center and provisions for mounting the bin vent filter, pressure relief
valve and high-level switch. Provide for access to the interior of the bin
from the roof through a hinged manway. Access, handrails, and kickplate
for the roof shall be provided as specified in paragraph entitled
"Structural and Miscellaneous Steel." A fill pipe shall be provided for
transporting pebble lime from self-unloading trucks to the storage and feed
bin. The fill pipe shall extend from the truck fill connection point,
approximately 1.22 meters 4 feet above grade, to the center fill collar.
The fill pipe shall be 100 mm 4 inch O.D. Schedule 40 carbon steel pipe. A
1219 mm 4 inch centerline radius bend shall be used for the direction
change at the top of the fill tube riser. The fill tube shall be complete
with a quick coupling hose connection with security chain, dust cap and
limit switch at the truck connection point and a clean-out cap at the inlet
target box. The inlet target box shall be provided with two openings for
fill piping connections: One for use with the 100 mm 4 inch fill pipe to be
provided under this contract and one for use with the pneumatic conveying
system piping to be provided by the Contractor. The opening for use by the
pneumatic conveying system piping shall be 150 mm 6 inches in diameter and
shall be suitable for attachment of a reducer for compatibility with the
conveying line size selected later for use with the pneumatic conveying
system. Provide a bin vent filter for mounting on top of the bin, with
retained dust discharge directly into storage bin. This unit shall have a
venting capacity of at least 472 L/s 1,000 scfm. Filter bags must be
readily removable for inspection or replacement without tools.
Construction of filter manifold shall prevent filter bags from falling into
storage bin. Operation of the filter shall be such that there will be no
escape of dust during truck unloading. Filter unit shall be fabricated
weatherproof and dripproof construction, with self-contained bag cleaning
system and fan assemblies. Weather and dripproof gasketed access doors to
bag compartment shall be provided. Parts of unit subject to service or
maintenance shall be not more than 1 1/2 meters 5 feet above the bin roof
and shall be accessible by a person standing on top of the bin without use
of ladders or platforms. The bin filter exhaust fan shall be the
squirrel-cage type, operating at less than 3,500 rpm, with mounting on the
bin vent filter. This unit shall have air handling capacity of at least
472 L/s 1,000 scfm. It shall provide a negative pressure within the bin
during unloading operations. The fan outlet shall be provided with a
louvered damper which automatically opens during operation and closes when
the bin is not being filled and shall be fitted with a removable bird and
insect screen. Electric connections shall be NEMA 3R, rainproof. A
disconnect switch in NEMA 3R steel enclosure shall be provided and mounted
on the vent filter unit to allow local shutoff of power supply to
electrical devices located at the bin roof level. Wiring connections to
these units shall be made by the Contractor. Two bin level switches shall
be mounted at a high and at a low level on the bin. These switches are to
be of the stainless steel, rotating-paddle type, electrically operated.
Indicating lights coincident with these switches shall be provided in both
the truck unloading panel and the main control panel. Top-mounted units
must have extension shafts and guards. Side-mounted units shall be provided
with inside shields and all units must be mounted adjacent to ladders or on
top of storage bin. The lower bin switch shall be located to represent
capacity in terms of complete truck loads of material, based on truck load
capacity of 18.82 cubic meter 665 cubic feet per load of quicklime density
at approximately 960 kg per cubic meter 60 pounds per cubic foot. One
heavy-duty vibrator shall be connected to the outside of each bin cone and
provided with suitable controllers and timers to allow pacing from the
quicklime feeder. Each vibrator shall be interconnected with the
associated feeder, in order that it operates in proportion to feed rate
only when the bin gate is open and the feeder operates. Live bottom type
SECTION 15864N
Page 54
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