History of Revolving Doors
Revolving Doors are used to control traffic or heating and air conditioning in a building. The revolving door structure consists of individual door panels (or wings), a center shaft with the hardware needed to support the door wings, a circular structure called a “rotunda” or “drum” that is usually fitted with glass, and the ceiling (supported by the rotunda) that contains either a mechanical braking device (used to control the speed of the doors) or an electronic device that uses a motor to drive the doors automatically. The main benefit of a revolving door is that it is always closed and always open. This means that the design of the system is such that there is at least one door wing sealing the opening at all times reducing the amount of heating volume and air conditioning (HVAC) that escapes from a building and these savings in energy costs can be considerable. The revolving door achieves these savings because the curved walls of the rotunda allow the seals to fit tightly as the door wings rotate. Each basic revolving door design is modified (with respect to dimensions, number of door wings, whether the function is manual, automatic or security, and finish or color) to suit the user’s requirements. The manufacturing process:
- All aluminum members are cut to length depending on the overall final dimensions of the revolving door. Aluminum extrusions are manufactured utilizing a very large press device called an extrusion press.
- The circular rotunda walls are formed from aluminum extrusions that are repeatedly fed through a bending machine until the correct radius is achieved. The radius depends on the required size of the revolving door.
- All aluminum parts (doors, frames, etc.) are welded together and prepared to receive the hardware components that make up the emergency breakout system.
- The circular ceiling is cut from 1 in (2.54 cm) thick marine grade plywood and then laminated with 0.125 in (0.318 cm) thick aluminum sheet to form the interior ceiling.
- The ceiling is prepared for the light fixtures (cut-outs) and the center shaft hole is cut at the very center.
- Steel angle is welded together in a grid pattern to provide support for the ceiling and to secure the mechanical speed control device. The grid is installed on top of the ceiling.
- The center shaft is fabricated and fitted with the balance of the breakout hardware. Revolving door systems must be fitted with a “panic collapsing mechanism” or “breakout system” that permits the door frames to fold against one another. This bookfold position permits an unobstructed exit from the interior to the exterior of the building in the event of a fire or other emergency.