precautions while using cng

Precautions while using CNG

Compressed natural gas can be used in place of gasoline Diesel fuel and propane/LPG.
11. General Safety Precautions
1. Follow all maintenance procedures in order; do not skip steps unless so noted.
2. Never use an open flame as a source of illumination in proximity to a CNG system.
3. Any process or procedure that generates sparks, flames or heated particles should not be practiced in areas designated for CNG.
4. If a CNG system requires a process or procedure that generates sparks, flames or significant heat, conduct the procedure in an isolated area and make sure the CNG system has been completely purged with an inert gas.
5. CNG fuel systems are to be serviced in designated areas that comply with all federal, state and municipal laws and regulations.
6. CNG servicing and fueling areas must be well ventilated.
7. Perform all maintenance and service procedures in a dust free environment.
8. Never attempt to depressurize or vent a system by loosening a fitting.
12. CNG Vehicle Safety Precautions
The following safety precautions should be considered at all times when operating natural gas fuel systems and equipment
1. A portable fire extinguisher must be installed on the vehicle in an easily accessible location.
2. Do not start the engine if a natural gas leak is detected.
3. Never attempt to open system components that are under pressure.
4. System pressure must not exceed 3000 psi for public vehicles in Canada.
5. For all other vehicles the system pressure must not exceed 3600 psi i.e. Private captive fleets.
6. Do not smoke or produce an open flame within 30 feet of a CNG vehicle or a CNG dispensing filling station.
7. Always ground a vehicle prior to defueling.
8. If a CNG vehicle must be out of service for an extended period of time, turn cylinder valves to the OFF CLOSED position and run the engine until it stalls. This will consume the residual fuel in the closed off lines.
13. Welding And Hot Work Precautions
For any welding in or near a CNG storage system, consider the following recommendations
1. Ensure the vehicle is in a well ventilated area. Do not park the vehicle in an area where natural gas may accumulate.
2. Turn all cylinder shutoff valves to the closed position.
3. Make sure the manual shutoff valve on the FMM is turned to the ON position.
4. Turn on the vehicle and run the engine until it stops.
5. Ensure the vehicle is off and proper vehicle lock out procedures have been followed. Remove ignition key.
6. Check gauges on FMM to ensure all pressure has been relieved.
7. Remove access cover to fill panel. 8. Slowly relieve excess pressure using the bleed valves.
9. The system is now fully depressurized up to the primary solenoid lock off valve. There may be residual pressure downstream of the solenoid valve.
10. To remove gas downstream of the primary solenoid lock off valve, disconnect the electrical connector from the fuel panel and use a 12V or 24V power source as the vehicle requires to activate open the solenoid lock off valve.
14. Repressurize After Welding
1. Make sure vehicle is turned off and keys removed from the ignition.
2. Ensure bleed valve is closed.
3. Ensure low pressure coalescing filter is reconnected.
4. Perform a leak test and repair any leaks.
5. Reconnect the electrical connectors and main vehicle battery.
6. Re install the FMM cover.
7. Slowly turn the cylinder shutoff valves to the ON position.
8. Start the engine.
15. Codes and Compliances
For complete and detailed information concerning CNG codes and regulations please refer to the following.
16. Storage Cylinders
The storage cylinders for CNG fuel are housed in metal frames that are bolted to the truck body or chassis. These structures are designed to protect the cylinders in a collision. Each individual cylinder has a valve at one end which allows the fuel in that cylinder to be isolated from the rest of the fuel system. During regular operation, all cylinder valves are open, although some operators prefer to close one cylinder and use it as a reserve tank. The fuel management module FMM is equipped with a 1 4 turn shutoff red handle valve which isolates the fuel storage system from the engine for emergency situations. This valve is OPEN for normal operation.
17. Emergency Response for Gas Leaks
If the vehicle has sustained damage or a gas leak is detected
1. Do not approach the vehicle if any sources of ignition may exist such as fire, sparks, electrostatic charges, lights or electronic devices.
a. If ignition sources may be present, vehicle fuel cabinet doors should remain closed.
b. I if no ignition sources are present, keep the vehicle and fuel cabinet doors open to prevent gas accumulation.
2. If the vehicle is indoors, move the vehicle outside and away from any ignition sources. 3. Do not use road flares.
4. Do not smoke or allow anyone else to smoke near the vehicle.
5. Turn the ignition switch off, set the parking brake and turn off the battery at the main disconnect.
6. If it is safe to do so, close the main shutoff valve and the cylinder valves. Check the fuel system near the damaged area for leaks by smell, sight, and sound. CNG is odorized.
7. Keep traffic and pedestrians away.
8. Beware that gas may continue to leak once ignition is turned off and the manual shutoff valves are closed.
18. Emergency Shut Down Procedure
To shut down a CNG storage system
1. Turn the ignition switch to OFF and set the parking brake.
2. Turn off the battery disconnect switch.
3. Shut off fuel at 1 4 turn valve on the FMM.
4. Inform emergency personnel.
19. Fuel System Components
All figures and illustrations are intended for reference only and do not necessarily reflect the exact configuration for any given system. All plumbing and fuel management module layouts are consistent across platforms; however there may be some differences depending on vehicle specific options. Please contact Agility Fuel Systems Product Support if you have any questions about your system that are not covered in this manual.
20. CNG Fuel Storage Cylinders
The composite containers cylinders on the vehicle are manufactured to comply with FMVSS 304, NAI IAS, or the CSA B51 Part 2 specifications. Containers must have permanent labels in accordance with applicable regulations. These labels provide valuable information to cylinder inspectors and service personnel.