Electrifying Exit Devices With the Command Access Electrified Latch Pullback

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. (See Solenoid Activated Kits chart)

In 2011, Command Access introduced its motor driven latch pullback mechanism. These motor driven retrofit kits pull the pushpad down to retract the latchbolt, the same function as if someone when exiting pressed the pushpad. (See Motor Driven Kits chart)

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, there is a potentiometer 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.

The Command Access motor has onboard self-diagnostics covering over voltage, under voltage or component malfunction. A motor driven latch pullback equipped exit device can be located up to 700 feet from the power supply using 18/2 wire. The maximum wire run is 1000 feet using 12/2 wire.

Important: Command Access motors are designed such that if power is lost when the latch mechanism is in the pulled back position, the spring pressure on the exit device pad will unwind the motor mechanism and the latch mechanism will extend.

The motor driven latch pullback mechanism incorporates a threaded shaft that retracts the pushbar and reverses rotation to extend it. A special threaded nut rotates as the motor turns, retracting or extending the linkage rod/bracket that is connected to the pushpad assembly. Using this design, the motorized mechanism unscrews when power is removed. The actual travel is approximately ¾ inches.

The motor technology has improved in speed and power to a point where the exit device latch mechanisms can achieve full retraction within ½ second. The Command Access motor driven latch pullback mechanisms can overcome stack pressure of up to 60 lbs pre-load on a rim exit device.

Command Access offers both solenoid-activated and motor driven latch pullback operation. Ten motor driven kits and nine solenoid activated kits are available. Latch pullback kits can be installed onto rim, mortise, surface or concealed vertical rod exit devices. Command Access has UL Listings for eight exit device latch retraction kits. Some of these kits require factory certification to be installed by locksmiths.

Solenoid activated and motor driven latch pullback kits are available for Von Duprin 33,l 35, 98 and 99 exit devices. Kits that have the solenoid or motor pre-installed on the baseplate are not UL Listed for Fire rated exit devices. These kits replace the dogging mechanism. Non-UL Listed exit devices comply with the NFPA 101 life safety code.

The solenoid-activated Von Duprin kits have a current draw of 12A@24VDC for 200ms to retract the latchbolt, then the current is electronically reduced to 250mA@24VDC to hold the latchbolt in a retracted (dogged) state as long as is desired. When powered, the pushpad and the latch mechanisms retract. When power is removed, the pushpad and the latch mechanisms extend locking the door.

Seven Command Access Motor Kits for exit devices are UL Listed and can be installed into UL Listed fire rated exit devices. UL Listed fire rated exit devices comply with both the NFPA 101 Life Safety Code and NFPA 80 fire doors and windows. A benefit of the UL Listed kits for Fire rated exit devices is latch pullback provides electronic dogging.

Four of the seven UL Listed Kits can be field installed. They are the:

• CRLP98-UL-M-KIT for specific Cal-Royal exit devices
• CYLP-UL-M-KIT for specific Corbin Russwin and Yale exit devices
• SLP-UL-M-KIT for specific Sargent exit devices
• VLP-UL-M-KIT for specific Von Duprin exit devices

The SLP-UL-M-KIT for the Sargent 80 Series exit devices has a voltage range of 22 to 30VDC. System protection shuts down the unit when voltage exceeds 30VDC. The current draw is 1A for 400ms, sufficient to retract the latch mechanism, then 125mA to maintain the electronic dogging.

For this article, we will install two Command Access UL Listed motor driven kits; the VLP-UL-M-KIT for Von Duprin 33, 35, 98 and 99 panic devices and the CYLP-UL-M-KIT for Corbin Russwin ED4000 and ED5000, and Yale 7000 Series exit devices. For this article, modifications are being made to rim exit devices.

Corbin Russwin-Yale Installation

The UL Listed Corbin Russwin and Yale kit, CYLP-UL-M-KIT, is a straightforward installation. There is no modification to the exit device. Important: Always install the motor driven kit with the exit device off the door.

Step 1. Remove the exit device from the door.

Step 2. Remove the end cover from the bottom rail.

Step 3. Attach the motor linkage assembly to the pushpad retraction mechanism.

Step 4. Screw the aluminum link in place using the provided setscrew and hex wrench.

Step 5. Slide the motor assembly into place directly behind the motor linkage assembly.

Step 6. Rotate the nut assembly onto the Acme threaded shaft until the motor assembly mounting holes line up with the dogging mechanism holes in the bottom rail.

Step 7. Install the two supplied Phillips Head screws securing the motor assembly to the bottom rail.

Step 8. Connect the MM1 Series module to the motor and connect the wiring to the power supply.

Step 9. Install the exit device onto the door, leaving the end cover and end cap off. To ensure proper operation, do not test the motor's operation until the exit device has been installed onto the door.

We will discuss testing, adjusting and troubleshooting latch pullback operation after discussing the installation of the Von Duprin Motor Driven Kit.

Von Duprin Installation

The UL Listed Von Duprin Motor Driven Kit, VLP-UL-M-KIT will be installed onto a 99 Series rim panic device. Because this is not a fire rated exit device, we must remove the baseplate assembly, take off the mechanical dogging mechanism, modify the activation shaft and drill a hole in order to attach the motor linkage assembly.

Important: Always install the motor driven kit with the exit device off the door.

Step 1. Remove the exit device from the door.

Step 2. Partially disassemble the exit device in order to remove the baseplate assembly from the rail.

Step 3. Remove dogging mechanism components.

Step 4. Use a hammer and punch to drive out the two rivets securing the dogging mechanism.

Step 5. Press and maintain the bar retraction mechanism in the depressed position. Using a hacksaw, cut off the activating rod at the base.

Step 6. Drill a 9/64" diameter hole ½" from the end of the activating rod to secure the motor linkage assembly. Remove any burrs on the activating rod.

Step 7. Slide the aluminum link onto the end of the activating rod and secure using the provided setscrew.

Step 8. Slide the motor assembly into place directly behind the aluminum link.

Step 9. Rotate nut assembly onto the Acme threaded shaft until the motor assembly mounting holes line up with the holes in the rail.

Step 10. When in position, install the two supplied Phillips Head screws securing the motor assembly to the baseplate assembly.

Step 11. Attach the baseplate assembly onto the center case.

Step 12. Connect the control link pin and retaining ring attaching the bar retraction mechanism to the center case.

Step 13.  Slide the baseplate into the rail.

Step 14. Secure the center case to the rail using the two bolts.

Step 15. Attach the pushpad and components.

Step 16. Connect the MM1 Series module to the motor and connect the wiring to a 24 VDC regulated power supply.

Step 17. Install the exit device onto the door, leaving the end cover and end cap off.

Important: When testing and adjusting the motor operation, always have the exit device mounted onto the door.

When mounted onto the door, power the motor driven latch pullback. On the initial fire-up, the motor will retract the pushpad and the latch mechanism. Check to see if the latch is fully retracted. If adjustment is required, the potentiometer is within the rubberized cover of the MM1. The latchbolt travel can be adjusted up to ¼" in or out. Turning clockwise increases the travel. Turning counterclockwise decreases the travel.

Once adjusted, test the exit device three times to be certain the latch mechanism properly operates.

The motor’s on-board self-diagnostics monitor over voltage, under voltage or component malfunction to protect the motor assembly and MM1 module. In addition to the on-board diagnostics, enable fine tuning of the latchbolt travel.

Should troubleshooting be required, count the number of beeps to identify the problem.

Two beeps indicate over voltage.

Three beeps indicate under voltage.

Four beeps indicate a problem with the travel location switch. This switch is in the normally close state. The MM1 series module must see the close state to function. Four beeps occur if there is a faulty switch or tampering where the switch does not close.

Five beeps indicate the latch pullback mechanism is not able to retract completely. Five beeps occur when the motor has cycled and the switch has not changed state to the open position. This condition may occur when there is tampering to the pushpad, the switch has not changed states, or the aluminum link is not able to travel far enough to depress switch.

Continual beeps indicate that the pushpad is being obstructed and the mechanism cannot reset. To reset the pushpad, depress pushpad until beeping stops. Releasing the pushpad enables the system to reset and return to the dogged condition.

Once adjustments have been completed, install the end cover and end cap.

Test the latch pullback to be certain of proper operation.

Pushpad exit devices using the Command Access motorized kits can be powered using any 1A or greater 24VDC regulated power source. A pushpad exit device using the Command Access solenoid activated kit can be powered using the Command Access PS1N linear power supply. The UL Listed PS1N delivers 24VDC, providing sufficient power for the in-rush requirement for one solenoid activated electric pullback.

In addition to the kits, three Command Access motor driven exit devices  are available: the PD10, PD15 and PD25. The PD10 can also be order with a solenoid activated latch pullback mechanism.

The solenoid activated and motor driven latch pullback kits have a "no hassle" three-year warranty.

For more information, contact your local locksmith distributor or Command Access, 22901 La Palma Ave., Yorba Linda, CA 92887. Telephone: 888-622-2377. Web Site: www.commandaccess.com.

To read additional Locksmith Ledger articles about electrifying door hardware, visit http://tinyurl.com/electrify413.