April 5, 1994
Circular Letter E-94-1
T0: Elevator Companies, Elevator Inspectors and Other Concerned Parties:
SUBJECT: Elevator Door Detectors
With safety edges or electric eyes, they either work, or they do not. If the safety edge broke, the doors stayed open. When the electric eyes were blocked, the doors stayed open.
With the advantages of door detectors also come disadvantages. Recently, the Division checked an elevator with a door detector. The detector did not start working until the doors had traveled 22 ½ in. of the 48 in. opening. It was determined that the detector was out of adjustment. The Division had the detector adjusted to provide coverage for the full opening.
Detectors must provide protection for inanimate objects as well as animate objects. Recently, an incident was reported to the Division that a cane was knocked out of an elderly person's hand. It was discovered that the detector was insensitive to inanimate objects. The detector had to be replaced.
We are all aware of the advantages of door detectors. If the design and maintenance are going to be such that safety hazards are created by the use of detectors, the Division will have to review the acceptance of their use to provide the door protection required by the Elevator Safety Orders.
W. E. McTiernan
Principal Safety Engineer
DOSH - Elevator, Tramway, and Amusement Ride Unit