Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11C - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Commercial › Section 51-11C-40378 - Section C403.7.8-Shutoff dampers

Current through Register Vol. 24-14, July 15, 2024
C403.7.8
Shutoff
			 dampers.
Mechanical openings shall be provided with shutoff dampers in
			 accordance with Sections C403.7.8.1 through C403.7.8.4.
C403.7.8.1
Shutoff dampers for building
			 isolation.
Outdoor air supply, exhaust openings and relief outlets and
			 stairway and elevator hoistway shaft vents shall be provided with Class I
			 motorized dampers. See Sections C403.10.1 and C403.10.2 for ductwork insulation
			 requirements upstream and downstream of the shutoff damper.
EXCEPTIONS:
1. Gravity (nonmotorized) dampers shall be permitted in
						  lieu of motorized dampers as follows:
1.1. Relief dampers serving systems less than 5,000 cfm
						  total supply shall be permitted in buildings less than three stories in
						  height.
1.2. Gravity (nonmotorized) dampers where the design
						  outdoor air intake or exhaust capacity does not exceed 300 cfm (142
						  L/s).
1.3. Systems serving areas which require continuous
						  operation for 24/7 occupancy schedules.
2. Shutoff dampers are not required in:
2.1. Combustion air intakes.
2.2. Systems serving areas which require continuous
						  operation in animal hospitals, kennels and pounds, laboratories, and Group H, I
						  and R occupancies.
2.3. Subduct exhaust systems or other systems that are
						  required to operate continuously by the
International Mechanical
						  Code
.
2.4. Type I grease exhaust systems or other systems
						  where dampers are prohibited by the
International Mechanical
						  Code
to be in the airstream.
2.5. Unconditioned stairwells or unconditioned elevator
						  hoistway shafts that are only connected to unconditioned spaces.
C403.7.8.2
Shutoff dampers for return
			 air.
Return air openings used for airside economizer operation shall be
			 equipped with Class I motorized dampers.
C403.7.8.3
Damper leakage
			 rating.
Class 1 dampers shall have a maximum leakage rate of 4
			 cfm/ft2 (20.3 L/s x m2)
			 at 1.0 inch water gauge (w.g.) (249 Pa) when tested in accordance with AMCA
			 500D and shall be labeled by an approved agency for such purpose. Gravity
			 (nonmotorized) dampers shall have an air leakage rate not greater than 20
			 cfm/ft2  where not less than 24 inches (610 mm) in
			 either dimension and 40 cfm/ft2 where less than 24
			 inches in either dimension. The rate of air leakage shall be determined at 1.0
			 inch w.g. (249 Pa) when tested in accordance with AMCA 500D for such purpose.
			 The dampers shall be labeled by an approved agency. Gravity dampers for
			 ventilation air intakes shall be protected from direct exposure to wind.
EXCEPTIONS:
1. Gravity (nonmotorized) dampers are not required to
						  be tested to verify the air leakage rating when installed in exhaust systems
						  where the exhaust capacity does not exceed 400 cfm and the gravity damper is
						  provided with a gasketed seal.
2. Motorized dampers on return air openings in unitary
						  packaged equipment that have the minimum leakage rate available from the
						  manufacturer.
C403.7.8.4
Damper actuation.
Outdoor air intake, relief and exhaust shutoff dampers shall be installed with
			 automatic controls configured to close when the systems or spaces served are
			 not in use or during unoccupied period warm-up and setback operation, unless
			 the systems served require outdoor or exhaust air in accordance with the
International Mechanical Code
or the dampers are opened to
			 provide intentional economizer cooling. Stairway and elevator hoistway shaft
			 vent dampers shall be installed with automatic controls configured to open upon
			 the activation of any fire alarm initiating device of the building's fire alarm
			 system or the interruption of power to the damper.