| 1. |
- Eidissen Jensen, Ulla, et al.
(författare)
-
The effect of fire retardants on smouldering fires in loose fill wood fibre building insulation
- 2017
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Building insulation products produced from renewable biomass is becoming increasingly common in buildings due to environmental lifecycle requirements. Biomass insulation products are combustible and can contribute to fires through flaming and smouldering combustion. Incidents have been reported where insufficient spacing between combustible insulation and heat-producing electrical appliances has led to smouldering and subsequent development of flaming fires. Insulation materials often contain fire retardants, though their performance with regard to smouldering fire is not well understood. [1, 2] This study investigates the temperature exposure needed to initiate self-sustaining smouldering fires in loose fill wood fibre building insulation, focusing on the effect of fire retardant content and fibre size. The study is a part of the EMRIS (Emerging Risks from Smoldering Fires) project. The test set-up is shown in Fig 1a [3]. The tested material was 100 grams, 34 kg/m3 spruce wood fibre loose-fill insulation with 4 and 9 % added ammonium polyphosphate fire retardant. Tests with short, fine fibres (Fig 1b) were compared to testst with long, thin fibres. The sample was heated from below until a given temperature was obtained 20 mm above the heater. Temperature and mass loss measurements as well as visual observations of the residue after test (Fig 1c) were used to characterize the onset of self-sustained smouldering. An iterative process was used, with 5 to 8 tests per product. It was found that a high level (9 %) of fire retardant gave an onset of smoldering at lower temperatures (225 °C) compared to a low level (4 %) of fire retardant (290 °C). The lower onset temperature indicates that the insulation with the highest fire retardant content is more prone to smouldering, which is contradictory to the expected performance of the fire retardant. For the same fire retardant content, the onset of self-sustained smouldering combustion was obtained at lower temperatures in insulation materials with smaller fiber sizes than in insulation with larger fiber size (225 vs 280 °C). This study is indicative, the absolute temperatures relate to the given test set-up. Further studies should include a range of fire retardant types and content, to obtain knowledge on their effect on smouldering fires.
|
|
| 2. |
- Fjellgaard Mikalsen, Ragni, et al.
(författare)
-
Extinguishing smoldering fires in wood pellets through cooling
- 2017
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Extinguishing smoldering fires is a severe challenge for fire brigades, and has proven to be difficult even on the lab scale. In this study, the influence of a closed water cooling loop located within the fuel bed was investigated experimentally. Increasing the cooling led to a system less prone to intense combustion at an early stage, and eventually to complete extinguishment of self-sustained smoldering fires. Extinguishment was obtained in half of the cases with maximum cooling. Extinguishment occurred soon after smoldering had been established, giving a significant reduction in fuel consumption compared to the self-sustained smoldering fires that continued to complete burn-out.
|
|
| 3. |
- Fjellgaard Mikalsen, Ragni, et al.
(författare)
-
Smoldering combustion- from pulsations to extinguishment
- 2017
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Smoldering is known as a slow, but unpredictable form of combustion. In this study we have looked at how smoldering is affected by water cooling of the fuel bed without direct contact between fuel and water flow. The study is a part of the EMRIS project, and its findings have possible implications for preventing and suppressing fires in industrial storage units.
|
|
| 4. |
- Valdés, Virginia, et al.
(författare)
-
Smouldering fires in wood pellets: the effect of varying the airflow
- 2017
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Smouldering is a flameless form of combustion, deriving its heat from heterogeneous reactions occurring on the surface of the fuel when heated in an oxidizer environment. Smouldering is of interest both as a fundamental combustion problem and as a practical fire hazard, for instance in industrial storage units [1]. Many materials can sustain a smouldering reaction, among them wood pellets, which are becoming more widely used as an alternative to oil -fired central heating in residential and industrial buildings. Smouldering fires are difficult to detect, becoming a hazard that must not be underestimated [2]. The influence of varying the airflow, using two different configurations of smouldering combustion was studied: reverse and forward propagation. These are defined according to the direction in which the smouldering reaction front propagates relative to the oxidizer flow. In reverse smouldering, the reaction front propagates in the opposite direction to the oxidizer flow. In forward smouldering the front propagates in the same direction as the oxidizer flow: convective transport is in the direction of the original fuel ahead, preheating it before the smoulder zone is reached.
|
|
