Page 36 - ESP (CNG) Participant Guide

Module 4: NGV Safety Practices and Procedures

Safety Practices and Procedures When Servicing NGVs

CNG Vehicle  NHTSA FMVSS 304 requires CNG cylinder inspection
Inspection o After any fire on any vehicle
Requirements o After any vehicle accident

o Vehicles with GVWR <10,000 pounds – at least every three years/36,000 miles,
whichever comes first
o Vehicles with GVWR 10,000 pounds or greater – at least every 12 months
 Expired CNG cylinders must be removed from service
 Industry best practice recommends entire CNG fuel system inspection

General Safety  Leak check all vehicles prior to bringing into maintenance facility
Practices o NEVER bring a leaking vehicle inside a maintenance facility
 Close CNG cylinder valves or fuel system isolation valve

Natural Gas Leak  Hand-held electronic gas detector
Detection  Leak detection solution

Signs of a Leak The major signs of a leak on a natural gas vehicle are:
 Hearing a hissing sound
 Smelling the odorant added to natural gas (“rotten
egg” smell)
 Observing ice formations around a leak point

If you Detect a Leak  Leave the vehicle outdoors
 Shut off the cylinder valves
 Locate the source of the leak using methane detector and leak check solution
 Depressurize that portion of the system
 Repair the leak according to manufacturer’s procedures

Safety Practices to  Identify the component you are servicing and determine whether it is a high- or low-
Address Pressure pressure component
 NEVER put a wrench on a pressurized fitting
 Turn off gas supply to appropriate section of the fuel system
 Depressurize the work area and/or defuel the fuel system
 Do not perform work on any fuel system component near any ignition source
o Including, but not limited to, welding, cutting, power tools, cell phones,
computers, etc.
 NEVER perform maintenance on a leaking vehicle
o Sparks from cordless electric tools can act as an ignition source and start a fire
 ALWAYS follow manufacturer’s procedures for servicing, repairing or defueling NGVs

NGV Essentials and Safety Practices (CNG) © 2023 NGVi All Rights Reserved Page 4-2