What safety device prevents the elevator doors from closing on passengers?

What safety device prevents the elevator doors from closing on passengers?

• A. Brake sensors
• B. Infrared light curtains or door zone sensors
• C. Emergency stop buttons
• D. Load sensors

Answer: (B)

Infrared light curtains or door zone sensors are critical safety devices used in elevators to detect the presence of passengers or objects in the doorway. These sensors create an invisible barrier using infrared beams; if the beams are interrupted while the doors are closing, the system detects this disruption and immediately stops the doors from closing. This feature effectively prevents accidents and ensures passenger safety, making it essential in modern elevator systems. In contrast, brake sensors are primarily responsible for detecting issues related to the elevator's braking system, and while they enhance the overall safety of the elevator by ensuring it stops properly, they do not directly prevent doors from closing. Emergency stop buttons serve to halt the elevator in case of an emergency but do not specifically address door closure prevention. Lastly, load sensors monitor the weight in the elevator cab to prevent operation when it exceeds safe limits, but they do not interact with the door closing mechanism. Thus, infrared light curtains or door zone sensors are specifically designed for the purpose of keeping the doors from closing on passengers.

Infrared light curtains or door zone sensors are critical safety devices used in elevators to detect the presence of passengers or objects in the doorway. These sensors create an invisible barrier using infrared beams; if the beams are interrupted while the doors are closing, the system detects this disruption and immediately stops the doors from closing. This feature effectively prevents accidents and ensures passenger safety, making it essential in modern elevator systems.

In contrast, brake sensors are primarily responsible for detecting issues related to the elevator's braking system, and while they enhance the overall safety of the elevator by ensuring it stops properly, they do not directly prevent doors from closing. Emergency stop buttons serve to halt the elevator in case of an emergency but do not specifically address door closure prevention. Lastly, load sensors monitor the weight in the elevator cab to prevent operation when it exceeds safe limits, but they do not interact with the door closing mechanism. Thus, infrared light curtains or door zone sensors are specifically designed for the purpose of keeping the doors from closing on passengers.