Inspecting the Vaporizer

p3 mm 47.05.000

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 plumbing 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. 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 mounting bracket for looseness.
  6. Inspect the overpressure regulator for signs of leaks or damage.
    1. Ensure that the regulator is mounted securely.
    2. Check the overpressure regulator fittings for signs of leaks or damage.
    3. Ensure that the adjustment handle locking nut (at the bottom of the overpressure regulator) is tightened securely.
    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 vaporizer components.
Note:
Parent topic: Inspecting the LNG Fuel System
Document Number: 0000116615
Manual Publication Date: 2024-05-15
Topic Publication Date: 2024-11-22