56. MODERN TYPE OF DOORS.

Mechanism of the sliding door of an elevatorbe a pressure mat fitted on the swing side of the door. The purpose of the safety sensor is to prevent the door from colliding with an object in its path by stopping or slowing its motion.Inward opening doors are doors that can only be opened (or forced open) from outside a building. Such doors pose a substantial fire risk to occupants A sensor detects traffic is approaching. Sensors for automatic doors are generally.


A pressure sensor - e.g., a floor mat which reacts to the pressure of someone standing on it. An infrared curtain or beam which shines invisible light onto sensors; if someone or something blocks the beam the door is triggered open. A motion sensor which uses low-power microwave radar for the same effect. A remote sensor (e.g. based on infrared or radio waves) can be triggered by a portable remote control, or is installed inside a vehicle. These are popular for garage doors.


A switch is operated manually, perhaps after security checks. This can be a push button switch or a swipe card. The act of pushing or pulling the door triggers the open and close cycle. These are also known as power-assisted doors.
In addition to activation sensors automatic doors are generally fitted with safety sensors. These are usually an infrared curtain or beam, but can of occupied buildings when they are locked.


As such doors can only be forced open from the outside, building occupants would be prevented from escaping. In commercial and retail situations manufacturers have included in the design a mechanism that allows an inward opening door to be pushed open outwards in the event of an emergency (which is often a regulatory requirement). This is known as a 'breakaway' feature. Pushing the door outward at its closed position, through a switch mechanism, disconnects power to the latch and allows the door to swing outward. Upon returning the door to the closed position, power is restored.