Hospitals
have a population with special concerns and vulnerabilities in case
of fire. To maintain an effective passive smoke management system in
health care environments, make sure you know how to incorporate and
maintain smoke dampers in a life safety design meeting IBC, NFPA, and
JCAHO requirements.
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
- Location
- Actuation methods
- Reliability
- Access
- Identification
- 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.
Reliability.
The fact that smoke dampers must meet requirements of UL 555S goes a
long way towards ensuring reliable function of the damper. Motorized
actuators are normally used for the operation of smoke dampers. The
designer must consider the case where there is loss of normal power
to the damper actuator. Either emergency power should be provided or
smoke dampers should be arranged for fail-safe closure upon failure
of power to the actuator.
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.
