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Going Up In Smoke
The Impact Pallets Can Have On A Warehouse Fire
By Chaille Brindley
Date Posted: 10/1/2001
Just imagine a fire blazing through your customer’s warehouse or DC. It leaves behind a path of destruction resulting in thousands — maybe millions of dollars — in property damage, not to mention the productivity loss. Packaging, especially pallets, can significantly increase the fire hazard in a facility. Thus knowing how to deal with them can reduce a company’s risk.
Fire issues for transit packaging have literally become a hot topic recently for some plastic pallet manufacturers and end users. Pallet users, packaging providers and fire code officials have all started to evaluate the impact that pallets can have on a facility’s fire hazard. Pallet providers should educate themselves and become aware of how the issue affects them and their customers.
Regardless of the material that they are made of, pallets pose a strong fire hazard according to Joe Hankins, a senior engineering specialist with FM Global, a major insurance provider for warehouses and industrial manufacturing companies. Pallets have plenty of surface area to burn and open space for oxygen to fuel a fire. These characteristics create an ideal situation for fire to spread.
Wood vs. Plastic
The material the pallet is made of can affect the severity of the fire. "It is certainly easier to light a rough-sawn edge of wood used in a wood pallet than an edge of a plastic pallet. But once a plastic pallet gets going, it will give off more energy than a wood pallet of the same size and weight," said Charles Gandy, a fire protection engineer with TVA Fire & Life Safety. TVA is a major fire protection consultant for industry.
Plastic has 2.5 to 3 times the potential heat energy of wood. As a result, plastic can cause a bigger fire than wood. Typically, plastic pallets require more fire protection than wood. But there can even be differences in how wood pallets burn, depending on the moisture content and species of the lumber in the pallet.
"The problem is that most warehouses have been designed to protect wood not plastic pallets,"said Hankins.
Most older warehouses use standard control mode sprinklers. These standard sprinklers pre-wet areas adjacent to the fire and contain it. Standard sprinklers were initially designed to protect manufacturing facilities where wood and paper were typically the most hazardous materials involved. But the introduction of plastic into manufacturing and packaging has raised the bar. Newer sprinkler technology, especially early suppression fast response (ESFR) systems, is designed to actually extinguish a fire by delivering a heavy discharge of water onto the fire source. ESFR can provide adequate protection for building with plastic pallets. The cost for these new technologies may not be much more than that of the standard systems for a new installation. But the cost to upgrade an existing facility can be significant depending on what needs to be done.
In general, the fire safety issue has been seen as an advantage for the wood pallet market. But keep in mind that fire safety is just one of many issues that pallet users consider when selecting the proper packaging for a particular application.
Most local fire codes in the United States are based on consensus standards developed by the National Fire Protection Association (NFPA) and other organizations. NFPA 13, the standard covering sprinklers, is the primary basis for fire codes governing pallets used in warehouses. Different materials are given different commodity classifications, which reflect their fire hazard and the level of protection required. Commodity classifications take into account the item being stored as well as the packaging. As the commodity classification increases, so does the level of protection required to meet the NFPA standard.
Until recently, plastic pallets were out of the scope of the sprinkler standards. Some people treated them just like wood or metal pallets. But NFPA has adopted code changes that increase the commodity classification of plastic pallets by one class. There are plastic pallets that are exempt from the code change because they have been tested and proven to have a fire danger similar to wood. But these pallets can be very expensive and may not offer the same strength characteristics of more conventional plastic pallets.
The code changes in process tend to favor the UL/FM-listed plastic or wood pallets with no extra sprinkler protection. If a facility has newer technology sprinklers, the occupant may be able to switch to plastic pallets with no extra fire protection required. If a pallet manufacturer can furnish fire test data that shows its product does not increase the fire challenge, then no additional sprinkler protection may be required when using that particular pallet.
Even before the new NFPA 13 code changes, some insurance companies had been increasing the commodity classification for conventional plastic pallets by one class. Insurance companies have recognized that plastic can pose a significant challenge to older sprinkler systems and have required more protection as a result.
There are some common misconceptions about plastic pallets that need to be corrected. Many wrongly believe that plastic is more toxic than wood. But we are unaware of any research that backs up this idea. There is very little data available on the whole issue of toxicity. Both materials release toxic fumes. Prolonged exposure to smoke from either one can result in death. The materials simply release different toxic chemicals into the air. Also, toxicity may not be easy to quantify. It can depend on how complete the combustion is. The hotter a fire becomes, the less smoke it produces.
Regardless of the material, fire can weaken a pallet to the point of load failure. Although plastic does melt and puddle, both wood and metal can lose strength as well.
Reduce the Fire Hazard
Three major factors affect the fire hazard in a building — the material being stored in it, storage practices and the level of fire protection. Using or storing less flammable products in a building, upgrading sprinkler systems, or taking other preventative steps can reduce the fire hazard.
The first step is to evaluate current fire protection systems as well as the configuration of loads and the material being stored in a facility. Fire protection engineers or other independent fire experts are a wealth of knowledge and can help identify what changes may be needed to existing systems and storage practices.
Companies with newer technology may not have to upgrade at all if they decide to switch to plastic pallets. Many businesses, such as automobile manufacturers, which use considerable amounts of plastic in manufacturing, already have had to install sprinkler systems capable of extinguishing plastic pallets.
How much will a sprinkler upgrade cost? "Upgrading can range from changing sprinkler heads to completely removing the protection and starting all over again," said Hankins. When retrofitting a facility, you may need different outlets for the sprinklers, a new pump or larger pipe. This can all impact the price tag for the upgrade.
Beyond upgrading sprinklers, there are number of other ways to reduce the fire challenge including: reducing stack heights, increasing aisle widths, changing the space between unit loads, removing solid shelves and other sprinkler obstructions, and reducing ceiling clearance. One of the greatest challenges may be the storage of idle pallets. Make sure to consider your customer’s pallet storage practices. FM Global offers a data sheet (8-24: Idle Pallet Storage) covering this topic. To order a copy, visit www.fmglobal.com.
Challenges, The Future
NFPA 13 will be revised next year. The proposed changes favor either wood pallets or UL-listed plastic pallets. However, the changes do not prohibit the use of plastic pallets. They simply would require additional fire protection for non-listed plastic pallets. After NFPA adopts changes to the code, it will take some time for local authorities to enforce the new standards. Usually, there is a grace period where companies have the opportunity to comply. After the grace period ends, facilities that are not in compliance could be fined or in extreme cases conceivably shut down.
The level of enforcement can vary from place to place. Sometimes local officials do not want to press the issue when codes change. But don’t just expect your local officials to ignore pallets. The National Association of State Fire Marshals (NASFM) has targeted plastic pallets as a product to watch. NASFM’s Catastrophic Fire Prevention Task Force is studying the use of plastic pallets in warehouses. It is working with the materials handling industry, insurance companies, retailers, and others to ensure proper protection across the country.
Jim Burns, the fire marshal for the state of New York and chairman of the NASFM’s committee overseeing this issue, said, "What we have discovered is that the rate of burn of plastic pallets will probably overcome some of the older systems if people don’t upgrade their systems to meet the new standard." Others believe that the NASFM is overreacting. "One of the things that we look at is loss history...I don’t know of any major fire where plastic pallets have been a significant contributing factor," said Gandy.
Code officials may also target totes and other plastic storage containers in the near future. Currently, NFPA 13 does not cover plastic containers. But NASFM has indicated that it will evaluate them in due time.
Fire is just one variable in determining whether or not to use a particular type of pallet. In many cases, it will not be the deciding factor. From automation advantages to the elimination of expendable packaging to the reduction of total system costs, there are many other factors to consider. But fire should be factored into the equation when designing a new building or switching transit packaging.
Fire Commodity Classifications
Class 1: Noncombustible product, placed directly on wooden pallets, placed in single layer corrugated cartons.
Class 2: Noncombustible product in wooden crates, solid wood boxes, multiple-layered corrugated cartons, or equivalent combustible packaging material, with or without pallets.
Class 3: Wood, paper, natural fibers, or Group C plastics with or without cartons, boxes, or crates and with or without pallets. May contain a limited amount (5 percent by weight or volume) of Group A or Group B plastics.
Class 4: Contains itself or packaging an appreciable amount (5-15% by wt. or 5-25% by vol.) of Group A plastics. Remaining—metal, wood, paper, natural or synthetic fibers, or Group B or Group C plastics. Constructed of Group B plastics.
Group A Plastics: Highest hazard category, polyethylene, polypropylene, polystyrene. ABS, acrylic, FRP, PET, polycarbonate. Polyurethane. PVC with plasticizer greater than 20%
Group B Plastics: Cellulosics (cellulose acetate, etc.). Chloroprene rubber, certain fluoroplastics, nylon, silicone rubber. Protect as Class 4 commodity.
Group C Plastics: Fluoroplastics, PTFE (Teflon). Melamine (melamine formaldehyde.) Phenolic. PVC (polyvinyl chloride), flexible, PVCs with plasticizer less than 20%. Protect as Class 3 commodity.