439_cng Conversion General Manual

8/2/2019 439_cng Conversion General Manual

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Updated January 2001

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NGV MANUAL

lo. gas srlVia dellEdilizia 70/B 36100 Vicenza Italy

Tel. +39-0444-563901 Fax +39-0444-564189

Website: www.lo-gas.com

The herein Manual is property oflo. gas srland cannot be divulged, distributed or modified without prior written consent


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INDEX

NGV SYSTEM MANUAL

CHAPTER 1 INTRODUCTION........................................................................................2

CHAPTER 2 NGV (Natural Gas FOR Vehicles) ............................................................ 3

CHAPTER 3 COMPARATIVE PROPERY OF FUEL...................................................... 3

CHAPTER 4 CHARATERISTIC OF PRINCIPALS FUELS............................................. 4

CHAPTER 5 OCTANE RATING OF NGV.......................................................................5

CHAPTER 6 ENGINE LIFE AND ENGINE WEAR ......................................................... 5

CHAPTER 7 DISTRIBUTION OF NGV FOR MOTOR VEHICLES ................................. 6

CHAPTER 8 HOW CONVENIENT IS NGV..................................................................... 7

CHAPTER 9 NGV SYSTEM COMPOSITION- GENERAL CARACTERISTICS ............. 8

CHAPTER 10 FILLER VALVE........................................................................................ 9

CHAPTER 11 THE CYLINDER VALVE........................................................................ 10

CHAPTER 12 GAS TIGHT BOX................................................................................... 11

CHAPTER 13 NGV CYLINDER .................................................................................... 11

CHAPTER 14 PETROL SOLENOID VALVE ................................................................ 11

CHAPTER 15 NGV PRESSURE REDUCER ............................................................... 12

CHAPTER 16 MIXERS..................................................................................................14

CHAPTER 17 GAS SWITCHES AND ELECTRONICS ................................................ 16

CHAPTER 18 ACCESORIES........................................................................................ 20

CHAPTER 19 TECHNICAL DICTIONARY ...................................................................21


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CHAPTER 1 INTRODUCTION

Natural Gas Vehicles (NGV) has become one of the most important of thealternative fuels in the automotive sector, and it is also becoming one ofthe most important in the conversions of internal combustion engines.

NGV is being used for automotive uses since the early years of the lastmillennium. Italy has been making extensive use of NGV for at least 40years.

Today many Governments are becoming increasingly aware of thebenefits in contributing in energy security, to the economy and to theenvironment advantages when using NGV.

NGV is a renewable source of fuel, the availability of the fuel makes it veryattractive for use as a substitute for traditional fuels, such as petrol anddiesel.

The installation of an NGV system, even thought it is a simple oncetrained, does require technical expertise. The ability of a well trained

technician will guarantee the compliance with the regulations in force withsafety and professionalism.

It is necessary for the NGV installer to understand the characteristics ofthis fuel, and to have an in-depth knowledge of the components of thesystem so as to be able to install it correctly and carry out programmedperiodic maintenance.

This manual is designed to provide basic knowledge of the lo. gas s.r.l.

NGV system in order to provide the first approach to our innovativeequipment. lo. gas s.r.lguarantees the installer with the necessary basicinformation useful to successfully install an NGV system, and to performedits maintenance in a professional way.


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CHAPTER 2 NGV (Natural Gas FOR Vehicles)

As NGV is stored at high pressure in its gaseous state is practically withoutimpurities and is the most suitable for combustion specially because can bemixed with air in stechiometric proportions.

NGV in its can be stored in liquid state going through a cryogenic process.This process at its end result is also known as LNG.

Due to the high cost of the conversion of the fuel from its gaseous state tothe liquid state makes LNG attractive technically speaking but veryunattractive economically speaking.

One of the main characteristics of NGV:

NGV MAIN CHARACTERISTICS

Symbol CH4

Gaseous Density at 0C 0,717 (kg/m3)Density compared to air 0,554559

Auto Ignition Temperature 549 C

CHAPTER 3COMPARATIVE PROPERY OF FUEL

DESCRIPTION UNITS GASOLINE DIESEL LPG NGV

Auto Ignition Temp. C 200 225 450 540

Flammability Limit % 1.4-7.6 0.6-5.5 2.1-9.5 5-15

Stoichiometric A/F Ratio kg/kg 14.7 15.0 15.7 17.2

Flame Temperature C 1,977 2,054 1,990 1,790

Heat of combustion HHV MJ/m3 3.5x107 3.9x107 2.5x107 9.3x106

Heat of combustion LHV MJ/m3 3.2x107 3.6x107 2.3x107 8.3x106

Octane Number 89 104 120

Cetane Number 10 45 -2 -10


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CHAPTER 4 CHARATERISTIC OF PRINCIPALS FUELS

Vehicle fuel consumption, when comparing the fuels, it is well known thatNGV has a slightly greater consumption when compared to diesel andpetrol. This, however, is true when comparing the fuels in terms of volume.

The "coefficient of theoretical equivalence" is defined as the volume ofcombustible substances that contains the same quantity of energy as thelow heat value of petrol.

The "coefficient of equivalence" is defined as the actual ratio of theconsumption of engines. Experimental tests have shown that specific LPGengines have a better performance when compared to engines fuelled withpetrol.

It is also to note that since NGV is always in a gaseous state it mixes withair much better than if compared to petrol or diesel.

The air-gas mixture passes easily through the intake, resulting in theengine better performance.

In the case of diesel engines, however, it is difficult to define the coefficientof equivalence. For the reason that it is hardly comparable; in practice,ratios vary from engine to engine.

Power of the engine, according to lab tests, in must petrol enginesconverted to NGV show a power loss of approximately 13%. If the same iscompared to diesel engine we find a maximum loss of 35%. This fact is truebecause diesel vehicles are equipped with larger capacity engines whencompared to the corresponding petrol or supercharged versions.

It is also known that exhaust gases generating from NGV engines are lesspolluting when compared to diesel or petrol engines. It is a fact that NGVdoes not emit fumes, particulates, sulphur oxides, lead, lesser carbondioxides, nitrogen oxides and fewer unburned hydrocarbons.


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Furthermore, unburned hydrocarbons emitted after NGV combustion doesnot contain benzene, 1,3-butadiene, formaldehyde, acetaldehyde and other

aromatic polymers, which are contained in green petrol. No need tounderline that these substances are dangerous and extremely carcinogens.

Type of fuel Kilogram of CO2 per Km.

Petrol 0.26Diesel 0.21Propane 0.20CNG 0.17

CHAPTER 5 OCTANE RATING OF NGV

The octane rating of NGV is higher than the octane rating of petrol, or LPGthe difference is of about 31 octane number when compared to petrol and16 if compared to LPG. A higher octane number signifies that NGV has agood anti-knock characteristics and a higher compression ratio. A higher

compression ration means an optimize engine providing higher engineefficiency and power to weight ratios.

CHAPTER 6 ENGINE LIFE AND ENGINE WEAR

The cleaner burning characteristics of NGV are considered to reduce

maintenance requirements. The advantages offered also include increasedoil change intervals, increased spark plug life and generally extendedengine life.


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CHAPTER 7 DISTRIBUTION OF NGV FOR MOTOR VEHICLES

The distribution of NGV for motor vehicles is usually made by using anindependent distribution infrastructure or in some cases combined with thegasoline stations.

The NGV stations are composed of;

A. The Storage Cylinders.B. The Dispenser.C. The Pump.

The Storage Cylinders are mounted above ground and are filled thru thepump directly from the distribution lines of the city methane distributionnetwork.

The Dispenseris just like for other fuels the dispenser is used to measurethe quantity of fuel flowing into the vehicle and it measures in terms ofmonetary value the total amount to be paid.

The pumps are available in many versions and types.

The distribution of NGV the filling stations is normally performed by the citypipes for the distribution of the CNG for industrial of civil use.

The filling procedure of an NGV vehicles is safe and without the risk ofleakage, because it is performed on a closed circuit.


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CHAPTER 8 HOW CONVENIENT IS NGV

When buying a vehicle it is a good practice to analyze your choice in termsof costs. But, If you also include the ecological advantages of the vehicle tobe chosen the preference is NGV.

The economic analysis can be calculated then we should calculated asfollows:

Cb

LA

K

B

KN

PY

++

=

Y kilometer cost ($ per Km);P total cost of the car (including extra cost of diesel or gas system) ($);K annual mileage (Km/year);B road tax ($ per Year);

A coefficient of equivalence;L fuel cost ($ per liter);Cb car petrol consumption (Km per liter of fuel);N years of use;

The above formula is composed of three addends:1) purchase cost of the car related to Km;2) cost of road tax for the car related to Km;3) fuel cost related to Km;

The application of the above formula will result in the cost in $ perkilometer. The above Formula does not take into consideration the interestson the capital financed, insurance costs, maintenance and repair costs.


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CHAPTER 9 NGV SYSTEM COMPOSITION- GENERALCARACTERISTICS

The installation of an NGV system in a car is subject to local regulationsand in many cases are subject of approval.

1. CNG Reducer 6. Flow ActuatorA. Gas hose 7. Lambda Control Unit.2. Mixer 8. CNG Cylinder3. Filler Valve 9. Lambda4. Timing Advanced Processor 10. Emulator5. Gas Change over switch B. Water T

Herein, we underline generalized procedures for the installation of thecomponents that make up an NGV kit, required for a correct installation.

In general, local certification is required. The certification consists in testingthe high-pressure parts.

It is important to note that a conversion of a petrol-fuelled car to NGV doesnot require modifications to the original engine, but only the installation ofspecific additional equipment.


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COMPOSITION OF AN NGV KIT.

1. Filler Valve2. Cylinder valve3. Gas Tight Housing4. Cylinder5. Petrol Solenoid Valve (only for carburetor vehicles)6. NGV Pressure Reducer7. Step motor (only for fuel injection catalytic vehicles)8. Mixer9. Gas switches and related electronics.

10. Accessories (hoses, pipes, ..etc)

In general, high pressure NGV flows into the vehicle thru the NGV fillervalve, into the cylinder, thru the Cylinder Valve. The Cylinder Valve isprotected by a Gas Tight Housing. The Gas Tight Housing has the functionto convoy possible gas leakage toward outside of the cylindercompartment. The CNG is stored in a steel cylinder. NGV is feed to theengine from the Cylinder thru the Cylinder Valve. With the use of a specialcopper or steel pipes (the types to be used is defined by the local regulation

and/or local standards).

Form here the high pressure NGV is conveyed to the NGV PressureReducer. The NGV Reducer is heated and reduced in pressure. At thispoint, the NGV is convoyed to the engine thru the step motor (not requiredwith carburetor engines) thru the mixer. The mixer is used to input and mixNGV-AIR into the engine intake. The mix NGV-AIR, once in the engine, willflow into the combustion chamber for final combustion.

All the above, simplified process, is controlled by the use of speciallydesigned electronics.

CHAPTER 10 FILLER VALVE

The filler valve is a very simple item and is shaped to couple with the NGVfilling nozzle.


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The filler valve has the function of maintaining a gas tight condition duringrefilling procedure.

NGV Filler Valve

CHAPTER 11THE CYLINDER VALVE

The Cylinder Valve is an important part of the Cylinder assembly. TheCylinder Valve is provided with a series of safety devices; in some casesincluding the thermal fuse and the pressure plug.

The Cylinder Valve is available in many versions, depending on thestandard of reference.

NGV Cylinder Valve


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CHAPTER 12 GAS TIGHT BOX

The Gas Tight Box is installed over the cylinder valve. Its main function is toconvey any gas leaks outside of the vehicle and to keep the Cylinder valveventilated at all times.

The gas tight box is connected to the external of the vehicle thru ventilationhoses.

CHAPTER 13 NGV CYLINDER

NGV Cylinders for motor vehicles are manufactured in many lengths anddiameters.

The Cylinder is most commonly manufactured with special steel alloys. Insome cases its weight may be reduced thru a special manufacturingprocess in which the steed thickness is reduced and covered with a coatingof a special resin.

The Cylinders are also available in full composites of with an aluminumcore with an outer rapping of composites.

In the vehicle, the reservoir, are normally installed inside the vehicle and insome times under the vehicle. In the last case a protective plate is installedto protect the tank from FOD (Foreigner Object Damage).

CHAPTER 14PETROL SOLENOID VALVE

The Petrol Solenoid Valve is an electromagnetic device widely used incarburetor vehicles. Its function is to stop the flow of Petrol when vehicle isrunning on NGV and vice versa when the vehicle is operated with Petrol.

The petrol Solenoid valve is installed in the line of Petrol fuel near the

engine compartment.


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The petrol Solenoid Valve is basically composed of a shutter operated by amagnetic coil and two nipples.

The Petrol Solenoid Valve is equipped with an emergency device tomanually reset the petrol flow in case of a break down in the electricalsystem.

The Petrol Solenoid valve is normally closed when electricity is switchedoff.

Petrol Solenoid Valve

CHAPTER 15 NGV PRESSURE REDUCER

The pressure reducer is a build in three stage pressure reductionchambers. It is especially designed for NGV application. Inside the NGVreducer body there is a heat transfer cooling water system. The heattransfer from the hot engine water helps to keep the temperature of NGV atits most optimal condition. The lo. gas NGV pressure reducer was designedfor simple installation on vehicles equip with either a carburetor and fuelinjection catalytic engine. The NGV pressure reducer has the function toreduce the pressure arriving from the cylinder at a pressure of 22 MPa. TheNGV arrives at the reducer through the Reducer solenoid valve and into thefirst reduction chamber. In the first reduction chamber the pressure from 22MPa to approximately 280 kPa. In the second pressure reduction chamberthe pressure of the NGV is additionally reduced from to approximately 80kPa. After the second pressure reduction process the


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NGV enters through the inlet valve to the third pressure reduction chamber.In this chamber the NGV has a pressure nearest to atmospheric.

NGV Pressure Reducer


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CHAPTER 16 MIXERS

The mixer is an important part of the NGV system. The mixer has thefunction of providing the correct AIR-FUEL ration suitable for a correctcombustion.

The mixer is connected to the NGV pressure reducer by a gas hose thru anadjuster or in the case of a fuel injected vehicle thru a step-by-step motor.

The way the mixer is installed is very important and its correct positioning isfundamental for a successful NGV system.

Given the level of specialization and function that has been achieved in thecar industry, it is clear that mixers are subject to continuous development.

Mixers for vehicles equip with carburetors; the mixer in a carburetor enginehas an extremely important function. The right AIR-FUEL ration depends onthe mixer and this is the reason for the existence of so many versionsbearing so many shapes.

The mixer for vehicles equip with a carburetor may be manufactured with aspecific Venturi or by implanting a nozzle in the proximity of the carburetororiginal Venturi.

The nozzle system type mixer can perform very well if executed with careand knowledge. In any way, is good to remember, that this system is notalways possible to adapt to all carburetors and if not properly installed itmay create irreversible damages to the carburetor. Therefore, it isadvisable to obtain proper training prior any installation of this kind.

Another system is the fork system. The fork system is easier to apply ifcompared to the above nozzle pipe system. It is placed above thecarburetor. During its installation it is necessary to pay attention to theexact height in which this mixer must be positioned.


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The must widely used mixer is the round or Venturi type mixer. It can beinstalled very fast and is very effective.

The plate mixer is another mixer easy to install. The plate mixer is installedunder the throttle body.

FUEL INJECTION VEHICLES

On vehicles with electronic MPI (Multi Point Injection) and SPI (Single PointInjection) can use the traditional mixers and plate mixers.

These mixers can be installed between the monoinjector and the throttlebody

Mixer for L-JETRONIC, MOTRONIC and MONO-JETRONIC fuelinjection system. How does mixer work?

The Purpose of the mixer is to guarantee a constant NGV-AIR ratio in orderto ensure efficient combustion.

In order to achieve the above functions it is necessary; to measure the flowof air and to provide the exact quantity of fuel.


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The formula used to established the air flow is the following:

Air Flow = Ka x (P x A)where:

Ka = Air constant of proportionality

P = pressure drop in the narrow section of the Venturi tubeA = air density

The second function, comes about when the pressure drop in the Venturi

tube draws a flow of gas related to the pressure drop:

Gas Flow = Kg x (dP x mg)

where:

Kg = Gas constant of proportionalityG = Gas density

Making R the gas-air ratio:

R = Ka (A) / Kg (G)

CHAPTER 17 GAS SWITCHES AND ELECTRONICS

NGV Carburetor Systems, in countries where vehicles have strictemissions requirements a conventional NGV can be effectively used.

Besides the described mechanical description above, it is important tomake use of the correct electronics.

In the case of a Carburetor system, the electronics used is limited to thegas switch. The electronics used must be equipped with a three-position

switch. The first position is PETROL and the second is NGV. Obviously


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when positioning the switch on petrol the switch will close the NGVSolenoid Valve and it will open the Petrol Solenoid Valve and vice versa isdone when positioning the switch to NGV. The Mid position of the switch

(third position) is use to maintain the NGV and the Petrol Solenoid valves inthe OFF position until the carburetor uses the small Petrol reserve housesin its carburetor reservoir. With a carburetor engine gas switching is alwaysdone manually. The switch for carburetor engines also has a safety feature;it stops the gas flow to the engine when engine accidentally stops.

Fuel Injection or electronically controlled NGV carburetion systems;

With increasingly stringent requirements for emission requirements it hasgreatly improved NGV conversion technology.

Electronics, such as Lambda control systems have helped to overcomesome shortcomings of conventional NGV systems it has lead to thedevelopment of the step by step motor for metering and electronicallycontrol the gas flow to the engine. The Lambda system is used in all vehicle

TBI ( Throttle body injection) petrol system and closed loop 3 way catalyst.


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Flashs general installation schema

The input signals of the electronic unit are derived from engine RPM, TPSand lambda sensors signals.

Basically the system controls the unit control and the stepper motor thatadjusts the main gas stream.


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The step motor is used in catalytic fuel injected engines. The step motorregulates the flow of gas to the engine in accordance to the amount ofoxygen present after combustion.

The use of a step motor will help decrease the amount of unburnedhydrocarbons and thus guarantees an optimum combustion. Resulting inless pollution, and in a decrease of fuel consumption.

In order to have a correct installation in a catalytic vehicle it is alsoadvisable to make use of the EMULATORS. The Emulators have thefunction of emulating the signals to the original vehicle on board computer.

Emulators general installation schema


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CHAPTER 18ACCESORIES

Copper/Steel Pipes: Copper/Steel piping is normally accepted as the mostsuitable high-pressure piping to convoy the high pressure NGV. The pipingused to connect the filler valve, to the Cylinder valve and to connect theCylinder to the NGV reducer.

Rubber hose: Rubber hoses are always installed in conditions of lowpressure part of the system. Usually, installed on the vacuum part of thesystem. The rubber hoses are used to connect the NGV Pressure Reducerto the stepper motor and from the stepper motor to the Mixer. The sizes ofthe rubber hoses can vary depending on the type of mixer used.

Vent Hose; Vent hoses are used to connect the Gas Tight housing to theexternal of the vehicle.

Other accessories are requested but very specific for each and everyconversion and the details can be found in the instructions of each lo. gaskit or box.

Instructions to the installers

Prior to every NGV installation perform the following checks:

1. Control and verify the condition of the ignition system. (spark plugs,wires etc.)

2. Control the functionality of the injection system

3. Control the idling speed system etc.

4. Control and change if necessary the air filter

5. With a gas analyzer run a test to check the exhaust-gasses (Nox, co,hc, co2, o2)

6. Control if the lambda sensor is working and performing well.

7. Verify the efficiency of the catalyst converter

8. Perform the complete engine control.


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When ordering an NGV equipment always specify the following:

1. Vehicle model and year of manufacture

2. Type and make of fuel-injection system or carburetor installed in theengine.

3. Type and make of the of the electronic control unit (ECU), Marelli,EFI, Motronic, multipoint, K-jetronic, L-jetronic etc,

4. For the engines or vehicles not available in the lo. gas-cataloguemixer catalogue also provide of the throttle body inner and outer size.

CHAPTER 19 TECHNICAL DICTIONARY

Lambda electronic control FLASH; Is the computer that controlsthe fuel quantity and is able to correct fuel ratios.

Catalyst: A catalyst is a device in the exhaust of the engine thatenvelops a chemical reaction between the exhaust gasses, thus limiting the

emission of harmful fumes and unwanted components. Also known as thecatalytic converter.

Closed Loop control: Closed loop is a term used to indicate therelative air/fuel ratio is determined from the exhaust gas and adjustedthrough the feeding when necessary.

ECU: Electronic control unit.

Lambda sensor; is a device that establishes the relative air/fuel ratiofrom the measurement of oxygen content in the exhaust gases. It serves toestablish a closed loop in the case of stoichiometricly operating engine atlambda=1.0.

OEM; Original equipment manufacturer.

OBD; On board diagnostic, is a system that performs constant forengine monitoring. OBD I checks for simple malfunction. OBD II (USA) and

E-OBD (Europe) checks for emission performance of the engine.


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Open Loop; Open loop is the situation where a process is onlyregulated through forward control and without measurement of the endresult to readjust the control. In the case of a catalyst it indicates the

situation where the air/fuel ratio is not readjusted on the basis of a gasmeasurement.

Stoichiometric, it indicates a chemically correct air/fuel ratio, and itcorresponds to lambda=1.0.

TBI (Throttle body Injection) is a single point injection that iscombined with the throttle valve assembly.

3-way catalyst; is a term used to indicate a catalyst that limits theemissions of the three regulated exhaust gas components, by promotingboth oxidizing and reducing reactions at the same time. In order for a 3-waycatalyst to work it must operate strictly stoichiometrically.

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439_cng Conversion General Manual