Page 35 - CNG ESP Participant Guide2024

Module 4: NGV Safety Practices and Procedures

NGV Maintenance Facilities

Modified vs. ▪ Modified Facility
Unmodified o Designed or modified to allow safe maintenance or repair of natural gas vehicles
✓ Lighter than air fuel that will rise
▪ Unmodified Facility
o Facility used primarily for gasoline/diesel vehicle repairs that has not been
modified to accommodate natural gas vehicles
✓ Heavier than air fuels that will pool on the ground
✓
Any repairs or maintenance to CNG vehicles should be performed outdoors if a facility
is unmodified

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

NGV Essentials and Safety Practices (CNG & LNG) © 2024 AFVi All Rights Reserved Page 4-2