The features of these wind-load doors are similar to those on standard impactable doors mentioned earlier that can help prevent moisture infiltration and subsequently slips and falls, with an extra layer of protection. They include:
- heavy-duty, retractable plungers;
- an impactable track;
- damage-resistant panels with polycarbonate skin; and
- slide locks with lock-out pins.
The damage-resistant panels with polycarbonate skin also guard against damage from flying debris and materials, as well as provide a layer of ultraviolet (UV) protection from the sun’s harmful rays that can weaken the door panels.
The high-density impactable tracks mounted flush to the jambs are another part of these wind-load-rated impactable assemblies, which enable the door to remain attached to the wall. Unlike standard door tracks, the high-density tracks fight off the most abusive forklift impacts on the inside, while providing the necessary strength to withstand negative and positive wind pressures on the outside during a storm.
With regard to wind storms, negative wind pressures are a particular issue with overhead doors in general. To combat these forces, wind load-rated impactable doors have multiple slide-locks mounted securely to a steel plate on the panels. As a storm approaches, the crew can engage the slide locks into holes along the height of the guide track and secure with a pin attached to the tracks. This is an extremely important consideration in facilities that have a large number of these doors with limited time and resources to prepare for a high-wind event. As a way to combat these high-wind events, rigorous testing establishes whether a door design meets static air pressure resistance.
Canadian Standards Association (CSA) Group works with manufacturers and key industry associations to develop and maintain harmonized standards that help meet the needs of the North American market. It tests requirements per the American National Standards Institute/Door and Access Systems Manufactures Association (ANSI/DASMA) 108, Standard Method for Testing Sectional Garage Doors and Rolling Doors: Determination of Structural Performance Under Uniform Static Air Pressure Difference, or ASTM E330, Standard Test Method for Structural Performance of Exterior Windows, Doors, Skylights, and Curtain Walls by Uniform Static Air Pressure Difference.
Though static air pressure (positive and negative) is one issue (measured in lb/sf or Pascals), some localities require door testing to determine the ability to resist penetration of airborne debris. The testing involves hundreds of simulated wind gusts and impacts from a 2×4 stud shot from a cannon at 15.24 m (50 ft) per second.
Essentially, testing has determined these impactable door designs meet even the most stringent building codes, such as those enacted by the state of Florida after Hurricane Andrew in 1992.
The same door panels, which stand up to the forceful impact of speeding forklifts carrying heavy loads, were able to pass the wind gust and projectile tests and still provide coverage for the doorway. To provide additional assurance to overcome these forces, there is a flexible tubular frame reinforced with a steel angle inside the panels.
Warehouses and other facilities throughout Canada face the potential of damage in varying degrees, ranging from extreme weather events to normal wear and tear of everyday operation. However, innovative and stringently-tested impactable doors can help distribution and warehouse facilities of all sizes reduce worker slip-and-fall injuries, realize reduced property damage from extreme weather, and maintain a more secure loading dock, minimizing disruption of the supply chain.
Steve Kalbfleisch has almost 25 years of experience in loading dock equipment sales and service. He currently serves as Canadian sales director of industrial door and docking solutions for Assa Abloy Entrance Systems in Mississauga, Ont. Kalbfleisch can be contacted by e-mail at email@example.com.