that includes possible growth of the CNG vehicle fleet over time will aid in determining the best option for the fleet. Certain work only allowed in a major repair garage (hot work or engine overhauls, for example) might be performed off site, while minor repair garage work could be conducted on site. This could reduce the complexity and costs of facility modifications. protocols. Deviation from protocols has the potential to create a dangerous environment as well as violate the codes and ordinances. The fleet or facility manager should critically review any choices being considered that may cause deviations.
If there is any doubt regarding the classification of specific work activities, it is recom mended that the fleet or facility manager opt for the more stringent codes—those relating to major repair garages. Another possibility to consider is whether or not major garage maintenance work can be performed outdoors. In some areas, the weather is suitable to allow this either in the open or under a canopy.
However, if heavy maintenance is required, outdoor facilities may not have the infrastructure—overhead cranes, pits, or other equipment—necessary to support the work needed, or may not be a suitable environment due to wind, dirt, dust, and abrasive materials that may hamper the main tenance activities. Identification of Required Upgrades Once a maintenance facility has been classified as either a minor or major repair garage, an evaluation of the existing facility should be conducted to determine what modifications will be required to achieve compliance with the respective classification.
The following sections of this handbook address the physical elements of the facility that will require evaluation when assessing the modifications necessary to maintain CNG vehicles: If outsourcing or off-site maintenance is not cost effec tive or practical, it is possible that certain areas within the facility can be isolated and modified to perform maintenance on CNG vehicles. This depends on the number of maintenance bays and the layout of the existing facility.
In some cases, bays used for the majority of the maintenance activities (minor repairs) can be modified according to the requirements for minor repair garages, and separate, segregated bay(s) can be modified according to the requirements for major repair garages. It is not always necessary to modify an entire mainte nance facility to major repair garage standards if such activities can be performed in a separate location that is appropriately protected. • Paths of migration • Ventilation • Space heating • Electrical wiring, lighting, and appliance considerations • Methane detection, alarm, and control systems.
It is essential to use a trained, experienced assessor to conduct the initial inspection of the facility. Whenever possible, up-to-date/as-built drawings of the facility should be provided to the facility assessor. A scaled floor plan of the entire facility is important. Other useful drawings include electrical plans that define the location and capacity of existing switchboards, a listing of exist ing electrical equipment, and elevation drawings of the facility. Newer facilities may have these drawings avail able in computer-aided design and drafting format, elec tronically stored, whereas older facilities may only have paper copies of original construction drawings.
In some cases, construction drawings may be unavailable, thereby requiring more time and additional resources for the facility assessor to make an assessment. It should be noted that some operational risks may be reduced by establishing operating protocols and training programs. Such protocols may include the appropriate preparation of a CNG vehicle prior to bringing it into the facility (e.g., checking for fuel system leaks, noting CNG tank pressure and temperature) and ensuring that only maintenance permitted for the garage classification is conducted within the facility.
If there is any doubt regarding the classification of specific work activities, it is recommended that the fleet or facility manager opt for the more stringent Paths of Migration Natural gas used as a vehicle fuel is composed mostly of methane (CH 4 ) with small amounts of other hydro carbons. It is lighter than air and will rapidly rise and dissipate once released. When a natural gas release occurs indoors, the gas initially accumulates near the ceiling before dispersing throughout the structure and becoming codes—those relating to major repair garages.
While every effort can be made to ensure strict adherence to operating protocols, human involvement presents an opportunity, deliberate or not, to deviate from such COMPRESSED NATURAL GAS VEHICLE MAINTENANCE FACILITY MODIFICATION HANDBOOK 8