Tom has more than 35 years in the door hardware industry: over 16 years in hardware distribution, and 17 years as a commercial locksmith.
Electromagnetic locks, otherwise known as magnetic locks, maglocks, or mags, require a releasing device, or switch, to cut power to and thereby unlock the maglock to allow free egress from inside the locked space to the outside. Maglocks are not the most popular kind of lock with inspectors, so before installing any kind of electromagnetic locking system it is a good idea to run your plans past the local Authority Having Jurisdiction (AHJ) such as your local Fire Marshal or Building Inspector. Since the releasing device will be the device that allows people to exit the space in the event of a fire, you can expect the releasing device to attract special attention from the AHJ.
For more information about electromagnetic locking systems, click here.
There are two kinds of touchbar releasing devices on the market today:
Mechanical touchbars work by motion. When pressed, they activate an interior microswitch or microswitches.
Electronic touch bars use capacitance, pressure or a beam of infrared light to sense the touch of the person who wants egress.
All bars discussed in this article meet the NFPA code requirements for egress with one motion with no prior knowledge of how to exit required. All devices require some means of transferring power from the door frame into the device.
Mechanical Touch Bars
The advantages of mechanical touchbar releasing devices are:
- No power required to operate
- Inspectors like them because they are mechanical
- No redundant time delay pushbutton is usually required
Schlage Electronics 672 TouchBar comes standard with "Push to Exit" signage and a single pole, double throw (SPDT) internal switch rated at 3 amps at 30 volts DC. Unlike counterparts based on latching exit devices, the 672 requires only 1/4 inch of movement for activation. Optional double pole double throw (DPDT) switch and lighted "Push to Exit" signage available. Available in standard anodized aluminum and dark bronze, or in a variety of special order finishes. 36-inch, 42-inch, 48-inch, and factory custom lengths available. Power transfer cord sold separately.
Adams Rite 8099M active dummy touch bar device with SPDT switch is a simple mechanical touch bar device based on a latching exit device. The 8099M has the same backplate and touch bar mechanism as any of the Adams Rite 8000 series devices. The 8099M is available in three standard anodized finishes: aluminum, dark bronze, or black, as well as a variety of US finishes. The 8099MM touch bar features a DPDT switch. No amperage rating available. 30, 36, 42, and 48-inch models available. Devices can be cut down up to six inches. Power transfer hardware sold separately.
Security Door Controls (SDC) MSB550 mechanical switch bar has a SPDT switch rated at 5 amps at 30 volts DC. Optional second switch available for DPDT operation. Activation requires only 1/8 inch of movement. Available in aluminum, dark bronze, and black anodized finishes as well as satin stainless steel, polished stainless steel, and bright brass. 36-inch, 42-inch and 48-inch models available. Optional Herculite door mounting kit available. Power transfer door loop available separately.
With a SPDT switch that is rated at 500mA, the Von Duprin RX-330 and RX-350 should probably be used with a relay. On the upside, the devices are built on the grade one backplates and extrusions made famous by the 98/99 and 33/35 series devices. Typical of touch bar release devices that are based on latching devices, the mechanism travels more than an inch during activation. This device is usually used in buildings where Von Duprin mechanical devices are widely used. Second switch available for DPDT effect. Available in 36-inch and 48-inch versions, and in all the finishes in which Von Duprin exit devices are made. Power transfer hardware sold separately.
Most standard exit devices can be used as touchbar releasing devices. Most exit device manufacturers offer an add-on request-to-exit (aka RX) switch to their grade 1 exit devices, and Security Door Controls also offers a variety of after-market switches that can be field installed into existing exit devices. Many standard exit device manufacturers also offer mechanical touchbar release devices as well.
Electronic touchbar releasing devices have no moving parts. Since they are electronic, they can offer features such as lighted "push to exit" signage or a door propped alarm.
Both these features are available with the Schlage Electronics 692 SmartBar. The 692 features a double pole double throw relay as a standard feature. Dual infrared detectors sense the presence of an object in contact with the bar. The standard audible alert sounds when a prolonged interruption of the infrared beam occurs.
The SDC PSB560 Pressure Sense Bar senses pressure to release. DPDT contacts standard rated 3 amps at 30 volts DC. Available in aluminum, dark bronze and black anodized finishes as well as satin stainless steel, polished stainless steel, and polished brass. Lengths available: 36-inch, 42-inch, and 48-inch. Optional Herculite door mounting kit available. 18-inch door loop and 10-foot, 8-conductor power / contact transfer cable included.
Securitron TSB-3 Touch Sense Bar is perhaps the most widely used touch bar on the market. Available in 36-inch, 42-inch, and 48-inch lengths. Clear aluminum and anodized black finishes available. DPDT contacts rated 2 amps at 24 volts DC. Integral redundant pushbutton on side of bar that faces the door. 16-ft cable and armored door cord included.
Some local AHJ's may require a redundant push button for use with an electronic touch bar, because an electronic touch bar requires power to operate. Therefore if the electronic touch bar malfunctioned or is deprived of power while power to the magnet is maintained, people trying to exit the building could be locked in. Usually the redundant button is expensive because code requires it to have a pneumatic time delay - a fully mechanical timer that works by drawing air through a diaphram and an adjustable valve.
Securitron's integral redundant pushbutton sometimes does not meet with inspectors' approval because its location is not immediately apparent - not quite in compliance with NFPA code mandating no prior knowledge necessary to operate the egress device. Securitron does offer the EEB2 and EEB3N electronic pushbuttons at a fraction of the price of a pneumatic pushbutton, and ships them with wiring instructions that they say allow the electronic pushbutton to meet life safety code.