2.9
ISOLATION DAMPERS
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NOTE: Depending on system design requirements,
isolation dampers may or may not be part of the
filtration system design. The gasket material shall
be butyl rubber for Class 0, zero leakage dampers,
and EPDM for Class 1 low leakage dampers.
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Isolation dampers shall be provided as an integral part of the filtration
system. [An individual damper shall be provided to isolate the filtration
system.] [Multiple dampers shall be provided to isolate individual sections
of the filtration system.] Dampers shall be classified, constructed,
inspected, and tested in accordance with ASME N509 construction Class B as
a single blade damper or a combination of single blade dampers. The
leakage of the isolation dampers shall conform to ASME AG 1, Section DA,
Class [0, zero leakage] [1, low leakage]. The blade/disk, frame, shafts,
and linkages shall be constructed of Type 304 stainless steel. The dampers
shall have Type 304 stainless steel disk with a [butyl rubber] [EPDM]
gasket. The isolation damper disk gasket (seal) and shaft seal shall be
replaceable. Each isolation damper shall be operated by an independent
electrically-actuated drive mechanism [with manual backup]. Isolation
dampers shall be of all welded design. [Isolation damper flanges shall
have factory drilled 11 mm 7/16 inch holes, located on the filtration unit
[as indicated] and shall be no more than 100 mm 4 inches apart as described
in DOE HDBK-XXXX]. The flanges shall be reinforced with flat stock of the
same material to provide a combined minimum thickness of 6.35 mm 1/4 inch.
2.9.1
Electrically and Manually Actuated Isolation Damper Operators
Damper operators shall operate in an automatic mode [with manual backup].
The electric/manual operator shall be of sufficient capacity to operate the
damper under all conditions, and to guarantee tight close-off of the damper
against all system pressures encountered. The maximum force required to
manually actuate the damper shall be 11.3 kg 25 pounds. Controls shall be
as specified in Section 15951 DIRECT DIGITAL CONTROL FOR HVAC AND OTHER
LOCAL BUILDING SYSTEMS.
2.9.2
Fan Unit
Fans, airflow control dampers, and actuators shall be as specified in
Section 15895 AIR SUPPLY, DISTRIBUTION, VENTILATION, AND EXHAUST SYSTEM.
Fans shall be a single-inlet, centrifugal type, with the fan [inlet]
[outlet] connected to the filtration unit with a flexible duct connector
and duct transition to the filtration unit housing. The fan shall be
controlled by [a manually] [an automatic electrically] actuated, [inlet
vortex] [outlet opposed blade] damper suitable for the specified static
pressure.
2.9.3
Flexible Duct Connectors
A flexible duct connector approximately 152 mm 6 inches in width shall be
provided where sheet metal connections are made to the fan unit. The
flexible material, chemically resistant butyl rubber, shall be locked to
metal collars and installed using normal duct construction methods. The
flexible material shall withstand the indicated system pressures. The
composite connector system shall comply with UL 214 and shall be classified
as flame-retarded fabrics in UL 723.
SECTION 15860A
Page 17
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