Double Acting Traffic Doors Provide an Entreé to Efficiency

Facilitating accessibility and screening for aesthetic and environmental effect

As a movable structure used to open and close an entrance, a door has many jobs. Doors admit people, ventilation, and light. They create privacy, distance, and space from the other aspects of a building. They keep cold or heat in or out, control the spread of dust, and noise, and provide security. In commercial applications, the list of door functions and objectives grows to include the efficient passage of people and goods, the ability to withstand moderate and heavy traffic, and the capacity to separate building functions coupled with ease of maintenance and aesthetic qualities consistent with the look of the facility.

Opening with a light assist and closing automatically in a safe, gradual manner, double acting traffic doors are one option that achieves these goals. As opposed to doors that swing one way, and open and close manually via a knob, lever, push bar, or related device, double acting traffic doors open easily in both directions, simply by pushing on them, after which they automatically return to their closed position. Used extensively in restaurant, retail, institutional, and industrial situations, double acting doors allow personnel and materials to travel more quickly between two sections of a building while acting as a separation between public and backroom operations. In commercial scenarios where bottom line considerations are key, double acting impact traffic doors represent a basic cost-effective strategy for efficient movement, while providing necessary screening functions. This article will discuss the basics of double action doors, their applications and various hinge scenarios, focusing on where and how to specify them to meet goals.

Double Acting Traffic Doors—The Basics

Double acting describes a door that swings in both directions, in and out. Because of this feature, the door always swings away from the person or load passing through it, allowing easy and safe passage. In addition to being bi-directional, double acting doors open upon impact, automatically center in the opening upon closing, and do not typically close against a door stop. Double acting doors facilitate small or very large openings by using a single panel or a double panel, or a pair configuration. In the most efficient double acting traffic doors, impact “shock” is spread throughout the door components so it is absorbed without damage. The doors open with minimal impact (typically less than 10 pounds of pressure) and then automatically return to the closed position.

Double acting traffic doors promote efficient movement while acting as a barrier for visual, sound, and environmental purposes. Photo courtesy of Eliason Corporation

Impact traffic doors are constructed utilizing a variety of core and cladding materials and construction methods. Panel cores can be wood or foam and are clad with high-pressure laminate (HPL), stainless steel, aluminum, or impact-resistant plastic. Some models feature stainless steel edge caps or internal steel reinforcements for increased durability. Some typical benefits include:

Efficiency

Because double acting doors do not close against a stop, they facilitate smooth, efficient traffic flow in either direction. There is no need to stop to open the door, operate knobs or levers. The doors simply open upon impact from personnel, hand trucks, pallet jacks, or even forklifts and then close automatically after the traffic has passed through the opening.

Physical and Psychological Screens

Double acting traffic doors act to separate various functional spaces in a facility, restricting access and screening cluttered or unsightly work areas, stockrooms, and the like. In addition to visual separation, they provide thermal and environmental separation and sound attenuation as well as a visual barrier between disparate operations that reinforces the facility's commitment to maintain an aesthetic public space for customers and patrons.

Quick Installation

As a result of pre-drilled frames that are correctly sized for the door opening and reinforced at all hinge locations, some 36-inch by 84-inch traffic doors can be installed in 30 minutes or less by one person, while other traffic doors take more than 60 minutes to install with a two-person crew—a factor that can result in a significant cost savings, particularly when numerous doors are required in one facility or in a chain with multiple facilities. By eliminating on-site drilling for the hardware, hole location errors are minimized, further reducing installation time and costs.

Energy Efficiency

Double acting doors improve efficiency and reduce energy costs as they are less likely to be propped open during loading and unloading of product in refrigerated areas such as coolers and freezers and in temperature-controlled processing areas.

Insulated double acting doors provided with perimeter gasket seals are effective in minimizing the flow of air, moisture, dust, and particulate matter through the opening. This is particularly important in temperature-controlled environments.

Applications

No one door will fit all requirements, and there are a multitude of models available on the market to suit a wide variety of applications. Cladding materials are available to match the surrounding décor and options can be applied to the door to provide protection against impact from pallets, carts, forklifts, and other traffic utilizing the opening. Vision panels can be sized and located to meet regulatory and safety needs.

Applications for Double Acting Doors

Manufacturing Facilities Between processing areas and in loading dock areas Hotels and Casinos In dining, dock, and service areas Food Processing Facilities Between processing areas, in coolers, and in dock areas Hospitals In dining facilities, walk-in coolers, and in surgical prep areas Pet Care Facilities In pet grooming and vet service areas Country Clubs, Banquet Halls Between dining and kitchen facilities and in coolers Pharmaceutical Plants In processing areas Restaurants Between kitchen and dining areas and in coolers Retail Stores Between sales floors and stockroom and in loading dock areas Supermarkets Between sales floors and stockroom in walk-in coolers and in loading dock areas

As has been mentioned, double acting doors are used primarily where a separation of areas is needed for visual, thermal, environmental, or sound control. For example, kitchens in restaurants, hotels, resorts, and institutions take advantage of the easy passage for waiters to carry food to and from the customers' dining area without having to use their hands to open the door. Retail stores use double acting doors to maintain a separation from the not-so-attractive warehouse area to the customer sales area. Gate or café-style doors are popular options in restaurant and retail environments, particularly in convenience store applications. Food markets also find the doors useful for efficient stocking from the storage areas. Perimeter gaskets allow double acting doors to be used in an area where a temperature differential exists as in walk-in coolers. See chart listing applications for double acting doors.

With restaurants, presentation is key. Double acting doors are a good choice for kitchen to dining area openings where it is important to separate the sights and sounds of the kitchen from patrons. New product options for double acting doors include flush windows and internally hidden or externally concealed hinges. Doors with internally hidden hinges are typically 1-½ inch thick overall and doors with externally concealed hinges are typically ¾ inch thick overall. A combination of flush windows and hidden or concealed hinges creates a sleek, attractive door panel suitable for upscale restaurants, banquet halls, country clubs, and hotels. The surface of the door panel is available in an almost limitless selection of HPL choices or stainless steel.

With a wide range of door construction, cladding, and custom graphic options, decorative possibilities abound. Some choose to design the look of their double acting doors simply for aesthetic appeal, while others choose a more functional approach. For example, some restaurants utilize two separate door openings allowing for one-way traffic into the kitchen through one opening and one-way traffic into the dining area through the other. In one case, a restaurant owner designed these one-way doors with red laminate on one side and green on the other so that his employees knew which door to safely pass through. With the use of vinyl overlays and silk screening, double acting doors can be designed to include logos and graphics. Sports bars, for example, have opted to incorporate images of beer bottles and sports images into their double acting doors. Double acting doors can even be built with a white board laminate so that management can remind servers to ask about dessert or to inform customers about the “special of the day.”

A whiteboard option is a welcome feature to restaurateurs. Photo courtesy of Eliason Corporation

Doors for retail environments tend to be unique, with solutions customized to a particular style from elegant to contemporary to playful. For example, a national sporting goods chain that sought a rough, rustic look to match the appearance of their distressed wooden door frames opted for a “hammered” metal finish on their double acting door. Custom graphics can work to inform and reduce maintenance costs. A national arts and crafts chain attached an “Employees Only” sticker to their traffic doors. Over time, the stickers peeled off, leaving a gummy residue on the doors. They opted to have their message silk screened on the vision panel, which proved to be more attractive and eliminated the cost and issues associated with the sticker.

Double acting doors are well suited for use in supermarkets as they open and close easily and are built to take the abuse present in sales to stockroom applications. The double acting nature of these doors maximizes efficiency as pallet after pallet of groceries and dry goods slam through these openings on a daily basis. Insulated models are frequently used in coolers as the primary door and in freezers as a secondary door.

Solutions for walk-in coolers and freezers help ease access to the cooler while complying with the Energy Independence and Security Act of 2007. For situations where there is an existing freezer door, flexible doors or strip doors can help to save energy and money when the door is open for stocking. Photo courtesy of Eliason Corporation

It is important to note here the requirements of the Federal Energy Independence and Security Act (EISA) of 2007, which became effective January 1, 2009. The purpose of the act is several fold: to move the United States toward greater energy independence and security; to increase the production of clean renewable fuels; to protect consumers; to increase the efficiency of products, buildings, and vehicles; to promote research on and deploy greenhouse gas capture and storage options; and to improve the energy performance of the federal government. To be in compliance with the act, walk-in coolers and freezers installed in the U.S. and occupying less than 3,000 square feet in floor space have to meet a new set of rules. Among them, there must be:

• Automatic door closers that firmly close all walk-in doors that have been closed to within 1 inch of full closure, with the exception of doors wider than 3 feet 9 inches or taller than 7 feet.

• Strip doors, spring hinged doors, or other method of minimizing infiltration when doors are open.

• Wall, ceiling, and door insulation of at least R-25 for coolers and R-32 for freezers.

• If the walk-in cooler/freezer has reach-in doors, it must have a window of triple-pane glass with either heat-treated reflective gas or gas fill. Alternatively, the window must comprise double-pane and heat reflective treated gas and a gas fill.

Double acting traffic doors are used extensively in supermarkets between sales and stockroom areas. Photo courtesy of Eliason Corporation

Double acting EISA-compliant cooler doors are available in several finishes, including ABS, anodized aluminum, and stainless steel. Each model is filled with CFC-free high-density urethane foam. Optional triple pane, argon gas-filled windows are available as required. As with all double acting doors, these R-25 cooler doors open upon impact and close easily, maximizing efficiency.

Hinge Choices

The service life of a double acting traffic door depends on the integrity of its hinge. No one hinge serves all applications, so it is important to make an appropriate selection based on the required function of the door. Each hinge type offers distinct features and benefits, with typical options including:

• Roller and cam gravity hinge

• V-Cam hinges (90 x 90 degree)

• V-Cam hinges (90 x 180 degree)

• Top-mounted only gravity hinges

Roller and Cam Gravity Hinge

Top-mounted hardened steel cam plate and rollers, combined with a hardened steel bottom pivot pin, create a durable and dependable hinge system that allows the door to open with minimal impact and close automatically, while offering smooth, quiet operation. Because these hinges open with minimal impact, the force required to open them is reduced, thereby minimizing damage to the door panel itself. Roller and cam gravity hinges are faster and easier to install than V-Cam double acting door hinges. Doors equipped with these hinges easily meet ADA requirements regarding the amount of force required to open a door.

This type of hinge is available in several configurations, including gate and café models and double Dutch configurations in which one door is mounted above the other to fill extremely high openings. Optional features include lower hinge guards as well as an integrated hold open feature that allows the door to be propped open for clean up or at stocking time.

Various door types are suitable for this type of hinge, including the following:

Lightweight partition doors. These doors can be fabricated from a variety of materials suitable for different applications. Material options range from .063 aluminum (tempered and anodized), 16-gauge stainless steel, or .063 anodized aluminum with a high-pressure laminate.

Solid core partition doors. Core consists of exterior grade plywood clad with aluminum (tempered and anodized), 20-gauge stainless steel, high-pressure laminates, or ABS.

Insulated partition doors. Core consists of a rigid PVC full perimeter frame filled with CFC-free urethane foam. Panel thickness options are 1.5 inches and 3.5 inches (EISA compliant). Cladding options include ABS impact-resistant thermoplastic, anodized aluminum, or stainless steel.

Rotationally molded insulated doors. The 1.5-inch-thick monolithic door panel is rotationally molded and features an outer skin made of recyclable linear low-density polyethylene (LLDPE). The core is foamed-in-place with CFC-free urethane foam for enhanced insulation properties. Internal vertical tubular steel reinforcements stabilize the panel. This type of door is suitable for retail, walk-in coolers, and light industrial applications.

V-Cam Hinges

Typically the upper V-Cam casting is ductile iron or stainless steel and features a ramp that is available in low or standard rise configurations. The roller assembly attaches to the upper hinge post and the door rises upon opening as the roller travels up the ramp in the V-Cam.

Because they offer greater resistance to opening, doors equipped with V-Cam hinges are more resistant to blowing open due to high wind or negative or positive pressure in the opening. V-Cam hinges are usually preferred when the impact traffic door will be subjected to high volume or highly abusive forklift traffic. A spring assist option is available for applications where increased resistance to opening is desired, typically where high wind or draft, or pressure conditions exist, such as on dock openings.

V-Cam hinges are typically more difficult to install as a top seal must be used and the roller assembly must be drilled and pinned to the upper hinge post. Greater impact is necessary to open these doors, but they are usually compliant with ADA opening force requirements (unless equipped with spring assist).

Typically, V-Cam hinges are available in 90- x 90-degree or 90- x 180-degree configurations. The 90-degree x 90-degree swing configuration mounts in the center of the doorjamb and allows the door to travel 90 degrees in each direction. The 90-degree x 180-degree configuration mounts on the corner of the door jamb and allows the door panel to travel 90 degrees in one direction and 180 degrees in the other direction. The 90-degree x 180-degree cam allows the door panel to literally “wrap around” the wall in one direction in applications where traffic passing through the opening makes a sharp turn before clearing the leading edge of the door. Other options include low or standard rise cams, lower hinge guards, and spring assist for high draft or pressure conditions.

Image courtesy of Eliason Corporation

Designed for heavy-duty industrial impact traffic situations, doors with V-Cam hinges are designed with a heavy-duty internal steel framework or are monolithic in design with internal steel reinforcements. Typically, the outer cladding is either ABS impact-resistant plastic or rotationally molded LLDPE. In either case, the core is foamed in place with high-density CFC-free urethane foam.

V Cam 90 x 180 options allow doors subjected to loads making sharp turns to literally “wrap around” the wall in one direction. Image courtesy of Eliason Corporation

One factor to note is that in order for traffic doors with V-Cam hinges to center properly in the opening, the supplied roll pin used to lock the roller assembly in the proper position must be installed. Otherwise, frequent adjustments may be required, as the roller assembly mounted to the upper hinge post will move as the door is impacted.

Top-Mounted Only Gravity Hinges

Top-mounted gravity-operated hinges are limited to flexible impact traffic doors. They enable the door to open easily and close automatically, allowing easy access and conserving energy. These hinges are available only on flexible double acting traffic doors. Typically, an angled steel hinge base with a welded steel hinge arm is attached to top of the door frame. The arm is then inserted in a hinge pocket on the door panel. As the door opens, it rises due to the angled bracket. Gravity then pulls the door back to its closed and centered position. There is no bottom hinge to damage or maintain.

Top-Mounted Flexible Doors

There are several types of doors that are suitable for top-mounted only gravity hinges. They include medium- and heavyweight flexible doors for retail, supermarket, commercial, and industrial applications. Typically, flexible door panels are constructed with two or more layers of colored textured vinyl, clear non-textured PVC, or nylon reinforced PVC coated material bonded back to back. In food processing and low-temperature freezer applications, a heavyweight USDA-accepted belting material is used to manufacture the door panels. Optional large vision panels maximize visibility and safety. Pairs of doors feature an overlap at center. Options include ABS, polyolefin, or PVC/acrylic impact plates and various size and shape windows.

There are no bottom hinges to install or maintain. Flexible impact traffic doors are often the best solution for those difficult applications where wide loads are passing through narrow door openings. No bottom hinge means that push carts, pallet jacks, and forklifts can easily pass through the opening. The door closes behind the traffic, minimizing the loss of refrigerated air or the infiltration of warm air into the cooler, freezer, or processing area.

Tips on How to Use Double Acting Doors

While specifying doors will depend on a variety of factors in any given situation, some rules of thumb apply to facilitate the process. Use the lightest, easiest-opening door that will survive in the application. Specify limiting posts for rigid doors that will be subjected to forklift traffic. Specify lower hinge guards for doors that will be subjected to heavy pallet jack or forklift traffic. Specify spring bumpers for heavy cart, pallet jack, or motorized traffic. The recommended minimum opening width for forklift traffic is 7 feet wide. Use flexible double acting doors for narrow openings—less than 7 feet wide—that will be subjected to wide loads or forklift traffic.

 

Top-mounted flexible doors allow maximum clearance for loads. Photo courtesy of Eliason Corporation

These doors are extremely durable, can be washed down, and allow maximum clearance for wide loads passing through narrow openings. Typical applications include food processing plants, cold storage facilities with temperatures as low as -30 degrees F, high-volume industrial settings, and shipping and receiving areas.

Specification Considerations

With the various hinges and door panel materials available, specification decisions must be carefully considered. In order to determine the appropriate type of double acting traffic door, architects must explore the following parameters.

Type of Traffic

The first factor to be explored is the type of traffic that will be using the door. Will the doors be used by pedestrians, two wheel carts, push carts, or motorized pallet jacks? Will the doors be used in areas where a temperature differential is required, like a cooler box or freezer? What are the traffic patterns—will sharp turns be made upon entering or exiting? What is the expected traffic volume? To what extent is energy efficiency a concern?

Finished Opening

The dimensions of the finished opening—the inside measurements of the doorjamb—will determine the size of the door required. All doors are available as singles or pairs, with the smallest pair typically for a 36-inch-wide opening, and the largest single door for a 48-inch-wide opening. For light traffic, a double studded 2 x 4 is adequate. For medium traffic, a reinforced hollow metal jamb should be used and for high-impact and heavy-traffic openings steel “C” channel or structural tubular steel frames are preferable.

Regulatory Requirements

Depending on the use of the door and its application, several regulatory issues may apply, including those of the USDA, the National Sanitation Foundation (NSF), and the Occupational Safety and Health Administration (OSHA). ADA requirements may apply as well, including specifications for the width of the door, placement of any hardware, size and placement of windows, and the force required to open a door.

Production Time

Time is always a critical factor in any building product. Architects should look for double acting traffic doors with a normal production time of not more than two to three weeks, unless a special laminate, custom graphic, or other unique feature is required.

Finish Material

Is durability a factor? How will the doors be cleaned—is a full wash down necessary? Most manufacturers provide a wide variety of metal clad, stainless steel, plastic or decorative laminates to meet these requirements. Are aesthetics important?

Custom finishes can reflect the personality of the facility. Image courtesy of Eliason Corporation

Optional Accessories

After the proper type of door panel and hinge type have been established, any optional accessories can be considered. The following is a list of common accessories and their applicability:

• Lower hinge guards. Recommended for pallet jack and forklift applications to protect the lower hinge area from errant loads.

• Bumpers. Heavy-duty plastic spring bumpers in various heights protect the door surface from impact from forklifts, motorized pallet jacks, and carts.

• Impact plates. Heavy-duty plastic, stainless steel, or galvanized steel plates are available in various heights to protect the door surface.

• Bumper strips. Extruded aluminum bumper strips can protect the door surface from repetitive cart traffic.

• Windows. Windows are available in various sizes and shapes. A 9-inch by 30-inch ADA-compliant window should be specified if necessary. Manufacturers are now offering a flush window option in which a double-glazed clear acrylic window is set into a pre-formed PVC inner frame. A variety of graphics are available, including logos and designs. High-impact window frames are available usually by custom order.

• Perimeter edge gasketing. This option provides a seal between door panels and between door panels and frame.

• Locks. Hasps, surface mounted deadbolts, and chain sleeves are available, with internally mounted deadbolt locks often a preference on door panels with a minimum thickness of 1-½ inches.

• Limiting posts. Steel or heavy-duty plastic posts are required on doors subjected to forklift traffic to limit the travel of the door panels beyond 90 degrees.

• Frames. Predrilled structural tube steel frames, “C” channel steel frames, and flush hollow metal frames and stainless steel frames are among the available options.

Sustainability

Architects in alignment with green building goals should determine whether candidate products can potentially contribute to the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED) points. In many cases, double acting traffic doors can earn points in the following LEED-NC (New Construction) categories.

Energy and Atmosphere
EA Prerequisite 2: Minimum Energy Performance
EA 1: Optimize Energy Performance. Double acting doors can have energy savings characteristics, such as insulating foam core assemblies with an R-factor of 25.

Materials and Resources
MR 4.1: Recycled Content. Doors with ABS material that has an allowable regrind of 20 percent can prove helpful in this category, as can hardwood or plywood core panels and LLDPE door skins that are renewable, biodegradable, and recyclable.
MR 5.1: Regional Materials. Credits are earned for materials sourced within 500 miles of the project site.
MR 6: Rapidly Renewable Materials. Hardwood and plywood panels produced from logs and veneers that are harvested from sustainable, secondary growth forests can contribute to points in this category.
MR 7: Certified Wood. Manufacturers whose hardwood and plywood supplier practices have Forest Stewardship Council (FSC) certification can be considered here.

Indoor Environmental Quality
EQ 4.1: Low-Emitting Materials. Potential qualifying materials include foam core doors filled with reactive foam that chemically formulates with a non ozone depletion potential, non global warming potential, and volatile organic compound-exempt blowing agent; green adhesives for flush windows, and zero emitting adhesives in the manufacturing process.
EQ 4.4: Low Emitting Materials Composite Wood and Agrifiber Products. Eligible materials include hardwood / plywood containing less than 0.01 ppm formaldehyde from manufacturing; and hardwood and plywood that are below CARB limits.

A product's manufacturing process itself should also be considered when evaluating its sustainability. Among the factors pointing to a green process: whether scrap metal is either recycled or used for manufacturing and fabricating small parts such as hardware covers; scrap wood products used in packaging; recycled paper and cardboard; programmable furnaces equipped with automatic off/on timers.

BIM Files for Traffic Doors

In today’s world of design-build, building information modeling (BIM) files are key to specification decisions and to improving productivity and project management. BIM allows users to simulate the different components of a building before it is built in terms of cost, schedule, performance, and other factors. Because the data is in one place and easily accessible, BIM enables building simulation, data management, and project coordination, while reducing operational costs. Increasingly, manufacturers are offering BIM files for their products. Such a file is a prepackaged 3D model that comes with substantial information for the architect, eliminating the need to sift through paper documentation, drawings, and online files. Products that are available in BIM format enable the customer to download product specifications, dimensional information, and links to the manufacturers’ website for information that may need more explanation than what is in the BIM file, this is where traditional CAD falls short. This level of information enables the architect to manage and specify characteristics that are not shown on a drawing or 3D model, and to communicate instantly with other people working on the project when a change is made.

 

Doors That Make Sense for Business

Restaurants, hotels, retail and grocery stores, industrial and pharmaceutical plants, food processing facilities and hospitals all need doors between utility and public sections of their facilities. Because they open and close with minimum effort, double acting traffic doors promote efficiency, save energy and cost, and meet various regulatory requirements. Double acting doors expedite travel between areas and provide the visual, thermal or environment separation desired between two sections of a building. With the appropriate hinge system, panel construction and hardware options, double acting traffic doors are a green, low-maintenance solution that can meet green building goals, enhance aesthetics and add to a building's operational integrity.

Eliason Corporation is a leading manufacturer of high-quality, custom traffic doors used in many applications, including restaurants, retail stores, supermarkets, and industrial facilities. Well-known for double acting traffic doors, Eliason also offers sliding, strip, FRP, and fire-rated doors, all made to exacting specifications. Committed to green manufacturing, their products can contribute to points in many LEED-NC categories. www.eliasoncorp.com