a.
Retainers: Cage type construction,
fabricated from No. 1018
rounds or equal, using minimum of 3
mm 1/8 inch diameter rounds on
vertical strands and 5 mm 3/16 inch
diameter rounds on horizontal
strands. Coat retainer with nickel
and zinc after completion of
fabrication.
b.
Filter Bags: Not less than 474 g per square meter 14 ounces per
square yard felted material. Provide felted polyester or dacron
bags when operating temperatures are below 135 degrees C 275
degrees F. Provide Nomex bags or bags of similar abrasion and
temperature resistant qualities when temperatures are above 135
degrees C 275 degrees F but not greater than 218 degrees C 425
degrees F. Bags shall have an exterior finish to aid in dust
release.
2.12.14.6
Control Panel
Provide NEMA 4, wall mounted control panel to sequentially control the bag
cleaning and dump operations of the filter unit. Locate panel near the
filter unit to permit easy field adjustment of sequence timers. Panel
overall dimensions shall be not less than 610 mm wide by 762 mm high by 200
mm deep 24 inches wide by 30 inches high by 8 inches deep. As a minimum,
the panel instrumentation shall include a dump cycle timer, pulse valve
sequence timer, two high differential pressure delay relays, alarm relay,
time delay relay, manual/auto selector switch, pulse valve "ON" indicating
light, high differential indicating light, terminal blocks and internal
wiring. Welds and scratches of panel enclosure shall be free from
blemishes. Paint panel exterior with manufacturer's standard enamel.
Interior of panel shall be white enamel. Shop inspect panel and test prior
to shipment.
2.12.14.7
Vacuum Breakers
Provide two air cylinder operated vacuum breakers. One shall be a pop-up
or single ported type for installation in the air line between the
secondary separator and tertiary bag filter. Second breaker shall be a
three-ported type for locations in the air line between the tertiary bag
filter and the exhauster. Each breaker shall use a disc type gate or
equivalent to ensure full closure of the gate against its mating seat.
2.12.15
Steam Exhauster
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NOTE: The steam exhauster system requires 0.32 kg
2500 pounds of steam per second hour for a 150 mm 6
inch system (8 to 23 Mg9 to 25 tons per hour) and
0.44 kg 3500 pounds of steam per second hour for an
200 mm 8 inch system (13.6 to 31.75 Mg15 to 35 tons
per hour) and approximately 1.89 L/s 30 gpm of water
to the air washer. A steam condenser, air washer
and silencer should be used when the steam exhauster
is used and should not be used when a mechanical
exhauster is specified.
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Provide a steam jet exhauster of cast iron construction with venturi throat
of the high efficiency type for producing the vacuum necessary for handling
ashes through the system. Make inlet air connection on the steam jet
exhauster through a special spiral fitting so that the air enters the
SECTION 15502N
Page 137
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