INDUSTRIAL doors are essential equipment for controlling a factory’s environment and maintaining its security. In busy operations, these requirements must also be balanced with speed and worker safety.
DMF International’s sales director, Mark Fell told Manufacturers’ Monthly doors must be capable of opening and closing at high speeds to preserve internal environments.
“Where there’s a lot of traffic going from one area to another, and one area is air conditioned but the other area is not, doors can control the environment between the two areas,” he said.
In addition to rapid roller doors, which are widely employed, Fell says bi-flex doors have also been recently introduced.
“The new bi-flex door works on a concertina action; it opens sideways,” he said.
“They’re less expensive for one and you’ve got full opening height as soon as the door starts to open. You can also walk through without the need for opening it and it allows a controlled environment on either side of the opening.”
Fell said bi-flex doors and rapid roller doors had similar opening speeds of between one metre and 1.2m a second, with closing speeds around half that rate.
The maintenance required for each door style was also similar, he said.
Both bi-flex doors and rapid roller doors are typically made from soft PVC materials, and are not designed for security.
“The rapid roller door will provide you with internal security, but you can cut a hole through it with a Stanley knife. The bi-flex doors are not considered as a security door because you can walk through the strips when the door is closed,” he said.
Albany Door Systems’ Len Davies told Manufacturers’ Monthly high-speed metal doors had been developed to help improve security in factories that required rapidly opening doors, especially for access between external and internal factory areas.
He said before the development of high-speed metal roller doors, manufacturers had to install outer steel roller doors for security and internal high-speed doors for use during factory operation. “Now you can replace two doors with one door.”
Davies explained the main advantage of using a single metal high-speed door, in addition to improved security, was a reduction in maintenance requirements.
“Generally speaking the high-speed door people don’t service the roller door; it’s from a different manufacturer. Using one door, you eliminate one person from the loop in the maintenance of the high-speed door. You can get one maintenance program,” he said.
Installing one door instead of two also reduced space requirements, Davies added.
Fell said safety was one of the most important considerations when installing an industrial door and using materials such as clear PVC panels, which the bi-flex doors are made from, could reduce the risk of injury or damage in the case of an accident.
He said roller doors especially required contact sensors that would make the door immediately retract on contact with any object. These sensors are typically air pressure sensitive and mounted on the door’s bottom beam.
Davies said some door designs have now gone one step further.
“Instead of the beam coming down and the sensor being on the beam, the sensor actually travels in front of the beam by about 200mm so the bottom of the beam never touches anything,” he said.
Fell said as a fail-safe measure, his company’s rapid roller doors used flexible bottom bars.
“The bottom bar of the door is designed in such a way where if something hits it, it flexes, or if it comes down on something, it will fold around the object,” he said.
Davies said one disadvantage of doors with flexible bottom bars was that they could not be balanced and tensioned.
Balanced and tensioned doors have weights or springs in their side columns, which counteract some of the door’s weight making them easier to lift.
“The top roller is electrically driven, but everything works much better if it is balanced and tensioned. You don’t need as big a motor and the components last a lot longer because they are not under so much strain,” he said.
Balanced tension doors can also be “over-tensioned”, which Davies says can allow people to exit a building in the case of a power failure.
“You can set the doors up so that if you release the brake on the door, it will float up by itself without any power.”