2.
3.
4.
5.

Do not attempt to start vehicle.
Do not smoke or allow anyone else to smoke near the vehicle.
Evacuate area and keep traffic and pedestrians away.
Do not use road flares.
Do not approach vehicle if any ignition sources such as fire, sparks, electrostatic
charges, lights, or electronic devices may be present.
6. If ignition sources may be present, vehicle doors and compartments should remain
closed.
7. If no ignition sources are present, open vehicle doors and compartments to prevent gas
accumulation.

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8. If vehicle is indoors, push or tow vehicle outside and away from any ignition sources.
Open building windows and doors to allow ventilation. Avoid turning on any lights, fans,
or electronics which may spark. Pay special attention to overhead sources of ignition
since natural gas is lighter than air.
9. Turn ignition switch OFF, set parking brake, and turn battery OFF at main disconnect
switch.
10. If it is safe to do so, close 1/4-turn manual shutoff valve and both cylinder manual
shutoff valves. FIGURES 1 and 2. Beware that gas may continue to leak with ignition OFF
and manual shutoff valves closed.

.⚠ WARNING.

NEVER use a flame to detect natural gas.
11. If it is safe to do so, check fuel system near damaged area for leaks by smell (rotten
egg odor), sight (ice or bubble formation), and sound (audible hiss). Verify leak
location(s) with Swagelok® Snoop® leak detection fluid.

.⚠ WARNING.

Fuel system leaks must be repaired by a qualified technician.
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1.8.
1.
2.
3.
4.
5.

Vehicle Fire Procedure

Always call 9-1-1 first.
Get all persons out of vehicle as quickly as possible.
Evacuate area; proceed to the front of the vehicle and move to a safe distance.
Inform any emergency personnel present that the vehicle is a CNG vehicle.
Be prepared to show first responders the locations of 1/4-turn manual shutoff valve
and cylinder shutoff valves. FIGURES 1 and 2

.⚠ WARNING.

If fire is confirmed to be limited to vehicle components such as overheated brakes,
burning hydraulic lines, or combustible cargo, trained personnel may attempt to
extinguish fire to prevent spread to fuel system components.

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1.9.

Vehicle Jump-Starting

Refer to OEM manual for proper jump-starting procedures.

.⚠ WARNING.

 If CNG fuel system has a leak, spark from jumper cables could ignite gas, causing
injury or death.
 Do not attempt to jump start vehicle if a strong smell of natural gas is present or
if a continual hissing sound is audible. Immediately close all manual shutoff
valves if either condition occurs.
 Have vehicle towed to an authorized repair facility. Refer to Section 1.10.

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1.10. Vehicle Towing
Refer to OEM manual for proper towing procedures.

.⚠ WARNING.

Towing vehicle with improperly positioned tow straps, hooks, or chains can damage
CNG system components including cylinders and fuel lines. Serious damage or
injury could result. Do not use fuel system components as tow attachment points.

1.11. Vehicle Storage
If vehicle will be stored for an extended period (60+ days), follow OEM vehicle storage
procedure.

.⚠ WARNING.

If a fuel leak is suspected, vehicle must be inspected by a qualified fuel system
inspector before it is stored.
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1.12. Vehicle Lifting Precautions
Never place a jack on CNG cylinder, cylinder shield or other fuel system components to
raise vehicle. Serious damage to CNG system components, cylinder, cylinder shield or
cylinder mount may result. Lifting on cylinder structure, valves, or mounting attachments
can result in fuel leaks or damage to cylinder mounting devices.
Refer to OEM vehicle manual for proper jacking instructions.

NOTICE.
 Use only OEM recommended jacking points.
 Always inspect lift/jacking point to avoid contact with fuel lines or cylinders.

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1.13. Welding and Hot Work Precautions
Metal cutting, welding, brazing, soldering, grinding, and other procedures which involve
flame or generate heat, hot particles, and/or sparks present dangers to the vehicle, fuel
system, and all persons in the vicinity.

.⚠ WARNING.

 Before performing any hot work procedure, verify fuel system is leak-free by
performing a leak test with Swagelok® Snoop®.
 Verify vehicle is parked in a well-ventilated area. Do not park vehicle in an area
where CNG may accumulate.

NOTICE.
 Before performing any welding on the vehicle chassis or body, verify the main
battery disconnect switch is turned off. Follow OEM or body builders’ manual for
welding procedures.
 Disconnect CNG fuel system electrical connector at Hexagon Agility® ECU to
prevent damage.
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For any welding or hot work in or near a CNG vehicle, fuel storage, or fuel dispenser,
always observe the following safety recommendations:
1. If welding or hot work is performed more than 6 ft (2 m) from the CNG vehicle fuel
system, it is not necessary to defuel the system. However, the fuel system must be
depressurized. Refer to Depressurization Procedure in DSM.0008.
2. If performing hot work closer than 6 ft (2 m) to a CNG vehicle fuel system, the fuel
system must be defueled (refer to Defueling Procedure in DSM.0008), and the
following additional precautions must be followed:

.⚠ WARNING.

Cover all CNG components including cylinders and fuel lines with fireproof blankets
or a metal shield. Isolation must prevent sparks and slag from hitting the cylinders.

NOTICE.
A single spark or weld slag could compromise CNG cylinders or components.

.⚠ WARNING.

If a cylinder is hit by a spark or slag, the vehicle must be removed from service and
inspected.
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1.14. Vehicle Painting
If the vehicle or components need painting, Hexagon Agility® recommends selecting a paint
process which does not require heat curing the finish.
Temperatures required to harden some paint finishes could cause pressure relief devices
(PRDs) to activate.

.⚠ WARNING.

If selected vehicle paint method requires heat curing, the fuel system must be
defueled (Refer to Depressurization Procedure in DSM.0008.) and CNG cylinder(s) must
be removed and reinstalled by an authorized service provider (ASP).

1.15. Returning Vehicle to Service
1. Verify battery is fully charged.
2. Perform pre-trip inspection. Refer to Section 2.1.
3. Start engine. Refer to Section 2.3.

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1.16. Compressed Natural Gas (CNG) Blue Diamond Decal
United States and Canadian law require vehicles
powered by compressed natural gas display the
CNG blue diamond decal to alert emergency
personnel in the event of an accident. FIGURE 4
This decal must be affixed to the right rear of the
vehicle body, above the bumper and NOT to the
bumper. CNG blue diamond decals also appear on
both body sides adjacent to the DOT number.
CNG blue diamond decals are available from
Hexagon Agility®.

FIGURE 4. CNG blue diamond decal

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1.17. General Safety Precautions
.⚠ WARNING.

1. Follow all maintenance procedures in order; do not skip steps unless noted.
2. Never use an open flame as a source of illumination near a CNG fuel system.
3. Hexagon Agility® CNG fuel systems are to be serviced in designated areas that comply
with all federal, state and municipal laws and regulations.
4. CNG servicing and fueling areas must be well ventilated.
5. Perform all inspection, maintenance, and service procedures in a dust free
environment.
6. Never attempt to depressurize or vent a system by loosening a fitting.
7. DO NOT cut fuel lines.

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2. Operation
2.1.

Pre-Trip Inspection

2.1.1. Coolant Level Check
Refer to OEM service manual for coolant level check and inspection. Cooling system
maintenance is critical for proper engine and fuel system operation.

NOTICE.
The cooling system is a sealed system. An annual top off is normal; take vehicle to a
repair facility if frequent top off is required. Warranty may be voided if under full
condition is ignored.

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2.1.2. Fuel System Check
Inspect CNG fuel system prior to vehicle operation:
1. Inspect for structural damage to fuel system housings, covers, fasteners, cylinder
mounting points, etc.

.⚠ CAUTION.

2.
3.
4.
5.

If any system components or structural parts are damaged, the vehicle must
be removed from service and a qualified fuel system inspector must perform
a detailed inspection.
Check entire fuel system for any signs of damage or wear.
Check fuel system for gas leaks by smelling for rotten egg odor, looking for frost or
ice formation on system components, and listening for hissing noises.
Verify cylinder manual shutoff valves are OPEN. FIGURE 2
Verify red handle 1/4-turn manual shutoff valve is OPEN. FIGURES 1 and 2

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6. Verify PRD vent lines are not kinked, plugged or damaged, and PRD vent cap is in
place. FIGURES 3 and 5

.⚠ CAUTION.

If PRD vent cap is missing, inspect PRD
vent tubes for moisture and debris and
replace fitting and cap.*

FIGURE 5. PRD vent fitting and
cap assembly.

7. Verify dust cap is securely installed** on fuel fill receptacle. FIGURE 6
8. Check high pressure gauge to confirm at least 400 psi (27.5 bar) of fuel is onboard.
FIGURE 6. Refuel if necessary. Refer to Section 2.4.
9. Turn ignition to ON position.
10. Verify instrument panel fuel gauge is functional.
*Obtain replacement fitting and cap assembly from Hexagon Agility.
**Drive away protection (DAP) will prevent vehicle start unless dust cap is properly in place.
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FRONT

dust cap

high-pressure
fuel gauge

NGV1 fuel fill
receptacle
FIGURE 6. Fuel fill panel is located on the middle of the driver side of the vehicle body.

If all is normal, the vehicle is cleared for operation. If anything appears wrong, a qualified
CNG system technician must make necessary repairs.

.⚠ CAUTION.

Fuel system check is required each day of operation. Information on detailed, formal
CNG system inspections is provided in Subsection 3.2.1.
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2.2.

Fuel System

2.2.1. CNG Storage
A pair of Type 4 CNG cylinders are mounted on the driver side and passenger side chassis
frame rails. The cylinders store a combined 30 gasoline gallon equivalent (GGE) of CNG at
a nominal pressure of 3600 psi (250 bar).*
The cylinders are protected from physical damage and UV exposure by removable shields.
Each cylinder is safeguarded against rupture by thermally activated pressure relief devices
(PRDs) integral to the manual shutoff valves and PRD plugs. FIGURE 2
PRD vent lines (FIGURES 3 and 7) branching off cylinder manual shutoff valves and PRD plugs
are plumbed into a PRD vent system which allows controlled release of CNG from a vent
fitting at the top rear of the vehicle. FIGURE 5

*Depending on the fill process and the ambient temperatures, the high-pressure gauge may show 4000 psi (275 bar).
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2.2.2. CNG System Flow
The FCCC MT fuel system begins at the middle of driver side of the body at the fuel fill
panel. High-pressure hoses and tubes convey CNG to the chassis mounted components
bolted to the driver side frame rail and connect to the passenger side CNG cylinder via a
HP fuel crossover tube. FIGURE 7
The pressure regulator conditions fuel for the engine by reducing gas pressure from 3600
psi (250 bar) to approximately 125 psi (8.6 bar). Low-pressure CNG then flows to the LP
filter, through a flexible LP fuel hose to the fuel rails on the OEM intake manifold where fuel
injectors supplying each cylinder bank. FIGURE 7

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FRONT

KEY: HP fuel lines ▬ LP fuel lines ▬ PRD vent lines ▬ DS – driver side PS – passenger side
manual shut off valve
LP flexible
fuel hose

PS cylinder

LP fuel filter

HP fuel
crossover tube

fuel rail
assembly

LP fuel
tube

pressure
regulator

HP fuel filter

DS cylinder

1/4-turn manual
shut off valve

manual shut off valve

fuel fill panel

HP flexible fuel hose

FIGURE 7. FCCC MT CNG fuel system flow:

Fuel fill panel → HP flexible fuel hose → cylinders → 1/4-turn manual shutoff valve → HP fuel filter →
pressure regulator → LP fuel filter → LP flexible fuel hose → fuel rail assembly → fuel injectors (not shown)
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2.2.3. CNG Fuel System Components
Beginning at the driver side rear of the vehicle, the function, operation and location of each
component in the Hexagon Agility® FCCC MT fuel system is described below.
1. Fuel fill panel. The fuel fill panel is the initial operator interface between the vehicle
CNG storage and delivery system and the engine. FIGURES 7 and 8. The panel is located
on the driver side of the vehicle body just behind the door, and consists of multiple
components performing the following respective functions:
a. NGV1 fuel receptacle. The standard CNG receptacle at fueling stations across
North America. FIGURE 8
b. Fuel receptacle dust cap. Protects fuel system from moisture and debris intrusion;
integral Drive Away Protection (DAP) prevents engine start if cap is not installed.
FIGURE 8

NOTICE.

DAP dust cap must be installed before starting engine.
c. High pressure fuel gauge. Indicates fuel pressure in the cylinders and plumbing
components flowing to the pressure regulator. FIGURE 8
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