THOUGHTS ON FIRE DOORS
BY GLENN P. CORBETT
The fire door plays a critical role in maintaining the integrity of a fire wall or other fire-related separation. The failure of a fire door to “do its job” makes a fire wall/separation useless. The fire door can be the weakest link in a fire barrier.
Fire doors may be classified as one of three types–swinging, sliding, or rolling. Swinging fire doors are the most common. This is the type that you walk through when you enter a fire-rated corridor or stairwell. Sliding and rolling fire doors often are found in industrial buildings and usually are fusible link-activated. Sliding fire doors use inclined tracks to slide into place when the link is fused. When the link is fused on a rolling fire door, the door rolls out of a large overhead “drum” in which it is stored (similar to the new shutters on fire apparatus compartments).
FIRE TESTING
Before we look at specific important issues, let`s review the fire testing used to evaluate fire doors and the building codes used to regulate them. Fire doors are tested in accordance with ASTM Standard E152, Fire Tests of Door Assemblies. The test is a rigorous one involving mounting the door and door frame in a wall with one side of the door/wall facing into a furnace. Extreme (albeit regulated) heat in the furnace and subsequent blast of water from a hose stream on the unexposed side are used to test the door. “Swinging” fire doors are positioned so that they swing into the furnace. Passing the test necessitates that heat transmission is limited on the unexposed side of the door, the door does not separate from the frame and create gaps, and the door doesn`t open when hit with the hose stream.
The door hardware (including latching devices for swinging doors) is important, especially to keep the door in place and not let it open. Steel doors have a tendency to wedge into the door frame when they are heated during the test. If a particular fire door is to be installed in a gypsum wall, it must be tested in such a wall (some doors are tested only in masonry walls).
When the particular door type has been listed/approved by the testing agency, a label is required to be attached to all subsequently manufactured doors of that type. Some large “oversize” doors (usually of the rolling type) may have a certificate of inspection instead of a label. These oversize doors are certified to be of the proper de-sign, materials, and construction but have not been subjected to an actual fire test due to their size.
BUILDING CODE REQUIREMENTS
Building codes regulate the actual door installation. (I have prepared this column using the 1996 National Building Code, or N.B.C. Consult your own building code for specifics.) These codes specify the rating of the door (which ranges from one-half hour to three hours, depending on the location), glazing in the door, and the door`s closing features.
Doors in one hour-rated corridors usually are required to have a fire rating of at least 20 minutes, whereas doors into a two hour-rated stairwell are required to be 112 hour fire-rated. Doors in exit enclosures (stairwell or exit passageway) have a special requirement. They are to be tested to verify that they have a maximum transmitted temperature (on the unexposed side) endpoint of 4507F above ambient at the end of 30 minutes of the standard fire test exposure. An automatic sprinkler system installed throughout the building eliminates this requirement.
Wired glass is permitted in some fire doors. Fire doors in fire walls (as defined in the N.B.C.) are not permitted to have wired glass except for those doors that are part of a horizontal exit and are limited to 100 square inches in each door leaf. One and one-half hour-rated doors in fire separations (as defined in the N.B.C.) and “looking” into stairwell/elevator shafts are limited to 100 square inches as well. Doors of one- hour fire rating have limitations of a maximum of 100 square inches glazing while three-quarter hour-rated doors are permitted to have a maximum of 1,296 square inches. Fire doors with ratings of 20 minutes are permitted to have unlimited wired glass glazing.
Wired glass, in all cases, is required to have specific labeling as to the manufacturer, the fire test standard, and the fire protection rating. The wired glass must be installed in “approved” frames.
In terms of closing devices, special requirements apply to doors that serve the means of egress. Specifically, fire-rated doors that are part of the exit (i.e., stairwell doors), doors into exit access corridors, and doors in horizontal exits are required to be self-closing or to close automatically by smoke detectors located at the door opening (or by loss of power to the smoke detector or hold-open device). Fusible links are not permitted in these locations.
INSPECTOR CONCERNS
Over the years, I`ve seen different problems with installed fire doors and related equipment. Here are a few.
Improper fire rating. As previously discussed, specific fire walls/separations have specific ratings for fire doors in them. Very often, an “underrated” door is installed. Put a copy of the building code`s door-rating requirements (usually in tabular form) on the inside cover of your metal inspector`s notepad holder.
The “four-hour wedge.” This is probably the most common problem with fire doors. Occupants place wedges under the door because the door is a barrier to their normal movement in the area. Telling them to remove the wedge is a temporary solution–occupants soon will forget you and your “silly” requirements. Normally the only solution that works is the use of a smoke detector-activated closer and hold-open device. This gives the occupant unimpeded access and gives you compliance and peace of mind.
Blocked sliding fire doors–the fire door is impeded. Sliding fire doors “slide” down a tilted “track” on rollers. Anything in the track or in the “slide zone” at the base/sides of the opening will prevent the door from closing properly. The track itself may be dented or out of proper shape. If you have any reason to believe the door will not close, have the owner test it in your presence! Make sure it moves and closes the opening without assistance.
Rolling doors that are binding–the fire door will not “drop” properly. Similar to the previous discussion on sliding fire doors, rolling doors often get hung up when they try to close. They can bind up in the enclosed roller itself or stop coming down because of an errant forklift dent in one of their tracks. A few years ago, Factory Mutual performed field tests on a number of rolling fire doors and found a large number of them would not work properly in a real fire. The solution is to have them tested often–in your presence, if possible.
Fusible links are blocked, missing, or painted. Fusible links on fire doors are the same as those found in many sprinkler heads. They must be in place over the opening where the heated gases of a fire will “wash” over them. If they are missing or painted, the door will not close properly.
Latching hardware is not latching. The door must remain latched during the fire. If the door does not latch properly, it can open, allowing fire to pass. Check every swinging fire door by allowing it to close on its own and then pushing the door. Does it open?
Closer hardware is damaged/improperly set. Doors that are “beat up” because of heavy use often start to break down at the closer. To check the closer, watch it during the latch test discussed above.
Another problem is often found in door closer coordinators, which are used for pairs of swinging doors located directly next to each other in which one door shuts before the other (an “astragel” is installed on the “meeting” edge of one of two door leaves). When the coordinator fails, the doors close in improper sequence, and the astragel door closes last, leaving a gap between the doors. These problems must be repaired.
Hold-open devices don`t release. The smoke detector-activated magnetic hold-open device fails to release the door it holds. When a smoke detector system is used to “release” doors on their activation, the smoke detector “tells” the magnet(s) holding the doors to demagnetize and let the doors close. If the system is not properly installed/maintained, the doors fail to close. The only way to check this is to activate the proper smoke detector and watch each door close. Every door must be individually checked! (Minimum inspection staffing would require one inspector at the door and one at the fire alarm control panel.)
Fire exit hardware is chain locked. This is the one that made then-Chief of Department William Comer of the Paterson (NJ) Fire Department famous in the Warner Bros. movie “Lean on Me.” Drug dealers were gaining access to Paterson`s Eastside High School through the exterior fire door, so the principal chained the doors closed! Chief Comer got the principal`s attention through the state fire code`s “$5,000 per violation per day” fine. This has been the bane of fire inspectors everywhere–how do we prevent fire exit hardware from being chained? Fortunately, most new doors have the pushpad type of hardware rather than the older round bars as their fire exit hardware.
Have you noticed that I keep using the term fire exit hardware? That is the only opening type of hardware permitted on a fire-rated door when it serves a place of assembly or other similar occupancy considered a life safety risk in a building code. Most people are familiar with its close cousin, panic hardware, which is placed only on nonrated doors in places of assembly and the like. n
GLENN P. CORBETT is a professor of fire science at John Jay College in New York City, a technical editor of Fire Engineering, and a firefighter with the Waldwick (NJ) Fire Department. He previously held the position of administrator of engineering services with the San Antonio (TX) Fire Department. Corbett has a master of engineering degree in fire protection engineering from Worcester Polytechnic Institute in Massachusetts. He authored two chapters on fire prevention/protection in The Fire Chief`s Handbook, Fifth Edition (Fire Engineering Books, 1995). Corbett has been in the fire service since 1978.
