Prior to the 1970’s it was illegal to lock perimeter exit doors from the interior side. In fact, all that was permitted in most commercial buildings was an exit device to insure uninhibited egress at all times while locked on the exterior. This was problematic in that the exit devices left facilities vulnerable to employee theft and also to breaking and entering simply by using a clothes hanger to manipulate and unlock the exit device from the exterior. Still, most jurisdictions would not permit electromechanical locking due to fire life safety issues. For these reasons many facility owners, including commercial buildings, industrial facilities, banquet facilities, warehouse and convention centers, resorted to the illegal use of chains and padlocks to secure their perimeter doors after hours. To prevent employee theft, breaking and entering, and provide life safety, a solution was needed.
While it was obvious an electric lock connected to the fire command center was required, the AHJ’s concern was that electromechanical locks had the potential to bind and inhibit safe egress. In 1969, Art Geringer, founder of SDC traveled to Sacramento to visit the California State Fire Marshal. There, the fire marshal indicated that he would approve a lock that did not rely on a spring to retract the bolt and that the lock must pass a test of 800,000 cycles. Arthur returned home and designed a lock that met the state fire marshals criteria and approval. In 1971, SDC introduced the FS23M dual-failsafe bolt lock with features that helped ensure safe lock release. Still used today, the SDC bolt lock is listed for use by the California State Fire Marshal, City of New York MEA and City of Los Angeles.
Also in 1969, Locknetics founder Irving Saphirstein, designed the first electromagnetic lock that found approval for locking perimeter doors after business hours (See Figure 1). Unlike an electromechanical lock, the electromagnetic lock had no moving parts to bind or wear, making it ideal for fire life safety applications that require the assurance of trouble-free release during normal operation, a power outage or by a signal from the fire life safety system (see figure 2). However it took a while for this concept to be accepted by distributors for several reasons. It required a lot of current, had low holding force and required a special power supply to eliminate residual magnetism. Eventually improvements were made to eliminate these issues and several more companies, including SDC, began manufacturing electromagnetic locks.
Initially intended for securing perimeter doors after business hours, the simplicity of EMLock® installation made it popular for many other applications, even those for which it is not permitted by code, such as elevator lobby doors and high-rise stairwell doors, or the locking of entrance doors during business hours. However, only failsafe electrified locksets or electrified exit devices meet code criteria for the access control of stairwell doors or exit doors during business hours. Unlike magnetic locks, these locking devices provide uninhibited egress by manual means only.
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