Guide toCNGBrc Gas Equipmentgas systems formotor vehicles

UNI EN ISO9001:2000CertifiedCompany

M.T.M. s.r.l.

Via La Morra, 112062 - Cherasco (Cn) - ItalyTel. +39 0172 48681Fax +39 0172 593113http://www.brc.it/

90AV99001011 - N. 01 of 02.27.2004

2 GUIDE TO CNG

1. GASEOUS FUELS

Among the fuel classes, gathe-red according to their aggregationstate in solid, liquid and gaseousfuels, these latter are the freestfrom impurities, the most suitable tosupply burners, combustion cham-bers and furnaces, and they caneasily mix with air in stoichiometricor other required proportions.Being in phase with air, they can

easily create a complete combu-stion with a little air excess. But thisis the reason why they allow highcombustion efficiency and highflame temperatures. They are suita-ble for long-distance transportationby means of pipes, for a wide-spread distribution, and for the easymeasure by single users.

Of course, they can’t be stockedneither in the open air, nor in con-tainer with environmental tempera-ture or pressure.To increase its energy, with a

same volume stocked, it’s neces-sary to compress or liquefy it, andthen stock it in thermo-insulatingcontainers at a very low temperatu-re (for CNG - 180 °C).

1.1. COMBUSTIBLES NATU-RAL GASThese words indicate all natural

combustibles gases such as thefossil, the marsh, the volcanic andthe mine ones.Although largely diffused on

Earth, natural gas has been disco-vered and used just in recent times.Natural gas became a largely

used energetic source just after the‘30s, that’s to say when develop-ment of pipes building and placingtechnologies made possible use itas an “alternative” to the “city gas”coming from coal distillation. Sincethat, natural gas diffusion hasgrown even more, thanks to its

intrinsic qualities, to the technologi-cal progress, to the geographicalgrowing of the markets and to thediscover of big deposits in WestEurope, Russia, North Africa andMiddle East. Today, it’s the thirdworld energetic source after oil andcoal: every year, we consume morethan 2.400 billions cubic meters ofit, namely the 23% of the worldenergetic request.

In Italy, some big deposits havebeen found under the Padana Plainalluvial layer, near Ravenna, insome areas of South Italy and inSicily.

Pict. 1

Reserves andconsumptionof natural gas

(Source SNAM)

Africa

Asia andOceania

EasternEurope

WesternEurope

MiddleEast

Central andSouth America

North America

55

11.500

8.000

6.500

710

130

180

640415

6.500

Reserves andconsumptionsof natural gasBillion cubic meters

World consumptions 19992.400

World reserves at 1.1.2000155.000

3GUIDE TO CNG

2. CNG:GENERALCHARACTERISTICS

CNG means COMPRESSEDNATURAL GAS.We can consider natural gas as

only made up of methane (CH4),because the other hydrocarbonssuch as ethane, propane, butanes,pentanes, carbon dioxide, a part ofnitrogen and helium, are normallypresent in very low percentages.In Italy, methane quantity pre-

sent in CNG changes in accordan-ce with its origin (pict. 2): the gascoming from Algeria has a low con-tent (just 83,66%), while in thenational or Russian ones, we canfind higher percentages (more than98%). This is the reason why weusually identify Natural Gas with itsmain component, calling it “metha-ne”; but in this guide, we are goingto call it CNG.

CCNNGG MMAAIINN CCHHAARRAACCTTEERRIISSTTIICCSSSymbol: CH4Volume mass: 0,7172 kg/m3

Density related to air: 0,5546

Higher calorific power: 39,82 MJ/m3

Lower calorific power: 35,89 MJ/m3

Self-ignition temperature: 595 °C

Limits of flammability with percentage

volume in the air:

• Lower 5%

• Higher 15%

Thermic use of natural gas givesmany advantages in comparisonwith the solid and liquid fuels: betterflame adjustment, big combustionflexibility, absence of residuals andcorrosive components in the exhau-st gases.It’s mainly used in the domestic

field, for producing electric energyand for chemical transformations.Unlike petrol and diesel oil, it

doesn’t need complicated refiningprocesses to be extracted. Since itsorigin, it’s ready to be used as eco-logic fuel.CNG has the highest flash point,

compared to any other fuel. Its self-ignition temperature, in fact, is dou-ble (595 °C) than the liquid fuelsone, and its combustion concentra-

tion (5%) is higher than the petrol(1%) and the diesel oil (0,5%) one;this helps avoiding possible firesafter an accident.Density and specific weight of

gaseous CNG are lower than theair ones (air = 1,29 kg/m3; CNG =0,7172 kg/m3), so, in case of leaka-ges, it tends to volatilize, rise anddisperse in the atmosphere, withoutstagnate in dangerous concentra-tions at the ground level.

CNG is flammable l ike ALLfuels. So, it’s important to avoidtheir handling near naked flames orobjects with a high temperature.

GGAASS NNaattiioonnaall RRuussssiiaann DDuuttcchh AAllggeerriiaann

AApppprrooxxiimmaattee ccoommppoossiittiioonn %%mmooll.. %%mmooll.. %%mmooll.. %%mmooll..

MMeetthhaannee 99,62 98,25 92,66 83,66

EEtthhaannee 0,06 0,54 2,95 7,71

PPrrooppaannee 0,03 0,16 0,81 1,95

IIssoo--BBuuttaannee 0,01 0,03 0,11 0,28

NN--BBuuttaannee - 0,03 0,16 0,41

IIssoo--PPeennttaannee - 0,01 0,03 0,08

NN--PPeennttaannee - 0,01 0,03 0,08

HHeexxaanneess ++ 0,01 0,01 0,05 0,07

CCaarrbboonn ddiiooxxiiddee 0,03 0,08 0,89 0,20

NNiittrrooggeenn 0,24 0,87 2,28 5,40

HHeelliiuumm - 0,01 0,03 0,16

CChhaarraacctteerriissttiiccss

PPccss ((11)) kkccaall//SSmm33 9.011 9.014 9.131 9.498

PPccss ((11)) MMJJ//SSmm33 37,73 37,74 38,30 39,76

PPccss ((22)) kkccaall//SSmm33 8.113 8.118 8.234 8.583

PPccss ((22)) MMJJ//SSmm33 33,97 33,99 34,47 35,94

AAvveerraaggee mmoolleeccuullaarr wweeiigghhtt 16,11 16,33 17,38 18,78

VVoolluummeettrriicc mmaassss kkgg//SSmm33 0,6826 0,6921 0,7369 0,7964

Pict. 2Composition andcharacteristics ofCNG distributed inItaly.

(abstract fromsource SNAM).

(1) Higher calorificpower.(2) Lower calorificpower.

4 GUIDE TO CNG

CNG doesn’t need anti-detona-ting additives because it has anoctane number higher than thepetrol one and equal to 120-125(octane measures the anti-detona-ting power of a fuel, that’s to say itsability to avoid that mix ignition pro-vokes a detonation instead of a littlecombustion inside the cylinder).This ability makes possible to havehigher performances than the petrolones in dedicated engines (espe-cially planned for using CNG, sowith a higher compression ratio).Combustion completeness insi-

de the explosion chamber and per-fect thermic efficiency avoid incru-stations, particulate dust, residualdeposits in the oil, and make possi-ble longer maintenance gaps andengine life.CNG vehicles excel also for

easy maintenance; in fact, theydon’t need special and expensiveinterventions. Thank to its proper-ties, natural gas has a very cleanand complete combustion thatimpedes formation of residuals andincrustations, which could lead tothe engine bad working and to theconsumption increase in the midd-le- and long-term. In fact, is a mat-ter of fact that propellers of naturalgas vehicles have a longer life anda more homogeneous efficiencycompared to the petrol and dieseloil vehicle ones. Additional devicesof the CNG equipment don’t needspecial maintenance, if vehicle issubmitted to each normal car servi-ce suggested. Following the sugge-sted maintenance, the check ofCNG supply can be made at a kilo-metrical gap bigger than the petrol

one. Therefore, we suggest youcarefully realize the engine ordinarymaintenance. In this way, you willobtain all benefits of the CNG sup-ply with the lowest costs.

3. CNGIN AUTOTRACTION(Technical aspects)

5GUIDE TO CNG

FFuueell

Unleaded petrol (3-way catalyst)

Actual Diesel

Diesel (with catalyst for NOx)

Petrol (with “lean burn” supply)

Petrol (2-stroke engine catalyzed for NOx)

Ethanol

Methanol

L.P.G. (with 3-way catalyst)

C.N.G. (with 3-way catalyst)

Electric

Hydrogen

The traffic increase influencesmore and more environment andenergetic consumptions negatively.Especially the transport sector isresponsible for emissions of carbonoxide, nitrogen oxide, unburnthydrocarbons, lead, benzene, car-bon bi-oxide, sulphurous anhydrideand particulate dust (diesel) in theenvironment.

Combustion is inevitably pollu-ting. Emissions coming from it areconnected to the fuel chemical andphysical properties and to the fuel-comburent mixture composition, butalso to the combustion working andto the environment characteristics.

Every product of combustionnegatively influences air quality, butit’s more important to know toxicdegree of every single element,

than its quantity in absolute values,in order to establish its real noxiou-sness (see table in picture 3).

In the USA, vehicles CNG sup-ply is the less polluting at al l,thanks to their very severe legisla-tion about environment protection.Table in picture 4 (source Bosch)shows data detected by the“California Air Resources Board”centre, which compares emissionsof engines supplied with unleadedpetrol and with other alternative andtoday’s fuels, for what concerns CO(Carbon Oxide), HC (UnburntHydrocarbons) and NOx (NitrogenOxides).So CNG, together with LPG,

results the less polluting fuel, andonly two future “fuels” as hydrogenand electricity win it (but for thesefuels, big problems about environ-mental impact have still to be sol-

ved, such as production stationsand battery disposal).

It’s important to remember thatCNG doesn’t contain lead unlike“premium petrol”, doesn’t containsulphur unlike diesel oil and conse-quently emissions of Sulphur Oxideof diesel engines; it doesn’t containPAHs (Polycyclic AromaticHydrocarbons), very dangerousbecause the worst carcinogenicagents, presents in the unleadedpetrol.

Graph in picture 5 (sourceBosch) shows pollution reductionwe can obtain with alternative fuels.Pollution is calculated using the“Californian system” that gives a“bonus” to each fuel in accordancewith its danger for the ozone.

At the end, we want to remem-

4. CNGIN AUTOTRACTIONAND THEENVIRONMENT

CCOO

100

20,48

20,48

15,87

14,59

15,43

14,51

13,62

13,66

0

0

HHCC

100

80,93

80,93

9,51

10,09

9,47

10,92

9,56

10,02

0

0

NNOOxx

100

152,27

143,16

145,44

51,87

53,18

51,92

49,08

50,89

0

9,12

Pict. 4

CNG, togetherwith LPG, resultsthe less pollutingfuel, and only two“future fuels” ashydrogen andelectricity win it.

(Source Bosch -Consorzio EcoGas)

Actualfuels

Alternativefuels

LPG andCNG

Pict. 3TTooxxiicciittyy

ppaarraammeetteerrss

1

60

100

CCoommppoouunnddss

CO Carbon Oxide

HC Unburnt Hydrocarbons

NOX Nitrogen Oxides

6 GUIDE TO CNG

ber that CNG pollutes little becau-se:- combustion happens during

the gaseous state, so being CNG agas in its natural state, it suits betterto this process assuring a morehomogeneous mixture with noheavy particulate dust,

- its higher thermodynamic cha-racteristics make a better combu-stion easier,

- there are no additives such aslead, sulphur and aromatics.

Moreover, BRC Gas Equipmentproved that it’s possible to optimizeLPG combustion obtaining at thesame time better performances andless pollution.In order to respect the more and

more sever laws about environ-ment, some carburation controldevices have been realized, suchas the pioneering "BLITZ", “JUST”,and “SEQUENT”, which, submittedto various and hard anti-pollutingtests, have always given excellentresults about emissions and perfor-mances (pict. 6).

Petrol with

catalyst

“JUST” devicewith BRC ME reducer

Opel Agila 1.2i 16V - 55kWDirective 98/69/CE(B) - Euro IV

CNG G25

Emission values not multiplied by the wear factor

1,0 1,0 1,0

CO HC NOx CO HC NOx CO HC NOx

0,10 0,10 0,10

0,393

0,052

0,012

0,071

0,659

0,0420,071

0,22

0,029

0,08 0,08 0,08

“JUST HEAVY” deviceSkoda Octavia 2.0i - 85kW

Directive 98/69/CE(B) - Euro IVCNG G25

“SEQUENT” deviceFord Focus 1.8i 16V - 85kW

Directive 98/69/CE(B) - Euro IVCNG G25

Diesel

“Lean Burn”

petrol

Petrol 2 stroke with

catalyst for NOx

Methanol

Ethanol

LPG or CNG

Electric

Diesel with

catalyst for NOx

Hydrogen

0

20

40

60

80

100

120

140

160

Pict. 5 - Polluting emissions of the engines are obtained considering as 100 the emissionsvalues of unleaded petrol engine with catalyst.(Source Bosch - Consorzio EcoGas)

Pict. 6

Resume diagram of someanti-polluting tests carried out

by BRC Gas Equipment

CO - Carbonoxide

HC - Unburnthydrocarbons

Range value

Test Result

NOx - Nitrogenoxides

7GUIDE TO CNG

5.1. CNG IN THE WORLD

CNG for autotraction has quicklyincreased its development all overthe world thanks to its big availabi-

lity, to industrial and technologicprogresses and to economic andecologic good reasons. Manygovernments have already actuateda precise energetic policy introdu-cing this kind of fuel and supportingit with economic and fiscal incenti-ves.On April 25th 2002, American

Senate approved for the first time,with a 88 votes against 11, anenergy law. This law includes incen-tives about taxes on vehicles sup-plied with alternative fuels.Iran started an ambitious 10-

years program for natural gas deve-lopment, and addressed its interestto the international industry of assi-stance and programming. Thenational oi l company (NIOC -National Iranian Oil Company)wishes to use natural gas in all itsterritory in order to keep a high oilexportation ability. Moreover, Iranconsiders natural gas as a solutionto partially solve the pollution pro-blem in Teheran and other cities

CNG has also a very importantrole in domestic, industrial and agri-

5. CNG SPREADIN AUTOTRACTION

CCoouunnttrryy VVeehhiicclleess FFiilllliinngg FFiilllliinngg ssttaattiioonnss FFiilllliinngg LLaassttccoonnvveerrttiieedd ssttaattiioonnss uunnddeerr ppllaannttss uuppddaatteettoo CCNNGG ccoonnssttrruuccttiioonn

Argentina 951.842 1.068 98 - May 2003Brazil 550.010 570 150 - June 2003Italy 434.000 405 40 - May 2003Pakistan 360.000 360 200 - June 2003India 156.659 161 - - June 2003USA 130.000 1.300 - 3.271 May 2003China 69.300 270 - - April 20003Egypt 44.810 75 25 - May 2003Venezuela 44.146 147 - - January 2003Ukraine 41.000 130 - - June 2003Russia 32.000 216 - 2 March 2003Taiwan 24.000 12 - - February 2003Canada 20.505 222 - 3.208 August 2001Japan 16.561 224 - 606 May 2002Bolivia 15.000 30 6 46 April 2003Germany 15.000 330 500 450 April 2003Bangladesh 14.015 15 25 - June 2003New Zealand 12.000 109 - - March 2000Colombia 9.126 32 12 - April 2003Belarus 5.500 24 - - December 2001France 4.550 105 - 100 October 2000Trinidad & Tobago 4.000 12 4 - March 2003Malesia 3.700 18 - - October 2000Sweden 3.300 32 3 - January 2003Chile 3.000 12 5 - April 2003Indonesia 3.000 12 - - September 1996Korea 2.612 33 7 - January 2003Australia 2.104 127 - 55 July 2001Mexico 2.000 4 2 - April 2003Thailand 1.182 5 - - January 2003Iran 1.000 3 500 - April 2003Moldavia 800 87 - - December 2001Spain 403 21 - 12 February 2003Great Britain 400 40 20 40 April 2003Turkey 400 2 - - April 2003Belgium 300 5 - 60 February 2000Czech Republic 300 16 - - June 2003Holland 300 11 4 40 March 2003Switzerland 279 27 10 50 February 2003Austria 250 44 - 25 February 2003Portugal 243 5 2 - May 2002Poland 98 21 - 17 April 2003Norway 88 4 - - April 2003EIRE 81 2 - 6 September 2000Finland 75 3 - 2 June 2003Cuba 45 1 - - February 2001Iceland 42 1 - - June 2003Nigeria 28 2 - - May 1998Luxemburg 25 5 - - June 1999South Africa 22 1 - 4 January 2000Uruguay 20 - - - December 2001Denmark 5 1 - 3 February 2000Singapore 4 1 - - February 2003

Total 2.931.680 6.388 1.613 7.997

Pict. 7

Vehiclesconverted to CNGand filling stationsin the world

(Source: The GVR -Luglio 2003)

8 GUIDE TO CNG

cultural field.

5.2. CNG IN EUROPE

European Commission propo-sed a directive for promoting use ofalternative fuels (bio-fuels, CNG,hydrogen) for transportation, tocomply with the energetic securityschedule planned in November2000 with perspectives up to 2020.Table in picture 8 shows hypothesisabout possible use of the alternati-ve fuels mentioned above in placeof oil products (petrol and dieseloil). CNG has a big importancefrom this point of view.Some of the most impor tant

European cities (Helsinki, Athens,Porto, etc.) adopted fleet of busessupplied with CNG to reduce costsand urban pollution.All European Governments are

studying, or have already passed,laws and development plans forCNG in autotraction.

5.3. CNG IN ITALY

Italy, after Argentina and Brazil,is the third country in the world fornumber of CNG vehicles and thefirst in Europe for number of servicestations, but their increase inGermany and USA undermines thisrecord (see table in pict. 7).CNG Italian sales network has

more than 400 fi l l ing stationsalready operating, and many othersunder construction, where refuellingcan be realized in less than 3 minu-tes.By now, there are still a few

CNG fi l l ing stations along themotorways, but soon they’ll increa-se, thanks to the further opening of15 stations. In Italy, more than400.000 vehicles are supplied withnatural gas, and this number inclu-des urban buses, public or privatecompany fleet, taxi cabs and lightand heavy means for goods tran-sportation.Following new trends, many car

builders introduced in their offervehicles with current CNG andpetrol supply (bi-fuel) or CNG sup-ply.

Pict. 8

Prospect of theEuropeanCommission

(Source: Metano &Motori - October2002)

YYeeaarr BBiioo--ffuueellss MMeetthhaannee HHyyddrrooggeenn%% %% %%

2005 2 - -

2010 6 2 -

2015 7 5 2

2020 8 10 5

9GUIDE TO CNG

Pict. 9

“IMA5” refuellingcoupling:installation on“VMA3E WP”solenoid valve

6.1 LAWS IN FORCE

CNG equipment installation iswidely diffused all over the world.There are many laws regulating thisactivity, some with national influence,other with a bigger one. Among themost important laws, we find theregulation ECE ONU R110 part I,establishing rules for CNG compo-nents homologation, and part II esta-blishing rules about their installation.Norms ISO 15500 establish characte-ristics for components test; thesenorms are applied where R110 is notaccepted. Norms ISO 15501 and ISO15502 instead, concern CNGsystems installation on vehicles, andtests to be carried out on them.

Today in Italy the R110 regulationis in force for OEM installations (firstassembly), and Protocol n° 4043-MOT2/C of 11.21.2002 is in force for“after market” installations.

Italy adopted amendments ofEuropean Regulation N. 110, whereindications about approval of supplydevices for vehicles converted toCNG are defined. Previous nationallaws, therefore, became “obsolete”, asarticles 341 - 351 of Regulation foraccomplishment of Highway Code,and various circulars previously emit-ted by the Ministry of Transport.

After introducing the regulationR110, with prot. n. 4043-MOT2/C of11.21.2002, norms for installing thesecomponents on vehicles have beendefined. Provincial Offices of LandTransport Department verify the com-pliance of components installationwith laws and every system tightnessby submitting them to a hydraulicpressure of 300 bar. Test can be car-

ried out by installer’s workshop, ifrequired. CNG system doesn’t pro-voke vehicle substantial changes, butit just needs some components to beadded: we’ll describe them in the fol-lowing chapters.

6.2. COMPONENTSCOMMON TO ALLEQUIPMENT

Most of components you needto convert a petrol vehicle to CNG,normally the ones placed in therear side, are common to every kindof vehicle, namely to the carburet-tor, the injection and the injectionwith catalyst ones.We’re going to describe now

functions and main features of thefollowing components:

- Refuelling coupling,- Cylinders Valves,- CNG Cylinders,- High-pressure pipes and fit-

tings,- CNG Valve,- CNG Manometer.

6.2.1. REFUELLING COUPLING

Every CNG system needs arefuelling coupling to refuel theCNG cylinders.There are many kinds of refuel-

ling couplings, according to the dif-ferent countr ies, but work andsafety characteristics are the samefor each BRC model. There are twodifferent versions of refuelling cou-plings:with female fitting for installa-

tions combined with VMA3 CNGvalve inside the engine compart-ment (pict. 9);with female fitting for wall leadth-

rough installations on the carbodywork (pict. 10).For a wall leadthrough installa-

tion, realize a hole where you wishto install the coupling on the

CNG EQUIPMENT

Pict. 10

“IMA5/P” refuellingcoupling:wall leadthroughinstallation

“IMA5” refuellingcoupling

“VMA3E WP”solenoid valve

LEGEND1 = “IMA5/P” coupling; 2 = washers; 3 = cap; 4 = vehicle;5 = nut; 6 = locking ring; 7 = fitting; 8 = gas pipe.

12

2

3

4

5

7

6 8

10 GUIDE TO CNG

bodywork, and fix it with the suita-ble nut. Then, screw steel pipe tothe coupling with fitting and lockingring (pict. 11).All couplings are made up of a

main body, where refuelling gunhas to be hooked. Inside the cou-pling, there’s a non-return valvestopping the gas flow after refuel-ling. During the refuelling, pressureof the gas coming in pushes shutterdown; then, once gas flow stopped,it comes back to its previous posi-tion thanks to a spring. A plasticclosing cap, present or not in accor-dance with the refuelling couplingposition, protects it from possibleforeign bodies.Refuelling point assembly doe-

sn’t influence the working principleof CNG system in which it’s instal-led (it doesn’t need adjustments);however, it has to respect installa-tion norms in force in the countrywhere it’s installed.

6.2.2. “VB A1” CYLINDER VALVE

“VB A1” cylinder valve was plan-ned and produced by BRC to com-bined cylinder valve traditional func-tions with safety functions interna-tionally required for this kind ofdevice.BRC, on the basis of its expe-

r ience in national and foreignmarkets, realizes many versions of“VB A1” cylinder valve, according tothe laws in force in each country.Especially, the following func-

tions stay the same in each model:- Cylinder refuelling,- Cylinder supply,- Cylinder insulation by means

of a manual tap,- Ventilation for gas-tight hou-

sing.

The following safety devices canbe added to the standard model:- Excess flow valve,- Safety device for overpressure

with bursting disk,- Safety device with thermic

Pict. 13

“VB A1”cylinder valve:exploded view

Pict. 11

“IMA6/P” refuellingcoupling:example ofinstallationinto thepetrol filler

Pict. 12

“VB A1”cylinder valve:section view, instal-ledon cylinder

1

2

1

3

2

3

LEGEND1 = cylinder;2 = valve body;3 = clamp;4 = gasketsleeve; 5 = excess flowdevice;6 = vent hosebursting disk andthermic fuse;7 = ventilation breather;8 = closing pivot;9 = handle.

LEGEND1 = “VB A1 valve”;2 = Gasket sleeve;3 = Clamp

4 5 6

7

8

9

fuse.

“VB A1” cylinder valve is madeup of a main body with a threadedfitting for connecting it to the cylin-der, and two threaded fittings forconnecting it to the high-pressurepipes. Normally, we use one ofthese fittings for the connection tothe refuelling point and to the engi-ne supply, and the other one for theconnection to other cylinders. Lastvalve fitting is used for the connec-

tion to the steel pipe in case of wallleadthrough couplings. With cou-plings not needing a wall leadthrou-gh installation (applied on the “VMA3” CNG valve), we apply a blank-off plug on the last valve fitting notused.The CNG flow coming out from

the cylinder is intercepted by theconical shutter realized by the pivot.If shutter is open, CNG flowstowards the engine through the holeperpendicular to the section plane.

11GUIDE TO CNG

Through the same passages, but inthe opposite way, CNG flows duringthe refuelling.By turning clockwise the handle,

shutter goes down and valve clo-ses.

6.2.2.1. Excess flow valveExcess flow valve reduces as

much as possible CNG leakagesfrom the cylinder in case of too highflows due to anomalies, such asdisconnection or breaking of theoutlet pipe.

6.2.2.2. Bursting diskBursting disk is a security device

for overpressures.It has the task to intervene if

pressure inside the cylinder over-passes the setting value, and todischarge all the cylinder contents.

6.2.2.3. Thermic fuseThermic fuse is a safety device

intervening in case of over-tempera-tures (in case of fire, for instance); itallows evacuating the cylinder con-tents, avoiding so its explosion.

We can find the described threeavailable versions individually ortogether, according to the laws inforce in the destination country.Main body can have the shape

you can see in picture 12, or theone shown in picture 13.This latter has a square ridge

allowing tight the cylinder valve onthe cylinder itself, without needingany special wrenches.

6.2.3. “VB S1” (E13 110R)CYLINDER VALVE

“VB S1” valve (pict. 14) is theevolution of the “VB A1” one. It hasall the characteristics of this latter,but it adds a shut-off solenoid valvedirectly inserted on its body.BRC ECUs suitably pilot the

solenoid valve, stopping so the gasflow towards the engine in case ofaccident or accidental shutdown.

However, you can close the gasoutlet thanks to the manual tapsituated on the valve in case ofemergency or maintenance.

6.2.4. CNG CYLINDERS

CNG cylinders are the biggestadditional element of the equipmentand they are normally installed insi-de the luggage compartment, andsometimes under the bodywork,under the flatcar, or on the sunroof.Of course, cylinders have to

comply with prescr iptions ofEuropean Regulation n. 110, or withany laws in force in the destinationcountry. According to needs andspaces, one or more cylinders canbe installed on the vehicle.We can easily say that cylinders

are one of the safest componentsof the whole vehicle.Real experience, in fact, shows

that, even in case of serious hardcrashes, CNG cylinders are one ofthe few parts of the vehicle remai-ning complete. Even in case ofpileup collision, cylinders don’tchange its shape; so, it’s completelyuntrue the diffused preconceptionabout cylinders danger.

6.2.4.1. InstallationBefore going on with the cylin-

ders fixing, it’s necessary to installon them respective cylinder valvesdescribed in the previous para-graph.To descr ibe CNG cylinders

installation, we’ll follow what provi-

ded for the European Regulation nr.110 applied in Italy with Prot. 4043-MOT2/C.

6.2.4.2. General instructionsCylinders must be installed

inside the vehicle template, inclu-ded the vehicle rear side, and sothat they result protected enoughfrom crashes. Near the cylinders,sharp edges must be absent.Cylinders position in the templateis not submitted to special orienta-tion bonds. We can install on thesame vehicle one or more cylin-ders equipped with one or morerefuelling lines. For fixing cylin-ders to the vehicle, we have touse measured anchors resistingto stresses due to a vehicle acce-lerations with full tank.Please make reference to the

table in picture 15 to choose allfixing clamps and nuts.Cylinders position has to not

provoke friction while vehicle isrunning; so, it can be useful toinsert some anti-sparkling and nothygroscopic material among cylin-ders, and between them and thefixing system (pict. 16).Cylinder valve/s must be pla-

ced in a position easy to reach.Petrol tank and CNG cylindersdon’t have to touch, but rather bewell separated.

6.2.4.3. Installations underthe bodywork or underthe flatcarCylinders must be suitably

Pict. 14

“VB S1”cylinder valve

12 GUIDE TO CNG

insulated from silencers andexhaust gas ducts by means of ametal sheet, or of material withthe same characteristics and atleast 1 mm thick.Minimum distance between

cylinders and ground cannot beshorter than the one betweenvehicle and ground (in the table,you can find minimum valuesfixed by the Italian Prot. 4043MOT2/C).

6.2.4.4. Installations on thesunroofCylinders must be protected from

sunbeams by suitable containerswith pierced walls avoiding the gasaccumulation. This shield has tocover 180° at least. Placing cylin-ders to the bodywork or on the sun-roof, it’s necessary to follow themass placing and subdivision crite-ria indicated in the vehicle use andmaintenance booklet (table CUNANC001-51).

6.2.4.5. Installations inside therear luggage compartment withventilation systemIf cylinders have been placed

inside the rear luggage compart-ment, it’s necessary to realize a sui-table ventilation assuring that, incase of leakages or other anoma-lies, CNG could flow towards thevehicle outside, avoiding so itsaccumulation in dangerous and notsuitable areas. This ventilation canbe realized as shown in picture 16and 17, by making two holes con-necting the luggage compartmentwith the outside, and inserting herebreathers and vent hoses. The pas-sing hole on the valves body assu-res ventilation on each valve. Prot.4043 MOT2/C establishes thebreather inside diameter minimummeasure at 30 mm. Breathers andvent hoses are normally used forsteel high-pressure pipes passage(pictures 16 and 17).If, eventually, installation inside

the luggage compartment creates

closed spaces, Prot. 4043-MOT2/Corders to create two fur ther airintakes, with a inside diameter notlower than 25 mm. They must bedone on one side of the compart-ment, as high as possible. It ’snecessary to protect the two airintakes in order to avoid that lugga-ge compartment could obstructthem, and being careful with alwayskeep a good air circulation.

6.2.4.6. Assembly generalwarnings

Before realizing holes or breaksin the bodywork, be careful with nodamage pipes, cables, tanks andother elements. Before effecting thetanks full refuelling, check the pre-sence of leakages with soap water

with a pressure of roughly 20 barinside the cylinders.

6.2.5. HIGH-PRESSURE PIPESAND FITTINGS

With the words “high-pressurepipes”, we mean pipes connectingvalves with possible refuelling cou-plings, cylinder valves among them-selves, cylinder valve to the shut-offvalve of engine compartment, andshut-off valve to the reducer.This pipe, normally made of

unsoldered steel, is suitable for aworking pressure of 330 bar, and itcan be bended with suitable tools ifneeded.Unsoldered steel pipe used in

the high-pressure part is not sub-mitted to approval but, however, ithas to comply with requirements ofEuropean Regulation n. 110.Pipe is connected to the different

devices (cylinder valves, refuellingcouplings, shut-off valve, reducer)by means of suitable pipe-fittings(pict. 19, detail of steel pipe fitting).

CCyylliinnddeerr//ss RRiinnggss,, ppllaatteess oorrnnoommiinnaall ttwwoo tthhrreeee ssuuppppoorrttss ffoorr NNuuttssccaappaacciittyy ccllaammppss ccllaammppss ffiixxiinngg ttoo tthhee ddiiaammeetteerr

((CC)) ccaarr bbooddyy

litres (mm) (mm) (mm)

C ≤ 100 30 x 2,5 30 x 1,5 30 x 6 M12

100 ≤ C ≤ 150 50 x 2,5 50 x 2 50 x 6 M14

Pict. 15 - Resume table of minimum dimensions and characteristics required for clamps, nutsand supports for fixing cylinders, in accordance with the Prot. 4043-MOT2/C.

Pict. 16

Installation ofCNG cylinderinside the luggagecompartment:insulation andventilation

Steel pipe VBS1 valve

Cylinder

Breather

Vent hoses

VVeehhiiccllee MMiinniimmuummIInntteerrnnaattiioonnaall ddiissttaanncceeccaatteeggoorryy ffrroomm ggrroouunndd

((mmmm))

M2, M3, N2, N3 200

M1, N1, L4, L5 155

13GUIDE TO CNG

For fixing pipe to the carbodywork is better to respect pre-scriptions in force in the differentCountries, considering that it mustbe fixed at the bottom of the vehi-cle, far away from the exhaust pipeand from vehicle strengtheningpoints, at a regular distance byusing suitable clamps with self-tap-ping screws. Connections, wheresubjected to vibrations, must bemade by coil or elastic spirals (pic.20).

6.2.6. “VM A3” CNG VALVE“VM A3” CNG valve is a device

planned and produced by BRC tointercept CNG on the high-pressureline, normally between cylindersand reducer. Generally, “VM A3” isinstalled in the engine compart-ment, together with a quick cou-pling for CNG refuelling.BRC, on the basis of its expe-

r ience in national and foreignmarkets, realizes two versions of“VM A3”:- “VM A3/R” CNG valve with

manual tap.- “VM A3/E” CNG electro-assi-

sted valve.

6.2.6.1. “VM A3/R” CNG valve withtap“VM A3/R” (pict. 21) is made up

of a brass pressed main body (1).On the body itself, there are the twoopposite clutches for connection tothe high-pressure pipes, cylindersside and reducer side, and the clut-ches for manual tap on one sideand for refuelling coupling on theother side.As you can see in picture 21,

“VM A3/R” allows refuelling thecylinders, if combined with therefuelling coupling, and insulatingthe part of the system downstreamthe cylinders (refuelling couplingand pressure reducer) closing themanual tap.The handle allows moving the

shutter.

Pict. 17

Installation ofCNG cylinderinside the luggagecompartment:ventilationbreathersassembly

Pict. 18

Example ofinstallation ofCNG cylinderinside the luggagecompartment(Citroën XsaraPicasso)

Pict. 19

High-pressurepipe

Pict. 20

High-pressurepipe:elastic spiral

LEGEND1 = “VBS1” cylinder valve; 2 = gasket sleeve; 3 = clamp;4 = gas pipe; 5 = fitting; 6 = locking ring.

1

2

4

45

6

3

Steel pipes

14 GUIDE TO CNG

6.2.6.2. “VM A3/E” CNG valvewith solenoid valveAs you can see in pictures 21

and 22, “VM A3/E” keeps the samestandard functions of the manualtap version, being obtained fromthe same brass pressed, the sameshape too. The only difference is thepresence of a solenoid valve inplace of the manual tap. This diffe-rence allows insulating the part ofthe system downstream the cylin-ders (refuelling coupling and/orpressure reducer according to theversion) during every vehicle shut-down and every changeover topetrol, if suitably piloted by theECUs.

Pict. 21

“VM A3/R”CNG valve:exploded view

Pict. 22

“VM A3/E” WPCNG valve:combined with“IMA6” coupling

LEGEND1 = “VM A3” valve body; 2 = OR 2062; 3 = nut for pivot; 4 = pivot slide bush;5 = SR 007 anti-extrusion ring; 6 = OR 2015; 7 = tap group pivot; 8 = 7/32”ball; 9 = M16x0,75 fitting; 10 = valve handle; 11 = csk allen screw M4x10; 12= cap; 20 = M12x1 fitting; 21 = locking ring; 22 = bracket; 23 1/2” gas nut; 24= “IMA5” refuelling coupling.

15GUIDE TO CNG

6.2.7. CNG MANOMETER

Being CNG stocked in tanks atits gaseous state, fuel level is calcu-lated in accordance with pressurecoming out from the tank.This task is carried out by a

needle manometer, placed on thereducer inlet fitting (pictures 23 and24).It gives indication about tank

outlet pressure, and so about auto-nomy remained.Visual data given by the mano-

meter can be sent to the BRCECUs by joining the suitable con-nector.Fuel level, so, will be displayed

into the passenger compartmenttoo, on the ECU LED bar of thesystem installed.

Pict. 23

CNG manometer:exploded view ofassembly ongas fitting at“Genius.M” reducerinlet

Pict. 24

CNG manometer:example ofassembly onTecno.M reducer

16 GUIDE TO CNG

As we already said in § 6.2,mechanical and electric compo-nents situated downstream themanometer change according tothe vehicle original supply, whichcan be a carburettor, an injection, acatalyzed injection, or a superchar-ged supply.

Moreover, each kind of supplyneeds some special precautions togive a good vehicle working.

6.3. THE CARBURETTORVEHICLE

CNG conversion and compo-nents kind and position of a carbu-rettor vehicle are substantially thesame of the ones indicated in pictu-re 25. CNG, coming from the tank,by means of a high-pressure pipeand intercepted by “VMA3”, reachesthe pneumatic or electro-assistedreducer-vaporizer. Here, thanks tothe water coming from the enginecoolant equipment, it gets warm.On carburettor vehicles, a spe-

cial “petrol solenoid valve” has the

task to stop original fuel flow duringthe gas mode.

6.3.1. PETROL SOLENOID VALVEAND PETROL NON-RETURN VALVE

As already said in the previousparagraph, petrol solenoid valve isa device allowing the petrol flowinterruption when car works withCNG supply.It’s made up of a shutter moved

by a magnetic coil and by two fit-tings, an inlet and an outlet ones.Solenoid valve has also an

emergency device allowing themanual reset of petrol passage incase of problems with the wiringsystem.Petrol solenoid valve (pict. 26) is

closed at rest and it opens whencurrent passes through it. It must beinstalled in the engine compartmentbetween petrol pump and carburet-tor. It shows an arrow indicating theright petrol running direction inorder to simplify its assembly.Petrol solenoid valve must be

fixed with the coil upright, far awayfrom “dangerous” parts of enginecompartment. Anyway, its positionmight allow reaching the reset devi-ce.Moreover, it’s important to verify

if on carburettor there’s a by-passpipe for petrol coming back to thetank. In this case, insert on this pipea petrol non-return valve. Forobtaining a correct installation ofthe two devices, we suggest to fol-low instructions given by picture 27.

“VMA3/E”CNG valve

ChangeoverECU

FUSE

Coil

Adjustingscrew

Engine

Reducer

MixerPetrol solenoid valve

Pict. 26 - Petrol solenoid valve

Pict. 25Componentslayout ofCNG equipmenton carburettorvehicles

CNG cylinder

“VB A1”valve

17GUIDE TO CNG

6.3.2. TRADITIONAL REDUCER

Gaseous CNG, after overcomingthe “VMA3” CNG valve arrives tothe reducer that can be consideredthe real equipment “lung”, not onlyfrom a technical point of view,carrying out a primary role.It adjusts pressure to a value

near the atmospheric one, makingfuel available for the engine intake.Reducer lets pressure down

through three reduction stages:- first stage lets the pressure

coming from the tank down from220-250 bar to 5-6 bar.- second stage brings pressure

coming from the first one to 1,5 - 2bar.- third stage reduces pressure to

a value near the atmospheric one.

In order to avoid its freezing forthe abrupt gas expansion, reduceris warmed using the engine coolantwater, suitably derived.Reducer must be installed verti-

cally, with diaphragms parallel tothe vehicle running direction. Itmust be installed in a place easy toreach in order to carrying out adju-stment and maintenance. The holeon the cap of reducer second stagemust stay free, so that diaphragmnot touching the gas is always atthe environmental pressure.Special attention must be paid to

the reducer heating system. -Cutthe water pipes going to the heatingsystem of passenger compartmentand connect them with some “T” fit-tings to the reducer pipe-holders.Connect water delivery to the redu-cer “IN” inlet fitting, and water back-flow to the reducer “OUT” outlet(picture 29).This is a very important connec-

tion because engine coolant liquidbr ings inside the reducer heatnecessary to warm CNG after theabrupt pressure reduction.In the Pneumatic reducer, LPG

necessary to start the vehicle issupplied by an electro-pneumatic

device, while in case of engineaccidental or voluntary shutdown,vacuum lack impedes LPG rea-ching the engine. In order to correc-

tly adjust the reducer, however, it’snecessary to follow instruction youcan find in every pack.Moreover, for the vehicle correct

PICT. 27 - Installation of Petrol Solenoid valve and Petrol non-return valve on carburettorvehicles.

Tank

Pump OriginalBy-pass Petrol SV

Carburettor

Tank

PumpPetrol SV

Carburettor

Tank

Pump

Petrol non-return valve

Petrol SV

Carburettor

A) DON’T INSERT THE PETROL NON-RETURN VALVE

B) DON’T INSERT THE PETROL NON-RETURN VALVE

C) INSERT THE PETROL NON-RETURN VALVE

Pict. 28“BRC MP”pneumaticreducer

Pict. 31

Dual purposemixer(with clutch)

18 GUIDE TO CNG

working, we want to remember thatit’s necessary to block thermostatblade, in order to close hot airintake, orienting the frontal intaketowards lower or rear side of thevehicle.

6.3.3. MIXER

This device, situated down-stream the reducer, realizes theright air-fuel mixture.Mixer for carburettor vehicles

can be realized by using the carbu-rettor Venturi or by creating on it anindependent Venturi.To the first family belong:- dual-purpose system (nozzle

or clutch), consisting in a pipeinserted by drilling carburettor,- fork system, consisting in one

or more pipes inserted into the car-burettor without drill it,- separate Venturi system.To the second family belong:- "classic" mixers, installed

upstream the Venturi and whoseposition changes in accordancewith vehicle,- plate mixers, installed above

the throttle body, under the air filterbox.

6.3.3.1. Dual-purpose systemThis solution (pict. 31), can give

the best results if well done, but itcannot be realized on every kind ofcarburettor and it can seriouslydamage carburettor if not well done.Moreover, it requires much time andexperience to be realized.The choice of drilling position is

conditioned by the necessity toplace connection as in picture 32.Gas inlet must be made so that theclutch higher generatrix remains alittle under the narrow section ofVenturi pipe (2-3 mm); generally,this position coincides with the car-burettor separate Venturi extremity.Once the right position found,

pay the best attention with avoidinginterception of petrol while drilling.

Pict. 29

CNG reducer:water circuit

Pict. 30

CNG reducer:vacuum forpneumaticreducers

BRC

Engine

CNGreducer

CNGreducer

Engine

Intakemanifold

Exhaustmanifold

IN

OUT

Clutch, blunted at 45°, will haveto be screwed into the carburettorso that the clutch centre overpas-ses carburettor axis for some milli-metres. Then, clutch tight must beassured by using chemical productsor a nut.

6.3.3.2. Fork systemFor sure, this solution (pict. 33)

is easier than the previous one. Theonly precaution to adopt is slightlytrim the starter throttle body to allowits working.In this case too, you have to pay

attention with leaving a fork extre-mity long enough to reach 2-3 mmunder the narrow section of Venturipipe (if too long, you have to shor-ten it). Gas flow pipes don’t have topass through the air filtering ele-ment, but only through the air filterbox (normally in plastic) (pict. 34).

Pict. 32

Dual purposemixer(with clutch):installation

Gas inlet

Vacuum

Pict. 33

Fork mixer

Pict. 34

Fork mixer:installation

Gas inlet

Vacuum

Fork mixer

19GUIDE TO CNG

20 GUIDE TO CNG

6.3.3.3. Separate Venturi systemSeparate Venturi mixer (pict. 35) fol-lows substantially the same princi-ple of fork system. Generally it’sless economic, as it’s realized tosatisfy special requirements of aspecific vehicle. This system allowssometimes avoiding the startersthrottle bodies trimming.

6.3.3.4. “Classic” mixersThey represent another good solu-tion, because they allow a veryquick assembly. Normally, they’reinstalled on the air pipe coupling.Classic mixers can be both of clut-ch (pict. 36) and corollary (pict. 37)type, in accordance with the vehiclecharacteristics.

6.3.3.5. Plate mixersThey’re installed on the throttlebody. In most of cases, it’s neces-sary to lift up the air filter box andfix mixer on the throttle body withscrews you’ll find in the pack.These mixers, thanks to its littleoverall dimension, allow a goodworking and a very quick assembly(pict. 38).

Pict. 37

“Classic”corollary mixer

Pict. 36

“Classic”clutch mixer

Pict. 38

Plate mixer

Pict. 35

Separate Venturimixer

21GUIDE TO CNG

6.3.4. WIRING SYSTEM ON

CARBURETTOR VEHICLE

On this kind of vehicle, it’s possi-ble to install both a changeoverswitch with manual “star ter”(pict.39) and an ECU with automa-tic “starter” (pict. 40).In the first case, during the star-

ting up, it’s necessary to manuallyactivate a changeover switch buttonthat, thanks to its connection to thesolenoid valve situated on thepneumatic reducer, allows the pas-sage of a defined gas quantity tostart up the vehicle. “Safety” func-tion is obtained thanks to thevacuum realized on the intakemanifold (pict. 30).In the second case, instead, an

electronic circuit manages the pro-cedure and an electronic stage ofrpm reading allows the Safety func-tion.Connections, anyway, are extre-

mely easy, and following instruc-tions contained in the packs isenough to correctly install and adju-st the device.

Pict. 40

General connection diagram of “Bristol” ECUwith automatic starter, with electroassisted

reducer “BRC ME”

Fig. 39 - General connection diagram of “T100” changeover switch with manual starter, with“BRC MP” pneumatic reducer.

T100GAS/PETROLCHANGEOVER

SWITCH

Bristol

“VMA3/E”CNG valve

“VMA3/E”CNG valvePossible cable forconnection to theHall level sensors

Possiblereserveor resistivesensor

“BRC MP”CNG reducer

“BRC ME”CNG reducer

Coil

-+

Petrol solenoidvalve

Green

Grey

Grey Black

White

White/Black

Green Brown7,5A

White

Brown +12Vunder key

+12Vunder key

Ground

Ground

Ground

Ground

Ground

Ground

Possiblereservesensor

Orange

Petrol solenoidvalve

22 GUIDE TO CNG

(Lambda).Anti-polluting directives have

been acknowledged in the gas vehi-cles sector too. Also in this case,builders have adapted by creatingcarburation control systems thatdon’t change the original builder’sstrategies but satisfy the limits requi-red.

Before analysing necessary pro-ducts for gas conversion of an injec-tion vehicle, it’s better to understandwhich are the main electronic injec-tion systems you can find on vehi-cles, and how they intervene in gastransformation.

6.4.1. K-JETRONIC INJECTION

In accordance with the intakedair flow, washer moves to a definedbalance position which determines,in its turn, the injected petrol flow(pict. 41). During the gas mode, thewasher opening can be forced bythe suitable device while petrol flowis inhibited, or it can be free of float

thanks to a by-pass decreasing thepump pressure.

6.4.2. SINGLE POINT ELECTRONICINJECTION (SPI)

SPI systems generally inject fuelonce per drive shaft revolution, that’sto say twice per cycle. Fuel quantityis dosed by the injection ECU inaccordance with information gathe-red by the various sensors (pict. 42).

We can cut the single-injectorworking (pict. 43) by intercepting theconnection with the ECU.

6.4.3. MULTIPOINT ELECTRONICINJECTION (MPI)

MPI systems have an injectorper cylinder, standing very close tothe intake valve/s.In the Full-group systems (pict.

44) all injectors are piloted at thesame time and they supply one fueldose per drive shaft revolution.Operating on the only wire that con-

6.4. THE INJECTIONVEHICLE

Big international organisms haveplanned and applied more and moresevere norms and regulationsbecause of the increasing of pro-blems connected to the atmosphericpollution, in order to reduce noxiousemissions due to industr ial andurban sectors. In the automotivefield too, builders had to comply theiremission with more and more seve-re limits. These needs, and the con-stant progress in the electronic field,brought to the adoption of supplysystems more and more sophistica-ted that drastically reduced pollutingelements of exhaust gases, besidesto allow a better driveability of vehi-cles. So, builders progressivelyimplemented on their vehicles elec-tronic injection supply systemsmanaged by sophisticated electroniccontrol units allowing a “closed loop”control of carburation by means ofcatalysts and oxygen sensors

2

1

3

46

5

8

2b

7

K-Jetronic injection-1 Washer -2 Mixture governor-2b Fuel distributor -3 Fuel tank-4 Fuel Electro-pump -5 Fuel Accumulator- 6 Fuel filter -7 Pressure governor-8 Injectors

Pict. 41

Working diagramof K-Jetronicsystem

23GUIDE TO CNG

nects them to the injection ECU, wecan easily stop their working.In the sequential systems

(SEFI), every injector is pilotedseparately and it supplies one fueldose every two drive shaft revolu-tions, in correspondence with theintake phase of i ts cyl inder.Intercepting the common supply(pict. 45a) or the single negativebranches (pict. 45b) we can cut theworking of the different injectors.

16

10

9876

5

32

1

15

13

Fig. 42

Working diagramfo Single pointsystem

+

"

Pict. 43

+

"

Pict. 44

+

"

"

"

"

Pict. 45b

Single point injection- 1 Actuator with electric engine for idle - 9 Ignition changeover switch- 2 Fuel pressure governor - 10 Battery- 3 Ignition coil - 11 Fuel electro-pump immersed in the tank- 4 Electro-injector - 12 Fuel filter- 5 Throttle potentiometer sensor - 13 Coolant liquid temperature sensor- 6 Single point injection ECU - 14 Lambda oxygen sensor- 7 Remote control switch for system supply - 15 High voltage distributor- 8 Remote control switch for fuel electro-pump supply - 16 Tank

4

14

11

12

ChangeoverECU or

BRC emulatorChangeoverECU orBRC

emulator

ChangeoverECU orBRC

emulator

+

"

Pict. 45a

ChangeoverECU or

BRC discon-nectingswitch

Petrol ECU Petrol ECU

Petrol ECU

Petrolinjector Petrol

injectors

Petrolinjectors

Petrolinjectors

Petrol ECU

24 GUIDE TO CNG

Pict. 47

“Tecno.M”electro-assistedreducer

6.5. THE INJECTION

VEHICLE WITHOUT

CATALYST

As previously described, compo-nents situated upstream the CNGmanometer, necessary to convertan injection vehicle, are the sameof the ones used to convert a car-burettor vehicle.Downstream the CNG manome-

ter, instead, to convert an injectionvehicle you need to use an electro-assisted reducer, a changeoverECU connected to the vehicle origi-nal injection system, a special mixerand, eventually, other electronicand mechanical devices.Changeover ECU realizes the

“Safety” function and the cut-offfunction of injection system too.This is the reason why injectionsystems conver ted to gas don’tneed the petrol solenoid valvedescribed in § 6.3.1.

6.5.1. ELECTRO-ASSISTEDREDUCER-VAPORIZER

On injection vehicles too, redu-cer has a very impor tant rolebecause it allows the heat exchan-ge necessary to avoid CNG coolingfor abrupt expansion, reducingpressure almost until atmosphericvalues, so that fuel can be suckedby the engine.Also in this case you have to fol-

low the assembly prescriptionsdescribed in § 6.3.2, concerningthe vertical and parallel position incomparison with the running direc-tion, the easy access for adjust-ment and maintenance, the makingof the heating circuit (pict. 29), andthe air circuit changes.In the electro-assisted reducer,

an electro-assisted device suppliesthe CNG additional quantity neces-sary to start up the vehicle, and incase of accidental or voluntaryengine stop, the lack of electricsignals of ignition circuit impedes

Pict. 46

“BRC ME”electro-assistedreducer

CNG reaching the engine. In orderto correctly adjust the reducer,however, please make reference tospecific instructions you’ll find insi-de each pack.

25GUIDE TO CNG

6.5.2. MIXER

Mixer is situated downstreamthe reducer; it manages the rightair-gas mixture. On injection vehi-cles, we can have different kinds ofmixers.

6.5.2.1. Classic mixersThey’re installed upstream the throt-tle body, or along the air intake ductand they can be both of clutch (pict.48) and corollary (pict. 49) type.

6.5.2.2. Plate mixersGenerally, they’re used on SPIinjection vehicles (pict. 50). In fact,they’re installed between the single-injector and the throttle body thanksto its little height. Generally, theyare corollary mixers.

Pict. 50

Plate mixer

Pict. 49

Corollary mixer

Pict. 48

Clutch mixer

26 GUIDE TO CNG

6.5.3. WIRING SYSTEM ON INJEC-TION VEHICLE

WITHOUT CATALYST

On this kind of vehicles, we sug-gest installing ECUs that allow thestar ting up in petrol mode withautomatic changeover to gas, inorder to keep the injectors goodworking and correctly reset theworking of original electronic cir-cuits.For connections, please make

reference to the specific instructionsyou’ll find into every ECU pack(pict. 51). BRC ECUs for injectionvehicles carry out the Safety func-tion (interruption of gas supply incase of engine accidental stop);they’re also equipped with levelgauge and with many optional cha-racteristics according to the modelyou choose.

Elegant

“VMA3/E”CNG valvePossible cable forconnection to theHall level sensors

PossibleReserveor resistivesensor

To the injectors

Coil

InjectionECU

Brown

Green

Grey

+12Vunder key

Black

Orange

Purple �

inj. comm. cable

White/Black

Ground

Ground

Ground

Pict. 51 - General connection diagram of “Elegant” ECU with “BRC ME” electro-assisted redu-cer.

7,5A

“BRC ME”CNG reducer

27GUIDE TO CNG

they must be homologated in accor-dance with the anti-polluting directi-ves in force.We’ll better describe BRC carbu-

retion control systems in the fol-lowing chapters; for fur ther andmore detailed information, pleaseconsult systems specific hand-books.They can be grouped into:• “parallel” carburation control

systems,• “series” carburation control

systems.

In “parallel” control systems, gasis independently managed by theor iginal petrol engine control.Information about engine conditionand lambda oxygen sensor, andeventually about throttle positionand manifold absolute pressure(MAP) comes from the originalECU.

In “ser ies” control systems,instead, gas is managed on thebasis of injection times given by theoriginal petrol ECU, suitably conver-ted for the gas system. “Series”system acquires from petrol ECUalso signals about throttle position,engine condition, manifold absolutepressure, and eventually lambdaoxygen sensor.

For what concerns “parallel”systems, BRC can propose twofamil ies of products: “BLITZSystems” and “JUST Systems”, withdifferent technical characteristicsand different uses.

6.6. INJECTION VEHICLEWITH CATALYST

The continuous increase ofatmospheric pollution led to newand more severe environmentallaws. First of all, the compulsoryuse of catalyst on first registrationvehicles (in Italy since 1/1/1992).The three-way catalytic muffler

with Lambda oxygen sensor is themost advanced solution technologymay offer us in order to reduce pol-luting emissions of engines. Itallows eliminating more than 90%of HC, CO and NOx, but it can cor-rectly work only with electronic sup-ply systems.This is the reason why BRC Gas

Equipment realized and patentedmany devices allowing the conver-sion to CNG of vehicles with cataly-st. These devices perfectly integratethemselves with vehicle electronicand fluid-dynamic context, reducingmore and more the noxious emis-sions and allowing enjoy CNGadvantages: Ecology, Saving,Performances, Security.A catalyzed vehicle needs a

device able to acquire and elabora-te the Lambda oxygen sensorsignal in order to be converted toCNG. This device has also the taskto always give the perfect air/gasmixture and to manage automaticchangeover from petrol to gas.Except for systems of last gene-

ration (Just Heavy and Sequent),mechanical components necessaryto convert a catalyzed vehicle toCNG are the same used for injec-tion vehicles not catalyzed (CNGsolenoid valve, electro-assistedreducer, mixer).The main differences concern

the electr ic components of thesystem. Instead of a simple chan-geover ECU (§ 6.5.3.), both from afunctional and from a legal point ofview, it’s necessary to use a carbu-ration control system made up of anECU and a flow actuator. Beforeinstalling these two components,

28 GUIDE TO CNG

Pict. 53

General diagramof Blitz controlsystem

6.6.1. GENERALCHARACTERISTICS OF

BLITZ SYSTEM

Blitz system is made up of anElectro-Assisted Reducer (BRC MEor Tecno.M), an actuator for gasflow control, an adjusting screw, amixer and an analogical ECU.System acts in “closed loop”, correc-ting in real time the air/gas mixturetitle according to the informationcoming from the Lambda oxygensensor. As known, this sensor crea-tes a tension signal depending onthe oxygen present in the exhaustgases so that it supplies an indirectmeasure of mix title (poor, stoichio-metric and rich). This allows theECU acting on the actuator andchecking the gas flow through a sui-table power stage.Blitz was exclusively conceived

to only manage the actuator paten-ted for this system so that it is notcompatible at all with any othertypes of actuators.Besides, Blitz system manages

different functions such as: chan-geover, safety, level indication andLambda oxygen sensor signal emu-lation.The function of injectors cut-off

and emulation can be managed byan external emulator.Blitz ECU can be connected to

the Diagnostic Box device thatallows the system set-up and possi-ble diagnosis through a suitable barled.Blitz system is available in many

versions, different one from eachother by the presence or absence

of the functions described above.

CNG cylinder

ModularHI MM

“VM A3” refuellingsolenoid valve

Petrol injection ECU

“VB A1”valve

“Tecno.M”reducer

Mixer

Engine

LambdaOxygenSensor

Petrolinjector

Adjusting screw

CNGmanometer

BLITZ

Lambda Gasactuator

Changeoverswitch

Diagnostic Box

Pict. 52

Details of Blitzsystem

29GUIDE TO CNG

6.6.2. GENERAL CHARACTERI-STICS OF JUST SYSTEM

Just system too is made up of anelectro-assisted reducer (BRC ME orTecno.M), and an actuator equippedwith “step motor” for gas flow controlthat replaces the BLITZ classicactuator and the adjusting screw.Moreover, this system has a mixerand a digital ECU.

We can apply JUST on every kindof engine converted to gas, suppliedwith electronic injection both intakeand supercharged, and it can auto-matically recognise and use thesignal of lambda oxygen sensor cur-rent installed on each vehicle. It hasbeen developed to comply with mostof severe laws about vehicles pollu-ting emissions and ElectromagneticCompatibility.

ECU is based on a digitalhardware using a microcontrollerstructure. Microcontroller allows a bigflexibility in the management of theinput coming from the different engi-ne sensors and a successful mana-gement of the gas system output.

JUST acts in “closed loop”, adju-sting gas carburetion in feedback andoptimising in real time fuel quantity to

obtain a perfect carburation, for whatconcerns pollution too, and this notdepending on the outside conditions(as temperature) and on the fuelcomposition.

Just system was exclusively con-ceived to manage “Step” actuator. Itconsists of a step-by-step starter thatwith its movement put upright a pivotthat closes the gas passage towardsthe mixer. The actuator movement iscontrolled by the engine control stra-tegy according to the different inletsensors. The digital system decidesvery quickly, so that actuator move-ment can guarantee a constant kee-ping of the correct stoichiometricratio.

Moreover, Just manages differentfunctions such as: changeover,

safety, level indication and Lambdaoxygen sensor signal emulation.

An eventual external emulatorcan manage interruption and emula-tion functions of the injectors.

The set-up of this device can bemade both by the changeover switchand the BRC Diagnostic Box, and bya PC equipped with a programmingand interface software.

Pict. 55

General diagramof Just controlsystem

Pict. 54

Details ofJust system

“VM A3” refuellingsolenoid valve

CNG cylinder

ModularHI MM

Petrol injection ECU

“VB A1”valve

“Tecno.M”reducer

Mixer

Engine

LambdaOxygenSensor

Petrolinjector

CNGmanometer

“STEP”actuator

Changeoverswitch

Diagnostic Box

30 GUIDE TO CNG

6.6.3. GENERALCHARACTERISTICS OF

JUST HEAVY SYSTEM

Just Heavy system, addressed toCNG supply of controlled ignitionengines, is the new interesting evo-lution of Just system, born to extendthe application field and improve itsperformances.

Just Heavy, in fact, keeps practi-cally unchanged the main characte-r istics of the Just system (easyinstallation, parallel configuration,with possible cut-off and emulationof lambda oxygen sensor, self-set-ting, self-adaptativity, possible dedi-cated and deep set up by means ofan interface software on PC), buthas also some important mechani-cal and electronic features, that wecan resume in the following mainpoints:

• mixer is absent (gas is injectedinto the manifolds, not intaked by theengine), so consequently : there areno disadvantages for performancesin petrol mode, a possible powerloss in gas mode only depends on

characteristics of the gas itself, thereare no additional overall dimensionson the intake ducts;

• two-stages reducer, with smalloverall dimensions and bigger instal-lation flexibility;

• new actuator-distributor stillbased on a sole step-by-step enginethat allows dosing gas and directlyintroducing it into every single intakemanifold duct (near original petrolinjectors), eliminating the backfirerisk;

• P1 and MAP sensor, supplyingto ECUs information about vacuuminside intake the manifold (MAP)

and about reducer outlet pressure(P1).

• ECU microcontroller with capa-city and calculation ability biggerthan the Just system ones, able toallow managing the new actuatorand developing sophisticated carbu-ration control strategies, and withinnovative procedures for self-acqui-sition, self-adaptativity and self-dia-gnostic.

Main target of Just Heavy systemis to obtain a high level of perfor-mances with an easy installationand a quick set up.

Results of approval test for emis-

Pict. 57

General diagramof Just Heavycontrol system

Pict. 56

Details of JustHeavy system

Changeoverswitch

“VM A3” refuellingsolenoid valve

CNG cylinder

ModularHI MM

Petrol injectionECU

“VB A1”valve

“Genius HSM”reducer

Engine

LambdaOxygenSensor

Petrolinjector

CNGmanometer

“Step HS”actuator

P1-MAPsensors

Just Heavy ECU

Computer

Gas nozzle

MAP vacuum

31GUIDE TO CNG

sions proved the extraordinary qua-l i ty of the carburation controlsystem.

Approval tests for EuropeanRegulations nr. 110, especially aboutElectromagnetic Compatibi l i ty(EMC), brilliantly passed by thesystem, exalted its strength to elec-tromagnetic troubles and confirmedeffectiveness of planning and pro-duction strategies adopted.

32 GUIDE TO CNG

For what concerns “series”systems, BRC can propose“SEQUENT”, a supply system withCNG injection in gaseous phase.

6.6.4. GENERALCHARACTERISTICS OF

INJECTION SYSTEM IN

GASEOUS PHASE “SEQUENT”

SEQUENT is the most advan-ced product in the field of gas injec-tion equipment, and it can be con-sidered to all intents and purpo-ses as a “COMMON RAIL”system.In fact, it’s the first in introducing

in the gas supply field the winningevolution for modern Diesel engi-nes: a "rail-line" in pressure (rail),supplying fuel to all injectors (trueinjectors) assigned to inject it ineach engine cylinder.Moreover, SEQUENT introduces

the harness modularity concept.This means the possibility to installSEQUENT system on a vehicle byonly connecting three wiring cables,and adding further wiring connec-

tions only in case of sophisticatedvehicles.In the SEQUENT system, unlike

a continuous flow injection, ECUcalculates injectors opening times,cylinder by cylinder, and it actsthem separately on each gas injec-tor with the highest precision andthe best timing if compared to theintake valve opening instant.Sequential injection managementallows therefore obtaining the toptimeliness and precision of fueldosage.As in all electronic injection

systems, a mixer doesn’t aspiratethe gaseous fuel, but the correctquantity is determined through thecalculations made by the ECU. Itallows obtaining the well-knownadvantages of the injectionsystems, such as:• no disadvantages for perfor-

mances in petrol mode, because ofthe absence of a mixer,• best performances in gas

mode, typical of injection systems,• no additional overall dimen-

sions on the intake ducts,

• elimination of backfire risk, dueto the injection near the intake val-ves and increased by the fact thatinjection occurs in a timed way withthe intake valve opening.

The result is that the originalsequential working, for which engi-ne had been planned, built andoptimised, stay absolutely thesame, reaching the following practi-cal results:• better driving fluidity,• consumption optimisation,• reduction of polluting emis-

sions.

Other advantages, typical of“series” systems, are the followings:• normally, it’s not necessary to

delete error codes in the petrolECU, because they cannot appearanymore,• i t ’s no more necessary to

install “Memory” devices on vehi-cles equipped with OBD diagnostic,• all petrol ECU functions stay

efficient even during gas mode,assuring the respect of OBD regu-

Pict. 58

General diagramof SEQUENTcontrol system

Changeoverswitch

“VM A3” refuellingsolenoid valve

CNGcylinder

Petrol injectionECU

“VB S1”valve

“Genius.M”reducer

Engine

LambdaOxygenSensor

Petrolinjector

Gasnozzle

MAP vacuum

CNGmanometer

Rail withBRC injectors

P1-MAPsensor

“FJ1” Filter

“FLY SF” ECU

Computer

33GUIDE TO CNG

lations,• every gas injector is individual-

ly piloted, allowing to maintainpetrol injection ECU strategiesduring the gas mode,• it doesn’t need special adjust-

ments, if mapping is available.

Moreover, thanks to the ECU bigintegration:• no external device is neededfor injectors cutting and emula-tion,• we can read rpm from thecrankshaft with no need ofexternal adapters,• ECU is equipped with an inter-nal timing advance processorsuitable for most of cars,• we can connect two lambdaoxygen sensors in the one-connector ECU version andthree sensors in the two-con-nectors ECU version, withoutneed of adapters,• ECU contains the main adap-ters for “current” and “sup-plied” lambda oxygen sen-sors, • we can manage vehicles upto 8 cylinders in the two-con-nectors ECU version.

34 GUIDE TO CNG

An engine conceived to workwith petrol has an optimal ignitionpoint for that kind of fuel. Alternativefuels have, instead, different com-bustion characteristics.Using alternative fuels without

modifying the original ignition pointshould mean don’t exploit all engineperformances, having so bigger fuelconsumptions and lower availablepower.The only solution to this problem

is use a timing advance processor.Timing advance processors areelectronic devices that analyse theoriginal ignition point and change itin accordance with the fuel used..BRC has a wide range of pro-

cessors, able to optimise every kindof ignition, from the simplest onewith coil ignition, to the most difficultmanaged by the petrol ECU.

7. TIMINGADVANCEPROCESSORS

Pict. 59

“Aries” timingadvance processor