to ball or roller bearings. Idlers shall be 20-degree or 35-degree
three-roll type spaced on 1.2 m 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 IP-1. 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 1067 mm 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 1.2 m 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] [watertight] [dust-tight] [explosion-proof] enclosure.]
All 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 take-ups, belt cleaners, skirt
boards, and pulley scrapers. Dust controlling covers and inlet and
discharge enclosures shall be provided for each conveyor.
2.29.3
Flight Conveyor
[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 0.508 m/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,
spaced at least three times the largest lump size. Foot shaft shall have
protected screw take-up with adjustment of not less than 300 mm 12 inches.
Trough shall be made of 4.8 mm 3/16 inch steel plate, minimum. All sliding
surfaces in contact with the chain or flights shall be lined with 19 mm 3/4
inch thick, removable, ultra high molecular weight polyethylene liners.
Both sides of trough shall be provided with a warning sign "DANGER - DO NOT
WELD - FLAMMABLE PLASTIC LINER." Signs shall be visible on each floor
level and at frequent intervals. Conveyor shall be provided with discharge
openings as indicated, each of which shall be provided with
rack-and-pinion-operated gates with handwheels. Motor shall drive conveyor
through a speed reduction unit which is either direct-connected or
roller-chain-connected to the drive shaft. Motor shall be [totally
enclosed, nonventilated type] [totally enclosed, fan-cooled type] [totally
enclosed, fan-cooled type suitable for installation in a Class II, Division
1, Group F hazardous location in accordance with NFPA 70]. [Motor starter
SECTION 15559A
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