bearing shall be pressed onto a steel shaft via a knurled stud. A slotted
dowel pin is then inserted thru a hole connecting the two pins.]
2.12.1
Backdraft Dampers (Gravity Dampers or Shutters)
Factory-fabricated, with statically balanced blades that open automatically
when the fan starts and close by gravity when the fan stops. Provide the
edges of blades with felt or rubber strips to prevent rattling.
2.12.2
Manual Volume Dampers
Balancing, factory-fabricated type. Equip dampers with accessible
mechanism such as quadrant operators or 5 mm 3/16 inch rods brought through
the side of ducts with locking setscrew and bushing. Where quadrant
operators are furnished, provide chrome plated or enamel painted type with
exposed edges rounded.
2.12.3
Fire Dampers
Provide in accordance with UL 555.
2.12.4
Automatic Smoke-Fire Dampers
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NOTE: For smoke-fire dampers, use UL 555S Class
III, unless the particular building and application
such as hospital dictates the use of UL 555S Class
II instead.
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Multiple blade type, 82 degrees C 180 degrees F fusible fire damper link;
smoke damper assembly to include pneumatically powered operator. UL 555 as
a 1 1/2 hour rated fire damper; further qualified under UL 555S as a
leakage rated damper. Leakage rating under UL 555S shall be no higher than
Class [II] [or] [III] at an elevated temperature Category B (121 degrees C
250 degrees F for 30 minutes). Pressure drop in the damper open position
shall not exceed 25 Pa 0.1 inch w.g. with average duct velocities of 13
meters per second 2500 fpm.
2.12.5
Automatic Smoke Dampers
UL listed multiple blade type, supplied by smoke damper manufacturer, with
pneumatic damper operator as part of assembly. Qualified under UL 555Swith
a leakage rating no higher than Class [II] [or] [III] at an elevated
temperature category B (121 degrees C250 degrees F for 30 minutes).
Pressure drop in the damper open position shall not exceed 25 Pa 0.1 inch
w.g. with average duct velocities of 13 meters per second2500 fpm.
2.12.6
Automatic Dampers
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NOTE: Allow maximum 12 liters per second 25 cfm
leakage. For particular building and application,
such as hospital, 5 liter per second 10 cfm leakage
may be allowed.
**************************************************************************
[Section 15901N SPACE TEMERATURE CONTROL SYSTEMS.][Section 15910N DIRECT
DIGITAL CONTROL SYSTEMS.] Maximum leakage shall not exceed [50] [130]
SECTION 15810N
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