Exit devices are the second most common locking mechanism installed onto commercial/institutional doors. Exit devices are mounted onto the egress side of outswing wooden, hollow metal or aluminum stile glass doors. To unlock and exit through the opening, pressure is placed against the release mechanism. As pressure is exerted against the mechanism, the latchbolt retracts and the door begins to open. This enables people who are in danger to rapidly exit the building. Early exit devices were called crash bars, panic bars or panic devices as people in their flight to escape would crash against the door, hitting the bar and the door would open.
Exit devices come in two basic styles: cross bar and pushpad. The predecessor to the full cross bar exit device went to market in 1908. The Von Duprin narrow stile pushpad Series 33 exit device was introduced in 1972. This architecturally modern exit device style has been incorporated into the product lines by just about every exit device manufacturer.
In 1973, Von Duprin added latch electrification for the 33 Series exit device. The EL33 electrified pushpad exit devices are powered by a large solenoid. When powered, the exit device latch retracts creating an audible clapping sound. This sound, like that of an AC electric strike, notifies the person they can gain access. The Von Duprin solenoid requires an inrush of 16 Amps to retract the latchbolt. To provide sufficient power, 12 or 14 AWG wire was run between the exit device and the power supply.
For the next 30 or so years, electric latch retraction for exit devices was solenoid operation having wiring limitations. Then in 2006, Command Access patented their PM200 power booster interface module. Each module provides a high local current surge to pull back the exit device latch mechanism. The PM200 maximizes the efficiency and helps to extend the operational life of the solenoid, especially for those applications where the latch pullback is in the continuously on condition for many hours a day.
With the 24VDC power booster module installed within the pushpad exit device rail near the solenoid, the typical wire run and the power supply limitations are greatly improved. For example, the wire run between the power supply and the exit device can be up to 700 feet using 18/2 wire. The PM200 power booster enables multiple exit devices to be powered using a single centralized power supply.
Command Access field-installable solenoid activated latch pullback retrofit kits are available for Dor-O-matic and Von Duprin rim, mortise, surface and concealed vertical rod pushpad exit devices. Factory installed solenoid retrofit kits are available for Adams Rite, Command Access, DORMA, First Choice, Precision and Sargent.
In 2011, Command Access introduced its motor driven latch pullback mechanism. These motor driven retrofit kits move the pushpad to retract the latchbolt, the same function as if someone when exiting pressed the pushpad.
Command Access motor driven latch pullback retrofit kits contain the motor, linkage, MM1 Series module, wiring and other parts. The MM1 is a driver module that translates the typical “lock and unlock” signals into logic the motor uses to operate. To adjust the distance the linkage rod travels to lock and unlock the latch mechanism, a potentiometer is included in the MM1 Series module. Adjusting the potentiometer sets the degrees of motor rotation to determine the stop and start positions.
The latch pullback motor has low surge current draw of 1A for approximately 400ms to retract the pushpad. The motor driven latch pullback requires significantly less power than a solenoid to retract the latchbolt or to keep the latchbolt retracted. There is minimal sound when the motor operates or keeps the latch retracted. As a result, there is no sound to notify people the door is unlocked and access has been granted.
Command Access Technologies electrifies most commercial manufacturer’s locksets and exit devices for remote control by an access control system or a momentary contact. The company has developed...