bill of materials

NFPA

National Fire Protection Association

CAN

National Standards of Canada

NGV

natural gas vehicle

CGA

Compressed Gas Association

nm3/hr

normal cubic meters per hour

CNG

compressed natural gas

OEM

original equipment manufacturer

CSA

Canadian Standards Association

PRD

pressure relief device

FMM

fuel management module

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psi

pounds per square inch (lb/in2)

SCFM

standard cubic feet per minute

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1. Safety
In the interest of ensuring the safety of all personnel involved with compressed natural gas (CNG) fuel storage
systems, this section outlines general guidelines that must be adhered to when operating and servicing
equipment provided by Hexagon® Agility®. Please observe the procedures and recommendations below.

1.1. Warning Messages and Symbols Used in This Document
DANGER indicates a hazardous situation which, if not avoided, will result in death or
serious injury.
WARNING indicates a hazardous situation which, if not avoided, could result in death or
serious injury.
CAUTION indicates a hazardous situation which, if not avoided, could result in minor or
moderate injury.
NOTICE is used to address practices not related to physical injury, such as best
practices or tips to help an operation or procedure go smoothly and prevent equipment
damage.
SAFETY INSTRUCTIONS indicate specific safety-related instructions or procedures.

Critical
Characteristic

Product feature directly affects:
 Safety of vehicle users, people nearby and maintenance personnel, or
 Regulatory compliance.

Manufacturing  A product feature solely used to improve manufacturability or maintain process
control.
Characteristic
 A process parameter or step that has a significant effect on achieving a Critical
Characteristic or Significant Characteristic, or maintaining material
identification/traceability.

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1.2. Qualified Personnel

1.3. Safety Equipment

CNG systems should be maintained and inspected
exclusively by trained personnel with qualifications
in accordance with the applicable codes. As with all
pressure vessels, CNG storage and fuel delivery
systems are inherently dangerous.
Individuals involved in any aspect of CNG fuel
system
maintenance,
emergency
response,
servicing or testing must be properly trained.
Individuals who are not trained are not permitted to
service, maintain, test, or inspect a system.

Observe all recommendations below
operating or servicing a CNG fuel system.

when

1. CNG safety signage should be visible at all
applicable locations as stipulated by federal,
state, and municipal law.
2. Natural gas rated fire extinguishers should be
accessible and visible throughout all servicing
and fueling areas. Verify fire extinguishers are
charged, up to date, and rated correctly.
3. In case of emergency, self-contained breathing
apparatus should be on site in an easily
accessible area.
4. Areas designated for CNG fueling systems must
have adequate lighting that complies with NFPA
code.
5. Protective footwear and eyewear should be worn
by all personnel near a CNG system.
6. When locating the source of a leak only use
certified leak detecting solutions or equipment
such as Swagelok Snoop® or a combustible gas
detector. Any other product or solutions are
unacceptable.
7. Only use tools that are in good working order
with proper calibration.
8. Wear appropriate attire while servicing or
maintaining any CNG system.

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1.4. General Safety Precautions
Observe all recommendations below
operating or servicing a CNG fuel system.

1.5. CNG Vehicle Safety Precautions
when

1. Follow all maintenance procedures in the order
in which they are written, do not skip steps
unless with explicit permission.
2. Never use an open flame as a source of
illumination in proximity to a CNG system.
Natural gas is both volatile and explosive.
3. Any process or procedure that generates sparks,
flames, or heated particles should not be applied
in areas designated for CNG.
4. If a CNG system does require a process or
procedure that generates sparks, flames, or
significant heat, conduct the procedure in an
isolated area and make sure that the CNG
system has been completely purged with an inert
gas.
5. CNG fuel delivery systems are to be serviced in
designated areas that comply will all federal,
state, and municipal laws and regulations.
6. CNG servicing and fueling areas must be well
ventilated as stipulated by federal, state, and
municipal law.
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.

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Strict compliance with proper safety and handling
practices is essential when operating this CNG fuel
system.

The following safety precautions are vehicle specific
and should always be observed 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 engine if a natural gas leak is
detected!
3. Verify all systems are grounded before
transferring CNG fuel from one vehicle to
another. Transferring CNG may cause a buildup
of static electricity which could discharge and
ignite the fuel.
4. Never attempt to open system components that
are under pressure.
5. System pressure must not exceed 3600 psi (250
bar) @ 70°F (21°C) for other vehicles.
6. Do not smoke or produce an open flame within
30 feet (9 m) of a CNG vehicle or a CNG
dispensing/filling station.
7. Always ground vehicle prior to defueling.
8. If a CNG vehicle will be out of service for an
extended time, turn the quarter turn main shut off
valve to the “OFF/CLOSED” position and run the
engine until it stalls. This consumes residual fuel
in the closed off lines.

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1.6. Codes and Compliances

1.7.1. General Information

For complete and detailed information concerning
CNG codes and regulations please refer to the
following:

The CNG fuel storage cylinders are housed in steel
frames bolted to the roof. These structures are
designed to protect the cylinders in the event of a
collision.

USA: NFPA 52
Canada: CAN/CGA B109
North America: ANSI/AGA NGV 3.1 / CGA 12.3 and
NGV 12.3-M95

1.7. First Responder Guide
For
comprehensive
emergency
response
procedures, refer to Hexagon Agility publication
ENP-084, “First Responder Guide: CNG and LNG
Vehicle Fuel Systems.”

A vehicle equipped with natural gas will have a blue
reflective decal on the rear of the vehicle identifying
the fuel as compressed natural gas (CNG) or liquid
natural gas (LNG).

Each individual cylinder has a valve at one end
which allows fuel in that cylinder to be isolated from
the rest of the fuel system. During regular operation,
all cylinder valves are open.
Additionally, the fuel management module (FMM) is
equipped with a 1/4-turn manual shutoff valve which
isolates the fuel storage system from the engine for
emergency situations.
1.7.2. Vehicle Fire Procedures
In the event of a CNG fire it is imperative that the
vehicle operator acts quickly and efficiently by
observing to the following steps:
1. Turn off engine and set parking brake.
2. Get passengers out of vehicle as quickly as
possible.
3. Evacuate the area.
4. Call 9-1-1.
5. Notify attending emergency personnel the vehicle
is a CNG vehicle.
6. If possible and only with the proper training:
Extinguish fire using an appropriately rated fire
extinguisher.

Figure 1. CNG blue diamond.

Natural gas possesses unique hazards that are not
present in gasoline or diesel fuel. The primary
concern is that CNG is in a gaseous state at room
temperature and stored at 3600 psi (250 bar).
Hexagon® Agility® minimizes these potential hazards
through state of the art design and testing practices.

A CNG fire is like a gasoline fire. However, if the fire
is not extinguished quickly, CNG cylinder pressure
relief devices (PRDs) may activate to relieve excess
pressure from the cylinders.

PRDs activate at 230°F (110°C) and will cause CNG
to exit rapidly from the storage cylinders. Escaping
CNG may ignite and add to the fire.

1.7.3. Return to Service Inspection
If the vehicle has been subjected to a fire or collision,
the fuel storage system must be inspected by a
qualified inspector before it can be returned to
service.

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1.7.4. Emergency Manual Shutdown Procedures

Figure 2. Emergency shutdown procedure.

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1.7.5. Emergency Response

Figure 3. Emergency response procedure - precautions.

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2. System Schematics and General Assemblies
This section illustrates general schematics and high level assembly drawings. All figures and illustrations are
intended for reference only.

Figure 4. Electrical schematic.

Table 2.Connector pin outs

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Table 3. Electrical BOM

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1

1

17

1

1

3

2

1

1

1

11

4

12

1

14

13

10

16

8

ENGINE CNG FUEL SUPPLY

9
15

18

17

5
6

LEGEND
▬▬ Fuel line

---- PRD vent line

7
Figure 5. CNG system schematic.
Table 4. CNG system components (refer to Figure 5).

Item

Description

Item

Description

1

CNG cylinder

10

Fill manifold

2

Cylinder valve

11

Fuel fill / defuel receptacle

3

Pressure relief device (PRD)

12

Transit (fast) fill receptacle

4

1/4-turn manual shut off valve

13

Low-pressure gauge

5

Manifilter

14

High-pressure gauge

6

Pressure transducer (on Manifilter)

15

Supply solenoid

7

Bleed valve (on Manifilter)

16

Pressure regulator

8

Defuel valve

17

PRD vent cap

9

Check valve

18

Remote fill panel (optional)

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37

39

38

40

31

7
5

22

25
1

4

28

3

6

30

2

27

32

26

29

11

33

11

12

17
34
20
35

35
9

36

18
21
1

15

10
13
1

40

38