Inspecting the Fuel Tank and Shroud

p3 mm 47.04.000

Warning: As with all pressure vessels, CNG/LNG storage and fuel delivery systems are inherently dangerous 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 performed 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.

The following inspections must be performed by a qualified technician, in accordance with the manufacturer's established inspection criteria.

All tank components should be allowed to defrost before conducting the following inspections.

Notice: Do not use a high-pressure washer or steam cleaner on natural gas fuel system plumbing components, as this can introduce moisture and contaminants into the threads of the fittings and damage the sealants.

Gas detection sensors are located on the cab overhead console 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.

See Fig. for fuel tank and shroud component locations.

  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. 1, LNG Tank Plumbing Components

  1. Inspect the fuel tank outer shell for dents or other signs of damage. Inspect the bottom of the tank for deep scratches, flat spots, or gouges.
    Replace a leaking fuel tank.
  2. Ensure that the fuel tank is secured to its mounting brackets and that the mounting brackets are secured to the frame. Inspect for any signs of looseness.
  3. Ensure that all rubber isolator straps are present and secure.
  4. Look for signs of abrasion between the fuel tank and mounting brackets.
  5. Inspect the fuel fill fitting for signs of damage or leaks. Ensure the fuel fill cap is present and in good condition, and the fitting is mounted securely on the tank.
  6. Inspect the fuel outlet line and fitting for signs of leaks or damage.
  7. Inspect the primary relief vent and pipe-away line for damage, kinks, chafing, or loose connections.
  8. Inspect the fill vent fitting for signs of damage.
  9. Inspect the shroud cover for dents or other signs of damage. Ensure that the shroud cover latches are in working condition and fasten the shroud cover securely to the tank.
  10. Replace leaking or damaged fuel lines. Repair or replace leaking or damaged fittings.
Note:
Parent topic: Inspecting the LNG Fuel System
Document Number: 0000116618
Manual Publication Date: 2024-05-15
Topic Publication Date: 2024-11-22