High-speed doors: the specification is the clock

A high-speed door is not a fast shutter. It is a boundary that has to be closed most of the time, which makes cycle time the whole specification.

A high-speed door exists to keep a boundary closed. Between a chilled store and a dispatch bay, or a clean production hall and a general one, the door is open for the few seconds a forklift takes to pass and shut the rest of the time.

That makes cycle time the specification rather than a feature. Everything else follows from it: the curtain is light because it has to accelerate, the drive is sized for starts rather than for load, and the safety sensing has to work at speed.

What the boundary buys is measurable — temperature held, dust and insects kept out, and conditioning energy that is not being spent on the yard. On a food line it is also a hygiene control, and the door becomes part of the HACCP case rather than part of the building.