Modern air curtains conserve energy, maintain comfort
Block air movement, invisibly
From the time we were children, we remember being told, “Close the door. We can’t heat the whole outdoors!” That problem is acute in manufacturing, warehousing, and shipping operations. Outside doors on loading docks, or passages between manufacturing and warehouse areas are sources of huge potential energy losses. Yet safe and rapid passage of pedestrians, lift trucks and even conveyors through those openings is essential. Various approaches have been tried, but one of the most attractive is the use of modern air curtains, sometimes called air barriers.
Problems with Open Doors
Most manufacturing operations require frequent movement of pedestrians and vehicles between spaces with differing environmental conditions. It might be lift truck traffic between the manufacturing floor and warehouse or outdoor storage for parts, supplies or finished products. It might be loading docks for rail or truck access. It could even be wall openings for conveyor transfer of manufacturing inputs or outputs. In some industries, there is also a need for frequent traffic into and out of refrigerated or freezer areas.
The problem is that all of those openings allow the escape of conditioned air, and entry of undesired elements including dust, fumes or insects. Conventional doors are impractical because of traffic volume and because of the need for visual contact between areas for safety reasons. An approach that is sometimes used is suspended clear vinyl strips that push aside for vehicle or pedestrian passage. Although initially somewhat transparent, these strips quickly become scratched or clouded and visibility through the opening is lost, creating a safety hazard. Vinyl strips are also subject to damage by passing vehicles, so maintenance expense can be high.
Air Curtains -- A Better Way
An alternative approach increasingly being adopted is the use of air curtains. These create an invisible barrier across openings while not impairing safety or quick passage of pedestrians and vehicles. The air curtain uses a high-speed laminar flow of air across the opening to effectively block air flow from either direction.
Dan Hallihan is the National Sales Manager for Enershield Industries of Edmonton, Alberta. He explains that the barrier is mounted as close to the door opening as possible. “It takes facility air and disperses it across the doorway to create a 90% efficient barrier that prevents outside air from infiltrating in and inside air from escaping.” He recommends that for facilities that are trying to stop cold outside air from infiltrating, the air barrier be installed horizontally across the door opening so that it can pull waste heat from the ceiling area and recirculate it back into the facility.
He notes that the Enershield system uses a nozzle that spans the full height or width of the doorway and can be angled as much as 25 degrees outward. Hallihan advises, “The angling of the nozzle is crucial in offering resistance to any outside air trying to penetrate the doorway.” The air barrier uses the facility air to create a wind shear effect on the doorway, sealing the opening efficiently. For applications that do not have adequate head-room above the doorway for horizontal installations, the units can be installed vertically and be just as effective.
Steve Benes is the Sales Manager for Berner International Corp., another major manufacturer of these devices. He notes, “The demand for air curtains continues to grow as North American manufacturing companies look for cost effective solutions and products to save energy or create a more comfortable environment for their employees or clientele.”
Benes explains that with the use of various types of mounting brackets and accessories, most existing openings can accommodate the addition of air curtains. He points out, “The most common obstruction to the installation of an air curtain is the placement of the hardware for a roll-up garage door. We provide several options for our customers to solve this. Our air curtain systems are compatible for new construction as well as retrofit applications.”
A Clearer View
An important feature of the air curtain system is that it provides a clear view across the opening, helping to eliminate safety hazards from vehicle operators not seeing oncoming or crossing pedestrian or vehicle traffic. Where they are installed on multiple doors on loading docks, they typically turn on automatically when the overhead door is opened and shut off when it closes.
In many locations, preventing entry of outdoor insects is a high priority. This is a special concern for food processing or food service businesses. Benes notes that the U.S. EPA recommends the use of air curtains for integrated pest management (IPM) programs as a viable alternative to the use of pesticides. An application with which many are familiar is the use of air curtains across the windows in fast-food drive-up operations.
Built to Last
Air barrier equipment is built to provide long service with minimum maintenance. Most standard models have welded frame and powder-painted surface. Manufacturers offer models for harsh climate conditions and for areas that require frequent washdowns. According to Julie Konowitz from Mars Air Systems, their air curtains keep their effectiveness through their entire operating life.
She notes that Mars provides architects, engineers and food service consultants with a comprehensive line of air curtains and air door products. “This is achieved while giving building owners peace of mind of a reliable product and dedicated support. Our newest product line, the Series 2, includes slimmer units, updated colors, and a sleek new design for everything from a drive-thru window to a lobby entrance to warehouse loading dock doors.”
Konowitz indicates that there is growing acceptance of efficiency and effectiveness of air curtains in the food processing and general manufacturing industries, focusing on energy savings and sanitation management. She says that many times the installations are aftermarket applications where a solution is urgently needed for temperature control or to inhibit airborne contaminants. If your facility is struggling with any of these challenges, it may be time to consider today’s efficient air curtain solution.
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After almost a decade of uncertainty, the confidence of plant floor managers is soaring. Even with a number of challenges and while implementing new technologies, there is a renewed sense of optimism among plant managers about their business and their future.
The respondents to the 2014 Plant Engineering Salary Survey come from throughout the U.S. and serve a variety of industries, but they are uniform in their optimism about manufacturing. This year’s survey found 79% consider manufacturing a secure career. That’s up from 75% in 2013 and significantly higher than the 63% figure when Plant Engineering first started asking that question a decade ago.