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Staying Close-Minded about Doors

Wed, 01/10/2007 - 7:59am
Chris Leary, National Sales Manager, TKO Doors
Door technology and management techniques can help make your building a fortress against energy loss
Example of the kind of damage sustained by dock doors with light visibly shining through the gaps and cracks. An impact door is at the right. 

A food processing and distribution operation cannot make the mistake of assuming the doors on its docks are always completely closed, especially considering the dual roles a door has to perform.
       
When a door is open it provides truck access – and should provide ONLY truck access, rather than staying open between loads so the crew can catch fresh air. This access means the door becomes part of the overall material handling system by enabling unimpeded traffic flow between the truck and the rest of the facility.
       
When a door is closed it is part of the wall, protecting and securing building contents, insulating not only the employees but product as well and guarding against the invasion of pests. The door seals the building envelope. If the door is not completely closed it compromises the seal and can lead to problems and expense.     

New technology
Impact doors are designed to withstand the types of collisions that are common in many processing/distribution facilities.

For doorway-conscious building operations management, the latest in dock door solutions can offer the following benefits:
        • Track and door guidance hardware designs that enable doors to withstand impact.
        • Thicker, more flexible foam core panels that match the insulating qualities of the wall itself.
        • More effective door seals attached to panels, rather than jambs at the sides and bottom.
        • Elimination of wooden beams that can absorb moisture and deform the door.
        • Locks that keep the door snug against the dock floor, yet allow the doors to knockout, or automatically secure doors to the floor.    

Jeopardizing the door seal

There are two components to an effective door seal – the alignment of the door within the doorway and the condition of the gaskets around the perimeter of the door panels. Because the door is in the path of material handling vehicles the risk continually exists that the seal can be degraded by potential collisions. Any break in the seal has crucial implications for a food processing/handling facility. The major issue is energy loss, especially for lo-temp operations. A one-inch gap between the door and the doorway can lead to as much as $500 a year in energy leaving the building depending upon outside and inside temperatures and the direction the building faces.
       

View of a line of impact doors at a DC.

Energy loss leads to product quality issues. When handling sensitive product, temperature control is important in maintaining quality product and shelf life, and leaky dock doorways can have an effect on both. In busy locations staged pallets can wait on the dock an hour or more before going into the truck or the freezer.
       
The gap also brings on moisture problems. In locations where the differential can be as little as 20 degrees, the dock doors, walls, equipment and floors can turn into a condenser. The collected moisture leads to corrosion of nearby metal equipment or structures, and an increase in door panel weight. The condensation also makes the dock area less safe. Mixed with grease and grime the wetness can cause the floors to become very slick, exposing pedestrians to fall hazards.

Impact doors
Accidents in which the forklift clips the bottom panel occur with regularity in many facilities. This is referred to door sags and happens when the door springs loose tension.

For most food operations impact doors warrant serious consideration. Many food plant managers report that dock door damage is a regular occurrence and maintenance to repair the damage can run thousands of dollars for a typical dock. Often the damage can be severe enough to disable the door forcing trucks to be loaded/unloaded at other doorways on the dock. If the facility is very busy the trucks can fall behind schedule waiting for an available doorway.
       
But it is the less spectacular door accidents that put the door seal in jeopardy. On a standard dock door the roller hardware is enclosed in a sheet metal track, the slightest bump can put the door in misalignment.
       
Leak prevention is a battle of inches, and impact doors go to combat using several strategies. The basic idea behind these doors are they can be hit by a forklift and get knocked out of their guides sustaining no or very minimal damage. A quick jerk on the panel pulls the door back into working position. This solves the problem of losing a door position on the dock that can negatively impact the entire operation.
       
The design of the door also tackles the alignment problem. Spring-loaded pins direct the panel along the guide track. When the door gets hit the pins slide out of the groove cut into the track, without transmitting the force of the blow to the panel.  

Saving precious BTU’s
Depiction of how crowded a dock can become during a busy period.

To maintain door seal, the only time the door is open is when trucks are at the doorway. If the dock has made an investment in durable, snug-fitting dock seals the doorway should continue to be completely sealed. To retain every precious BTU the dockworkers must close the door just before the truck is pulling out – not after.
       
Short of a supervisor watching each time a door a truck departs, a master control panel at each doorway ensures the door is closed before the truck leaves. Proximity sensors tell the control panel the door is down before the restraint is activated to release the truck. Likewise, as a truck is pulling up to the door a light on the panel tells the worker when the truck is captured by the restraint before the door is opened. Having the door closed when trucks are not at the dock as well is an added measure of safety to prevent forklifts from accidentally falling off the dock.
       
Easy door operation contributes to the door being closed when trucks are not at the dock. Standard door alignment problems also make them more difficult to open, and when that happens dock workers will be tempted to keep the doors open between trucks to reduce the risk of back strain or out just plain neglect. Impactable doors are less prone to panel cracking, keeping the foam insulation sealed. At many docks their standard doors suffer panel cracks, letting the foam insulation absorb moisture like a sponge. As the insulation expands, so does the panel, making the door extremely difficult to open. In some cases docks have resorted to using forklifts to raise the door, running the risk of destroying the door and gaskets in the process.
       
Even though the food industry enjoyed a rollback in energy prices from the highs of this summer, everyone rationally knows that at some time they will start on their way back up. No matter what the unit price for gas or electricity, energy - whether it is for chilling product or HVAC - is still is a major part of a food processor’s budget. Both door technology and management techniques are teaming up to make the building a fortress against energy loss.

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