging ellipse properties, we define the aspect ratio as a function related to wind speed. Consequently, with knowledge of the fire duration, the model accurately estimates the area of fire spread. Our findings demonstrate the effectiveness of this model in predicting and evaluating fires in the Hulunbuir Grassland. The model offers an innovative method for quantifying grassland fires, contributing significantly to the understanding and management of grassland ecosystems.

Historical charcoal production as a factor in soil cover heterogeneity in a fluvioglacial landscape − A case study from northern Poland

Although in situ wood thermal processing, as a common practice in European forests in historical times, has been confirmed in many studies, the environmental implications of that process remain poorly explored. In this study, we focused on evaluating the impact of that process on forest vegetation and soil cover heterogeneity in a fluvioglacial landscape dominated by Brunic Arenosols. This study covered three 70–95-year-old stands of Scots pine in northern Poland. Three soil profiles, including from the relict charcoal hearth (RCH), from the surrounding ditch and a control, were examined from each stand, as well as associated vegetation. The studies showed that 19th century charcoal production platforms were overgrown with 20–60% fewer plant species than control stands. The effect on soils varied according to their characteristics. The presence of anthropogenic horizons consisting of a mixture of burnt soil material, ashes, charcoal particles, and other products of wood pyrolysis was the most distinguishing feature of RCH soils classified as Spolic Technosols (Arenic, Dystric, Pyric, Protospodic, Transportic). Typically, these horizons were characterised by lower bulk density, and higher porosity, as well as higher contents of total organic carbon, nitrogen, and exchange cations than the control soils. The differences between the RCH and control soils were highlighted by a comparison between the pools of the components in a soil column (pedon). Clear tendencies were not recorded for pH, the phosphorus content and stocks, the forms of iron and aluminium, the saturation of the soil sorption complex with bases or the trophic index. This may be due to the long-term neutralising effect of forest vegetation, dominated by Scots pine. Moreover, the results of our study may indicate the problem of toxicity of the RCH soils, which should be undertaken, considering the utilitarian importance of the issue.

Synergistic effects of Reflux Flotation Cell's downcomer and reverse fluidization bed in rejecting clay entrainment during particle separation

The Reflux Flotation Cell (RFC) technology is heralded as an innovative game-changer, promising significant advancements in particle separation, and offering generational benefits for the resources industry. This paper meticulously assessed the RFC's capabilities in tackling another critical industry challenge in resources processing— severe entrainment of waste clay particles during flotation separation and compared the performance with conventional mechanical flotation. Through flotation tests where kaolinite particles were separated from combustible materials, in-situ particle aggregation measurements and calculating air fractions in both flotation systems, this study identified the superior performance of the RFC in reducing kaolinite entrainment and producing a high product quality. This was attributed to a synergistic function between the RFC's downcomer for kaolinite dispersion and the RFC's fluidization bed for generating a low air fraction in reducing kaolinite entrainment. While kaolinite dispersion avoided the blocking of water drainage channels between air bubbles by aggregates, a low air fraction ensured a large gap between air bubbles to allow the displacement of entrained fine particles with fluidization water. Herein, the research findings will guide the resources industry to process low quality resources by successfully rejecting clay and other fine waste materials.

Use of a high-entropy oxide as an oxygen carrier for chemical looping

One mixed oxide with 5 cations in equimolar proportions in the sublattice, to fulfil high-entropy oxide (HEO) criteria, has been developed and investigated as oxygen carrier for chemical looping combustion processes. As far as we know, nobody has explored this class of material for chemical looping combustion. Material is prepared by direct mixing of five metal oxides (CuO, Mn2O3, Fe2O3, TiO2, MgO), followed by calcination at 1000, 1100 and 1200 °C for 6 h in air. XRD characterization provides strong evidence that the synthesized oxygen carriers possess the hallmark properties of HEO, and SEM-EDX analysis shows an overall homogeneous metal distribution. Materials have one main cubic phase with the empirical formula MnCuMgFeTiO7, dominating under all conditions. One of the key objectives of this study is achieved, reduce chemical stress during redox cycles. Oxygen transfer capability is investigated by thermogravimetric analysis and batch fluidized bed reactor experiments for different fuels and atmospheres. Mass-based oxygen transport capacities for lattice oxygen and oxygen uncoupling are around 5.5 wt% and 1.1 wt%, respectively. This work opens up a new dimension for the future preparation of oxygen carriers for chemical looping processes, since the vast compositional space of HEO provides opportunities to tune both chemical and physical characteristics.

Quantitative classification of equipment protection level in concept of zone classification with downtime of protective measures

Handling flammable materials has a risk that can create explosive atmosphere. Such locations are classified as hazardous area, depending on the frequency and volume of explosive atmospheres. General electrical equipment is prohibited in the hazardous area and explosion protected equipment is used. These are the spatial isolation of ignition sources within the fire triangle, but even time isolation can prevent explosion hazards as well. It is proposed a method to classify zones from the calculation of downtime of protective measures based on failure rates and repair times of protective measures related to ventilation in explosive gas atmospheres with the Functional Safety under the time isolation concept. On the other hand, according to International Electrotechnical Commission (IEC) System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres, explosion protected equipment was also classified as an Equipment Protection Level, "EPL". The EPL should be selected according to the risk of the hazardous area. However, in IEC60079–14:2013, users can choose any EPL according to their risk assessment. In this paper, we clarify the quantitative risk difference of EPLs with expansion the idea of classifying hazardous area from the downtime of protective measures and introduce a means to quantitatively classify the EPL of equipment in an explosive gas atmosphere.

In the shadow of the Lammermuirs

Wessex Archaeology completed archaeological investigations on the Onshore Transmission Works for the Neart na Gaoithe Offshore Wind Farm between 2015 and 2021. These included geophysical survey, evaluation trenching, targeted strip, map and sample excavations, and watching briefs on the cable route and associated infrastructure between the landfall at Thorntonloch and the grid connection at Crystal Rig II Wind Farm, both in East Lothian. The investigations found that few archaeological features were present within the section of the cable route within the coastal plain between Thorntonloch and Innerwick, and within the upland area approaching Crystal Rig (excluding the medieval township of Boonslie). Features relating to a wide range of periods, dominated by the prehistoric, were found within the transitional zone to the south-west of Innerwick between the Lammermuir foothills and the coastal plain. These included an Early Neolithic pit cluster and possible trackway, pits dated to the Late Neolithic and Early Bronze Age, and a Late Bronze Age/Early Iron Age pit alignment. Within the immediate area of the pit alignment there was also evidence for later Iron Age and early medieval occupation. The cable route was designed to avoid the extant remains of Boonslie, an upland medieval township around the headwaters of the Boonslie Burn, but some previously undetected earthworks were uncovered and investigated, as well as the earliest dated feature found in the works: a pit containing burnt material dating to the Mesolithic. The excavations also uncovered evidence for the deliberate landscaping of agricultural fields during the post-medieval and modern period to give a greater area of cultivatable terrain.