Fire and Smoke Dampering According to the International Building Code
Fire dampers, smoke dampers, smoke detectors, shaft enclosures, smoke barriers and fire-rated partitions, smoke compartmentation, ducted systems and transfer openings. There are a lot of different devices to consider in designing smoke and fire dampering systems. But while it may appear overwhelming and confusing, all these various types of equipment come down to one thing: life-safety protecti...
Fire dampers, smoke dampers, smoke detectors, shaft enclosures, smoke barriers and fire-rated partitions, smoke compartmentation, ducted systems and transfer openings. There are a lot of different devices to consider in designing smoke and fire dampering systems.
But while it may appear overwhelming and confusing, all these various types of equipment come down to one thing: life-safety protection for building occupants. Here, I want to concentrate on how these systems are defined by the International Building Code (IBC).
So far, I've only listed some of the types of dampering equipment used in these systems. But we need to backtrack and ask a basic question: Why install dampers at all? The answer is that dampers are the primary means of maintaining the required rating integrity of a wall, floor or partition in order to prevent fire or smoke in the compartment of fire origin from entering into adjacent compartments or means of egress. This allows occupants to either shelter in place or evacuate with the building components remaining intact during the design time frame.
The concept of sheltering in place is particularly important for facilities such as hospitals, outpatient facilities and nursing homes, where the occupants are generally not evacuated in the event of a fire and require special protection from the elements of a fire, of which smoke is one of the most dangerous. Smoke control, and thus, dampering, is especially critical in these facilities.
In the 2003 edition of the IBC (which I refer to because it is still more widely adopted by jurisdictions than the recent 2006 edition), Section 714 describes “opening protectives” and primarily identifies requirements for fire doors, glazing and fire shutters when required by other provisions of the code. Section 715, “Ducts and Transfer Openings,” governs the protection of ducts and air transfer openings and fire-resistance-rated assemblies. In these two sections, what the code seems to be saying is that dampers must be installed in air movement systems so that places of refuge, exit access and exits are maintained as smoke-free environments.
What is the difference between smoke and fire partitions and why are dampers required? A smoke partition's primary objective is to prohibit the passage of smoke. It may also carry a fire rating. A fire-rated partition is a continuous membrane with a specified fire rating. Let's first look at some fire damper specifics. Fire dampers are built with a 1.5- and 3-hour ratings. They are designed to be installed in duct systems, penetrating 1-, 2-, and 3-hour wall and floor assemblies. Refer to Table 607.3.1 (not shown here) of the International Mechanical Code (IMC). All dampers must be installed in accordance with the manufacturer's installation instructions and the UL listing for the damper. Fire dampers are tested in accordance with UL 555 and must be labeled for use in dynamic systems designed to operate with fans turned on during a fire.
Conforming to UL 555
Fire dampers are constructed to meet the UL 555 test as to minimum construction gauge and edge seals, and are manufactured in three types: Type A, Type B and Type C. Type A is a frame construction with the damper framed the same size as a duct size and includes the blade stack and edge seals within the airstream, creating the highest air pressure drop. Type B has the blade stack out of the airstream, but the receiving channel is within the airstream. Air pressure drop is substantially reduced but does not provide full duct opening clearance. Finally, the Type C damper is mounted within a sleeve and maintains a 100% free area through the damper for a minimal air pressure drop.
According to the IMC, an actuating device for fire dampers must meet one of three criteria:
The operating temperature must be not less than 160
The devices's operating temperature shall not be greater than 286
Where a combination fire/smoke damper is located in a smoke control system, the operating temperature rating should be approximately 50
Conforming to UL 555S
Smoke damper ratings are subject to UL 555S testing and must be no less than Class II leakage with an elevated temperature not less than 250that the UL 555S requires the smoke damper and its actuator not only to be tested together but the actuator must be factory installed.
Actuating methods for smoke dampers are identified in both the IMC and the IBC with one of five methods used for damper actuation:
When a smoke damper is installed in a duct, a smoke detector shall be installed within five feet of the damper. (Of course, smoke control system exceptions do exist)
Where a smoke damper is installed above a smoke barrier door, a spot-type detector listed for releasing service may be used
Where a damper is installed within an unducted opening in a wall, a spot-type detector listed for releasing shall be installed within five feet of the damper
Where a damper is installed in a corridor wall, the damper may be controlled by the corridor smoke detection system
Where a total coverage smoke detector system is provided within the area served, the damper shall be permitted to be controlled by the smoke detection system.
Inspection and testing
All fire and smoke damper installations must have suitably sized access panels for inspection and testing. All access panels must be labeled with minimum 1/2 in. high letters reading, “Smoke Damper,” “Fire Damper” or “Fire/Smoke Damper.” Fire dampers and fire/smoke dampers are required by code to be installed in rated partitions, walls and floors. There are also several instances where they can be omitted but, as a word of caution, all placements should be reviewed and approved by the authority having jurisdiction (AHJ).
It is also advisable to review the IMC and IBC, as the language for damper placement may not be exactly the same for these two codes. For example, in the IMC, fire dampers are not required to be installed in duct systems that are used as part of an approved smoke control system in accordance with Section 513 of the IMC. The IBC exception is similar, except it references Section 909 of the IBC. While both referenced sections are for smoke control systems, it is beneficial to read them both to ensure compliance with all aspects of the code.
Damper actuation is still the key to proper air system operation. Control of dampers by fire alarm initiation is an option, as is initiation by the fire alarm system with control by the building automation system.
Of course, exceptions exist for not installing dampers in corridor walls and shaft walls in some occupancies. These omissions generally require full sprinkler coverage and total coverage smoke detection. Or else they are allowed where the duct system is limited to a single smoke compartment.
As systems are designed, it is important to remember that codes are written to protect the occupants—not building contents—from fire and smoke. The AHJ always must be consulted to avoid any later surprises.
ICC, SFPE Collaborate on Key Initiatives
The International Code Council (ICC), Washington, D.C., and the Society of Fire Protection Engineers (SFPE), Bethesda, Md., announced last month that the organizations are working together on key strategic initiatives. The partnership is intended to facilitate fire protection design education and application and improve public safety nationwide.
“Fire protection is a crucial part of building safety and code compliance,” said ICC CEO Rick Weiland. “Performance-based fire protection designs are being used more and more. The code council's relationship with SFPE allows us to further the science of fire protection engineering and provide code officials with the technical assistance needed to review and evaluate these designs.”
SFPE's web-based training courses include the Code Official's Guide to Performance-Based Design, Fire Alarms Course for Fire Service/Fire Prevention Officer Training, Human Behavior in Fire, Principles of Structural Fire Protection, Sprinkler Course Fire Service/Fire Prevention Officer and Principles of Fire Protection Engineering.
Other areas of cooperation include the joint development and distribution of new publications and training, the exchange of technical articles and the promotion of each other's products and services.
“The new SFPE and Code Council initiatives will enhance the already strong working relationship between our members,” said SFPE Executive Director David Evans. “Knowledge gained will facilitate the use of science and technology to protect people and property from fire around the world.”
In other ICC news, code enforcement and fire service officials, architects, engineers and other construction industry professionals will meet in Rochester, New York, May 20-26, for the 2007 International Code Council Codes Forum. Codes Forum includes the Code Council's Final Action Code Hearings and code update seminars.