Filtern
Dokumenttyp
- Vortrag (3) (entfernen)
Sprache
- Englisch (3)
Referierte Publikation
- nein (3)
Schlagworte
- Insulation (3) (entfernen)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (3)
Several fires involving ETIC (external thermal insulation composite) systems with polystyrene foam insulation in Germany led to an extensive discussion about fire safety of such systems. A collection initiated by the Frankfurt fire service of façade fires which include polystyrene insulation foam shows that especially fires which started in front of the buildings led to more severe fires of the façade than fires that started inside the buildings. In several fires the ignition source were burning waste containers. Three large scale tests which were initiated by German building ministries showed weaknesses of the existing systems when challenged by a bigger fire source in front of the façade. Since then measures have been introduced to enhance these systems and an additional test with a 200 kg wood crib in front of a large test rig has been used for approval of ETICS. However, the recently introduced German draft standard DIN E 4102-20 does not take these changes into account although real cases and the large scale tests showed that fire scenarios with a bigger ignition source as a waste container are not covered by the DIN E 4102-20. Numerical investigations show that regarding the heat flux to the area above the opening (e.g. a window) also only a fraction of real fires is covered. Additionally damaged systems have been investigated using the Single Burning Item (SBI) test with higher heat release rates of the burner. The damage significantly influenced the fire development of the specimen. Collapse of a damaged coating of an ETIC system occurred during the test and had a sudden fire growth as a result as the whole specimen was suddenly on fire. Several effects which could be seen in the intermediate scale tests correspond to observations which were made in the real cases. In Germany insulation of existing buildings is often enhanced with application of ETICS. In most cases the buildings are in use at the time when the construction takes place. At several stages of the construction process large amounts of unprotected polystyrene are stored in immediate proximity of the building and unprotected polystyrene can be in place on the façade for several weeks. As a consequence of the investigations challenges and possible measures to enhance fire safety of ETIC systems are discussed.
Fires in homes are responsible for about 80 % of all fire fatalities in Germany. It has been known for some time that modern materials tend to burn differently from older materials and it has been acknowledged that the amount of combustible plastics in homes has increased significantly over the last decades. Complementary to the large scale tests performed before, a test series of four experiments in living rooms with adjacent rooms has been performed with the Frankfurt fire service and BAM, the German Federal Institute for Material Research and Testing. The influence of older and modern furniture and ventilation conditions on the fire and smoke development of fires in homes have been investigated as well as the differences in conditions for inhabitants who are in the room of fire origin or in the adjacent room were assessed, figure 1.In addition, buildings have changed significantly in recent years. The need for energy conservation has led to new applications as solar panels, batteries for storage of electrical power and a variation of insulation materials. The possible combustibility of all these applications only slowly comes into consideration. It has been known for some time that modern materials tend to burn differently from older materials and it has been acknowledged that the amount of combustible plastics in homes has increased significantly over the last decades. A test series of four experiments in living rooms with adjacent rooms has been performed with the Frankfurt fire service and BAM, the German Federal Institute for Material Research and Testing, to investigate on hand the influence of older and modern furniture and ventilation conditions on the fire and smoke development of fires in homes and on the other hand the to assess the differences in conditions for inhabitants who are in the room of fire origin or in the adjacent room.
At the same time we face an ageing population that will be less mobile and might need more assistance than ever before. This influences directly the ability to escape and the time needed.
Although for the last decades we saw a decrease in the number of deaths from fires we should not assume that this trend must continue. On one hand, we might have benefited from safer electrical appliances, measures as smoke detectors and non-combustible stair cases and advanced medical treatment. On the other hand, nowadays we face the situation that buildings change significantly in shape, air tightness and used building materials. At the same time building contents change significantly as in increasing amount of consumer products stored at home and change of the materials of the consumer products and furniture. In addition, we face changes in our demography with an ageing population and an increasing inclusion of persons with disadvantages which influences the ability to escape directly. This set of changes is not reflected by a change in the building codes yet.
The ongoing geo-political conflicts and the increasing need for the implementation of measures to improve the energetic system sustainability are increasing the importance of tanks for storing cryogenic fluids in the energy industry. The most common example of cryogenic tank applications is the transport of natural gas and hydrogen in their liquid form (LNG and LH2 respectively) for which, considering the same transport volume cryogenic storage ensures significantly higher transport capacities with respect storage based solely on overpressure.
A common feature of all cryogenic transported fluids is that their condition must be maintained minimizing heat leaks from the environment as much as possible. This is achieved by the implementation of thermal super Insulations (TSI) systems based on e. g. rock wool, perlites, microspheres, multilayer insulations (MLI), and vacuum which have proven to be effective in applications. However, due to the relatively short period of use in some applications, the small number of documented incidents, and the still few investigations carried out in the field, the exploitation of such systems in the cryogenic fluids transport sector still suffers from insufficient knowledge about the course and consequences of incidents. Accidents involving collisions, fires, and their combination are quite common in the transportation sector and may generate extraordinary loads on the tank and its insulation system, eventually leading to tank failure.
The present study focuses on the behavior of TSI systems in tanks when it is exposed to an external heat source representative of a hydrocarbon fire scenario. This may cause an increase of the heat flux into a tank by several orders of magnitude with respect to normal design conditions, thus inducing severe and in the TSI, causing the rapid release of flammable gas and even resulting in a Boiling Liquide Expanding Vapour Explosion (BLEVE).
To study such scenarios a test rig was developed at BAM that allows testing of TSI at industrial conditions and enables subsequent analysis of TSI samples. This test rig considers the typical double-walled design of tanks for cryogenic fluids with vacuum and an additional insulating material in the interspace. Adjustable electrical heating elements simulate the fire on one side of the double wall. This process allows the implementation of repeatable heat loads of up to 100 kW/m². The other side of the double wall is represented by a fluid-supported heat exchanger, which allows the simulation of cold or cryogenic conditions in the test rig, and to determine the heat flux transmitted through the double wall. Thus, the test rig allows thermal loading and performance analysis of TSI samples at the same time.
In the presentation, the results of diverse tested TSI systems will be presented and discussed. As a result of this study, the list of advantages and disadvantages for the choice of tested TSI expands. Within the test, all samples degraded as a consequence of a hydrocarbon fire-orientated thermal load. Strong differences in the behavior of the tested TSI systems over temperature, location, and time were observed. Additionally, the tested MLI insulations were significantly more resistant to their base materials. These results are relevant for the design, the definition of national and international regulations, the Risk assessment, and the development of safety concepts for cryogenic tanks.