This article originally appeared in Food Manufacturing's Jan/Feb print issue.
Over the past year, the buzz in the food industry has been that sales of frozen food have experienced a slight drop at around 3 percent, with many consumers switching over to fresh food. Despite this changeover in the market basket, a lot of the country’s food is still produced and packaged under low-temperature conditions.
So no matter if food is frozen or fresh, keeping the operation cold throughout the product handling chain is important for maintaining quality and avoiding failures that threaten a company’s market reputation. Yet protecting product also requires making sure the plant wastes as little of the cold air it generates as possible.
For these conditions it’s necessary to consider high-speed doors, typically those featuring a roll-up style design and operating at speeds over 60 inches per second. Just about every processor is a high-volume operation and doors have to get out of the way so that product can move quickly from room to room to boost profitability and get food out to market. Thanks to this rapid operation and the design of these doors, there are five reasons why high-speed doors can meet the goals of getting product safely into the freezer case or onto the produce rack while using minimal energy to do it.
1. Minimizing Room Exposure
When it comes to doors, the industry’s traditional mindset has focused on heat transfer between rooms – the thicker the door panel the better. But big and heavy means a ponderous door that takes longer to open, resulting in more air infiltration out of the cold room. The refrigeration system has to work harder to make up the difference to bring the cooler/freezer room below the maximum temperature allowed.
A system unable to keep up with the lost cold air threatens product quality and the operating budget. According to Steve Daniels, Facilities Engineer with Milwaukee-based Palermo’s Pizza, “with the old style doors, we lose at least seven to eight tons of refrigeration in a year.”
A recent study by the Door and Access Systems Manufacturers Association found that if a door is used frequently, panel thickness and heat transfer become less of a factor. In a typical operation – especially those running at least two shifts a day – the door can be cycled hundreds of times.
Slow-operating doors might do a better job of preventing a room from getting warmer when closed, but they do little good for high-traffic doorways. If traffic accesses the doorway frequently, the slower door leaves the opening exposed much longer than a high-speed rollup door and cancels out the benefits of an insulated panel. Rapid operating doors open in seconds, giving little time for cold air to escape and trapping more cold air in the chilled/freezer room.
“With the high-speed doors I’m using less refrigerant in the freezer than what I had before,” says Daniels of Palermo's.
Though the fabric panel on a typical roll-up door is not intended to impede heat transfer, roll-up doors can include an insulated panel for freezer applications. Along with adding to the energy-saving benefits, these doors can operate as fast as standard roll-up doors.
2. Providing a Tight Seal
Each time a door opens, the risk exists that a panel will be hit by passing traffic. When it comes to slow-operating doors, these collisions can happen frequently.
Even if the door is not totally disabled, the panel will most likely be misaligned with gaps created between it and the doorframe. The door’s gasket seal is generally attached on the panel, and it can be torn off as a forklift truck moves through the doorway. These gaps in the seal can result in the loss of thousands of dollars of energy annually and make it difficult to keep room temperatures within spec.
If that door is damaged, the energy loss and threat to product quality can be considerable while the facility waits for the repair crew. There is likely to be collateral damage to the operation schedule, since there is limited doorway access to many chilled/freezer rooms.
High-speed doors are too fast for vehicles to make contact and cause damage. If a collision should ever happen and the roll-up curtain is displaced from its guides, it’s easy to fix. Most high-speed doors have a self-repairing feature that enables the door to be back in business by simply activating the door. The door rolls its curtain up and then feeds it back down into the guides.
In addition, roll-up design provides for a tight, full-perimeter seal. The doors’ side columns protect roll-up door side seals. Brush seals along the top of the panels and soft seal bottom guides on some models hug the contours of the floor.
3. Keeping Microorganisms in Their Place
When product arrives, it can be loaded with microorganisms, even if the supplier has painstakingly washed it down. Just the journey alone can expose product to contamination.
According to significant research, sensitive food product can be exposed to any number of contaminants at critical control points (CCP) – the areas where contaminations occur. Rather than just making themselves comfortable in the area where they sprout, contaminants move along with the process as product moves from room to room, with some help from positive/negative air pressures.
Installation of recirculating air infiltration units, constant monitoring, consistent room temperatures and limiting employee traffic are among the many means to reduce contamination throughout the route to the shipping dock. Though total confinement of pathogens to their place of origin is beyond practicality, proper door selection and application can ensure that food travels through the plant safely and that an unacceptable level of the microorganisms does not.
Simple practices, such as keeping doors closed, can be essential in controlling air contamination. That’s easier said than done. Doors that experience heavy traffic suffer from maintenance issues that arise from frequent usage and from damage caused by inevitable crashes. Deficiencies in door design can mean that even when the door is closed, contaminants still find their way through.
According to Dr. A.J. Heber of Purdue University's Department of Agriculture and Biological Engineering, the dispersal of contaminants in the form of bioaerosol emissions can be carried throughout a processing plant via airflow through doorways and other openings. Both the minimal doorway exposure time and tight seal offered by high-speed doors can reduce the flow of pathogens through the material handling system.
4. Controlling the Airborne Debris Invasion
Just as with organic contaminants, the air system can carry dust into the operation, creating another problem for a chiller/freezer operation. If these particles find their way into the refrigeration system, efficiency suffers along with the energy bill and possibly the room temperature. High-speed doors can protect the refrigeration system from this invasion by reducing the flow of debris.
5. Garbage Out But Not Garbage In
All food-handling operations have a waste disposal area and though compactors and dumpsters might be at the tail end of the process, extreme temperatures, humidity, and contaminants can find their way back into the processing line. High-speed doors can dispose of these threats and keep them to a minimum, while enhancing the comfort and productivity of the workers in the vicinity of this least desirable part of the process.
High-speed doors, along with keeping a food processing operation’s energy bills low and their market reputation intact, greatly enhance an operation’s efficiency and material handling equipment return on investment. The minimal time for energy loss at the doorway also means less time spent waiting for the door to open. These seconds per cycle saved over a year results in a considerable number of hours saved. With these combined benefits, the investment in high-speed doors is well worth considering.
Rytec is the nation’s leading manufacturer of high-speed, high-performance doors for industrial, commercial, and cold-storage environments. From security doors to traffic doors, every door addresses a specific operational and environmental challenge, and is engineered for maximum safety, productivity, and efficiency. Corporate offices and manufacturing operations are headquartered in Jackson, Wisconsin. Customer support is provided through national and regional offices and a network of local dealers and installers throughout North America. www.rytecdoors.com