The Heat is On: Fire Fuels Research at FPL

Where there’s smoke, there’s fire — but where there’s wood, there’s always the chance of fire. Luckily, where wood and fire meet, there’s the Building and Fire Science work unit at the Forest Products Laboratory (FPL).

This CLT specimen survived almost 100 minutes of exposure in a standardized test reaching nearly 1000°C. The unexposed side of the specimen remained at less than 50°C for the entire test.

Throughout its existence, FPL has long been on the cutting edge of fire science. Fire prevention will continue to be a major area of study as wood expands into commercial and high-rise construction.

This unit is charged with researching how wood and fire interact, and help make wood products more fire resistant and in compliance with international fire safety standards. One way to accomplish this daunting task is through the use of flame-retardant treatments (FRTs) — but what exactly do these treatments do?

FPL Research General Engineer Mark Dietenberger, and Laura Hasburgh, a Fire Protection Engineer at FPL, know exactly how FRTs work. Their recently published document Wood Products Thermal Degradation and Fire in the Materials Science and Materials Engineering Reference Module for Elsevier takes an in-depth look at these treatments and explains how they work to keep wood from going up in flames.

Most FRTs delay ignition, reduce heat release, and reduce flame spread. Other possible mechanisms for fire retardancy include conducting heat away from the heat source, endothermic chemical reactions to absorb heat, or the releasing radicals that inhibit combustion. Some flame-retardant coatings can even swell to form an expanded low-density protective film for the material upon exposure to fire. These FRTs are known as intumescent formulations.

For interior applications, Dietenberger and Hasburgh note that water-soluble inorganic salts are the most common flame retardants. These chemicals are combined by researchers in specific ways to optimize a material’s fire performance and reduce individual aspects of a fire. Boric acid, for example, can be added to an FRT formulation to reduce smoldering or glowing.

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FRTs can reduce the heat release characteristics of wood. Above are heat release curves for untreated and FRT Douglas-fir plywood.

Although the FRTs decrease the flammability of a material, they can increase other dangers associated with fire, like the production of smoke or weaken a material’s structural integrity. Fire retardant-treated wood is often more brittle than untreated wood, and some FRTs can cause further losses in strength with continued exposure to elevated temperatures, for example, the roof of a burning building.

FRT research thus is a delicate balancing act, and researchers strive to create FRTs that allow wood to remain both strong and fire-free. Though the heat is on for the men and women from FPL’s Building and Fire Science unit, they have proven they are up to the challenge — continually pushing the limits of FRT with every experiment, and helping to make our wood, and us, safer.

For more information, please see the full article, Wood Products Thermal Degradation and Fire.

Holiday Trees: Go Real, but Water them Well!

Being the tree lovers that we are here at the Forest Products Laboratory (FPL), of course we’re going to recommend real trees for the holiday season.

TREEThe benefits are numerous. While they’re growing, real trees clean the air and provide us with fresh oxygen to breathe. Most Christmas trees are grown on farms (often on soil that doesn’t support other crops), so buying a real tree supports local farm families who plant new seedlings for every tree harvested. And when the new year rolls around, your real tree can be recycled for a new purpose — perhaps as mulch, or something more exciting, like being submerged in a lake to create a fish habitat!

Yet even as we encourage the use of real trees this holiday season, we must remind you to be safe! Christmas tree fires are rare, and well-watered trees pose very little risk. But when real trees are neglected and dry out, they can be consumed by fire in a matter of seconds if a flame or electrical spark gets too close!

Watch this video from the National Instituted of Science and Technology for Christmas tree safety tips and a sobering look at how quickly your holiday could go up in flames.

Temperature Down, Danger Up : Wood Heating Caveats From FPL

Most residential buildings in the United States employ wood as a primary construction material, and increasingly, commercial buildings are following suit. Although researchers at the Forest Products Laboratory (FPL) have spent the better part of a century formulating new treatments and methods for improving the fire durability of wood, fire safety remains a serious consideration, particularly during the winter.

Fire retardant test at FPL, 1940s.

A fire retardant test at FPL during the 1940s. FPL research has helped improve building codes, wood treatments, and testing standards.

This danger can be compounded depending on your method of heating. As the temperature goes down, if you choose to heat your home with wood, fire danger goes up. Proper precautions should be taken to ensure that the fire stays contained in the stove or fireplace, lest it spread to the surrounding structure.

According to The Wood Handbook: Wood as an Engineering Material, one of the most important problems associated with home fires is the smoke produced. The term smoke is frequently used in an all-inclusive sense to mean the mixture of pyrolysis products and air that is near the fire site. In this context, smoke contains gasses, solid particles, and droplets of liquid — but why is smoke so dangerous?

Smoke presents a potential hazard because it interacts with light to obscure vision, but the toxicity of combustion products is the primary concern. Fire victims are often not touched by flames but die a s a result of exposure to smoke, toxic gasses, or oxygen depletion. These life-threatening conditions can result from burning contents, such as furnishings as well as from structural materials involved.

The toxicity resulting from the thermal decomposition of wood and cellulosic substances is complex because of the wide variety of types of wood smoke. Composition and the concentration of individual constituents depend on such factors as the fire exposure, oxygen and moisture present, species of wood, any treatment of finishes that may have been applied, and other considerations.

The vast majority of fires that attain flashover (a fire’s sudden spread when an area is heated to its flashpoint) do generate dangerous levels of carbon monoxide, independent of what is burning. Carbon monoxide is a particularly insidious toxic gas and is generated in significant amounts in wood fires.

Even small amounts of carbon monoxide can be toxic because the hemoglobin in the blood is much more likely to combine with carbon monoxide than with oxygen, even with plenty of breathable oxygen present. Generally, two approaches are used to help deal with the smoke problem: limit smoke production and control the smoke that has been produced. The control of smoke flow is most often a factor in the design and construction of buildings.

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Wall test conducted in the large vertical furnace at FPL showing a wall panel at the point of fire burn through. Information of this nature is used in building designs to help ensure time for people to exit a burning structure and help contain the fire and smoke.

Draftstops are one useful control measure construction engineers implement. Draftstops are barriers intended to restrict the movement of air within concealed areas of a building. The are typically used to restrict horizontal dispersion of hot gases and smoke in larger concealed spaces such as those found within wood joist floor assemblies with suspended dropped ceilings or within an attic space with pitched chord trusses.

Doors can also be critical in preventing the spread of smoke and fire, even if they are made out of wood. Doors left open or doors with little fire resistance can easily defeat the purpose of a properly fire-rated wall or partition. Listings of fire-rated doors, frames and accessories are provided by various fire testing agencies. When a fire-rated door is selected, details about what which type of door, mounting, hardware, and closing mechanism must be considered.

Finally, keep in mind that smoke rises, and that when evacuating a burning building, clean air can usually be found closer to the ground. For more information on home fires, and tips to keep you and your family safe, visit Ready.gov.

For more information about the fire resistance of wood, please see Chapter 18 of The Wood Handbook: Wood as an Engineering Material.

 

 

 

 

Be Good to Your Christmas Tree And it will be good to you ...

TREE

Each year over 30 million Christmas trees will be sold in the U.S. Mother Nature’s kind. The real, beautiful, ever-green, ever-aromatic centerpiece of our holiday season. They will dress up our houses and maybe most important, will be the landing point for all manner of goodies when Santa pays his annual visit — assuming, of course, we were good this year.

Which is why it is vitally important to take good care of your tree, because a tree that goes unloved and uncared for can be deadly. We don’t want to throw water on the celebration, but facts are facts. Actually, maybe we do want to throw water on the celebration, or at least at the tree.

Simply keeping your tree properly watered significantly decreases the chances of a catastrophic fire in your home. Not convinced? Take a few seconds to watch this eye-opening video courtesy of the National Fire Protection Association. Wow.

While you’re at it, try to spend a few more minutes looking through these excellent basic tips for proper tree care brought to you by Purdue University.

If you don’t have a few minutes the easy-to-follow instructions below could mean the difference between a joyous holiday season and a really, really bad one.

  • Find a tree with pliable needles that stay on the branches.
  • Cut 1/2 inch from the end of the trunk, and use a tree stand that can hold plenty of cool water.
  • Water often. Be sure to keep the water level above the tree base, otherwise the end of the tree will seal, preventing additional water from entering the tree.
  • Keep the tree at least 3 feet away from any heat source and don’t let it block any exits.
  • And it goes without saying that candles should never be used on or near the tree.

And stop by our website for more information about past and present fire safety research at FPL.

Be safe and enjoy your tree!

All Hands on Deck to Lessen Wildland Fire Damage

Because wildland fires pose a significant societal threat, it is important to understand how to mitigate their damage. Lives and structures are at risk, particularly in the wildland-urban interface (WUI), where homes are constructed near or among areas prone to these fires.

Testing decking materials in FPL's Fire Test Lab.

Testing decking materials in FPL’s Fire Test Lab.

The Forest Products Laboratory’s Mark Dietenberger, a research general engineer, and Laura Hasburgh, a fire protection engineer, are studying a common scenario that results in property loss due to these fires in the WUI: ignition of attached wood decks.

A recently posted Research in Progress summary titled Fire Performance of Exterior Wood Decks in Wildland-Urban Interface explains how FPL and the American Wood Council (AWC) are working together to provide mitigation strategies that will reduce wildfire threats to structures and therefore preserve the marketability of wood decks.

The objectives of the research are threefold:

  • provide the AWC with a technical assessment of the fire performance of decking when subjected to relevant fire exposure
  • assess the related fire test methodologies using state-of-the-art flammability facilities
  • identify options for policy decisions pertaining to prescriptive regulations

This project began in January 2014 and will continue for three years, with an annual report compiled each July.