Model 4
1500 - 6000 MBTU/hr
Rev. 03-08
Section B2-20
Oil Piping
General
- Oil operation of the Model 4 boiler
requires
proper oil to the standard
burner mounted oil pump. As the combustion of oil utilizes mechanical
pre
s
sure
atomization,
line
sizing
to the pump must be
sufficient
to
provide
125 gph of oil to
the
suction side
of the pump.
Oil
Train Components
- Oil flow to the
burner
is
controlled
by four
solenoid
valves.
The oil flows through a primary or
safety
shutoff
valve
into a manifold block. This
valve and the low fire valve are
energized simultaneously
by the flame
safeguard control and when
opened,
allow flow of oil to the low fire nozzle.
As the
damper
motor
moves
to high fire position, the
damper
motor end switches
close to
energize
in
sequence,
the
intermediate
and then high fire oil valve. The
purpose
of the
intermediate valve
is to
smooth
the
transition
from low to high fire by
balancing
the oil input with
increasing
flow of air.
High fire rating of the
burner
is
obtained
when all
three nozzles are
firing, assuming
proper
oil
pressure
and
normally sized
nozzles.
Gas Piping
General
- The Model 4 boiler
requires appropriate gas
supply
pressure
and volume
for proper operation and long burner life. The gas
requirements
specified in this
section must be satisfied to
ensure
efficient and stable combustion. Installation
must follow these guidelines and of the local authorities that have installation
jurisdiction.
Gas Train Components
- Model 4
boilers
are
equipped
with a
gas
train that meets
the requirements of UL as standard. These components also comply with the
recommendations
of FM, XL
GAP
(formerly
IRI/GE GAP)
and
ASME
CSD-1. The
gas train and its
components
have been
designed
and tested to operate for the
highest combustion
efficiency.
Gas Pressure Requirements
- For proper and safe
operation,
each Model 4 boiler
requires a stable gas pressure supply. The pressure requirements are listed in
previous sections for standard gas train size, and
oversized
trains for
red
u
ced
available
pressure.
Gas Piping
- Model 4 units are
standardly equipped
with a
gas pressure
regulator.
If upstream
pressure
to the standard regulator will be greater than 1 psig, an
additional upstream regulator should
be
provided
with a
pressure
relief valve.
For buildings or boiler rooms with gas supply
pressure exceeding
28" w.c., a "full
lockup" type
regulator
is
recommended
along with proper
overpressure
protection.
In addition to the
regulator,
a plug type or
"butterball"
type
gas
shutoff cock should
be provided upstream of the regulator for use as a service valve. This is also
required
to
provide positive
shutoff and
isolate
the boiler
gas
train
during gas
piping
tests.
Drip
legs are required
on any
vertical
piping at the
gas supply
to
each
boiler so that
any dirt, weld slag, or
debris
can deposit in the drip leg rather than into the boiler
gas train. The bottom of the drip leg should be
removable
without di
sa
ssembl
ing
any
gas
piping. The
connected
piping to the boiler should be
supported
from pipe
supports
and not
supported
by the boiler
gas
train or the bottom of the drip leg.
All
gas
piping and
components
to the boiler
gas
train
connection
must comply
with
NFPA
54, local
codes,
and utility
requirements
as a minimum. Only
gas
approved
fittings,
valves,
or pipe
should
be used.
Standard industry practice
for
gas
piping is
normally Schedule
40 black iron pipe and fittings.
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