Fire walls and fire barriers are inserted into buildings to separate spaces into reasonably-sized fire areas, or because hazards are present. The separations must be continuous or their purpose will be defeated should there be a structural fire. They also provide an increased level of physical security when buildings, or certain areas of buildings, are to be closed after hours. Many customer service counters use rolling fire shutters to separate a factory or warehouse area from the customer service area, for example, after normal business hours.
NFPA 80, “Fire Doors and Other Opening Protectives” is where the provisions for the installation, testing and maintenance of rolling steel fire doors and similar protection for openings are found. NFPA 80 allows these special shutters to be released manually with a switch, lever or button of some kind. Once released, these rolling steel fire doors must close automatically. These doors automatically close by the operation of a “fusible link” positioned at certain points along a wire rope that holds tension on the closing device. The fusible link will soften in the heat of a fire and when the cable eventually parts, the tension on the cable releases and the lever moves on the closing device, allowing the shutter to close.
This wire rope and pulley arrangement is easily seen above and on each side of these doors/openings. The cable having the fusible links connects to the closing device, which is usually a lever attached to the drum that the rolling door wraps around, located at one end of the coiled door. Where no fire alarm system or smoke detectors are provided, the other end of the wire rope passes through pulleys and pipes so that there is a fusible link on each side of the door and one above the door. These doors are installed and listed as a complete system; and their installation, operation, testing, etc. is separate from the fire alarm system installation.
How Rolling Steel Doors Work
The more basic rolling steel doors are raised using a loop of chain, which someone must pull, to turn a sprocket, which very slowly raises the door to the open position, where a wire rope and lever closing device can keep it open. Since gravity provides the emergency closing power, usually a governor is used to control the rate of fall. NFPA 80 allows these rolling fire doors to drop at an average speed of up to two feet per second, but some seem to just come crashing down.
Another desirable door option can cause a 10-second delay in operation, during which an audible/visual warning appliance located by the doorway activates to warn occupants to keep clear (i.e. “run for your lives”). The pathway through these protected openings are usually not included in the emergency exit plan, and no one should ever be prevented from a short and easy access to a proper exit by the closing of these rolling steel doors. That said, vertical rolling doors in a pedestrian path must be released by either a fusible link or by smoke detectors using alarm verification, if interconnected with any fire alarm system present.
An even more desirable option for these rolling fire shutters is to have their operation motorized so that a switch is programmed to open and close them electrically instead of manually pulling a loop of chain. These electrically-operated doors have a safety sensor which will cause the door to stop moving if the leading edge encounters an object while closing. Electrically-operated doors are also permitted to have a unique option that lets them reverse direction if the leading edge of the door hits an obstruction while descending. This feature will cause the door to momentarily reverse its direction. However, on the door’s third attempt to close, it will simply stop against any obstruction that’s still present. The door manufacturer must provide emergency backup power if electrical energy is needed to release the door during a fire condition.
Tying it into the Fire System
When a fire alarm system is used to release the rolling fire door, the wire rope is not anchored directly to the wall. For fire alarm releasing service, the wire rope will be held by the door manufacturer’s listed releasing mechanism — picture a steel box about 8 inches square — which is securely anchored to the wall above the door. This releasing mechanism is then electrically wired to a fire alarm relay — located within three feet of the box — or smoke detector(s) having a relay base. Closed contacts cause the releasing mechanism to maintain its grip on the wire rope.
This arrangement allows the fire door to be released by a signal (an open) from a detector, or fire alarm relay, or a broken wire (fail safe), or by the melting of one of the fusible links. In any of these arrangements, when the tension is released on this wire rope, the door closes automatically. Rolling fire doors/shutters may only be opened again when the fusible link is replaced or the listed releasing mechanism (provided by the door manufacturer) is manually reset. For the door’s releasing mechanism to reset, any fire alarm relay must be in the “normal” non-alarm state.
Testing
Testing of your work, if releasing doors are requested to be interconnected with the fire alarm system, will only include the operation of the final relay connection controlled by the fire alarm system. Activation of the fire door, damper, shutter, etc., is not part of your fire alarm system’s responsibility. Fire alarm system testing, in these cases, is performed by the initiation of an alarm signal, and observing the status light on the addressable relay or detector; or witnessing the change in state of the actual electrical contacts controlled by the fire alarm system; or by performing a continuity test of the controlled circuit using a meter.
Proper operation and testing of any fire door, shutter, curtain or damper is to be performed “by others” who are factory certified/trained/licensed to perform the requisite testing and maintenance of this type of specialized life-safety equipment.
Special Considerations
There are a few notable differences regarding rolling fire doors/shutters and traditional fire doors. First, a “fire door” has been rated to survive in a fire for a set number of hours and usually closes a doorway or hallway commonly used by the building’s occupants. Fire doors can also include the horizontal sliding door, fire curtains and the typical fire-rated swinging door. A “fire shutter,” on the other hand, protects a window, door, or similar opening; and most people call any segmented rolling door a shutter, regardless of if it covers a door or window.
Secondly, similar to a kitchen hood suppression system, the fire alarm contractor will connect to the contacts of the manufacturer’s electrical releasing mechanism of the rolling fire shutter, which has already been provided, installed and tested. Unlike kitchen hoods, however, rolling fire doors may not be required to be connected to a fire alarm system.
Lastly, unlike other doors, the rolling fire door, once closed, will not allow occupants to walk through them. Some AHJs believe, incorrectly, that all fire/smoke doors should close throughout a facility, upon the activation of any fire alarm signal. This is not a code requirement, and these rolling doors are a deadly example of why.
Greg Kessinger is SD&I’s fire alarm and codes expert and a regular contributor. Email him your fire & life safety questions at [email protected].
