extensions as indicated of 6 mm 1/4 inch thick 410 stainless steel plate
with structural stiffeners. Hopper extension shall hold not less than
[_____] Mg tons of coal at a density of 800 kg per cubic meter 50 pounds
per cubic foot. Hopper extensions shall have bolted emergency firing doors
of not less than 610 by 610 mm 24 by 24 inches which shall contain a 152 by
152 mm 6 by 6 inch glass observation window. Connections shall be
dusttight.
2.9.15
Coal Valve
Dusttight and dripproof of the double ladder rack-and-pinion type sized as
indicated for each valve. Valve shall be capable of closing through a
standing coal column. Valve opening shall be full size with no bridges,
internal braces, or other barriers.
2.9.15.1
Valve Body
Not less than 6 mm 1/4 inch thick formed 410 stainless steel with heavy 19
mm 3/4 inch thick flanges. Continuously weld joints in contact with coal
both inside and out and grind smooth. Valve body shall have dusttight
steel gate assembly cover with molded gasket for removal of gate without
removing coal valve. Provide a minimum of two dusttight poke holes with
rigid covers and molded gaskets.
2.9.15.2
Valve Gate
Dripproof and siftproof of 10 mm 3/8 inch thick steel plate with an 11 gage
(3.04 mm0.1196 inch) 410 stainless steel liner. Support gate by ball
bearing rollers with 16 gage (1.52 mm0.0598 inch) stainless steel shells
equipped with felt grease seals and stainless steel grease retainers.
Provide rollers with grease fittings extended through valve body for
pressure lubrication. Design gate so that supporting rollers, racks, and
pinions are located completely out of the coal stream. Provide cold
formed, self cleaning racks, with stainless steel self cleaning pinions
located over racks for positive tooth engagement.
2.9.15.3
Operating Shaft
Mount operating shaft in ball bearings with felt seals, stainless steel
shells, stainless steel grease retainers, and grease fittings. Provide
handwheels with proper finger clearance or pocket sheaves with heavy
hot-dipped galvanized chain and chain guard as indicated. Handwheels and
sheaves shall be not less than 457 mm 18 inches in diameter. Provide
valves with mechanical type position indicator consisting of large pointer
and legend to indicate position of valve gate.
2.9.15.4
Electric Motor Operators
Provide motor operators where indicated and capable of remote operation
from the coal handling control panel. Operator shall consist of totally
enclosed, fan cooled, high torque, [_____] volt, [_____] phase, 60 Hz motor
as specified in paragraph entitled "Motors and Drives" with reduction gear,
clutch and limit switches. Motor horsepower shall be as recommended by the
manufacturer. Provide motorized valves that have manual operators, with
fail-safe interlocks that make manual operation impossible while motor is
operating.
SECTION 15501N
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