To date, nobody has invented a strong, durable type of exterior door that handles frequent traffic well. The doors covered by this Measure handle traffic well, but they cannot serve as primary exterior doors in most applications. In your planning, take into account these distinguishing characteristics of the quick-acting doors
covered by this group of Measures:
• little or no delay in passing through the door. These doors are intended to keep traffic moving. Unpowered types are simply pushed aside by the user, either a vehicle or a person. Powered types have actuators that operate very rapidly.
• designed to withstand impact. These doors are designed to be hit. Unpowered types tolerate impact because they are light. Powered models are also relatively light, and they may have breakaway features that limit damage if the door is hit.
• need for recurring maintenance. All types of doors have components that wear out occasionally from repeated cycling, impact, and weather. The doors are (or should be) designed for quick repair.
• minimal insulation value. The primary benefit of these doors is minimizing infiltration. Most have little insulation value, because they are light and thin. Some types do have a limited amount of insulation value, which can be important for some applications.
• minimal security. The light weight of these doors keeps them from serving as an effective barrier to forced entry. A small vehicle could drive through any of them.
• limited resistance to outdoor conditions. Unpowered types have virtually no resistance to wind. Powered types can resist varying wind speeds, depending on the model. Strong sunlight would weaken the plastic materials within a few months or years and make them brittle. The mechanisms of powered types may be vulnerable to precipitation.
• specific temperature ranges. Temperature affects the flexibility of plastic materials. Flexibility is important for the operation of door types in which the fabric folds, rolls, or bends in operation. Flexibility is also important for impact resistance.
Select a material that is suitable for the lowest temperature at which the door will operate.