Serious Safety Threat Revealed in Loading Dock Fires at U.S. Plants

The risk of burn damage to dock seal headers is virtually eliminated by a triple layer of heat dissipating and reflective foil sandwiched between the fabric layers surrounding the foam core of the Firefighter head pad.

Facility managers are aware that the loading dock is an inherently dangerous environment where the risk of accidents is high. What most don’t know, however, is that the compression-style foam seals used to guard against the outside elements and save energy costs at the dock can pose a fire threat. It’s hard to imagine that a foam dock seal can also be a fire hazard but there should be no mistake that the threat is serious. What’s more, thousands of docks are at risk. Here’s why it’s happening and what facility managers need to know to protect against the threat of a loading dock fire.

Fire Threat Comes to Light

Although they’ve been on the rise, loading dock fires are not new. Instead, it’s a problem that no one recognized as a legitimate safety issue –- until recently.

Based on years of field research, Frommelt Products Corporation has confirmed that hundreds of damaged dock seals have been burned to varying degrees by a surprising source. Previously, some of the damage had been mistakenly diagnosed as the result of normal wear and tear that occurs when a trailer is parked at the dock being loaded or unloaded. In other instances, the cause of severe burning was reported as “cause unknown,” or “arson,” as the real cause was a mystery.

In the late 1990s, Frommelt conducted research to identify the cause of the problem and a possible solution. The company identified what has proven to be a dangerous trend. Since 2001, Frommelt identified nearly 200 burned dock seal incidents at facilities across North America.

The fire hazard involves dock seals and semi-trailer marker lights. The problem occurs when energized semi-trailer marker lights are compressed against any make or model of compression-style foam dock seal, often creating a safety threat that can result in extensive damage to buildings, trailers and trailer contents. The number of fire incidents continues to grow as Frommelt receives reports of loading dock fires. The risk is also widespread, based on an estimate that over 200,000 U.S. dock positions are equipped with the type of dock enclosures most likely to burn.

Multiple Factors Contribute to Risk

Dock seal fires can cause extensive damage to seals and building walls, and in some cases, can lead to the total destruction of a parked trailer and its contents.

No single culprit is responsible for loading dock fires, which is one of the reasons why the problem has gone unchecked. Detailed tests have led Frommelt to understand that many factors are involved. Clearly, however, one factor stands out –- trailers docked while running, with their lights left energized, are at the root of the problem.

Tests conducted verified the mechanism by which low wattage bulbs in trailer marker lights can create the high temperatures needed to melt or burn vinyl, hypalon and polyurethane foam –- the components of typical compression-style foam dock seals.

Tests showed heat output of individual marker lights will build to a high temperature in a concentrated area due to the insulating effect of being compressed into a foam dock seal pad over a period of time. Additionally, research also indicates that, while trucks are manufactured with standard 12-volt single alternator electrical systems, it’s common for trucks to be fitted with secondary alternators. The additional alternators provide the extra power for appliances often found in sleeper cabs. The two-alternator systems produce a 14-volt output in most conditions. While this is not a cause of the problem by itself, it does impact the speed of the process.

Testing under these conditions revealed that undamaged trailer marker lights compressed against a foam dock seal can create temperatures at the seal/trailer interface that are in excess of 900°F, which is well above the auto-ignition point of polyurethane foam. The extreme temperatures can be reached in 20 minutes. Finally, research and testing showed that polyurethane foam can combust, or “auto-ignite,” at temperatures exceeding 800°F when exposed to a large quantity of oxygen –- like that from the air drawn into the header foam of a dock seal when a parked trailer leaves the dock. The end result can be a head pad that is engulfed in flames in minutes.

Polyurethane foam can combust, or "auto-ignite," at temperatures exceeding 800°F when exposed to a large quantity of oxygen -- like that from the air drawn into the header foam of a dock seal when a parked trailer leaves the dock. The end result can be a head pad that is engulfed in flames in minutes.

Virtually all dock seal manufacturers offer fire retardant fabric and foam components in their dock seals. These materials, however, do not protect the seal components themselves from damage. Instead, they are designed to “self-extinguish” after igniting to prevent the spread of fire. By definition, fire retardant materials must begin burning first in order to work. That means dock seal fire damage can occur even if the fire retardant materials are used.

Dock seals with heat dissipation technology, on the other hand, prevent the rise of temperatures to dangerous levels, so that dock seal materials will not catch fire from the heat of trailer marker lights. Dock seal heat dissipation technology limits marker light temperature buildup to a maximum of 400°F. As such, it prevents burning of the foam and fabric components under these conditions. The result is protection not only against the spread of fire, but also the start of a fire, since the temperature is kept at a level that is far below the auto-ignition point of 800°F.

Frommelt Products Corporation,

8900 N. Arbon Dr., P.O. Box 23043, Milwaukee, WI 53223-0043

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