Fire shelter
A fire shelter is portable fire protection in the form of a small tent or sleeping bag, which fire fighters in the USA should use as a final protection against the flames in the event of forest or field fires . It consists of several layers of heat-reflective and fireproof materials.
use
The Fire Shelter is folded up in a container on the chest, attached to a belt or backpack and is part of the personal protective equipment of firefighters. It is designed for single use and for only one person, but in an extreme emergency it can also accommodate two people. For use, it is removed from the packaging, held by two loops and shaken up. You climb into the shelter through the opening, lie face down on the ground with your feet in the direction of the fire and guide your arms through two lateral fixing loops. With these, as well as the feet, the shelter is held on the ground. Experienced firefighters need about 15 to 20 seconds for this process.
The shelters should be set up as close to each other as possible, this increases protection against thermal radiation and facilitates communication. The installation area of one or more Fire Shelters is known as the deployment site . The choice of the deployment site has a serious impact on the chances of survival and should therefore be explored or created in advance of the deployment. The duration of the use of a shelf in practice ranged from about 10 to over 90 minutes.
Material and heat resistance
The New Generation Fire Shelter consists of two layers of laminated material. The outer layer is made of aluminum foil , which reflects thermal radiation , and a layer of woven silica , which slows down the transfer of heat . The inner layer, consisting of fiberglass and another aluminum foil, is supposed to prevent the penetration of absorbed heat and gases .
According to the Forest Service, the aluminum layer begins to melt at a temperature of 1220 ° F (660 ° C ), the fiberglass layer becomes brittle and the silica layer becomes brittle when the temperature is between 1350 ° F and 1610 ° F (732 ° C to 877 ° C) Limit of brittleness at 2000 ° F (1093 ° C). The special adhesive that holds the individual layers together begins to dissolve at 500 ° F (260 ° C). The material is also sewn with fiberglass and quartz threads so that strong winds at the location of the fire do not wear away the outer layers of the fire shelter and thus reduce its protective function .
In a test with a 800 ° C to 900 ° C flame from a propane burner aimed at the outer skin, the fire protection material remained intact and provided protection from the flames for the duration of the one-minute test. In comparison, the previous model burned out after 15 seconds in the same test. Another danger, however, is the air we breathe inside the shelter, the maximum survivable temperature of which is given as 300 ° F (149 ° C) with one or two breaths. In the test, however, this temperature was exceeded after just 18 seconds.
history
The development of the first Fire Shelters began in Australia in 1958 . In 1959 the idea was taken up by the Technology and Development Center ( MTDC ) of the US Forest Service in Missoula , whereupon the two countries worked together over the next few years. The fire shelter should reflect radiant heat, keep the air inside at a breathable temperature and should not contain any materials or substances that could develop toxic fumes. Different shapes and material compositions were tested. Shelters were first used in 1964 during a forest fire in California .
In 1967 the first 6000 pieces of the "Standard Fire Shelter" were issued in the USA. It weighed 1.5 kg, consisted of an aluminum and fiberglass layer and resembled an A-shaped one-man tent. It was in an orange box and could be attached to the belt. The death of three firefighters in the 1976 Battlement Creek Fire in Colorado was the trigger for the mandatory introduction of Fire Shelters by the Forest Service from 1977. Small changes to the packaging were made during the 1980s and extensive tests were carried out in the 1990s.
In January 2000 the MTDC was commissioned with the development of a new fire shelter. By then, the Forest Service had registered around 1100 deployments of the Standard Shelter, about half of which were carried out as a precaution. During the 550 "sharp" operations, 275 people suffered burn injuries of varying severity, 20 of which did not survive. The most casualty tragedy occurred during the Dude Fire in Arizona in 1990 , when six firefighters were killed and four injured. According to the investigation report, the shelters failed in direct contact with the flame or did not offer adequate protection from hot gases, but some were not fully deployed or left too early.
The goals of the new project were to improve protection against direct flames and to consider material strength, durability, flammability, weight, mass, toxicity and cost. 60 materials and combinations as well as 17 designs were tested. In June 2002 it was decided to replace the model with a semi-cylindrical version with rounded ends, which was also longer and flatter, but around 0.5 kg heavier than the standard model. Made of more heat-resistant materials, it offered a shape that was more aerodynamic and better suited to reflecting radiant heat. The "New Generation Fire Shelter" was available from June 2003 and was supplemented in 2005 by a model for physically larger users. The new shelter was first used at the Tarkio Fire 2005 in Montana . The end of the conversion phase for all fire departments to the new shelter was announced at the end of 2009. A separate Interagency Fire Shelter Advisory Board is to lead the fire protection program into the future with the involvement of numerous interest groups.
In 2013, 19 firefighters died in their Fire Shelters in the Yarnell Hill Fire in Arizona when they were run over by a flame roller. According to the experts on the investigation team, direct flame contact was caused by dense bushes and the heat had exceeded the load limit of the shelter materials of a maximum of 2000 ° F (1093 ° C). The event was filmed in 2017 under the title No Way Out - Against the Flames (original title Only the Brave ).
Because of this tragedy in 2014 an improvement program was started in which the Langley Research Center of NASA involved. Testing of flexible heat shield materials from space travel began under the name Convective Heating Improvement for Emergency Fire Shelters (CHIEFS), but these had to be adapted to the acceptable level of mass, volume, durability, toxicity and cost of a shelter. NASA planned the delivery of the first shelters in 2018. In May 2018 it was announced that 60 firefighters are to be equipped with one of four new prototypes in the coming summer. Two of the prototypes are designed for ground crews, two more each for the operating teams of emergency vehicles.
Other countries
Australia, which was involved in the development, dropped out of the program in 1967, and protective equipment is no longer used in Canada, where fire shelters from the USA were in the equipment of some fire departments. British Columbia was the last province to stop using it in 2005.
Fire brigades in both countries justified this with the higher safety standards for the deployment of fire fighters in their countries, where forest fires are mainly fought from the air or with special vehicles. In addition, a shelter increases the willingness of individuals to take risks and, in extreme cases, does not offer any real protection.
Web links
Individual evidence
- ^ Fire Shelters: A Wildland Firefighter's Last Line of Defense
- ^ Fire shelter
- ^ Developing a more effective fire shelter
- ↑ NASA Is Testing Next-Generation Fire Shelters
- ↑ New versions of fire shelters to be tested this year
- ↑ Safety Bulletin
- ↑ Why emergency fire shelters aren't used in Canada
- ↑ personnel fire shelters not used in Australia
