The door to your process

Refrigerated plants must balance energy efficiency with sanitation concerns

They're the doors to your process , literally -- and whether you're keeping refrigerated air in or contaminants out, doors are a critical consideration for food plants, especially refrigerated plants.


A fast-rolling, seamless fabric door keeps the beer cold and fresh at Anheuser-Busch's Merrimack, N.H. brewery. Adding the corporate logo was the crowning touch. (Photo: Albany Door Systems)

One of the first choices is the level of sophistication. There are simple doors you or your product can push its way through, ones that can be opened at the push of a button or ones that can open when they see someone or something coming.

Between the heat and the insects, Florida would seem to be a difficult locale for a refrigerated seafood plant , despite the fact the Gulf of Mexico is pretty handy. The environment simply requires well-insulated doors that close rapidly, says Paul Cannon, chief refrigeration engineer at Tampa Bay Fisheries.

A refrigerated loading dock is one point where all the environmental factors meet. "We need to keep it at 35-45 degrees. But we have a lot of forklifts carrying product in and out. So we needed high-speed roller doors with good insulation," he said.

Nergeco USA, West Chester, Ohio, installed them with loops in the floor that open the doors within a few seconds of a forklift or other piece of equipment running over the sensor.

Temperature wasn't his only concern. "Another important issue was insects getting into the plant. Also, there occasionally is a lot of dust outside. So these doors have to shut as rapidly as they open."

Sanitation is another concern. "We do a cleanup every night. The vinyl fabric and other materials of construction are easy to clean. And despite their speed, there aren't a whole lot of moving parts, so maintenance has been pretty low."

Sanitation is something all door manufacturers are keenly aware of. "Your doors should be compliant with all USDA and FDA rules," says Randy Gale of Rytec Corp., Jackson, Wis. "Look for plastic or fabric materials that are durable but smooth. There should be no seams or pockets for food or bacteria to collect in. The door and its frame should be easy to wash down thoroughly."

Even further up the scale of sophistication are the doors in a Goldkist poultry plant in Sanford, N.C. Old-fashioned double-swing doors were replaced not only with high-speed ones, but with a sensing device that opens the door only for traffic perpendicular to the door, traffic that is assumed will be coming through the door.

"We have a lot of cross-traffic from forklifts running parallel to the door, but the door will not mistakenly open for them," said one plant engineer. "But make one small vertical move toward the door and it senses that change in movement and opens. It's amazing."


At the other end of the spectrum are manual doors, often double-swing units that have gravity-closing hinges that keep them closed. The only power needed to open them is the force of something going through them.

"Our doors are made to be hit. Everything passes through them," says George Rodriguez, plant manager of Morrison Meat Packers, Miami. "Everything" includes carts full of raw pork products. Rodriguez says he equates reliability with simplicity. But curtains would not be suitable, because they would rub over the entire load of pork as it passed through. Carts bang open the double-swing doors, giving the plant manager his simplicity with a minimal amount of product contact.


A folding door with clear fabric allows oncoming traffic to be seen. (Photo: Albany Door Systems)

"That means we have to wash these doors down at least once a day, sometimes twice. The plastic material is very easy to clean, and you don't have to worry about the effect the cleaning solutions will have on complicated electrical parts," he says. These simple impact traffic doors are the specialty of Chase Doors, Cincinnati.

"The main reason for these doors is insulation, and they maintain the refrigerated areas very well." Rodriguez notes that, by their very nature, the doors are literally open only as long as they absolutely need to be. He said he can't think of a more energy-efficient opening and closing process.

Cost and maintainability were Rodriguez's main concerns. "Some of these doors have been in place 10 years. They take some hard hits, and the only thing replaced on them are the gravity hinges." This very simple replacement occurs "maybe once in three or four years," the plant manager says.

The seal on a double-swing door was not energy-efficient enough for Anheuser-Busch's Merrimack, N.H. brewery, however. To maintain the 36-degree temperature critical to keeping its beer cold and fresh, the brewery replaced a bifold door with a rapid-roll seamless fabric door from Albany Door Systems, Lawrenceville, Ga.

Equipped with a two-speed motor, it operates at 5 ft. per second, avoiding accidental impacts from moving vehicles and minimizing energy loss. When closed, it provides a tight seal. Stainless steel side frames withstand harsh washdowns. Adding the corporate logo was the crowning touch.

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