the belt conveyor shall not exceed 15 degrees. The conveyor support frame
shall have sufficient rigidity to maintain belt alignment, at least 75 mm 3
inches clearance to prevent damage to the edge of the belt on its return
run, and adjustments for aligning shafts. Decking to protect the return
belt from coal sifting and to provide lateral stiffness shall be placed on
top of the stringers. Idlers shall be accurately made to provide a rigid
framework that will maintain permanent alignment of well-balanced,
smooth-running, easy turning idler rolls. Idlers and return rolls shall be
CEMA Belt Book. Pressure lubrication shall be provided to ball or roller
bearings. Idlers shall be 20-degree or 35-degree three-roll type spaced on
1200 mm 4 foot centers, except under loading points and skirts. Return
idlers shall be spaced on 3 m 10 foot centers. The belting shall be Grade
2 as defined in RMA Conveyor and Elevator Belt Technical Information. The
belting shall have field-vulcanized splices. Pulleys shall be designed in
accordance with CEMA B105.1, shall be heavy welded steel, true to diameter
and accurately bored, key seated and tightly fitted to the shafts. Pulley
face width for belts 1.1 m 42 inches wide and smaller, that are 150 m 500
feet or more in length, shall be belt width plus 100 mm 4 inches; less than
150 m 500 feet in length, shall be belt width plus 75 mm 3 inches. Pulley
face width for belts 1200 mm 48 inches and larger shall be belt width plus
150 mm 6 inches. Drive pulleys shall be provided with 19 mm 3/4 inch thick
vulcanized and grooved lagging. Snub pulleys shall be provided with 9.5 mm
3/8 inch vulcanized smooth lagging. All conveyor pulley shaft assemblies
shall be supported by two heavy-duty antifriction bearings having a minimum
life expectancy of 50,000 hours for 90 percent of bearings in accordance
with ABMA 11 for roller bearings. The pulley diameter shall be
sufficiently large to meet the requirements of the duck weight and ply of
the belt to permit flexing of the belt around the pulley circumference
without damaging the belt or shortening the belt life. The conveyor shall
be driven by a [totally enclosed, nonventilated type] [totally enclosed,
fan-cooled type] [totally enclosed, fan-cooled type suitable for
installation in Class II, Division 1, Group F hazardous location in
conformance with NFPA 70] electric motor connected to a drive-shaft-mounted
speed reducer unit by a [roller chain drive] [V-belt drive] [flexible
coupling]. [The motor starter shall be [manual] [[magnetic]
[across-the-line] [reduced voltage start]] type with [general-purpose]
[weather-resistant] [water-tight] [dust-tight] [explosion-proof]
enclosure.] Belt conveyors shall be provided with belt misalignment
switches, emergency stop pull cords and pull switches, galvanized expanded
metal shields over tail pulley, zero speed switches, loading skirts,
plugged chute switches, walkways, supports, belt takeups, belt cleaners,
skirt boards, and pulley scrapers. Dust controlling covers and inlet and
discharge enclosures shall be provided for each conveyor.
2.23.3
Flight Conveyor
**************************************************************************
NOTE: Where motor starters for mechanical equipment
are provided in motor control centers, delete the
description of motor starters.
**************************************************************************
[Scraper] [Shoe-suspended] flight conveyor arranged generally as shown and
of the single-strand type shall have capacity not less than [_____] metric
tons/hour tons/hour when handling coal with approximate weight of 800
kg/cubic meter 50 pcf and with maximum lump size of [_____] mm inches
diameter. Capacity shall be based on a maximum speed of 508 mm/sec 100 fpm
with conveyor operating up a [_____] degree incline. Chain shall be
drop-forged steel type with flights made of either steel or malleable-iron,
SECTION 15555A
Page 68
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