Cummins - Dual Tank LNG System Operation …...1.6 First Responder Guide 1.6.1 Identifying a Natural Gas vehicle A vehicle equipped with liquid natural gas will have a blue reflective

Dual Tank LNG System Operation Manual


ENP-064

Rev. A, February 2015


ENP-064: Dual Tank LNG System Operation Manual 2 of 16

Table of Contents Glossary ......................................................................................................................................................... 3

Proprietary Statement .................................................................................................................................. 3

Preface .......................................................................................................................................................... 4

1. Safety ........................................................................................................................................................ 5

2. System Schematics and General Assemblies ............................................................................................ 8

3. Fuel System Components.......................................................................................................................... 9

4. System Operation & Fueling ................................................................................................................... 12

5. General LNG System Testing & Maintenance ......................................................................................... 13

Figures

Figure 1 LNG Diamond .................................................................................................................................. 6

Figure 2 ......................................................................................................................................................... 8

Figure 3 Tank Major Components................................................................................................................. 9

Figure 4 Evacuation Port ............................................................................................................................. 10

Figure 5 Heat Exchanger ............................................................................................................................. 11

Figure 6 Automatic Fuel Shutoff Valve ....................................................................................................... 11

Figure 7 Mechanical Pressure Gauge .......................................................................................................... 11

Figure 8 Over Pressure Regulator ............................................................................................................... 11

Figure 9 Fuel Tank Vent Connector ............................................................................................................. 11

Figure 10 Tank Major Components............................................................................................................. 16

Tables

Table 1 Revision Level ................................................................................................................................... 4

Table 2 Plumbing Major Components .......................................................................................................... 8

Table 3 Tank Major Components .................................................................................................................. 9

Table 4 Maintenance Schedule ................................................................................................................... 14



Glossary AGA American Gas Association ANSI American National Standards Institute

ASM Assembly

BOM Bill of Materials

CAN National Standards of Canada

CGA Compressed Gas Association

CNG Compressed Natural Gas

CSA Canadian Standards Association

FMM Fuel Management Module

HP High Pressure

LNG Liquefied Natural Gas

LP Low Pressure

NFPA National Fire Protection Association

NGV Natural Gas Vehicle OEM Original Equipment Manufacturer

PRD Pressure Relive Device

PSI Pounds per square inch (lb./in2)

Proprietary Statement

The information provided within this manual is proprietary and confidential. All prior versions of this manual, including updates and revisions forwarded separately, are proprietary. The information provided by Agility Fuel Systems to its customers and clients is solely for the use of those customers and clients. No portion of this manual may be reproduced or distributed without express written consent of Agility Fuel Systems. Agility Fuel Systems reserves the right to utilize the intellectual property contained within this publication as content for any other publication produced by Agility Fuel Systems.

Agility Fuel Systems gives express consent to our customers to utilize portions of this manual, or the manual in its entirety, for the purposes of providing their customers and clients with information pertaining to the Agility Fuel Systems liquefied natural gas (LNG) fuel storage system as used on their LNG vehicles with appropriate acknowledgement of copyright.

It should be noted that the version of this manual dated 02/18/2015 replaces any prior version. Any

information reproduced by our customers for their use, or that of their customers and clients, should be

drawn from this manual.

View our series of LNG and CNG fuel system videos. Go to the Product Support page on our website www.agilityfs.com

Agility Fuel Systems 1815 Carnegie Ave Santa Ana, CA 92705 USA Product Support 949-267-7745 [email protected] www.agilityfs.com


PrefaceThis manual is designed as a supporting document to mechanics and operators trained in the operation procedures and maintenance of the liquefied natural gas (LNG) fuel system provided by Agility Fuel Systems. No attempt shall be made to fill, install, or maintain this system until this manual and all referenced supporting documentation have been read and fully understood. OEM Replacement parts may be obtained by contacting Agility Fuel Systems.

CAUTION: All replacement parts must adhere to the accepted standards and ratings as specified by Agility Fuel Systems. The usage of any part that is not approved by Agility Fuel Systems is not recommended and may compromise the integrity and safety of the system. Do not remove components from original packaging until absolutely necessary. Any components that are to be reinstalled must be thoroughly cleaned, inspected, and stored in a satisfactory manner until reinstallation.

Table 1 Revision Level

ECN Revision Description Author Approved By Date

10131 A Clarified fuel

requirements, Sect. 4.2.1

W. Yoshida A Bhakta 2/18/15

-- Initial Release W. Yoshida Y. Coy 5/13/13



1. Safety

In the interest of ensuring the safety of all personnel involved with liquefied natural gas (LNG) fuel storage systems, this section outlines general guidelines that must be adhered to when operating and servicing equipment provided by Agility Fuel Systems. Please consider the following procedures and recommendations:

1.1 Personnel

LNG systems should be maintained and

inspected by trained personnel.

1.2 Safety Equipment

1. LNG 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. Be sure that fire extinguishers are charged, up to date, and rated correctly.

3. Areas designated for LNG fueling systems must have adequate lighting that complies with all safety codes and standards.

4. Protective footwear and eyewear should be worn by all personnel in close proximity to a LNG system.

5. When locating the source of a leak use only certified leak detecting solutions and equipment such as FBI®, combustible gas detector, Swagelok Snoop®, Hoke Leak Detective®. Any other product or solutions are unacceptable. 6. Only use tools that are in good working order with proper calibration.

7. Wear appropriate attire while servicing or maintaining any LNG system.

1.3 General Safety Precautions

1. Follow all maintenance procedures in the order in which they are written, do not skip steps without explicit permission to do so.

2. Never use an open flame as a source of illumination in proximity to a LNG system. Natural gas is flammable.

3. Any process or procedure that generates sparks, flames, or heated particles should not be applied in areas designated for LNG.

4. If an LNG 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 LNG system has been completely purged with an inert gas.

5. LNG fuel delivery systems are to be serviced in designated areas that comply will all federal, state, and municipal laws.

6. LNG 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.

1.4 Natural Gas Vehicle Safety

Precautions

WARNING: Strict compliance with proper safety and handling practices is essential when operating any natural gas fuel system.

The following safety precautions should be considered at all times 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 the engine if a natural gas leak is detected.

3. Ensure that all systems are grounded before transferring fuel from one vehicle to another, or during defueling. Transferring natural gas 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.

7. Do not smoke or produce an open flame within 30 feet of a LNG vehicle or an LNG dispensing/filling station.

1.5 Codes and Compliances

For more information about LNG codes and regulations please refer to the following: USA National Fire Protection Association, www.nfpa.org: NFPA 52 Canada Standards Council of Canada, www.scc.ca/en: CSA B109 USA and Canada American National Standards Institute, www.ansi.org: ANSI/AGA NGV 3.1/CGA 12.3 and NGV 12.3-M95 International Society of Automotive Engineers (SAE), www.sae.org: J2343 Information on Handling Cryogenic Liquids Compressed Gas Association, www.cganet.com: CGA P-12

1.6 First Responder Guide

1.6.1 Identifying a Natural Gas vehicle

A vehicle equipped with liquid natural gas will

have a blue reflective decal on the rear of the

vehicle identifying the fuel as liquid natural gas

(LNG).

Figure 1 LNG Diamond

1.6.2 General Information

Natural gas possesses unique hazards that are not present in gasoline or diesel fuel. Liquefied natural gas is predominantly methane (CH4) that has been converted temporarily to liquid form for ease of storage and transport by cooling it to -260° F.

This process reduces its volume by a factor of more than 600 over natural gas at zero pressure.

The LNG fuel tank is a cryogenic container. This means that it stores the natural gas fuel as a refrigerated liquid under pressure from about 70 psig to 230 psig.

1.6.3 LNG Hazards

Flammability Although pure LNG is not flammable, it rapidly

evaporates in air into large volumes of gas. The

gas expands to 600 times its original liquid

volume. So even small liquid leaks can pose a

large fire hazard near the leak. The gas is

flammable in concentrations of between 5%

and 15% in air versus 1% to 99% for gasoline.

Cryogenic Temperatures

The liquid LNG is below -200° F. Since this liquid

is stored under pressure you can be

cryogenically burned very easily by coming in

contact with a pressurized liquid stream. You



can also be cryogenically burned upon contact

with a cryogenic temperature fuel line.

Large Expansion Ratio

Since LNG will expand to 600 times its original

volume when warmed from a cryogenic liquid

to a room temperature gas it will build

extremely high pressures (over 3000 psig) if

trapped in lines. Pressures this high will cause

lines and fittings to fail. Care must be taken

during maintenance operations to assure that

liquid cannot become trapped between two

valves.

Inert Gas

Although natural gas is non-toxic it is an inert

gas and can cause asphyxiation if present in

very large concentrations. This is a minimal

hazard with vehicle fuel systems as they simply

don’t contain enough gas to displace large

quantities of oxygen around the vehicle.

1.6.4 LNG Emergency Response

WARNING: DO NOT add water to a

natural gas spill. Water spray can cause LNG to

violently splatter, increasing the fire danger.

Allow the LNG to vaporize and dissipate into

the atmosphere. Use dry powder or Purple-K-

Powder (PKP) extinguishers

Be especially cautious when handling

an LNG leak. Cryogenic LNG can cause first

degree burns and frostbite on contact. Remove

sources of ignition and allow LNG to disperse

into the atmosphere.

If the vehicle has sustained damage or a gas

leak is detected:

1. Do not approach the vehicle if any

sources of ignition are present,

including but not limited to: fire, sparks,

electrostatic charges, lights, electronic

devices. Do not smoke or allow anyone

else to smoke in the vicinity of the

vehicle. Avoid using road flares.

2. Turn the ignition switch off, set the

parking brake, and turn off the battery

at the main disconnect.

3. If it is safe to do so, isolate the fuel by

shutting-off the “Red Handle” valve

located inside the “Cage” at the end of

the LNG tank.

4. LNG is NOT odorized and CANNOT be

detected by smell.

5. Make sure that traffic and pedestrians

steer well clear.

6. Keep the vehicle doors open for air

circulation.

7. If the vehicle is indoors, open windows

and doors to allow ventilation. Avoid

turning on any lights or electronics

which may spark. Pay special attention

to overhead sources of ignition; natural

gas is lighter than air and will rise.

8. Beware that gas may continue to leak

once ignition is turned off and the

manual shut-off valves are closed.

9. Check the fuel system again for leaks.

1.6.5 Vehicle Fire Procedures

In the event of an LNG fire it is imperative that

the vehicle operator acts quickly and efficiently

by observing to the following steps:

1. Evacuate the area.



2. Get passengers out of the vehicle as

quickly as possible.

3. Extinguish the fire using an

appropriately rated fire extinguisher.

4. If the vehicle has been subjected to a

fire or collision exceeding 5 mph, the

fuel storage system must be inspected

by a certified inspector before it can be

returned to service

2. System Schematics and General Assemblies

General schematics and high level assembly drawings can be found in the section below. Drawings are

intended for reference only

Table 2 Plumbing Major Components

Item

No.

Description

1 Fill Check Valve

2 Fuel Shutoff Valve (Red Handle)

3 Excess Flow Valve

4 Vapor Shutoff Valve

5 Pressure Control Regulator (Economizer)

6 Primary Relief Valve (230 psi)

7 Secondary Relief Valve (350 psi) and Red Cap

8 Fuel Gauge System

Item

No.

Description

9 Heat Exchanger

10 Fuel Fitting & Dust Cap

11 Automatic Fuel Shutoff Valve

12 Tank Pressure Gauge & Bushing

13 Over Pressure Regulator 30-100 psi (Red Handle)

14 Male Vent Connector & Dust Cap

15 Vent Check Valve

Figure 2 Dual Tank Plumbing Schematic

Figure 2



3. Fuel System Components

This section describes major system components as shown in Figures 2 and 3 and Tables 2 and 3. All

figures and illustrations are intended for general reference only and do not necessarily reflect the exact

configuration for any given system. Illustrations are not to scale.

3.1 Fill Check Valve (1)

A bronze swing check or swing poppet style

valve with soft seat prevents backflow through

the fill line if a fuel coupler fails or vehicle

accident occurs. It relies on tank pressure to

seal and should not be regarded as a positive

shutoff valve. The fill check valve connects to a

top fill line inside the tank.

3.2 Fuel Shutoff Valve (2)

The fuel shutoff valve (liquid valve) is a bronze

globe type with a soft seat. It provides a

positive fuel line shutoff for service and

maintenance operations. The fuel shutoff valve

connects to the liquid withdrawal line at the

bottom of the tank and to the vapor withdrawal

line at the top of the tank through the pressure

control regulator. The fuel shutoff valve is open

during normal vehicle operation.

3.3 Excess Flow Valve (3)

The excess flow valve is a specialized check

valve with a hard metal seat designed to cut off

fuel flow if it exceeds a certain limit. It is not a

positive shutoff valve. The hard seat allows a

Figure 3 Tank Major Components

Item

No.

Description

1 Fill Check Valve


3 Excess Flow Valve



6 Primary Relief Valve

7 Secondary Relief Valve

8 To Fuel Gauge Sender


12 Line to Tank Pressure Gauge

Table 3 Tank Major Components



small flow to make the valve automatically

reset when the fuel shutoff valve is closed. It

prevents an uncontrolled fuel release between

the tank and heat exchanger if a vehicle

accident occurs.

3.4 Vapor Shutoff Valve (4)

The vapor shutoff valve (vent valve) is a bronze

globe valve with a soft seat. It provides a

positive shutoff of the vapor withdrawal line for

service and maintenance operations. The valve

connects to the vapor withdrawal line at the top

of the tank. The vapor shutoff valve is closed for

normal vehicle operation.

3.5 Pressure Control Regulator (5)

The pressure control regulator (economizer) is a

bronze pressure-reducing valve that opens at

pressures above its set point (120 psi) and

closes at pressures below its set point. An

internal check valve in the fuel pickup line

provides a two psi bias pressure to assist vapor

flow. The regulator is factory-set and should not

be adjusted.

3.6 Primary Relief Valve (6)

A brass cryogenic relief valve sets the maximum

allowable working pressure (MAWP) of the

tank. Its function is to vent gas to the

atmosphere if the tank pressure exceeds the

MAWP, or relieves excess pressure caused by

fuel expansion in the tank. It is connected to the

top fill line and prevents over pressurizing the

tank during filling operations. The primary relief

valve is equipped with a pipe away adapter to

vent gasses to a safe location away from the

vehicle.

3.7 Secondary Relief Valve (7)

A brass cryogenic relief valve, set to 1.5 times

the maximum allowable working pressure of

the tank, prevents tank failure if the primary

relief valve or line fails. It is connected to the

vapor withdrawal line and provides a secondary

relief path for the tank. A red vinyl cap protects

the valve from debris entry and damage. If the

red cap is missing, the vehicle should be

immediately removed from service and the

primary and secondary relief system should be

inspected.

The Evacuation Port Located on the non-plumbing head of the tank,

the evacuation port provides a re-sealable

connection for tank evacuation. Its secondary

function is to provide a pressure relief path for

leaks in the vacuum space. The evacuation port

plug should not be removed, since it will cause

the tank to lose vacuum, and will void your

warranty.

3.8 Fuel Gauge System (8)

The LNG system comes with an electronic fuel

gauge, consisting of an in-tank level probe, a

sender unit mounted on the tank and a dash-

mounted gauge. The sender is a solid state,

sealed unit and no adjustments are possible. It

has an accuracy of ± 1/16th of a tank. Note: The

fuel gauge is calibrated as a system and must be

replaced with identical parts to maintain

accuracy.

3.9 Heat Exchanger (9)

The LNG heat exchanger warms and thus vaporizes the cryogenic liquid fuel for engine use. The heat exchanger connects to the engine

Figure 4 Evacuation Port



Figure 7 Mechanical Pressure Gauge

cooling system water jacket via flexible lines, and is mounted near the LNG tank.

Figure 5 Heat Exchanger

3.10 Fuel Fitting (10)

The fuel fitting connects to the re-fueling

station and enables cryogenic pressure transfer.

The fitting incorporates a positive shutoff

device to prevent fuel leakage when

disconnected. Fuel fittings include a dust cap to

prevent water or debris from entering the fuel

tank and system.

3.11 Automatic Fuel Shutoff Valve

(11)

The automatic fuel shutoff (solenoid) valve cuts the fuel flow to the engine when the ignition is switched off or when activated by an out of limit sensor. It is designed to protect piping downstream (warm gas side) of the heat exchanger.

3.12 Tank Pressure Gauge (12)

A mechanical pressure gauge is located on the primary relief valve tee at the 12 o’clock position on the plumbing manifold.

3.13 Over Pressure Regulator (13)

Some natural gas engines must operate at

pressure ranges below the MAWP of the fuel

tank. Fuel systems for these engines must

include an overpressure regulator in addition to

the pressure control regulator. The over

pressure regulator is set to 145 psi and is

mounted in the engine fuel line downstream of

the heat exchanger and automatic shutoff

valve. The regulator should not be adjusted.

3.14 Vent Connector (14)

If tank venting is required at the refueling

station, a compatible vent connector should be

used as shown in the system schematic. Note: A

relief valve in the vent line may be necessary to

prevent LNG from becoming trapped between

the vapor shutoff valve and the vent connector.

Figure 6 Automatic Fuel Shutoff Valve

Figure 8 Over Pressure Regulator

Figure 9 Fuel Tank Vent Connector



4. System Operation & Fueling

WARNING: The primary hazard of leaking natural gas is flammability. If the air-gas concentration reaches 5%, the mixture becomes flammable. Make sure adequate ventilation is provided in parking and maintenance areas to prevent flammable conditions.

4.1 Starting the Vehicle

Starting a natural gas vehicle requires a delay between the battery power being turned on and the starter motor being activated. 1. Ensure that the system has been properly

leak tested, this can be accomplished by following the Testing for Leaks procedure described in Section 5.2

2. Ensure that the cylinder shut-off valves (one on each cylinder) are “OPEN/ON” and the manual shut-off valve is turned to the “OPEN/ON” position.

3. Follow the standard OEM pre-vehicle start-up procedures.

4. Start the engine. 5. If the vehicle is starting from cold, let the

engine idle for five minutes. This will allow coolant to warm the fuel and ensure that the low-pressure lines do not freeze.

6. On extremely cold days, allow the vehicle to idle for a longer period until the coolant temperature is high enough to warm the fuel. (The vehicle defroster/heater output will be warm.)

4.2 Fueling

CAUTION: This section includes general

guidelines for LNG fueling. Always check your

local fueling station for specific rules and

regulations.

WARNING: Personal protective gear

must be worn when fueling – gloves, face

shield, anti-static coat, long pants and leather

boots. Check with your local authority to

comply with their requirements.

4.2.1 Fuel Station Requirements

The LNG fuel tank is designed to be filled from

any saturated LNG fuel source. Fuel must be

delivered in saturated condition at a minimum

pressure of 100 psi and a minimum

temperature of -200°F for proper system

performance. Filtration must be 100 microns

minimum.

4.2.2 Normal Fueling

The LNG fuel tank is designed to be top filled via

a single hose. A return hose is not needed to

achieve a 100% fill. A ullage tank above the

liquid level inside the main tank prevents over-

filling.

1. Most fuel stations automatically

monitor fuel pressure and flow, so the

only procedure is to properly connect

the anti-static line, the fuel hose and

push the start button to begin fueling.

2. When the tank is full, simply remove

the fueling connector, return the filling

nozzle to its holder and remove the

ground connector.

4.2.3 Fueling a Warm Tank

An LNG fuel tank that has been idle for two to

three weeks, still has fuel, and is at its relief

valve pressure is considered to be a warm tank.

A warm tank must be vented to or below the



fuel station delivery pressure (usually 145 psi)

before filling.

If pressure is above 150 psi, the tank should be

vented to no lower than 145 psi.

When the proper tank pressure is achieved,

follow the fueling procedures for first/hot tank

fill.

4.2.4 First Fill or Hot Tank Fill

A new LNG tank is called a hot tank. Hot tanks

build pressure rapidly during fueling, so fuel

must be added slowly, in 5 to 10 gallon

increments. Tank pressure should be 145 psi

maximum during hot tank fueling. The tank may

require venting between fills to maintain proper

pressure.

Check the plumbing for leaks. Drive the vehicle

for 10 to 15 minutes to bring the pressure and

temperature to normal levels. Re-check for

leaks and fill normally.

Note: The practice of vent filling, in which the

vent is connected and open during the fueling

process, is not recommended.

4.2.5 Rapid Pressure Changes

There are three main causes of rapid pressure

rise on LNG fuel systems.

First, overfilling a tank can cause rapid pressure

changes as the fuel warms and expands or cools

and contracts.

Second, fuel system leaks will reduce pressure

as the fuel escapes. While small leaks can be

ignored (diffusion leaks), larger leaks may

become dangerous and wastes fuel.

Third, loss of vacuum reduces insulating

capability of the tank, and fuel becomes more

susceptible to changes in outside temperature.

A properly functioning, properly filled LNG fuel

system should build less than 15 psig per day.

Any system that builds more than 40 psig per

day should be checked and repaired.

4.2.6 Overfilling

If the fuel tank is overfilled there will be little or

no space for the fuel to expand as it picks up

heat through the insulation. This is wasteful,

since the excess fuel will be vented to the

atmosphere. The most common cause of

overfilling is not shutting off a single hose fill

properly.

5. General LNG System Testing & Maintenance

In general, the LNG system is relatively maintenance-free, although some mechanical components (heat

exchanger, solenoid valve, pressure regulator) may fail due to normal wear. Routine inspection and

maintenance of the natural gas fuel system will help maximize vehicle life. This section is intended to be

a general overview of system components. Contact Agility Fuel Systems for more detailed service and

repair information.

WARNING: System components must not be under pressure during servicing to prevent serious injury.

WARNING: This manual is intended as a supplement to training in operation and maintenance of the LNG fuel system. Operating and servicing the LNG system must be performed by authorized trained personnel.



CAUTION: Replacement parts must be ordered through Agility Fuel Systems or through an approved Agility OEM dealer. Any other parts may be unsafe and will subsequently void the warranty. All replacement parts and components must receive approval from Agility Fuel Systems prior to installation.

5.1 Maintenance Schedule

Table 4 Maintenance Schedule

Item Frequency

Storage System:

Leak test Monthly

Component inspection

Monthly

Pressure rise test

Annually

5.1.2 Vacuum Loss

Total loss of vacuum (seen as outer shell

frosting) is unusual for an LNG tank. However,

normal vacuum will slowly decay over time as

gasses diffuse out of the tank materials. As the

tank ages, pressure rise times will occur more

quickly and may exceed 40 psi per day.

When vacuum loss achieves this level, the tank

should be re-evacuated by a competent

maintenance facility.

Note: Normal vacuum life should exceed the

engine life of the vehicle. We recommend

performing tank re-evacuation as part of the

engine overhaul or replacement procedure.

5.1.3 Pressure Rise Test To establish the pressure rise of an LNG fuel

system the following test should be performed.

Fill the tank to between 1/2- and 3/4-full. Drive

the vehicle for about 10 minutes. Park the

vehicle. After 15 minutes, record the tank

pressure. After at least 8 hours, record the

pressure again. Check to see that the plumbing

is thawed. Compare the difference between the

two measurements. This is the pressure rise for

the fuel system. Typical maximum pressure rise

is about one psi per hour. Higher changes may

require service.

5.1.4 Fuel Gauge System Testing Problems with the fuel gauge system can be

diagnosed with a fuel system tester. The tester

enables diagnosis of both tank-side and vehicle-

side circuits.

On dual tank systems, both tanks must be

connected since the connecting cable is an

active part of the circuit.

The fuel system tester plugs into the Weather

Pack connector in series between the fuel

gauge sender and vehicle wiring harness. The

tester is powered from the vehicle. Turn on the

power to the gauge circuit and observe the

lights on the front panel. If the gauge circuit is

functioning properly, all three green LEDs will

be lit and the fuel gauge will read 1/4 full.

An open or short on either the fuel tank or the

vehicle wiring is indicated by flashing LEDs.

If an intermittent problem is present, wiggle the

wiring and connectors and observe the LED

indicators.

The fuel tank can be tested off the vehicle.

Connect the tester to the 3-pin Weather Pack

connector on the tank and push the test top

panel button. In this mode, only one green

indicator will light if the tank side wiring is

functioning correctly. (Sender OK). A fault

condition is indicated by either sender defect-

open or sender defect shorted.

5.2. Leak Testing

CAUTION: Large leaks will create

bubbles so quickly they may burst and dry

before they can be seen. It is recommended

that general leak surveys be done with an



ultrasonic leak detector or flammable gas

detector in addition to bubble test solutions.

System leaks usually occur at fittings and

connectors and should be checked periodically.

Use only certified leak detecting solutions and

equipment such as FBI®, combustible gas

detector, Swagelok Snoop® or Hoke Leak

Detective®. Any other products are

unacceptable.

5.2.1 Locating Leaks 1. Apply leak detecting solution and look for

bubbling or foaming at the site of the leak.

2. Examine connections for icing or signs of

condensation around the tubing.

3. Check for physical damage.

5.3. System Leaks Leaks smaller than 100 cc per minute are best found with test solutions. Bubble testing will locate the source of small leaks. Large leak bubbles may blow away before they can be seen, but they may be audible and should be repaired. 5.3.1 Small Flammable Leaks Leaks between 25 cc per minute and 100 cc per minute are flammable in still air. If ignited the flame ranges from less than 1/16th of an inch to about 1 inch. This leak is characterized by bubbles that grow and burst at the site of the leak. These leaks pose no hazard in moving air, or in well ventilated compartments, but could accumulate inside small, poorly ventilated enclosed spaces. These leaks are typically caused by poor pipe support, routing or cyclic strain on joints. 5.3.2 Non Flammable Leaks Leaks flowing at or less than 25 cc per minute are not flammable in air, but can be considered an economic nuisance. They are characterized by a stream of bubbles that grow and foam away from the leak. Typically the bubbles range from 1/8- to 3/8-inch in diameter. The largest

leak in this group, 25 cc per minute, will cost a few dollars per year in lost LNG. 5.3.3 Insignificant Leaks (Diffusion) Leaks smaller than 1/2 cc per minute are so small and diffuse so rapidly that they can be ignored. They are characterized by a series of tiny (smaller than a pinhead) bubbles or foam emerging from the leak. This might show up immediately as foam around the leak or fitting for up to 5 minutes after the fitting is sprayed with solution. In either case the leaks are not flammable and will not accumulate in vehicle compartments.

5.4. Flammable Gas Detectors Handheld flammable gas detectors are available in a wide variety of configurations and sensitivities. They are useful for surveying for leaks, but are not good at finding leak sources. A thorough inspection procedure includes the use of leak solution and optionally, electronic detectors.

5.5. Tightening Leaky Fittings

WARNING: Never tighten a fitting

when the system is under pressure. Always

follow proper safety and service procedures

when fixing a leak. Failure to follow safety

standards and procedures may result in serious

damage or personal injury.

5.5.1 Repairing Leaks 1. Depressurize the system as described

below.

2. Remove the fitting and clean all mating surfaces. Make sure all gaskets and O-rings, if used, are not damaged or worn. Apply nickel tape on the threads and replace/re-tighten the fittings.

3. Repressurize the system. 4. Perform leak testing as described in

Section 5.2.



5. If this does not stop the leak, depressurize the system again and call Agility Fuel Systems support at 1-949-267-7745.

Refer to the callout numbers in Figure 10.

5.6 Depressurizing an LNG System

1. Turn the ignition off and ground the chassis.

2. Close the red handle shutoff valve (2). 3. Locate the engine low pressure filter

petcock, and slowly “crack open” the handle counter-clockwise to vent LNG to the atmosphere

4. Turn the ignition switch to ON, but do not start the engine. This activates the solenoid valve and vents the tank.

5. The system is now depressurized and work may be performed. Note, the tank is still pressurized.

5.7 Re-Pressurizing an LNG System

1. When work is completed, repressurize the system as follows:

2. Close the engine low pressure filter petcock.

3. Leave the red handle shutoff valve (2) open for normal operation.

5.8 LNG Tank De-Fueling

1. Depressurize the system by following Section 5.6, steps 1-5.

2. Remove the excess flow valve (3) and the 3/8-inch line (12).

3. Install a 3/8-inch NPT elbow onto the fuel shutoff valve (2).

4. Install a length of 3/8-inch tube onto the elbow to create a temporary vent. The tubing should be long enough to safely carry vapor away.

5. Secure the tubing since there will be as much as 200 psi flowing from this tube when the venting starts.

6. Open the shutoff valve (2) slowly and allow to drain completely.

NOTE: Although LNG is now removed, the tank may still be pressurized.

7. Connect to the station vent line 8. Open the vapor shutoff valve (4) to remove

pressure in the vapor line. 9. When work is completed, remove the

temporary vent tube, re-install the excess flow valve (3) and the line to the tank pressure gauge (12), and then repressurize and re-fuel the tank.

Item Description

1 Fill Check Valve


3 Excess Flow Valve



6 Primary Relief Valve

7 Secondary Relief Valve

8 To Fuel Gauge Sender


12 Line to Tank Pressure Gauge

Figure 10 Tank Major Components

Documents

Cummins - Dual Tank LNG System Operation …...1.6 First Responder Guide 1.6.1 Identifying a Natural Gas vehicle A vehicle equipped with liquid natural gas will have a blue reflective