Smoke Dampers: Part Of Critical Care
A full evacuation is often neither practical nor in the best interest of hospital patients. Therefore, the International Building Code (IBC) and NFPA 101, The Life Safety Code, both require that the safety of patients in hospitals be provided through the use of a defend-in-place strategy using multiple fire safety features, including construction, compartmentation, fire detection, and suppression, and a well-trained staff to assist in emergency relocation/evacuation of patients.
A key part of this strategy is to use smoke compartments formed by smoke barriers to create temporary safe areas for patients. Codes require that floors used for patients must be divided into a minimum of two smoke compartments. Patients in smoke compartments not directly involved in a fire are protected at least temporarily, and those patients in smoke compartments affected by a fire can be moved horizontally, on gurneys if necessary, across smoke barriers into an adjacent smoke compartment. This will buy valuable time before a total evacuation is necessary and depending on the circumstances, the need for a total evacuation.
Smoke barriers are used to separate smoke compartments. Walls and floors designed and constructed as smoke barriers separate adjacent smoke compartments in a building. As the name implies, smoke barriers are intended to restrict the movement of smoke.
Ensuring the ability of smoke barriers to restrict smoke movement in a fire incident is critical to the defend-in-place concept used in health care. Necessary openings and penetrations through smoke barriers represent potential smoke paths that must be protected. Therefore, ducts and transfer openings penetrating smoke barriers must also restrict the movement of smoke through the use of smoke dampers.
In this article, we will present the pertinent requirements contained in both the IBC and NFPA 101 as well as related standards pertaining to smoke dampers in smoke barriers. Both IBC and NFPA documents are mentioned because many health care facilities must often meet both sets of criteria. In the case with the political jurisdiction using International Code Council codes for building and/or fire code enforcement compliance with the IBC will be mandated. Also, hospitals and medical centers interested in accreditation by the Joint Commission for Accreditation of Health Care Organizations (JCAHO and now formerly referred to as “The Joint Commission”) will need to consider compliance with the requirements of NFPA 101 and related NFPA codes and standards.
NFPA 90A and NFPA 105 define a smoke damper as a device within an air-distribution system to control the movement of smoke.
The IBC defines a smoke damper as a listed device installed in ducts and air transfer openings that is designed to resist the passage of air and smoke. The device is installed to operate automatically, controlled by a smoke detection system, and where required, it is capable of being positioned from a remote command station.
Building codes require smoke dampers to be listed and to meet the requirements of ANSI/UL 555S, Standard for Smoke Dampers, 2006 edition. Smoke dampers can also serve double duty as a fire damper, in which case it must also meet the requirements of ANSI/UL 555, Standard for Fire Dampers, 2006 edition.
Engineers responsible for design, installation or maintenance of smoke dampers for smoke barriers must address several key items:
- Smoke damper ratings
- Actuation methods
- Inspection, testing, and maintenance
Ratings. Both the IBC and NFPA 101 require smoke dampers to have both a minimum leakage and temperature rating based on UL 555S. The damper must have a minimum Class II leakage rating and minimum elevated temperature rating of 250°F. It is noted that the leakage ratings are a maximum of 10 cfm/sq ft at 1 in. wg and 20 cfm/sq ft at 4 in. wg. These ratings must be maintained after the damper has gone through operational testing involving 20,000 cycles and at the elevated temperature rating.
Location. As noted, smoke dampers are required where ducts or air transfer openings penetrate smoke barriers. Smoke dampers in ducts must be located no more than 2 ft from the barrier and before any branch inlet or outlet. Combination fire/smoke dampers must be installed at the point where the duct penetrates the barrier, in accordance with the requirements for fire damper installation.
Actuation. In order to restrict the passage of products of combustion, smoke dampers must be actuated promptly upon the detection of smoke. The IBC and NFPA 101 both allow the following options for actuation of smoke dampers in smoke barriers:
- A smoke detector shall be installed in the duct within 5 ft of the damper, with no air outlets or inlets between the detector and the damper.
- Where a damper is installed above smoke barrier doors in a smoke barrier, a spot-type (area) smoke detector is placed on either side of the smoke barrier door opening.
- Where a damper is installed within an unducted opening in a wall, an area detector is located within 5 ft horizontally of the damper.
- By a total-coverage smoke detector system provided within areas served by the HVAC system.
Access and identification. Access to smoke dampers and in duct smoke detectors is essential to the proper functioning of smoke dampers in maintaining the integrity of the smoke barrier. Both the IBC and NFPA require that adequate access be provided to allow inspection and that maintenance of the smoke damper be provided. This access includes both in the duct and through ceilings or walls where dampers are installed. Access panels must also identify that the access is for a smoke damper. The IBC requires the lettering be a minimum 0.5 in. in height, while NFPA 105 requires the lettering be a minimum 1 in. in height.
Inspection, Testing, and MaintenanceRecent changes in NFPA 101 have clarified the requirements for inspection and maintenance of smoke dampers. Both The Joint Commission and NFPA 101 now require that smoke dampers and combination fire and smoke dampers be inspected, tested, and maintained in accordance with NFPA 105. These new requirements now serve as the industry standard of care.
Specifically, each damper must be inspected and tested within one year after installation. After this the test and inspection frequency changes to every several years for hospitals.
Inspections are to confirm full unobstructed access to the damper.
The tests include activation of the smoke detection or smoke detection system responsible for causing operation of the damper, and verification that the damper fully closes.
Inspection and testing must be documented, and records must be maintained by the facility and kept available for review by the authority having jurisdiction, be it the fire department or the Joint Commission. Maintenance performed on smoke dampers must also be documented.
Design and Installation IssuesSmoke dampers are located on the mechanical drawings, but the mechanical engineer must coordinate with the fire protection engineer to determine where smoke barriers are located, and/or where other construction requiring smoke dampers for duct or air transfer openings are required.
The mechanical engineer must also inform the electrical engineer where smoke dampers are located, so they can bring appropriate power to damper actuators. The fire protection engineer/fire alarm designer also must know where smoke dampers are located, so they can select the appropriate methods for smoke detector activation of the damper.
Specifications need to require access panels in ducts and in ceilings where smoke dampers are located. Specifications must also include requirements for identification of smoke detector locations.
Smoke barriers serve as a key component in the defend-in-place strategy so critical to hospital patient life safety. The proper design, installation, inspection, testing, and maintenance of smoke dampers serves to ensure the integrity of those barriers. ES
References1. NFPA 90A, Standard for the Installation of Air-Conditioning and Ventilating Systems, 2009.
2. NFPA 101, The Life Safety Code, 2009.
3. NFPA 105, Standard for the Installation of Smoke Door Assemblies and Other Opening Protectives, 2007.
4. International Building Code, International Code Council, 2006.
5. ANSI/UL 555, Standard for Fire Dampers, 2006.
6. ANSI/UL 555S, Standard for Smoke Dampers, 2006.