Table of Contents
Advertisement
Gaseous Fuel Systems
Pipe Sizing Considerations
General
Contact a local fuel distributor or licensed installer when
sizing and installing piping for any gaseous fuel supply
system. When using a local fuel distributor or installer,
verify they have correct documentation to support their
recommendations. Fuel system requirements and best
practices conveyed in this manual must be provided to
the representative responsible for sizing fuel system. The
final test of the system is measuring fuel pressure as
described in
Fuel Shutoff
is not correct if pressure requirements are not met.
There are several pipe sizing programs available for use
on the Internet and from various manufacturers. If used, it
is highly recommended that minimum pressure drop
value always be used (0.5 in water column [0.12 kPa] or
less). This verifies piping system is sized correctly to han-
dle generator volume at full load, and during cranking
and load transients, while also remaining above minimum
operating fuel pressure.
The following general rules apply to piping of gaseous
fuel systems:
•
Use black iron piping or other approved fuel line.
Fuel line must be rigidly mounted and protected
against vibration.
kW
0.75 in
(1.9 cm)
48
—
Note: Size the fuel pipe to the sizing charts or to local codes. When installing other than Sch. 40 black pipe, see manufacturer's sizing charts.
The liquid-cooled generator is not a constant flow appliance. The fuel pipe was sized large enough to supply at least 100% of the generator BTU/
hr rating.
Natural Gas
•
3
1 ft
(28.31 L) = 1,000 BTU (1.055 MJ)
•
1 therm = 100,000 BTU (105.5 MJ)
•
Fuel consumption = 13,000–16,000 BTU per kW/hr
Pressure
1 in mercury = 13.61 in water column
1 in water column = 0.036 psi
3.5–14 in water column = 0.126 psi to 0.50 psi
22
Valve. The fuel supply system
Table 4-1. NG Pipe Sizing
NG 3.5–14 in of Water Column (0.87–3.48 kPa)
Table values are maximum pipe run in ft (m)
1 in
1.25 in
(2.5 cm)
(3.2 cm)
—
40 (12.2)
•
Install supplied or recommended length of flexible
fuel line between generator connection point and
the rigid supply piping. Do not install flexible fuel
line underground or in contact with the ground.
NOTE: Some manufacturers offer flexible fuel line spe-
cifically designed to permit bends. Do not allow any
bends, twists, or kinks in the installation unless certain
the flexible fuel line is approved for that purpose. Contact
flexible fuel line manufacturer for specifications.
•
Correctly size piping to maintain required supply
pressure and volume under varying load condi-
tions.
•
Correctly purge and leak test installed piping.
•
Use an approved pipe sealant or joint compound
on all threaded fittings to reduce possibility of leak-
age.
•
Make provision for a fuel shutoff valve near unit.
Verify fuel shutoff valve is installed correctly and
works correctly.
•
Inspect entire pipe run for leaks using suitable
methods.
1.5 in
2 in
(3.8 cm)
(5.1 cm)
90 (27.4)
300 (91.4)
Note:
•
Pipe sizing is based on 0.5 in water column (0.12 kPa) pressure
drop.
•
Sizing includes a nominal number of elbows and tees.
•
Please verify adequate service and meter sizing.
•
Tables based on black pipe.
Installation Guidelines For Spark-Ignited Stationary Generators
2.5 in
3 in
(6.4 cm)
(7.7 cm)
750 (228.6)
—
Advertisement
Table of Contents
