ductwork,] and the bypass ductwork. Dampers shall conform to AMCA 500-D,
AMCA 801, and AMCA 802 and shall withstand, without affecting damper
operation, differential thermal expansion, 1464 kg/m2 300 lb/sq ft flyash
load at the bottom of the damper frame, 908 kg 2,000 pound concentrated
load at the maximum frame deflection point, and maximum loads specified in
paragraph entitled "Design Criteria."Damper frame shall support the damper
unit including controls, motors, drive mechanisms, and seal air system,
with only one flange bolted to the ductwork without swaying or without
causing the blade to blind. Bearings, bearing mount, and linkage system
including connections shall withstand three times the damper blade load
plus the operator output torque, at worst case design conditions. Damper
units shall include:
a.
Pneumatic operators; except guillotine dampers which shall have
the manufacturer's standard motor operators. Locate outside of
the gas stream and within access for maintenance during baghouse
operation.
b.
Control drive units with permanently mounted handwheels which may
be disengaged during pneumatic or motor operation; exclude poppet
damper actuators.
c.
Limit switches to show damper position (opened or closed).
d.
Mechanical position indicator, at the damper, to show percent of
damper opening.
e.
Flanged frames for bolting to connecting ductwork.
f.
Lifting lugs for transportation and installation handling.
g.
External, locally mounted audible alarms to signal loss of seal
air. Upon loss of power or air, dampers shall fail in [failshut]
[failopen] position.
h.
Bearings. Permanently lubricated, self-aligning bearings located
outside of the damper unit, insulation, and lagging, so that
leaking packing shall not contaminate the bearing with flyash.
i.
Sealing strips, bolting materials and backing strips:
ASTM B 443.
Not required for induced draft fan dampers.
j.
Nuts, bolts, and washers. Use self-locking Type 316 stainless
steel, Unified Numbering System Number S31600 (0.03 to 0.08
percent carbon) bolts, so that damper unit vibrations do not cause
bolts to back out.
2.4.4.1
Louver Dampers
Provide the induced draft fan inlet [and the reverse air fan inlet] with
parallel or opposed airfoil louver damper units. Frame length shall be 25
mm one inch greater than the blade width; blade width shall be maximum 610
mm 24 inches. Provide a minimum of two blades. Dampers having an open
area of 3.72 to 7.43 sq meter 40 to 80 sfshall have a minimum of three
blades. Dampers having an open area over 7.43 sq meter 80 sf shall have a
minimum of four blades. Allowable bending stresses shall not exceed 60
percent of yield at design conditions. Provide louver damper units with
the following:
SECTION 15863N
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