control and light indication for combustion air blowers and on-off
control of convenient groups of heaters. Provide on-off control
with indicating light for each thawing pit. Panel shall have a
NEMA [12] [3R-8], dust-tight enclosure with internal equipment and
wiring accessible from panel front. Provide nameplates on panel
front to designate function of switches and indicating lights.
Controls shall be suitable for [_____] volt, [_____] phase, 60 Hz
operation. Provide and mark terminals for connections with the
exception of the neutral. Terminal blocks shall be 600 volt
rated. Control relays shall have convertible contacts and shall
have rating suitable for intended services but not less than 10
amp, 600 volt rating. Components shall be oiltight type.
Connections to panel shall be watertight. Motor starters for
combustion air blowers shall be installed in each respective
blower cabinet.
][2.9.1.2
Surface Mounted Enclosed Railroad Hopper Car Thawing System
**************************************************************************
NOTE: Choose this subparagraph or the subparagraph
above entitled "Pit-Type Railroad Hopper Car Thawing
System."
**************************************************************************
**************************************************************************
NOTE: Choose item a. or item b. that follows.
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[a.
Surface Mounted Enclosed Thawing Unit (Gas): Burner shall be of
multiport cast iron construction and provide for even heating of
radiant elements. Heater design shall be essentially the same for
undercar and sidecar heaters, with heat transmitted to hopper car
by both radiation and convection. Design burner and radiant
element for radiation being the primary mode of heat transfer.
Radiant element over burner shall be of a heavy
corrosion-resistant metal material. Design burner to operate on
[natural gas] [liquified petroleum gas], and such that open flame
from combustion will not extend beyond emitter surface either
during normal operation or in the event of emitter deterioration
or burnout. Provide shields where necessary to direct radiation
and hot exhaust gases to hopper car surface. Provide means for
shielding car air hoses, air brake equipment, and bearings from
excessive heat. Provide each heater with individual heater control
boxes constructed as to provide positive air pressure inside
control box. Control boxes shall contain mixing valve for
maintaining proper gas-air ratio for satisfactory combustion.
Locate gas and air piping connections for easy removal of
individual burners. Deliver combustion air to heaters by means of
pressure blowers which take fresh air from outside thawing area to
ensure continued satisfactory combustion of gaseous fuels.
Factory wire and assemble thawing units, control panels, blowers,
and zone controls.]
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NOTE: Choose item b. or item a. above.
**************************************************************************
[b.
Surface Mounted Enclosed Thawing Unit (Electric): Thawing unit
may be an electric radiant heat thawing unit which includes
SECTION 15501N
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