Flame-Retardant Pallets

March 1, 2003
If youre contemplating the switch to plastic pallets, or have already done so, and youve heard the stories about higher insurance premiums because of

If you’re contemplating the switch to plastic pallets, or have already done so, and you’ve heard the stories about higher insurance premiums because of fire potential, here’s the full story. Recently, Larry Porter, manufacturing market manager at Buckhorn, talked with me about the fire issue and what it takes to create a flame-retardant pallet.

It’s estimated that there are 48 million plastic pallets at work today. The estimated number of wood pallets is upward of 500 million. Nothing sets off a fire marshal quicker than the sight of plastic pallets in a warehouse.

Bill Tomes, chairman, TVA Fire & Life Safety Inc., says there is a plethora of National Fire Prevention Association (NFPA) standards in practice and development; however, the key to understanding the issue seems to be education.

“A single company, because of the global nature of business today,” explains Tomes, a former fire marshal, “will deal with many state and local fire codes, all of which vary. And the people enforcing those codes can vary as widely.”

The truth of the matter, says Tomes, is that many fire marshals have little or no training. “Some are local fire protection engineers,” he says, “and the better ones have attended local, possibly national, NFPA classes.”

Porter echoes this concern about warehouses that use plastic pallets being at the mercy of the local fire marshal.

“The key issue with plastic, versus wood,” explains Porter, “is that when plastic burns, it places a higher demand on the building’s sprinkler system.” Historically, sprinkler systems have been designed assuming the pallets in the building will be wood, not plastic. Porter says many of the newer-designed buildings have a higher level of sprinkler protection.

What many fire marshals do not recognize is that existing fire protection codes provide an exemption for plastic pallets that present a hazard “equal to or less than that presented by idle wood pallets.” Exempt pallets, such as those listed by Underwriters Laboratory (UL), must meet its 2335 classification for flammability.

Flame-retardant pallets on the market today offer a burning rate equivalent to wood pallets, in some cases even better when various species of wood are compared. However, you pay a premium in terms of cost, an estimated 25 percent to 35 percent up-charge.

“Often our customers know nothing about the issue of plastic pallets causing an increase in insurance premiums [or having a higher commodity rating] until they see the bill,” says Porter. As a result, much of Porter’s efforts go into educating the customer and local authorities.

When a company gets a notice from the fire marshal, or larger bill from the insurance company, it has a problem and few solutions. It can upgrade its sprinkler system to cover the increased hazard, buy a flame-retardant pallet; designate an exterior storage area, or retreat from plastic pallets altogether.

Pallet development

The development of a flame-retardant pallet at Buckhorn represented a team effort that reached beyond the walls of the building. It involved various resin makers, fire-retardant compound makers and others. While the size of the team fluctuated, Porter says it averaged about eight people working intensely for at least eight months.

Much of the development process is proprietary; however, one key thing that had to be considered was determining the amount of flame-retardancy material to be added to existing pallet formulas. “Building a flame-retardant pallet is one thing,” says Porter. “Building one that would meet UL requirements is something else.”

Once the level of flame-retardancy material was determined, the impact of that material on the pallet’s composition had to be measured. Would it change the physical properties of the pallet?

“Finding the best formula for a pallet that would maintain the performance criteria we’d established,” says Porter, “ and offer flame retardancy, was the objective.”

Plenty of pallet designs went up in smoke. And you can’t build just one and test it. Just for the final UL test, 200 pallets were made. Porter estimates more than twice that many were actually built for testing before the final UL test for certification.

Flame-retardancy compounds add about 10 pounds to the weight of a pallet. The compound is mixed before it is added to the high-density polyethylene (HDPE) used in the pallets.

Testing process

A point to keep in mind if you’re considering plastic pallets, says Kevin Faltin of UL, is that the pallet, not the material, is the item that is certified. One reason the number of configurations of flame-retardant pallets is so limited is that manufacturers must go through an excruciating, expensive testing procedure with each size they wish to offer. Porter says the reason each configuration must be tested is because fire is dynamic. It responds differently in each situation.

I watched two tests at the UL laboratory that were done on Buckhorn’s pallets. The first was a test of pallets as they might be found in idle storage. As we entered the massive UL burn room, an army of more than 170 pallets stood bravely in a half-dozen 12-foot-high columns in the center of the room. As UL folks busied about their tasks, test procedures were reviewed and hoped-for results explained.

The fire was ignited. Flames started slowly, creeping up the chimney created by the pallets. Quickly, flames shot from the top of the stack, then through stringers and deck boards. Dense black smoke, looking as deadly and toxic as it was, curled and rolled across the ceiling so close to the observation room windows I could reach out and touch it.

Suddenly, four K-11 sprinkler heads deployed. Water sprayed in all directions and knocked down the smoke and flames. When I lost visual contact with the fire, I swiveled to the bank of monitors overhead in our safe room. Engineers watched data stream in from sensors placed throughout the burn room. I was transfixed as spectral, infrared images, transmitted onto the screens, appeared as firemen walking through billowing smoke.

It was mid-afternoon before we re-entered the burn room. Firefighters had hosed the mountain of pallets, washed the floor and moved on. A lift truck separated columns of burned pallets so we could look inside. The first thing we noted was no puddle of plastic. In this test you can burn but you can't run. Next, except for some disfigurement and serious charring on the faces of pallets nearest the ignition point, pallets were in remarkable condition.

The commodity test was more realistic. It involved burning pallets in racks, with cartons in place. Again, smoke billowed from the fire as corrugated and plastic ignited. Along with the firefighters, we watched and waited until the fire ran it’s course.

What you need to know

The Reusable Plastic Container & Pallet Association (RPCPA), a product section within Material Handling Industry of America, has been working to establish NFPA standards. Its task force on fire safety sponsored burn tests and submitted data to NFPA more than a year ago.

Using a variety of types of plastic pallets, tests were conducted at UL’ s facility to determine burn characteristics of different pallet configurations and material.

While the results of these tests were mixed, it was enough to show that plastic pallets should not be rated higher than one commodity classification. Flame-retardant pallets have an equivalency with wood.

“NFPA revises its standards on a five-year cycle,” explains Porter, “so we had an opportunity to submit changes to its proposals.”

RPCPA offers a brochure, Fire Protection Resources, that discusses economic benefits of plastic pallets and other pertinent information. For a copy, contact RPCPA at www.mhia.org/rpcpa.

Porter notes that if you’re considering flame-retardant pallets, performance is a key issue. Building a flame-retardant pallet is more than just adding components to the mix. The chemicals used to create the retardancy can change the performance characteristics as well.

Ask a potential supplier for results from impact tests of flame-retardant pallets. Impact resistance changes when flame-retardant compounds are added to the mix.

“Another thing to ask for,” says Porter, “is the results of UL testing. UL provides only a pass/fail certification.” The actual test results are not made public.

Even after rock-solid standards are established and all the fire marshals trained, dealing with plastic pallets in the warehouse, even testing pallets under controlled laboratory conditions, will be a challenge. The key variable is the fire itself. It is dynamic. There’s no sure way of predicting how it will react. The best you can do is be prepared.

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