C-Series Book - Industrial Engine Service

2
FUEL SYSTEM AND
CARBURETOR
The engine normally operates on gaseous
fuels. Proper fuel adjustments are important
to assure effi cient operation, full rated power,
longer life and emission requirements.
The carburetors, furnished as standard
equipment on Arrow engines, are suitable
for effi cient operation on pipeline natural
gas. For best results, the Arrow Gas Volume
tank Model HBD-2459 should always be
installed in the fuel system at a convenient
location next to the engine, but not more
than ten (10) feet away. The volume tank
should have a minimum capacity of 100
cubic inches (1.6 M3) per horsepower (.75
KW).
ARROW ENGINE NATURAL
GAS SPECIFICATION
Arrow certifi ed engines are certifi ed on
Commercial Quality Natural Gas (CQNG),
sometimes referred to as Pipeline Quality
Natural Gas, and also thought of as the
quality of gas supplied by a utility to a
customer. CQNG is not consistent and
varies from countries, states and locally over
time. Emissions certifi cation is based on the
fuel specifi ed by the EPA test requirements,
having a minimum of 70% methane by
volume or have a gross calorifi c value
between 950 and 1,100 British thermal units
per standard cubic foot.
Other limits (Trace Gas, Temperature,
Water, etc…):
1. Maximum liquid hydrocarbons at the
coldest expected engine mounted
regulator fuel outlet is 2% or less by
gaseous volume.
2. Maximum total organic halide content,
as expressed as chloride concentration
(TOHC1), is 60 micrograms/liter.
3. Maximum permissible sulfur bearing
compounds (H2S, etc…) is 30 ppm total
by volume.
4. Maximum Free hydrocarbon content is
12% by volume.
5. Maximum solid particle size is 5 microns.
6. No water/glycol is permitted into the
engine via the fuel system at anytime.
7. Maximum total siloxanes allowed is 5 ug/l.
8. Due to emissions requirements/
restrictions, no compressor oil carry over
is allowed.
9. The fuel gas temperature at the inlet to
the engine must be between -20°F (-29°C)
and 130F (60°C).
STANDARD COMMERCIAL
QUALITY NATURAL GAS
Methane
Content
Noncombustible inerts (N2,
CO2, He, etc)
Non-methane hydrocarbon
mass fraction
Liquid
Hydrocarbon
Oxygen
Water Vapor
Saturated low
heating value
Stoichiometric air/fuel ratio
Hydrogen/carbon ratio.
93% by Volume Maximum
3% by Volume Maximum
0.15 Maximum
2% by Volume Maximum
0.2% by Volume Maximum
100% Relative Humidity
900 BTU /cu ft
(approx.)
16.08:1 by Mass (approx.)
3.85:1 (approx.)
1-800-331-3662 ARROW ENGINE COMPANY
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