Freightliner Cascadia. Instruction - page 29
Plumbing Components
Inspecting
See
for plumbing component locations.
Use a bubble solution to check for leaks while per-
forming the following visual inspection.
1.
Check the following components for signs of
damage or leaks.
• Pressure control regulator
• Vapor shutoff valve
• Secondary relief valve
• Primary relief valve and threaded connec-
tions
• Excess flow valve
• Fuel shutoff valve
• Fill check valve
2.
Inspect the fuel fill line for signs of damage,
kinked or crushed piping, or chafing.
3.
Ensure the red cap is present on the secondary
relief valve.
4.
Inspect the fuel tank pressure gauge for cracks
in the sight glass. Ensure the indicator needle is
present and in working condition. Inspect the
gauge face for accuracy and legibility.
5.
Inspect all vent lines for kinks, and signs of leaks
or damage.
6.
Replace leaking or damaged fuel lines. Repair or
replace leaking or damaged fittings.
Fuel Level Sender Component
Inspecting
1.
Inspect the fuel level sender wiring harness for
signs of loose connections or damage. Look for
cracking or signs of moisture intrusion.
2.
Inspect the fuel level sender box (
) for
signs of leaks or damage. Ensure that the re-
tainer clips are installed on the mounting ears.
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11
12
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5
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10
1.
Pressure Control Regulator
2.
Vapor Shutoff Valve
3.
Fuel Fill Hose
4.
Secondary Relief Valve (red cap)
5.
Fuel Fill Fitting
6.
Fuel Level Sender Box
7.
Primary Relief Valve
8.
Tank Pressure Gauge
9.
Fill Vent Fitting
10. Excess Flow Valve
11. Fuel Shutoff Valve (liquid)
12. Fill Check Valve
Fig. 6, LNG Tank Plumbing Components
Fuel
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3.
Inspect all connectors and wiring for signs of
loose connections, damage, or chafing.
4.
Turn the ignition switch to the ON position and
check for fuel gauge response.
5.
Repair or replace any damaged fuel gauge
components.
Vaporizer Inspecting
See
for plumbing component locations.
1.
Ensure that the vaporizer is secured to its
mounting brackets and that the mounting
brackets are secured to the frame. Inspect for
any signs of looseness.
2.
Inspect the vaporizer fuel inlet and outlet lines for
signs of chafing, damage, or leaks.
3.
Inspect the vaporizer coolant hoses for signs of
chafing, damage, or leaks.
4.
Inspect all fittings for leaks.
5.
Inspect the fuel shutoff solenoid valve for signs
of leaks or damage. Inspect the solenoid mount-
ing bracket for looseness.
6.
Inspect the overpressure regulator for signs of
leaks or damage.
6.1
Ensure that the regulator is mounted se-
curely.
6.2
Check the overpressure regulator fittings
for signs of leaks or damage.
6.3
Ensure that the adjustment handle locking
nut (at the bottom of the overpressure
regulator) is tightened securely.
6.4
Inspect the pressure gauge for damage.
Ensure that the gauge sight glass is clear
and legible.
7.
Repair or replace any leaking or damaged vapor-
izer components.
47–05 LNG Vacuum Integrity
Testing
WARNING
Natural gas is highly flammable. See the safety
precautions listed in Group 47 of the Cascadia
Workshop Manual. Failure to observe these pre-
cautions could lead to the ignition of the natural
gas, which could cause serious bodily injury or
death.
1.
Ensure the fuel tank is between 50 and 75 per-
cent full.
2.
Check the fuel tank pressure gauge (
,
Item 8) to ensure that pressure is within the nor-
mal range of 120 to 150 psi (827 to 1034 kPa).
3.
Inspect the fuel tank for signs of frost spots or
outer surface sweating. Frosting or condensation
on the outer surface of the fuel tank may indicate
a loss of vacuum.
4.
Check for a large variance in temperatures be-
tween the fuel tank and the fuel tank shroud. A
large variance in temperatures between the fuel
tank and the shroud may indicate a loss of
vacuum.
5.
Operate the vehicle for ten minutes. Shut down
the engine, apply the parking brakes, and note
the time.
6.
Wait fifteen minutes after shutting down the en-
gine, then record the fuel tank pressure and note
the time.
7.
Allow the vehicle to stand for at least eight
hours, then record the fuel tank pressure again.
8.
Use
to determine whether the pressure
increase is within an acceptable range.
Vacuum Integrity Test Results
Pressure Increase Over Eight-
Hour Period
Remedy
Less than 20 psi (138 kPa)
None – Tank is normal
20 to 50 psi (138 to 345 kPa)
Monitor tank and test vacuum integrity again at next maintenance date
Fuel
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Vacuum Integrity Test Results
Pressure Increase Over Eight-
Hour Period
Remedy
More than 50 psi (345 kPa)
Remove vehicle from service and evacuate the tank per the tank manufacturer’s
instructions
Table 1, Vacuum Integrity Test Results
47–06 CNG Fuel System
Inspecting
WARNING
As with all pressure vessels, CNG/LNG storage
and fuel delivery systems are inherently danger-
ous and should be treated as such. Beyond the
visual inspections listed below, all maintenance
and repairs to compressed natural gas (CNG) or
liquified natural gas (LNG) systems should be per-
formed by trained personnel. Individuals who are
not trained in all aspects concerning CNG/ LNG
fuel delivery systems are not permitted to service,
maintain, test, or inspect a system in any way.
Failure to comply with safety regulations may lead
to fire or explosion, resulting in property damage,
personal injury, or death.
NOTICE
Do not use a high-pressure washer or steam
cleaner on natural gas fuel system plumbing com-
ponents, as this can introduce moisture and con-
taminants into the threads of the fittings and dam-
age the sealants. It can also harm the integrity of
the CNG tank, and can cause premature failure of
the pressure relief devices (PRDs) causing loss of
CNG.
Gas detection sensors are located on the cab
overhead console, the sleeper, and in the engine
compartment on the frontwall. The sensors are
located in high areas, where rising gas vapors will
pass by or accumulate. Do not use a high-
pressure washer, steam cleaner, or silicone-based
chemicals on the gas detection sensors, as this
may permanently disable the sensors. When
cleaning the vehicle, cover the sensors with a
plastic covering. Keep the sensors covered until
the area has been cleared of any cleaning fumes.
Harsh chemicals and extremely high temperatures
may damage the sensor.
IMPORTANT: Use an approved NG leak check-
ing solution while preforming the following in-
spection.
For Fuel Managements System inspections refer to
the suppliers procedures and best practices. These
below should be competed in accordance with FMS
inspections.
1.
Ensure that the fuel cylinder storage box is se-
cured to the frame. Inspect for any signs of
looseness. If necessary, tighten the storage box
mounting bolts 160 lbf·ft (217 N·m). See
.
If necessary, tighten frame-rail-mounted tank
mounting nuts and bolts as follows. See
.
• Tank mounting bracket to frame rail nuts
and bolts, 130 lbf·ft (176 N·m)
• Top plate bolts, 160 lbf·ft (217 N·m)
• Gusset bolts, 160 lbf·ft (217 N·m)
NOTE: During initial pre-delivery inspection
(PDI), tighten the storage box mounting bolts
(shown in
) 180 lbf·ft (244 N·m).
2.
Inspect the fuel fill port for signs of damage, oil
residue, or leaks. Ensure the port dust cover and
the O-ring inside the port are both present and in
good condition. See
and
.
3.
Ensure that caps are present on all pressure re-
lief devices.
4.
Check the following components for signs of
damage or leaks.
• Manual fuel shutoff valve
• Coolant hoses and fittings
• Fuel lines and fittings along the frame rails
to the low pressure filters and going in to
the engine
• All fittings, connections, and joints
Fuel
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5.
Replace leaking or damaged fuel lines. Repair or
replace leaking or damaged fittings.
47–07 CNG High-Pressure Fuel
Filter Element Replacing
CNG filter element replacement cycles are an impor-
tant factor in maintaining the CNG fuel system integ-
rity and ensuring maximum operating performance.
Actual frequency of the filter element replacement
could increase or decrease depending on the cleanli-
ness of the fill station fueling system. Refer to manu-
facturer of the fuel management system (FMS) for
the proper CNG high pressure fuel filter maintenance
and procedures for replacing filter.
47–08 CNG Fuel Cylinder
Inspecting
Have a qualified inspector inspect compressed natu-
ral gas (CNG) fuel cylinders for damage or deteriora-
tion. Note cuts, cracks, gouges, abrasions, discolor-
ation, broken fibers, loose brackets, damaged
gaskets or isolators, heat damage, or other prob-
lems.
Refer to the Compressed Gas Association’s (CGA)
pamphlet C-6.4, Methods for External Visual Inspec-
tion of Natural Gas Fuel Containers and Their Instal-
lations, for inspection requirements and inspector
qualifications.
For more information, go to
After inspection, an accurate and reliable written re-
port should be provided for each container inspected.
Place an inspection label stating the inspection date
and inspecting agency identification on each con-
tainer.
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1.
Frame Rail
2.
CNG Fuel Cylinder Storage Box
3.
Mounting Bolts (qty 12 per side)
Fig. 7, Fuel Cylinder Storage Box Mounting Bracket
(passenger side shown)
Fuel
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