CHAPTERS
cated
in
number 7.
If
there are any devia-
tions, refer
to
the trouble shooting section
in the technical bulletin.
P.
GAS
PRESSURE
AND
FLOW
INFORMATJON
Because
of
variables in both the properties
of
gas
and the supply system,
it
will
be
necessary to
regulate the pressure
of
the gas to a level that
produces a steady, dependable flame that yields.
the highest combustion efficiency at rated
perfor·
mance yet prevents overtiring. Once this op-
timum pressure has been established,
it
should be
recorded and periodic checks made
to
verify that
the regulator
is
holding the pressure at this level.
Occasional modification
in
fuel
comp(:>sition
or
pressure by the supplier may, at times, require
readjustment to return the burner
to
peak ef-
ficiency. Since the gas pressure regulator itself
is
usually furnished by others, detailed adjustment
instructions and adjusting procedures
recom-
mended by the manufacturer should be followed.
Pressure
The gas supplied must provide not only the quan-
tity
of
gas demanded by the unit, but also must
be
at a pressure high enough to overcome the
pressure-loss due to the frictional resistance
im-
posed
by the burner system and the control val-
ves.
The pressure required at the entrance to the
burner train (Figure 1-3) for rated boiler output
is
termed "net regulated pressure." The gas pres-
sure regulator must be adjusted to achieve this
pressure to assure full input.
The pressure requirement varies with boiler size,
altitude, and
type
of
gas train. Refer to Table 1
for
pressure requirements.
CHAPTER 5-12
ADJUSTMENT
PROCEDURES
TABLEt
Minimum Net Regulated Gas Pressure
For
Rated Boiler
Output
cr
Horse
er
100
125
150
9.0"
w.c.
200
lS.O"W.C.
250
16..5"
W.C. 22.0"W.C.
300
21..5"
w.c.
26.5"
W.C.
350 30.5"
w.c.
37.5"
w.c.
400 23.5"
w.c.
33.5"
w.c.
The
pressures
listed
are
based
on
1000
BTU/CU.FT. natural gas at elevations up
to
700
feet above sea level. For installation at higher
altitudes, multiply the selected pressure by the
proper factor from Table
2.
TABLE%
(Altitude Correction Factor)
Altituc.le
Correction
Feet
Above
Sea
Leve)
Factor
1000 1.04
2000
1.07
2500 1.09
3000
1.11
4000
1.16
5000
1.21
6000
1.25
7000
1.30
8)()()
1.35
~
1.40
Gas Flow
The volume
of
gas flow
is
measured
in
terms
of
cubic feet and
is
determined by a meter reading.
The
gas flow rate required for maximum boiler
output
depends
on
the
heating
value
(BTU/CU.FT.)
of
the gas supplied. The supply-
ing utility can provide this information.
750-150
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