shall be [manual] [[magnetic] [across-the-line] [reduced voltage start]]
type with [general-purpose] [weather-resistant] [water-tight] [dust-tight]
[explosion-proof] enclosure.] Conveyor frame shall be constructed
essentially as indicated, with additional bracing as required for rigidity.
Dust controlling covers and inlet and discharge enclosures shall be
provided for each conveyor.
2.29.4
Bucket Elevators
Vertical bucket elevators shall be furnished dust tight, complete with
continuous chain and attached buckets, upper and lower sprockets, gears,
shafts, bearings, casing with flanged connections including top hood and
discharge spout, bottom boot, access doors, electric motor drive, and all
accessories. Bucket elevators shall be [vertical spaced centrifugal
discharge] [positive discharge] [continuous bucket type]. The capacity of
the elevator shall be not less than [_____] metric tons/hour tons/hour when
handling coal weighing approximately 800 kg/cubic meter 50 pcf. Linear
velocity shall be as indicated below:
Type of Bucket Elevator
Linear Velocity (meters per second)
Centrifugal discharge
1.1-1.6
Continuous bucket
0.508-0.686
Positive discharge
0.610 Max
Type of Bucket Elevator
Linear Velocity (fpm)
Centrifugal discharge
225-305
Continuous bucket
100-135
Positive discharge
120 Max
The head shaft and foot shaft shall be constructed of cold-rolled steel
with the shaft diameters in accordance with manufacturers' standards. Both
shafts shall be mounted in roller bearings with forced-type lubricating
fittings. Foot shaft shall have screw take-up with adjustment of not less
than 225 mm 9 inches. An automatic backstop shall be installed on the head
shaft to prevent any backward motion of the chain. Boot plates [, loading
legs of continuous bucket elevator,] and bottom plate of stub discharge
chute shall be 4.8 mm 3/16 inch thick, minimum. All other flat casing
members shall be 2.657 mm 12 gauge steel thick, minimum. Corner angles and
stiffeners shall be provided to make the elevator self-supporting. In
addition, the elevator shall be tied to the adjoining structure at close
enough spacing to increase the rigidity of the elevator. The boot section
shall be provided with clean-out doors, as well as front and back removable
panels. An inspection door large enough to remove a bucket from either run
of the chain shall be provided in the intermediate section at operating
level. The elevator shall be driven by an electric motor installed in a
suitable housing at the top of the flight. Motors shall be [totally
enclosed, nonventilated] [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
shall be [manual] [[magnetic] [across-the-line] [reduced voltage start]]
type with [general-purpose] [weather resistant] [water-tight] [dust-tight]
[explosion-proof] enclosure.] A platform shall be installed adjacent to
the motor for servicing the motor and equipment mounted in the hood.
Access to the platform shall be by an approved type of safety ladder.
Controls for the operation of the elevator shall be located as indicated.
Dust control covers and inlet and discharge enclosures shall be provided
for each conveyor.
SECTION 15559A
Page 82
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