Synergistic fire-retardancy properties of melamine coated ammonium poly(phosphate) in combination with rod-like mineral filler attapulgite for polymer-modified bitumen roofing membranes

A novel intumescent (carbonization, acid donor and foaming) fire retardant that mimics carbon nanotubes was introduced into bitumen roofing and characterized using cone calorimetry as the main analytical tool. The experimental results indicate that 18% (by mass) attapulgite mineral (ATTP) mixed with base bitumen decreased the peak heat release rate per unit area (pHRRPUA) by 10%. Further, incorporation of melamine coated ammonium polyphosphate (MAPP) decreased the pHRRPUA by 52% and a mixture of these (3:1, ATTP:MAPP) decreased the pHRRPUA by 25% as compared to adding CaCO₃ as a filler. The residual mass loss after the cone test was also improved with up to 3%. The indication of a positive synergistic flame retardant effect of the ATTP-MAPP mixture is supported by thermogravimetric analysis. The addition of this rod-like mineral improved the general fire retardant properties of the base bitumen and increased the viscosity. Therefore, the polymer-modified bitumen with both fire retardant and rheological properties (providing mechanical strength) is a promising novel approach in the design of bitumen roofing membranes.     

Identifying Community Fire Hazards from Citizen Communication by Applying Transfer Learning and Machine Learning Techniques

Fire Technology - A cross-region transfer learning method is proposed to identify community (e.g. car parks, public spaces and shopping centers) fire hazards based on text input provided by...     

Firefighter Nozzle Reaction

Nozzle reaction and hose tension are analyzed using conservation of fluid momentum and assuming steady, inviscid flow and a flexible hose in frictionless contact with the ground. An expression that is independent of the bend angle is derived for the hose tension. If this tension is exceeded owing to anchor forces, the hose becomes straight. The nozzle reaction is found to equal the jet momentum flow rate, and it does not change when an elbow connects the hose to the nozzle. A forward force must be exerted by a firefighter or another anchor that matches the forward force that the jet would exert on a perpendicular wall. Three reaction expressions are derived, allowing it to be determined in terms of hose diameter, jet diameter, flow rate, and static pressure upstream of the nozzle. The nozzle reaction predictions used by the fire service are 56% to 90% of those obtained here for typical firefighting hand lines. Sharing these findings with the fire protection community can improve the safety of firefighters.     

Experimental Study on the Burning Behavior of Pool Fires in Rooms with Different Wall Linings

An experimental test series, comprising 10 experiments with varying pool sizes, lining materials and amounts of liquid burning, was conducted under free burn and room burn conditions. The thermal feedback from the enclosure (ISO 9705 Room Corner Test facility) enhanced the burning rate of the pools and resulted in a thermal runaway in some of the runs. The onset of the thermal runaway, which can be associated with flashover, varied with all the input parameters. The lining with the lowest thermal inertia lead to the fastest increase in the heat release rate (HRR) in the enclosure and caused flashover in the shortest time. Given the profound difference between the enclosure tests and the free burn tests and also between enclosure tests with different linings, it is recommended to show great caution if free burn tests are to be used in design fire scenarios.     

Fire‐induced reradiation underneath photovoltaic arrays on flat roofs

The impact of the reflection of fire‐induced heat from a gas burner was studied experimentally to gain knowledge on the interaction between photovoltaic (PV) panels and a fire on flat roofs. The heat flux was measured in a total of eight points at the same level as the top of the gas burner. The gas burner was placed underneath the center of a PV panel, installed in a geometry similar to a commercial east‐west orientated mounting system, and the eight points were symmetrical pairs of two at four different distances from the burner. Measurements were compared with tests with no PV panel, and thereby without the reflection from the PV panel. A significant increase of the received heat flux was recorded, with ascending percentage‐wise difference for increased heat release rates. This indicates that PV panels can have a significant contribution in roof fires, primarily because they stimulate fire spread over the roof on which they have been mounted. The received heat flux is higher underneath the most elevated part of the PV panel, due to two important, flame‐related reasons: 1) the flame deflection toward the most elevated part of the panel and 2) a nonhomogeneous temperature distribution on the PV panel surface, due to the deflected flame, and thereby a nonhomogeneous emission from the heated PV panel. Finally, the results were very similar for a brand new PV panel and a PV panel tested for the fourth time, except during the period when the thin combustible film underneath the new PV panel is burning, supporting that it is the fire dynamics and not the fire load associated with the PV panels that is promoting fire spread associated with PV panels on flat roofs. With this in mind, the current results are relevant not only for PV panels but also for any inclined roof covering panel with limited combustibility.     

Fire Performance of Sandwich Panels in a Modified ISO 13784-1 Small Room Test: The Influence of Increased Fire Load for Different Insulation Materials

Four sandwich panel rooms were constructed as prescribed in the ISO 13784-1 test. However, the construction followed normal industry practice, and the panels were also subjected to the kinds of damage typically found in commercial premises, although such damage may not typically be concentrated in such a small room. The fire load was increased to simulate fires actually occurring in commercial premises by stepping up the propane burner output from the usual maximum of 300–600 kW, and by placing a substantial wooden crib in two of the rooms. The results showed significant differences in fire growth rate and burning behaviour between those panels filled with polyisocyanurate (PIR) and those filled with stone wool in both the experiments without and with the wooden crib. Most significantly, the PIR pyrolysis products caused earlier ignition (by radiation from above) of the wooden crib 11 min into the experiment (1 min after the burner was stepped up to 300 kW), whereas the crib ignited 22 min into the test (2 min after the burner had been stepped up to 600 kW, which is beyond the test standard both in time and heat input) for the stone wool panels. This interaction between building and contents is most often ignored in fire safety assessments. After a few minutes, the PIR pyrolysis products that escaped outside the room, from between the panels, ignited. The extra thermal exposure from the PIR-fuelled flames distorted the panels, which in turn exposed more PIR, resulting in large flames on both the inside and outside of the enclosure. From a fire safety perspective this is most important as it shows that with the large fire loads that are commonly found in commercial premises, steel-faced PIR filled panels are not capable of acting as fire barriers, and may support flame spread through compartment walls and ceilings. In addition, the PIR panelled rooms produced very large quantities of dense smoke and toxic effluents, whereas the stone wool panelled rooms produced small amounts of light smoke of lower toxicity. Furthermore, the experiments showed that modifications to the standard test can lead to extremely different outcomes for some of the products. As the modifications simulated real-life situations, it seems important to discuss whether the standard is robust enough for property safety scenarios encountered in industrial premises.     

Critical radius for sustained propagation of spark-ignited spherical flames

An experimental study was performed to determine the requirements for sustained propagation of spark-ignited hydrogen-air and butane-air flames at atmospheric and elevated pressures. Results show that sustained propagation is always possible for mixtures whose Lewis number is less than unity, as long as a flame can be initially established. However, for mixtures whose Lewis number is greater than unity, sustained propagation depends on whether the initially ignited flame can attain a minimum radius. This minimum radius was determined for mixtures of different equivalence ratios and pressures, and was found to agree moderately well with the theoretically predicted critical radius beyond which there is no solution for the adiabatic, quasi-steady propagation of the spherical flame. The essential roles of pressure, detailed chemistry, and the need to use local values in the quantitative evaluation of the flame response parameters are emphasized.     

Evaluation of the Onset of Flashover in Room Fire Experiments

Two series of full scale room fire tests comprising 16 experiments are used for a study of the onset of flashover. The fire loads were varied and represented seven different commercial applications and two non-combustible linings with significantly different thermal inertia were used. The test results showed that by lowering the thermal inertia and thereby lowering the heat loss from the room and at the same time increasing the thermal feedback, a thermal runaway occurred before significant fire spread; but only for objects composed of a mixture of plastic/rubber/textiles and wood/celluloses. In these cases the onset of thermal runaway was found to occur at room temperatures in the range 300°C to 420°C, supporting that the room temperature at the onset of thermal runaway is strongly dependent on the thermal inertia. It also shows that the onset of thermal runaway cannot in all cases implicitly be predicted by the traditional flashover temperature criterion of 500°C to 600°C. For fire loads composed of pure wood/celluloses the onset of flashover occurred about the same time as fire spread irrespectively of linings and at significantly higher room temperatures (725°C). This can be explained by flammability parameters making wood/celluloses less sensitive to thermal feedback.     

Experimental Study of the Fire Dynamics in a Semi-enclosure Formed by Photovoltaic (PV) Installations on Flat Roof Constructions

Fire Technology - Flame spread experiments upon a BROOF(t4) compliant flat roof mock-up located below a vertical barrier were carried out for variations in gap height, inclination, subjacent...