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From: Food Quality & Safety magazine, December/January 2010

The Case for Product Protection at the Dock

On the loading dock, use the proper equipment to maintain a clean, temperature-controlled environment

by Michael Brittingham

Quality is no longer just “job one,” as a popular automaker once touted. Quality is, for food manufacturers, their lifeblood. Whether it is a cold storage or dry warehouse facility, maintaining a clean, temperature-controlled environment that is ideally suited to keeping products fresh can be challenging without the proper equipment.

Temperature control along the supply chain is crucial to maintaining product quality and the safety of frozen and chilled products. Just the softening of product edges can be an invitation for bacterial growth. Though thawing may not necessarily lead to a harmful product, it can affect quality.

For both food service companies and grocers, the other crucial issue is quality perception. Once frozen food thaws and refreezes, cell walls break down, making the product mushy and telling the consumer that something is wrong with the food. According to Rich Barthel, general manager for the Koch Foods Inc. facility in Franklin Park, Ill., “to us and our customers, a bulging box is a damaged box.” To eliminate the risk of the perception of poor quality, many manufacturers toss out all questionable products along with the profits they might have generated.

Dock Door a Major Air Vent

Dock doorways, such as those at Fieldale Farms, are covered and accessible by impactable doors, which release from their guides when hit, yet are easily reset and back in operation in seconds.
Dock doorways, such as those at Fieldale Farms, are covered and accessible by impactable doors, which release from their guides when hit, yet are easily reset and back in operation in seconds.

From the field to the table, the food chain has many links that can affect product quality, and the loading dock is no exception. The dock door can be a major vent for air to escape from the building during loading/unloading. Worse, a closed dock door may not really be closed, allowing energy loss or air infiltration even when not in use.

The invasion of warm outside air through any cracks in the building seal is also a threat for chilled operations, making it more difficult for the DC refrigeration system to keep temperatures at specified levels.

One meat packer points out that as warm air works its way into the dock, it is drawn through the refrigeration coils, threatening ice build-up. The system has to interrupt the cooling cycle to run hot gas through the coils to defrost them, a process that takes about 45 minutes.

Several factors can cause a refrigeration system to labor, and the expense can be considerable. A one-inch gap around a dock leveler pit or dock door can mean the use of approximately one additional ton of refrigerant a year, an additional expense of about $800.

The threat to product quality, however, is not confined to warm weather months. Anderson-Dubose, located in Carnegie, Pa., is a distributor for a major national restaurant chain. Fast food is becoming healthier, and that means an array of salads and other fresh items. Mark Latsko, manager of operations for Anderson-Dubose/Carnegie, points out that product quality is susceptible to cold temperatures as well. “The weather here in western Pennsylvania can dip below zero for a week to 10 days. With salads, tomatoes, fruits, and other produce coming in here, the dock has to be kept above 32°F.”

Temperature control along the supply chain is crucial to maintaining product quality and the safety of frozen and chilled products. Just the softening of product edges can be an invitation for bacterial growth.

At one time, Anderson-Dubose had to rent portable heaters to keep the temperature up. “That creates a safety hazard and additional energy costs, whether we are using electricity or kerosene, as we did during one power outage,” Latsko says.

Dock Doorway the Greatest Threat

The doorway provides the greatest threat of energy loss and air infiltration in the building. A dock can have anywhere from four dock doors for a food processor to dozens of doorways at a distribution center.

A typical door is 8’ x 10’, a rather big opening for air to flow through. Even a closed doorway can present a risk to both food quality and energy conservation programs.

The problem starts with the doors themselves. Unlike the more complex refrigeration, material handling, or processing systems, doors are often given little consideration either from management or the forklift drivers that operate around them.

Standard dock doors, which are similar to the doors on a home garage, cannot withstand the often abusive world of the loading dock. If a forklift drives into a door or the forklift mast clips the bottom panel when the door is raised, a standard dock door will likely be damaged.

Vertical levelers store upright to protect doorways from forklift collisions and attach to the floor, eliminating the need to cut an energy-wasting pit into the dock.
Vertical levelers store upright to protect doorways from forklift collisions and attach to the floor, eliminating the need to cut an energy-wasting pit into the dock.

The door guidance system is also no match for a forklift. Again, much like a home garage door, the door panels attach to mushroom-shaped rollers that run along a sheet metal track, which can be hammered out of shape when hit by a forklift.

Two problems tend to occur. The pounding sustained by the doors forces them out of alignment, forming energy-robbing gaps between the doorframe and the door. Meanwhile, the impact on the tracks closes them around the rollers, making the door hard to open and tempting workers to save their backs by leaving the doors open as one truck leaves and another approaches the dock, leading to a massive loss of conditioned air.

Impactable Dock Doors

A growing number of food docks are combating this problem with impactable dock doors. While impactable bottom panels and other partially impactable or “flexible panel” systems are also available, fully impactable dock doors can take the abuse anywhere on the door or track.

Impactable dock doors are designed with spring-loaded plungers on each door panel that retract when hit, releasing them from the guide tracks rather than resisting the force and causing damage. These same doors are designed with impactable tracks, which, unlike conventional steel tracks, can take a direct forklift impact without suffering any damage. Additionally, with fully impactable doors, the door seal is attached to the door panels, not the track, so the seal travels up with the door—and out of harm’s way—during loading.

The other drawback of standard dock doors is that the metal panels and track can conduct heat into the building, causing moisture to form around the dock, which then becomes a bacteria breeding area. Impactable doors can be equipped with plastic tracks, which do not conduct heat, keeping moisture off the dock area.

Even with an impactable dock door, energy can escape through the gaps between the dock leveler platform and the concrete pit cut into the dock floor beneath the leveler. Vertical storing dock levelers are a remedy. Vertical levelers provide the same bridge into trailers as traditional dock levelers, but they do not need a traditional pit cut into the floor for installation. And because they store upright, vertical levelers allow the door to close tight against the warehouse floor, sealing off any gaps.

Dock Seals Are Critical

Powered truck restraints maintain a firm grip on truck trailers to prevent separation from the dock that could affect both safety and energy retention.
Powered truck restraints maintain a firm grip on truck trailers to prevent separation from the dock that could affect both safety and energy retention.

Dock seals are critically important to maintaining dock-doorway seals. As with damaged dock doors, a poorly specified seal or shelter allows moisture and air to infiltrate.

Dock seals have fabric-covered foam pads that compress when a trailer backs into them to provide a tight seal around the sides of the trailer as well as to seal off the gaps between the trailer’s door hinges. Dock shelters consist of fabric attached to side/head frames to create a canopy around the full perimeter of the trailer while allowing full, unimpeded access to the interior of the trailer.

Galvanized steel backing offers many advantages over the wood backing that is used on some models. Wood backing has a solid mass (1 1/2” thick) that does not yield when the seal is compressed, often leading to building damage. On steel backing, the solid mass is replaced with compressible foam on a steel frame. Steel backing also offers superior durability: It does not rot, split, crack, or warp. In addition, steel backing uses plated screws with load-spreading washers to provide a stronger, more durable hold on the fabric.

Though largely regarded as a safety device, the vehicle restraint also plays a role in helping to seal the dock doorway. Many food-handling docks use rubber wheel chocks to hold trucks in place during loading/unloading; however, rubber chocks are no match for the forces exerted by forklifts driving in and out of trailers. This force can gradually cause a trailer to “walk” away from the dock, forming a doorway gap. A powered truck restraint ensures that the trailer is held snugly to the dock, with the back end of the trailer fully enveloped by the dock seal.

Demands for product quality in light of recent recalls are causing consumers and purveyors alike to be more mindful of all elements that contribute to that quality. “We are held strictly accountable at all points along the supply chain, and all our customers have the highest quality standards,” Barthel says. “To that end, we are working to be sure we do not have dock doors weeping warm air or the dock area dripping with condensation so that we can assure our customers that we have a clean environment.”

Temperature control along the food supply chain is crucial to maintaining product quality, and consideration of unconventional loading dock equipment specifically designed to address the unique challenges faced by this industry is a quality commitment that all consumers can appreciate. ■

Brittingham is marketing communications manager for 4Front Engineered Solutions. Reach him at sales@4frontes.com.

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