Model 4
1500 - 6000 MBTU/hr
Rev. 03-08
Section B2-6
Gas
Train
consists
of the following:
•
Primary gas shutoff valve
with
integral proof
of
closure
switch.
•
A
manual shutoff valve located ahead
of the primary
gas
valve.
•
A
plugged leakage
test
connection
and a
second manual shutoff valve
for tightness
checking
of the
primary shutoff
valve.
•
Separate Gas Pressure Regulators
for the pilot train and main
gas
train.
•
Low
Gas Pressure
and High
Gas Pressure Switches
for units at 3000 and greater.
•
A
second motorized gas valve
is
provided
in addition to the primary
valve
on size
6000
un
its.
•
The
pilot
gas
train
includes
a
manual shutoff valve
and
solenoid shutoff
valve.
3. Boiler Trim and
Controls
A. 15 psig or 150 psig set
A.S.M.E. safety
relief
valves.
B.
Steam pressure gauge
with
inspectors
test
cock
and connection.
C.
Primary Water Column complete
with
gauge glass
and column drain valve.
D. Low Water cutoff switch and pump control switch, integrally mounted in the
primary water column.
E.
Auxiliary
Low
Water Cutoff,
manual
reset
type.
F.
Steam Pressure
Controls:
•
Operating
Limit.
•
Excess Steam Pressure
(High Limit),
manual
reset.
•
Burner
firing rate, low high low.
4.
Burner Control Panel
and
Controls
A. The control panel is
enclosed
within a NEMA 1A
Rated enclosure, mounted
on
the
burner
wind
box
at
approximately eye level
height.
B. Mounted within or on the control panel box are the following controls. Panel
wiring is
factory
tested.
•
Combustion Flame Safeguard Control, Model
CB120 that
provides
pre
purge,
post
purge,
trial for ignition, main
flame/burner operation,
and
safety
shutdown.
•
Fan
Motor
Starter
wired into the non
recycling
circuit of the flame safeguard
control.
•
Indicating Lights
for low water, flame failure, load
demand,
and fuel
valve
on.
•
Burner On/Off
Switch.
•
Damper Positioning
Switch.
•
Fuel Selector Switch
for
combination
fuel fired burners.
•
Control
Circuit
Step-down Transformer
with primary
fuse
protection.
•
Terminals
for
interface
wiring
connection
of controls.
•
Oil, heat, and
moisture resistant
wire used.
Each
wire is
number coded relative
to
the wiring diagram.
5.
Electric Service
Panel
An electric
service
panel
(entrance
box) is
provided
on the side of the boiler for all
external
wiring
connections
to remote control
devices
and the main power for the
boiler. Wiring to this panel
eliminates
the
need
to
disconnect
wiring when the front
burner
wind
box
is
opened
for
burner
or boiler servicing.
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