a.
Damper blade shaft assembly. Limit deflections at maximum damper
seal conditions to L/360 (L = blade length in mm inches) or 6 mm
1/4 inch, whichever is less, and to deliver the full operator
torque to a blade without exceeding one-third of the shaft yield
stress when operating at the worst case design conditions.
b.
Stuffing boxes. Provide dust-tight stuffing boxes, to seal shaft
openings, so that fluoroplastic packing may be adjusted or removed
from the outside of the duct without removing bearings or linkage.
c.
Linkage system. Provide fully adjustable self-locking linkage
system outside of the damper unit. Key arms to the shaft for easy
removal. Pin or bolt stub shafts to the through shaft or blade so
that individual damper blades may be adjusted or removed. Use
Type 304 stainless steel, Unified Numbering System Number S30400
(0.03 to 0.08 percent carbon), linkage pins or bolts to connect
carbon steel clevis arm to the stub shaft. Provide two operators
on the linkage system, one to operate the top blade, and one to
operate the bottom blade. The upper blades shall closed first,
then the bottom blade shall close. Design linkage so that the
number of blades operated by each operator may be changed.
d.
Lock system. Provide a lock system using heavy-duty padlocks so
the damper system can not be operated until the padlocks are
removed.
2.4.4.2
Poppet and Butterfly Dampers
Provide each compartment with an inlet [, an outlet, and an inlet reverse
air] damper having a maximum air leakage rate of 0.5 percent to provide for
essentially zero leakage at maximum baghouse design differential pressure.
Dampers shall be either poppet dampers or butterfly dampers with adjustable
speed and stroke operators, shaft packing glands, replaceable seal plates,
and machined steel seating cylinder and guide shaft. Provide a lock system
to lock dampers closed to protect service personnel. Locate shafts out of
the dirty gas stream, otherwise provide shaft seals.
2.4.4.3
Double Guillotine Dampers
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NOTE: An outlet manifold damper is not required for
single baghouse installations. Where two or more
baghouses share a single stack, provide dampers at
each baghouse outlet manifold to prevent flue gas
from exiting one baghouse and entering another.
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Provide the inlet manifold, [the outlet manifold,] and the inlet bypass,
with double plate steel guillotine dampers having a maximum air leakage
rate of 0.5 percent to provide for essentially zero leakage at maximum
baghouse design differential pressure. One damper shall be open while the
other damper is closed. Include a mechanical crank for manual operation.
Provide dampers with carbon steel bonnets over the top frame, removable
side plates for inspection of the damper drive assembly, and a removable
bottom plate for access to the frame seal. Design bonnet for continuous
seal air purge and provide an air reservoir to activate the damper upon
loss of plant air. Design damper drive to lift the damper blade evenly on
both sides. Provide damper units with the following:
SECTION 15863N
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