Larry Haftl.com
PRODUCT REVIEW: Fire Shelters
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Since 1977 more than 950,000 shelters have been manufactured and issued to wildland firefighters in the United States. Only about 700 shelters have ever been deployed in an emergency, and of those only three have resulted in deaths from shelter failure. At the same time, more than 270 lives have been saved and several hundred more firefighters have been saved from severe burns by using the shelters.
If you ever wonder whether the standard personal fire shelter can save your life, call Steve Stubelt, a firefighter with the Florida Division of Forestry's Forest Protection Bureau. Stubelt is, quite literally , living proof that a properly deployed shelter can mean the difference between simply being scared near to death and actually dying.
On the afternoon of May 5, 1997, Stubelt was using a John Deere 550 tractor with blade and plow to cut a fireline along the right (southern) flank of a fire in Collier County, Fla. He was working in heavy pine with a palmetto and skunk cabbage understory when the wind shifted 90 degrees, increased to about 15 mph and sent the fire heading right at him. Stubelt has 14 years of experience fighting fires in that area, and when the wind shifted he immediately knew he was in trouble. "The wind was mostly from the east," said Stubelt, "but sometimes it would switch and come from the north for a few minutes. The fire would take off and then it would switch back again. I was working about a hundred yards from the fire when it switched, and I started seeing spot fires ahead of me. I cleared a safety zone about 40 feet wide and 50 feet deep, put the rear of the tractor facing the fire, and deployed my shelter downwind of the tractor using the blade on the front end for extra protection."
According to Jim Karels, assistant chief of forest protection for the Florida Division of Forestry and head of the team that investigated the incident, it took Stubelt only 20 or 30 seconds to clear a safety zone and another minute or so to deploy the shelter. It was enough time, but barely.
"When I started to deploy, the red ring on the plastic case broke off and I had to take off my gloves to tear the cover off," remembers Stubelt. "By the time I got the tent out, the wind was catching it like a kite and it was extremely hard to get into. I deployed it over my gloves and was able to put my gloves back on after I got in the shelter. But by then I had trapped a lot of hot air inside. The wind from the fire made it hard to hold the shelter down. It was constantly coming up, and embers were blowing in. I was not really sure if it was going to work or not."
Stubelt had been issued a face mask for use in prescribed burns, but it proved useless. "It's a little paper mask with two plastic filters on it," he said. "But when I tried to put it on, the filters fell off and it was too dark and too hectic in that tent for me to find them. I just did what I was taught in fire school. I dug a small hole, laid down in the dirt, and tried to breathe the cooler air in the hole."
It took about eight minutes for the fire to blow past Stubelt. An examination of the shelter by the U.S. Forest Service's Missoula Technology and Development Center (MTDC) - the agency's division charged with developing the fire shelter - determined that the outside temperature of the tent reached between 400 and 500 degrees Fahrenheit. Eight feet from the shelter, a 65-foot-tall pine tree was charred black 35 feet up the trunk, with most of its needles completely burned off. "I just waited until the wind died down enough so the embers weren't coming in anymore," said Stubelt. "Then I peeked out and saw that the fire had passed. All that time I figured I only had a 50/50 chance of making it. I'd hate to have to use it ever again, but I'm a believer in them."
"I believe he would never have made it without that shelter," said Karels. "Steve did all the right things and it saved his life."
"Like everybody else," said Stubelt, "I never thought I'd use it. My advice to other firefighters is that if you ever get in a situation where your heart or mind wonders if you should deploy, do it. Don't think twice. Just get to a safety zone and open it, and it will probably save your life."
Stubelt is one of hundreds of firefighters in the U.S. whose lives have been saved over the last 20 years by properly deployed shelters. But deploying a shelter is not a guarantee of safety. It must be "properly" deployed. That means in an adequate deployment zone and in a timely manner. The National Wildfire Coordinating Group (NWCG) standards specify that there are four different types of deployment zones. They are:
Safety Zone, an area where firefighters can be safe from hazards without having to deploy a fire shelter;
Survival Zone, an area where firefighters will be safe inside a fire shelter; Injury Zone, an area where injuries or fatalities are likely to occur even in a fire shelter; and Dead Zone, which is self-explanatory.
The current fire shelter is designed to be used only when all other remedies have failed - when a firefighter becomes trapped in a situation from which there is no other means of escape. Even then, there is no guarantee that the shelter will save a life. The shelter's primary limitation is that it is designed to protect from radiant heat, not intense or prolonged contact with direct flame. The outer foil actually melts at 1200 degrees Fahrenheit. To be effective, the shelter must be deployed in at least a survival zone that eliminates - or at least greatly minimizes - the chances of the shelter's coming into direct contact with flame. Prior to the 1990 Dude Fire in Arizona, this limitation was not seen as a major problem because there had been no incidents where a shelter failed and a life was lost due to direct flame impingement.
On July 6, 1994, a wildfire on Storm King Mountain in Colorado (referred to as the South Canyon fire even though the fire never touched South Canyon) blew up, trapping 22 firefighters. Fourteen died. Two of the ten who were able to fully deploy their shelters died. Four who only partially deployed shelters died. The other eight firefighters who died still had their shelters in their cases. Ted Putnam, equipment specialist at MTDC - and the top fire shelter expert in the United States - was responsible for investigating the shelter deployments. "It was a mixed call," said Putnam, "because we don't know in each case if the firefighter was critically burned before getting into the shelter and flames destroyed the shelter from the inside, or if the shelter was overloaded and failed because of the flames. Before South Canyon, the worst problem we saw with the shelters themselves - in more than 1,700 deployments - was some delamination during the Dude Fire. We thought all we had to do was find a better adhesive. The shelter had been doing a wonderful job, but at South Canyon we saw that there was a possibility that some of the shelters had failed in an injury zone. We started asking what were the actual conditions that caused the failures, how much fuel and heat there was, and we asked the fire lab to get involved."
Bret Butler, a research scientist at the fire lab - the Forest Service Intermountain Fire Sciences Laboratory in Missoula, Montana - and MTDC began instrumented prescribed burn tests of shelters in 1995 to determine the temperatures, duration, and heat intensities that shelters may be subjected to in actual field conditions.
One of the 14 firefighters who died in the Southh Canyon incident was Roger Roth. In response to his death and those of the other firefighters, Roger's brother Jim Roth organized a group of volunteers from private industry in August 1994 to work on improving fire shelter materials and design. The group became Stornm King Mountain Technologies (SKM), and their primary objective was to develop a shelter that would give firefighters a better chance of surviving a fast-moving flame front than the current shelter does.
They began prescribed burn tests on several prototypes five months later. "When we first got started, we weren't able to get much quantitative information from MTDC about the conditions that cause shelter failures," said Roth. "I don't think they had much at that time. So we put various prototypes along with the standard shelter out in four prescribed burns; we gathered performance information using heat sensors and a computer data logging system. Then I took our data out on road trips and talked to any firefighter that was interested. I showed them how fast a flame front moved through, and what the temperatures were like inside and outside the shelters in various fuel types. People started to take notice. People started asking questions about the current shelter design and its proper deployment zones."
Roth had set out to design a shelter that would better survive direct flame contact. Gentex, a manufacturer of components used in life support systems, had been working with MTDC for a number of years to get their materials approved for use in fire shelters, but they'd had little success. "It's a complicated situation," said Lou Ott, textile representative for Gentex. "The way the current NFPA specification is written, only the current shelter material qualifies. We haven't ceased all development effort, but we're waiting for standard test specifications to be released. We're waiting for a target to shoot at. We don't want to manufacture shelters - we want to sell our materials to shelter manufacturers."
Gentex has been providing Roth with shelter materials and has participated in some of SKM's field tests. Outside of MTDC, only SKM and Gentex have developed products that can be tested against the standard shelter.
"After South Canyon, six or seven people contacted MTDC asking for technical information and indicating that they were seriously going to work on a better design," said Putnam. "So far only Roth has done anything substantial about it."
Field testing shelters in prescribed burns is not only very costly, but also does not provide the easily repeatable conditions needed to accurately evaluate new materials and designs. At this time there are no NFPA standards for measuring shelter performance. MTDC, working with Bret Butler and Jack Cohen from the fire lab, has been charged with developing a test rig that can be used to accurately compare shelter designs and materials. They are also charged with developing minimum performance standards for fire shelters based on the existing model. According to Butler, the test rig should be developed and in use by mid-1998, and is designed to be inexpensive enough to allow private developers to build one for their own testing. Developing performance standards will take longer - perhaps as much as two years.
Developing and implementing performance standards is where decisions begin to be based on the real world of politics, fire management strategies, and economics instead of available technologies.
Carrying fire shelters became mandatory for all Forest Service firefighters in 1977. Since then all other federal fire fighting agencies in the U.S. - and most state agencies - have also made it mandatory. Shelter use in British Columbia is man datory, and Alberta is considering their use. Australia, which played an important part in early shelter development, has chosen not to use them.
If fire shelters are proven life-savers, why aren't they universally adopted? Because the use of fire shelters is directly dependent on fire fighting tactics: If your policy is to always have one foot in the black, your chances of entrapment - and the subsequent need for a shelter - are greatly diminished. If your primary method of initial attack is a brush truck with a water misting system to protect it, you may not need shelters. If you sometimes do aggressive initial attack during extreme fire behavior, though, the likelihood of entrapment and the need for shelters goes up.
Fire line tactics also play a direct role in defining the maximum size and weight of the shelter. The standard shelter weighs about 3.5 pounds, but it feels like 50 pounds after a 12-hour shift digging line in rugged terrain. Weight and size are serious considerations for those on hand crews, but less important to dozer and engine crews. According to Dick Mangan, chair of NFPA's wildland fire committee, when NFPA sets performance standards for fire shelters, they will be more concerned about the shelter's ability to protect from heat than they will be with size and weight. Those factors may, however, become part of the standard.
According to Dave "Shag" Aldrich, chair of the NWCG safety and health working committee, size and weight maximums will definitely be part of their requirements. Maximum costs may also be specified. The NWCG requirements are used by all federal and most state agencies when purchasing equipment. Because these agencies represent the dominant segment of the fire shelter market, shelter manufacturers who can't meet all the NWCG requirements will automatically lose that market segment. Such a company may not make enough non-government sales to remain in business, no matter how much better their shelter is.
Limits on size, weight, and cost all directly affect the level of protection that can be built into a shelter. It may not be possible to produce a shelter with substantial direct flame resistance that is still light and small enough to meet the current size and weight standards.
That is the dilemma faced by SKM.
In the field trials they did in conjunction with MTDC, the SKM shelter repeatedly had better survivability performance, but because it weighs about 4.5 pounds and is twice the size of the existing shelter package, it may not meet the NWCG standards. And if size and weight didn't eliminate it from consideration, the cost probably would. The current shelter costs the government $40. SKM's shelter would probably cost closer to $250.
While it's easy to say that you can't put a price on human life and that cost therefore should not be a consideration in choosing a shelter, the reality is that the agencies have only so much money to spend. Incident investigations repeatedly show that human factors and human decision making in entrapments play a much greater role than shelters do. It's possible that the agencies could come out ahead by spending that extra $200 on improving firefighter decision making rather than on a better shelter.
NWCG is also considering requiring that shelters have full floors, be able to accommodate two people, be one-size-fits-all, and be bi-directional (able to use either end as the head or foot).
Full floors would reduce the chances of flames and embers coming under the shelter. A full floor would also make it easier to hold the shelter down in the high winds associated with extreme fire behavior. MTDC developed a full-floor model prior to South Canyon; it goes into production in time for the 1999 fire season. It has an 18-inch accordion-folded panel on each side, which can be unfolded from the inside to make a full floor. SKM's design also has a full floor, but it uses a full-length slit in the floor for entry.
The requirement that a shelter accommodate two people is a result of the number of instances in which people tried to double up in entrapments. "Any time you had five or more people entrapped," said Putnam, "we saw someone doubling up. That was before shelter training became mandatory every year. NWCG is concerned that if they don't have that requirement someone in an entrapment will get panicky, and instead of getting their own shelter out they will try to get in with someone else. Maybe that concern will disappear, because it used to be that once you were trained in deployment you didn't have to do it again. Some people had gone 10 or 12 years since they last practiced, and then had to do it for real. Now it's mandatory for all federal agencies that they practice every year."
The SKM design is too small to meet the doubling-up requirement. It's smaller by design and is not bi-directional - it has a definite head and foot. "The modeling we did early on showed us that if you have a large area confronting the fire, you are increasing the heat in the shelter," said Roth. "But if you have a smaller tapered end toward the fire it is more aerodynamic and the fire goes over the shelter more easily with less heat buildup. It also saves on weight. One concern is that by reducing the physical size you reduce the amount of oxygen available. We think this is offset by keeping the air cooler, but we have to prove this."
According to Putnam, MTDC, NFPA and NWCG are also concerned about oxygen availability and requirements. There is no current data, but MTDC, the fire lab, and SKM will start collecting data in future tests.
Because the SKM shelter has a definite head and foot end, it raises issues about getting the shelter oriented properly before it can be entered. This is especially important in situations with extreme fire behavior and stress - when a shelter is most likely to be needed. "We have a long color-coded strap," said Roth, "and you pull on the strap to remove the shelter from its pack. That automatically orients the shelter correctly for entry."
How quickly and easily his system can be deployed, though, has not been demonstrated.
NWCG's one-size-fits-all requirement is the most confusing. Anyone taller than about 6'2" begins to deform the current shelter once they are in it and holding it down. Prior to South Canyon, MTDC developed and tested three different shelter sizes. Based on firefighters' comments, MTDC recommended at least two different sizes - the standard size and a larger one for taller people.
NWCG said no.
"I think one-size-fits-all has a lot of merit, pragmatically," said Aldrich, "because there may be a mix-up when it is issued. Also, we have a lot on engines where shelters are not issued to specific firefighters."
Putnam considers this a matter of training, and of management's making sure that everyone has the right size when they go out. "If we had a standard and a large size," he said, "even if there was a mix-up and a tall person got a standard size shelter, they would be no worse off than they are now. And with the full floors, a shorter person can keep a larger shelter down much easier than they can with the current model."
SKM agrees with Putnam and plans to provide two sizes.
While there are definite form differences between the two shelters, the major difference is in the materials. The standard shelter uses an aluminum foil backed by a fiberglass mat held together by adhesive. The SKM design uses five layers of material bound together by stitching. The outer layer is a fiberglass mat. Beneath that are two layers of reflective material, a layer of insulation, and an inner layer of fiberglass. The outer layer of fiberglass is more flame-resistant than the foil and fiberglass used in the current shelter, and the insulating layer provides additional thermal protection.
How do the two shelters compare in performance? That will finally be established when the new test rig is available to test them under controlled circumstances. Preliminary tests conducted by both SKM and MTDC indicate that the SKM shelter is far more effective in protecting from direct flame impingement. The most recent tests were conducted during a crown fire modeling experiment in the Canadian Northwest Territories this summer.
"My shelter survived longer than the Forest Service model," said Roth, "but nobody inside would have been able to. We are never going to be able to protect everybody in every situation and fuel type."
Results from one of the tests, however, indicate that it may be possible to develop a shelter that would give full protection even in an injury zone. Strangely enough, the test involved a standard shelter. A stainless steel foil model developed at MTDC actually survived in the fuel bed, but anyone inside it would have died from the intense interior heat. The stainless steel foil made the shelter act like an oven. A second test in which a standard shelter was positioned inside the stainless steel model indicated that a person inside would probably have survived.
It may be possible to develop a shelter which would allow firefighters to survive in extreme conditions, but that is far from certain. The size and weight of such a shelter may also be problematical. MTDC is continuing to look at the possibility of a stainless steel outer foil and some sort of insulating inner liner.
SKM is not waiting for the NFPA and NWCG standards to be adopted before they release a product to the market. "We are about 80 percent there," said Roth. "We plan to release our product in time for next year's fire season. From our lab and prescribed burn tests we know that it will meet whatever minimum performance standards NFPA will set, because those standards will be based on the current Forest Service shelter. We will probably sell shelters to private firefighters and in other countries before any of the federal agencies are ready or willing to buy them, but at least it gives firefighters an option."
SKM does not plan to manufacture the shelters; they expect to license the design to other companies. Until that actually happens, however, fire shelter choice will be limited to the standard Forest Service design.
As for the new Forest Service model with the full floor, don't hold your breath waiting to get one. According to Putnam, under a Forest Service/General Services Administration agreement, all of the shelters still on the shelves have to be distributed before the new models can be issued. That could take two to three years - depending on the severity of the fire seasons - and it will be at least one year before the new shelters will be manufactured.
While agencies, manufacturers, and developers debate the merits of reflective versus direct flame protection, uni-directional versus bi-directional designs, and size/weight/cost limits, it is important that firefighters not lose sight of two critical points.
The first is that the current shelters, when properly deployed, will save lives. Since 1977 more than 950,000 shelters have been manufactured and issued. Only about 700 have ever been deployed in an emergency, and of those only three have resulted in deaths from shelter failure, according to Putnam. At the same time more than 270 lives have been saved and several hundred more firefighters have been saved from severe burns by using the shelters. Like Steve Stubelt said, if you get in a situation where your heart or mind wonders if you should deploy, don't think twice-just do it. But make sure you deploy in at least a survival zone and not in an injury or dead zone.
The second point is that those statistics, along with all the recent tests, prove that the way to avoid death or injury by entrapment is to not be there in the first place. Your life and safety depend far more on making the right decisions than they do on the protective value of a fire shelter. And if the only decision left to you is whether to deploy or not, listen to Stubelt and just do it.
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