PROTOTYPE
DEVELOPMENT
OF A SINGLESTEPPRESSURE
REGULATION
SYSTEMFORTHENATURALGASMOTORCYCLE
Dr, Rahmatlbhstn, Dr,ZrJlkefliyaacob,
ZulkifliAMul Majjd,Shameed
Ashraf
ABSTRACT
.J
The use of Compressed
NaturalGas(CNG)for vehjciehas provedto improve€misslon
quaiity/reducesdependency
of majnstreamfuels and increaseslubrtcatjonoii lifespan.The
successfulutilizauonof CNGon the Kriss Nlodenas11occ has been proven by p.evtous
researcher.
The currentstudyis carriedout in the attemptlo improvethe pressurelegul€tot
whjchisd€emedcrucialin dte CNGfuel system,Variousd|awbackof the previously
imptredunt
prove the need for dtis strdy. Thjs study begins $/jd] a comprehensiveulrde|standingof
dte
pressurercgulationsystem.Designconsiderations
are taken afd optimizedaccordingiyto
enhancethe final prctotype.Theflowwiftin the regulatoris optjnizedusingFLUENT+,white
the
structuralintegrity is backedby AmericEnSocietyof MeclEnicalEngineer(ASME)pressurevesser
ccEe and related standardson threadedfasteners.The fabricationof fie prototypenas Deen
fonnulatedfrom findingsand anaiysison the d€signmethodology
lsing suitablemachining
tec.hniques. The p€rformanceof the flnal prototype is obtainedfrom the specjallyoeveopec
p.essure regulato. test bench. It is cleady proved that the developedpressureregulator is
capableof providing the downstreamcomponentswidt natural gas at 48ar up to 24liters per
minute. This performanceis seen cont@ntfegardlessof the upstreampiessureano me
dowr$rean flowdemand.
1.0
Natural Gas Motorcycle
The flrst generation prototype
modelof the nafural gas vehjclemotorcycle
wasdesignedand developecby the Nacural
Gas Vehide-Motorcycle(NGVM) Research
Group under Gas Technology Center
(GASTEG)of UTM back in 1997.The Kriss
l4odenas110cc was selectedas it was the
one of dle most wideiy used locally
paoduced motorcycle. The four stroke
natural gas prototype motorcyde was
prepared foa testing with a new set of
conversionkjt that includesairltafuidl gas
mixer, preasureregulator, storage tanh
'elated conuol elemenEsano measuring
appaidtusrr. The motorcyclewas then pqt
!o several tests to attain the engine,s
p€rToTmance,exhaust ernission and the
lubrication oil quality to conduc a
comparisonbetween the nafural gas and
pefuoloperations !'r. The power ouFut of
d'e engineand exhaustemissiondaE wa5
successfullyrecorded using Ute CycleDyn
ProSF250 chassisdynamorneEr
anc 'lonba
vE{A 3241 emissron a']aifzer aL b'e
llodenasass€mblyplant in Gurun,Kedah
Phlslc"l aad chemicEt Lesdng or dre
lub.ication oil was conducted in the
lrboratory Service Unit (UNIpEt4) of
Universiti Teknologi Malaysia which is
accreoiredby SAl4l4 (ISO/IECG25) r'.
bahaustemissiontesr wa9 conductedat
constant speed using the standard
procedure from ISO 3929 trl while the
physical and chemical testing of dre
iubricabon
oil wasbasedon ASTMstandards
as oL'dined in the following s€ctiod. The
motorcycjehad a maximumnatural gas
consumption
of 24litershinutesuppliedat 5
psig during full throtile. In general,the
NGVII offers great advantagesover pefol
operabonin terms of emissionwheredre
CarbonFlonoxide(CO) is reducedby 99.7olo
whiie the unbumed hydrocarbon (HC)
emjtted is reduced by 79.3Vo. the
degGdation
of fle engineoji afteroperating
for a distance of 2500 km, favours fle
naturai gas operdtionover petrol. The only
drawbackis U'e €ductionin oo!./€rby l5o,t
at l'igh enginespeedsdue ro fl.e gaseous
nediLm of d1e_aturdlgas wr:ch o:sptaces
the amountof air induced.
I
l
Figure1: NatuGlGasFlotorcycle
FuelLtne
2.O
Current Research.
The secondgeneration fuel system
under deveiopnrent differs from the
previoLsly 'rroiied sys(en In lerms of
storage pressure, pressure requlation and
fuel metering. The previous system had a
sto.age system of 1800 psig as it was
conducted on a trial basis. The s€cond
generation's
designed
to'.andlefull suppr,
pressureof 3000 psig as dispensedat fie
CNGre'uelingstation.ThevacuumactLatea
venfuri type Fueimetering device operating
wi$ naturalgas supplyat 5 psigis replaced
wlh an .rlection system. The injection
system uses an injector actuated by an
electroniccontlol unit and suppliedwith
natural gas at 4 bar. Differencein storage
pressureand the supply pressureof the fuel
metering device on dle second generdtion
fuel system l_as rmposeda need for the
currentdudy. The pressureregulato.woulo
b€ designedto meet the 3000 psig storage
pressureand to supply d'te injectol' with a
constantpressureof 4 bar regardlessof u1e
demandpos€dupon it. This paperwould
disorss tf|e mechanism,elements,design
parameters,add related testing involvedin
designing a pressure regulator. Among
variouscriteriaand consideration
that are
indicated by market resea.ch I1l, Ute flow
periormance, heat exdlange control and
oLtlet pressure enor are the prirne
goveming factors that are taken into
consideration during the design and
development
of tre regulator,
3.0
Methodologyof Res€arch
T'1rs s€cdor covers Lhe med'tods
i|rolied rc desrg'l ard developmenr!_e
singletceDpressureregLlatordeaicaleo.or
tr)e \GVY <nss 110a.d rre corresponding
o.essLre -eguiatorfest be^cn, -1e tes!
bench enabies performancetest to be
condrated 01 'he -ewrv devetopeo
.eguldtor.8€sicwo*tng ard -nechariqrof
lfe pressJrereguiatonsysler are ioendf,eo
and developedpat by part. This wo.k is
arranqed n sequel*lich oegi-s wEh lre
materialselectionfollowedby the design
and deveiopment
of the restictingelement,
loadingand measurin!eiementmechani€al
hnkageand lastly rne pressLreregutator
try,
Equal attenUon is given to d1e
oressure'equlatorLestberch,whe-evarious
comp,onentsele'ctionand assemblyare
conduced !o ensure safe high pressure
gawLs fluid flow couptedvvitn suttaole
data acquisibonsystem to monilor thc
occuring phenomenonof the regulatio.r
system.
3.1
PressureRegulator
Components
Pressurcrcguiatorsare prmucedir,
many srzesand configurations,
oLr all are
bounded to three basic coFrponem
categories which are the valve Lrody,d.le
valve trim and tre actuaror tsl, These
components can be further described in
lems of elefientswhichare E-erestricring,
oadingand measuring16r.
The .oadingano
measuring element together form iie
acfuatingcomponentof the regutaLor.
The
valvetrim comprises
the restrictjnqetemenr
and relaced link?ges that enables the
regulatorto operate.The r€stricringelement
is made up to the \€lve s€at and valve pad
or obturator. Lastly ule valve body houses
all th;s componenEand orovidesphysica.
Supporl to the componentsLo ensure
wod€bility.
The aegulatoris designto provid€
constant outlet pressureregardlessof the
demandopposedupon it 14.Fromthe flgure
be{ow we s€e that d1e loading element
(spring)exertsforceagainstthe measuring
eiemenl (diapl-€gm) wi-icr opens he
restrichngel€ment.Whenrhe cofipartmenr
pressuaeej(ceedstre s€t-porrr level fre
measuring element wolld actuate Sle
resfictjng elemenE for full ctosufe. This
wouid cease the natural gas suppiy into the
CorrpArtmeni dl the oressure oepteres
beiow
ser oo,n!
leve{,
Strppor0rE
conDore4l5 sltch as sLpoort d:sc, ser poinr
Screvr,vert aTd so on are provideOrc ajo
file .egL]lationmechanism.
'l
Figure2: SpringLoadedftessure.Regulator
Componmts
3.1,1 Matedal Sel€<tion
The mater'al serected For Lhe
pressureregulator fabric"tion is requiredto
handlethe typical operatingtemperatureof
an \GV regulatorwhidt variesfronr-206Cto
120"C.A non corcsivemetalis preferedas
it wourdsuit the operacing
condihonberter.
The mechanismoF $e pressureregulaLoerforcesrhe intemarcoinponents
especiarly
U]e sprrng to resisr fatigue End shoc(
loading.S€lectjonof conponentlnateria{s
for high temperafureor corrcsiveserviceis
gene€lly limitedto s€rnlessstee$ or .tigr
niclerarloysL"l.
Thehighricke{afoyssucli
as lnconei and $e beryliiumropperare
dbouL3 fo 4 lmes d^e cosr of fype 18_8
stainlesss,eet t,l, --hereare a rLnoer of
groupsor far]|liesof inrness sreel,eacn
Corrarrt'g a _UmDerof Soeatf(tyoFsarc
e9ch wrti
ils owd stt-gJisl-irg
cnaraclersfics. These tnree Lerms_
martensite,ferrite,and auStentteare aJSo
.drl:es of
dessroLjveol .d-e trree
stainless
sieelsL''r
-ajoThe martensitic
stainlesssteelsare
nomi'lajly tl-l3o,o chfoni-n. arc
fradenable bv hear rfeaL-lent€'1o arc
exerrplrfredbv grade $pes 4rO (S4rOO0)
and 420 f5a2000). Thrs q-ade is
susceptibilityto absorption of atomic
nycrogen, resulting in frydrogen-assisted
ciacking add has poor low-temperature
impact resistance. Fenitic Gradesclass of
al{oysusualy contains15-18o/o
cnromium
The turritic grades,exemplifiedby S43OOO
(16-18c|-0.12C).
have corrosionresistance
slpenorto the martensitic
grades,p.imariiy
by virtueof rhetrhtqnerchromiumcoT[enL.
Their high-temperatureoxidation resistance
is also gciodbL'r rhey ha,/e ooor impac
resisGnce. Heat treatment uFon drcse
gradeshas no effec on its hardness,
The
austeniticarodpis rhe mo$ imFoftanc.or
prcess industryaoplicadons.
By urIue of
therr aus66;1g6o-;"9 aloy addirjons.
notabiynickelard manganese,
theyare no!
hardenable
by heEttreatrnen!but can be
strain-hardened by cold-wo*. The
conventional
18-8austeniticstaintess
steels
are exenplifed by Type 30a (S3OaOO).
These al{oys have rdrc combinationof
cotrosion resistance, high-temperature
strengtf, acd oxidationresistance,
easeo.
good ouctilityand gooo:rpacr
fabdcacion
resii.ancedownto acleEst-193.cc215.0.
Their medEnicalprop€rtiesin general,are
excellent.
Heat beatment used upon spring
materialto improvethe material propertjes
is preferdbly
avoidedas it commonM
@Ls€g
spring failLre t"l. Wid^out consideraole
expeHencein Ute techniquesof heal
beabnent, rherefore, sprirg marcnats
sroulcalwaysbe usea'as is' tlrl, Amongb.e
lyp€s of $ainless$eet, me Type (18-B)
cannot be heat tr'eatedas these alloys do
not resoondrc the |-a-denrrg
andLemDeflng
method sr. At low temperaturesthe
stainlesssteelsof lhe 300seriesare usefui,
but those of the 4OOseriesare not lr3l.
These argumentsaboveprove that the best
common componentmateriaitlrat would
oblige the design requireneni is the
<"F'nlo cq
q oe'
-+
304
, ap\
-}rs
material would be used throughoutthe
design and fabricationof the pressure
fegulatordue lo its advantages
over other
matedais,
3.1,2 Restricting Element
The -e51ricti'1g
elemer! desjgn is
'- given the primeattentionas $is would be
the componentthat would deter..inethe
pressurecontrol. The obturator that moves
againd and away frcn the v€lve seat to
preventand permitthe flow of gas to the
regulator compartment serves as the
restiictingelement.The limitingfactor of
flow witninthis systemis the occufience
of
choke.The equationgoverningthe area of
tl_e conduit ard mass flow s given by
trqr
oosthuizen
and carscallen
u '=- L [L 1 "'u'
'Jf'P"\/+tJ
From the equationwe see that dle
mass flow rate drroughthe closeconduit is
proportional to dle closs sectionalarea of
flow. The supplyof naturalgas froflr ure
storage tank is suppiied brough high
pressurefubing, the intemaldiameterfor
this commonlyus€dtubingfor CNGsuppiy
is 3 mm. The designof a vaiveseatwith an
area larger then this value would be
unnecessaryas the choke would have
aiready occurred downstream where fie
diameteris smaller.The desigoof a valve
s€at smallerdiameterwouid causefurther
c,hokeand redLrcethe mass flow into dle
regulator.Forthis reason,the valves€at is
designedto be 3 |-nrnin diaaneter.
The movement of the obturator
which moves against the valve seat to
restrict flow and movesas/ayto pernit flow
requiresevaluation.How far shouid tfre
obtlratormoveln orderto providesuiflcient
naturaigasto fiaintaind]e desiredprcssure
within the re€ulatorat the feguiatorsfull
capacjty?The compliaatedgmmetr_yof the
flow makesmanualcElc!iationtediols,dlus
requirinqthe use of ComputatiofalFluid
DynarnicSoftwa
relt5. The impiem€ntEtion
oi lhis methodhelpsdeienninethe mass
flow |ate of gas flowing betweend1evalve
seatand obturalorat a glvenopeninqgap.
The simul:tion is condlcted on a
compressible,
steadystate conditionwith
adiabaticwall basis.The fluid is taken as
methanedue to the nature of llalaysian
natural gas which contains over 93?o
methane.
Various position of the obtltlator
from the valve seat is simulatedusing
FLUENTfi CompltationalFluid Dynamic
Software. The geometry is generated and
meshed using GAMBffft which is a
Computer Aided Design Soft;ware. The
illusbation below depicts the neshed
geometry that would be imported into
FLUElffn. The boundaryconditionsand
fluid propertiesare definedwidrin FLUENTft
and simulatedto obtainfie corresponding
mass flow .ate at different oL\turator
positions away from the !€lve s€at. The
resulls obtainedfrom the simulationa.e
comparcd with dle
Elermophysical
properties provide by NIST 1161.Tne
following picture shows the results of fie
simulation fiafs shows properties of a
plane.This methoddeterminesthe d€sired
openingto provideu]e massflow rate that
would meet fle need of dle natural gas
motorc/cle.The sfudy moveson the design
^a
tha
mtrF,ni.rl
Ii.lz:na
:
g.!;:;i
- il:ii
l :r ::
8. .
E, r,,
,
I ii',
\
resultof $e comparbnent
fluid acbirgupon
rne orapirEgm which seRes as ihe
.n€asurlng
element.This force resftjctsthe
entr;nce of the gas to the compartnent
wn€n recucesthe compartmeftDressure.
B:sedon fundanrental
calculations
on Forces
a|jd knowinglhe desiredcompafn-nent
set
polnt presslre and maximum obtu€tor
movernentaway ftom dte valve seat, a
suitab{e loading element (spring) is
oesrqnec.
,,..,,,,,,,,, .," ,.l l 1;l ;j i ,,:
')
t
3,1.4 LoadingElement
3,1.3 MechanicalLinkages.
-t
The mechanical
linkagerelatesthe
restictjngelement,measu.ing
elementand
fie lo€ding eiemencto form a workirg
pressureregutationmectranism.
The linKage
is pivoted to the regulatorbocy at Doin!"X,,
shownin the diagram.Thereare t€sically
firee forcesactjng on the liakagewheredle
re$ltant of 6ese forceswill determineiJr€
actuationof dte resrictirg elernent.The
iorce denoreoas "1" is fie force exerteoD,
the flujd enteringthe regulatorcomDaftment
on to the obtuGtor. The rnagnifudeof this
force varies due to $e depletjng storage
pressure. As we know, force is pfesslre
acting over a surface area. The force
denoted as '2" s caLsed bv tne orecompression of Ute spring (Loading
element). This seEng cause fe
compartment pressureto rise, *te greater
the force dle greater the comfErbnent
pressure.The force denoted as '.3,, is fte
Compressionsprings made from
rounOwtre aaetj-e easiestto oesignEnd
produce. They are accurate. retiable
Lolerdole
to hrghstress,havelonqerfatioLe
life,and shouldb€ usedin prefere-nce
ro in
or.' tr* t'r.*";;-
d;ili;:;#
of ends for a Futv formed fel:cal
cornpression
spring $ey are plain end!,
plarnendsgrcund,dosed endsaod dosed
endsground.The loadingelementspringoF
tne pressureregutatorwill be dedgnedto
have&e closedendsgroundas it requires
acq.rrateprecisionforce requirementsand
resistancetowardsbudding.
Th€ singlecoil of d€ compression
spfrngshownin Ulefigurebelowwill haved
oadterdingLocompress
.t. Tiis ;eEns drac
d1ere is a force, tending to pull .A
downwards
ard "8" Jpwards,The effecrot
rl_isiorceis to tr-yto rwisrdte sprnq,rlre a!
"C". Therewii o€ a lirde beno;ng;ctjon iUle iengths AC aM BC, $rerefore tle
cnterionfor [J-esprng wrrewill be fle shear
s!'engln.
Single Co;ls of CompressionSpring
D
I
T
ofsingleCoil
CrossSection
The twist of 'torqLe"In fle springwire aL
point "C" is d]e load"W" multipliedby the
lever arm, tie lengthof which is D/2, D
beingthe meandiameterof the coil.So,dle
torque is 1/2DW. Now, in a round rod
subjecrto a hvisdngadjon, the sbessis noc
uniformoverrhe wholeareaof fte wire,buL
is zero at the core and rnaxiftum at the
surface.The maxjmumshearstressis given
by
1 6.T
.
'"
z . d'
ButT = W.D/2, so that
R.W
f =-
, f)
.-
(2)
or, to put it ff]e other way round,
I.D
Tles€ are dre basrceqLatior For
ioad, where the load which a springcan
carry is proportional to the sfess, to tire
cube of the wire diameter,and inversely
proportionalto d1ecoil diarneter.A ten coil
sorirg w il carryeraclt Lhesafte sdfe baa
as one with only two if the wire and coil
diarnetersare Bte same. The number of
coils do€s have an effect on the spring
terorma'lce: in -any cdses me spri.E
deflecdonurder loadis a,-roslas t-rpo(dnL
as lhe load ilself,The con-esponding
end B
oi the bottom haf coil is thus displaced
uowards wiere as erd A s d splaced
downwards.Tle iota deflect.ons 2 '6
wFere'6" nolecrerl oowrwarosror poinrA
and 6 upwardsfor B. Add anotherpair of
haF co,lsano tne rext end wril rrove oy 4
"6". and so on. Deflectjondependson dre
nLn'ber of corls. Ir sprirg wor\ b is
deflection is usuaily stated as Sre Rate of
d-resoflng 'R" and In Inrpe.ialmeasureis
d€iinedas the load i.l lbf/rr. (i- S.I. un,ts
61iswouldbe stated,for our slzeof spring,
in Ne!^/ton/mm.)rr. Rate shouid be
determinedbetween20 and 60 o/oof total
defiFchon when Lesa engrhs are not
otherwise established ttal. 'the deflection
urder a given load W s g,ve'] oy ftl
formLrla
below:
-
8 W D' . n
W
G.d'
6
8 . D3 . n
(41
From (3) above you will see d]at &e
deflectionfor a given load dependsdirecty
on the size of the load, on the cub€ of the
coil diameter.on the numb€rof coils,and
invelsely as the fourdr power of the wire
diameter. And, of cou6e, invelsely as the
value of "G", whichdependson the material
used- and on the temperature of that
material, a fact not always remembered
when dealingwith springsworkingat fle
temperature.
In arrjving at expression(1) we
assumedfrat the torquewas appliedas in
dre caseof a drve shaft.Buca coilspringis
coiled,fte shaftis cuwed.This makesa big
difference, for the surface stress is no
lorger uriform aroLndSe circLmference.
It
is higheron the insideof the coil d]an on
Ure outsrde. To recifu thrs condibo., Ere
correctton Facor rs Inlloducm. Thc
cDr-ectionis also neededbecduserhe wire s
curved wfere t'te curvaEre deFendsor me
.dtio o'cotl diare(er lo wi-e oianerer.fh(
.or-ec(ion 'aclor fo- snear stress.5 given as
(- where as lfe coarecuon -a(tor
fof
deflectjon is grven as Kr. Adding drese
valu€s to equation (1) and (4) we get
equatjon(5) and (6).
,,
4C-l
4C -4
0.615
C
2C 2
D
d
-
,- 8.fi'. D
'8 D',.n
A5 vle c"n see sle correttior Factcl
given above is a function of the spring
index.The ratioof the meancoildiameterD
dividedby the wife diameterd is calledthe
spring index and is one of the most
imrcrtant factors in d€sign and
ma4ufacture.Low raciosunoer 4 @nnot
always be coi'ed on automaciccoilerJ
becalse the high pressureof dte otoff tool
needed to sever the wire may bre€k the
portion of the arbor usedas a cutting dge.
Low idtios also may causepretemperedwke
Io cracx or may reduce its ability to
withstand the deflection desired t1el, High
indexesover 16 and partcLlarlylhoseover
20 causesgreaterflexibiiityIn dre coilsana
requiretoleranceac least50 percentlarger
flan standard. Higher rdrios reqLire
modifrcation
on fte coilingtoolsand caus€
diffcuity large variabonsn coil oiafiere'
Inderes3.5-15are commerciatly
practicat
Lo
manufactlre,bLt indexesin $le rangeof
5.5 9 afe Dreferfed,o€rtcLtEnyfor dose
loterancesor,ngsand tfose suDlectedLo
cyclrc
lo€orng,'!,
3.1.5 PressurcRegulatorBody
There
are
bEsicllly two
constderations
lhat are tnvolvedin designing
a suttaDLepressureregulatorbody. The
r.Ie-nElConoafrent of the -egutALor
boo,
rs Cv'rnOnc!'n slape rrtf 50 T-n Oiarnecer
and 28 mm ln height.It is fitted with d
bonnet cover at the top to ease accessto
the intemalcomponent.
The determinatjon
of the mininrum wall thicknessof this
companmentand the bonnet cover is
evaluatedbas€don the ASlvlEBoilerand
PressureVessel@e kion VIn Divisiof
1. The selectioo of suitable threaded
fastener to hoid the bonnet cover in p{ace
agarnstthe internalforcesis dealt with in
the followingsection.Thematedalusedfor
fe developnenrof the booy is sbinress
ste€l 304 as it complieswith the pressure
vesseicodeano sUiGrhe workjngcondkion
or tlre reguratorbest. The desiqnwoulo
carerfor fle rull CNGscoragepr;ssureo.
1000psrgto providemaximumsafetyas r ;s
a preliani.Erydesignprototyp€,The bottom
wErl,cyliMricatside wall and the bornel
covefminimalwail d.tickness
are presented
ln the finalprcductdrawingwhichis labeiled
with dimensions.
3.1.6 ThreadedFasteners
Ore of the d;stinctaovanLaqes
of
$e l5O mearicnLt strergd sy$en -'s har
eacnproFelryclassof nut was specificarll
designed,dimensionally
and rnetallurgicllly,
lo orcoerly mate \,ridr a prcperry class of
bolt L"r. C-onsequenu,
when the conect
ciassof nut is selected,evenunderthe mo6t
adveEecohbinationof conditions,
dte bolt
will nomaily break fi|sl This occurrence
eases the detection of failures prior to
loading. There ar€ just two metric sqe!{
bread forms, dte M profilewhidt is dre
standardfor commercialfastenerand fie
lvll which is dte standard for aercspace
qualityfasteners.The Standardcommercial
fastener1"1proflle is selectedfor fle cltrrent
stLdyas it is easilyattainablein *re ma*et
and economically
favourable.fused on SAE
11199,Solto'class 4.6 havingY6 r 1 rs
seJecied
as lt has suitableproperqto hold
the calculated force e\erted on to the
fastener,The gLidet.ne n bott aro -L!
seieciroroLtl;res LhaLd e nLt selecrmshatl
be of a higi_ercjasscompareo!o tre oo.t.
Thereforc based on ASTNlA3561,1
nut f.om
class5, f'16x1 Hexstyle1 wasseiected.
3,1.7 Structural Integrity Simulation
The fi-al design of fle des,greo
prototype is evaluated in tenn of its
sfructural .1'egrity Lsing a sguclural
soft\,are based on f,rtte etementca.leo
Nasuan 5/mllarrc me approacntmP{red
in rhe compLrarional
flurddynamicmetnoc,
the geomeay is set using a computeraided
designsoftt/are cnlledPafanfr. The figure
below shows the model that has be€n
neshec, All the cornponenrsprevious,,
described are housed within this
companmenl
3,2
Pressureregulator test Bench
Designand Development
The reg-iarorLesr-,g wascestgnec
and buiftto gaugethe perfonnance
of NGV
pressureregulators.Suitableports on the
rcgllalof were useo to piace pfessure,
'emoerafL.e
ard fow neas.-ng oevices.
-ne posiltoringoF the seTsorsar la-oLr
co ris
of
the recu.alor prolioos
cornpreiensrve understanding of the
-€!Llato-. esDecjallvrl'e abrirY of b-e
regllator to leducepresslreand maintain
the outlet pressureregardless
of the flow
den_and dow_rsueam, o-essLre anc
te'nperdftre difference after pressure
redLction:s o99edand dral'ze'owiLn dris
test rig fof varjousoLtlet flow Gtes.
fhrsLestrg s sutablero be _sed-o
test most NGVpressrrrerequlatoras d]ey
l'avesrr',lardesrqns
andooe.atingpressLre,
We couid srmolyremoveanc nstarl Ehe
probesto accommodate
any similar b/pe
NGV pressureregulatorwith the help o.
sui(ablefittinqs.The dyranic F€rfor_1ance
of pressurere!ulatorcooingwiu_fluctuatinE
odlet flow ("n be us€dto s€lect regulators
3.2.6 ComponentS€lectionand
Assembly
The pressureregulatorten bench
comprisesof a compilationof equipmenl
asserrbledat a desiredorientation!o won(
as desi€d. It is speciallyfabricatedto
provide encouragingworking space to
conducttest on the .egulator,The benchis
cap€bleof holdingall the relatedapparatus
in place.The storagec/linder containing
highpressure
test gasis pracedat the top o'
ttre b€ndl.This ea*s maintenance
slch as
chargingof gas, leakschecksand enabies
qasio d sperseto tre surroundirgia caseo
leak
-
'j
z
6
8
l0
l2
Frgure1: SdlemahcDrawrng
of the Pressure
ReguiatorTest Rig
Pressure sensors selected have
pressurerangeof 250 Bardown
measuGble
to 0, whilethermocouples
are pickedto suit
pressure
the typical NGV
regulator
temp€raturerange of -20oC to 120.C
Previous test conducted on $e fi|5t
generddonfuel Systemproveaa rarmum
consumptionof 24 Liters per minLte of
naturalgasat full throtlje.Dueto Utisa flow
meterhavingan ooeratjngrangeoF0 to 30
Lrrersp€r rrinute was selec-Ld!o worr on
fiis lest bendr. Suitableadaptersand power
sLpply lnils are selecled-esDedvelyto
c?terfor the equipments.
ThethemocoLlple
:s
s operatedwiLh tfe PrCoTC.08wl_rcl_
connectedto the personalcomputerfor data
oggrrg.Bodrthe signalsFom fle pressLre
senso€ and the flow meter are process€d
by fte Pico ADC'16 powered by trle
pel.sonnelcomputer. Pico iog software
p.ov,dedwidr bodrtheTC-08ero ADC-16.s
usedlo providercaltimedatalc€gin€.
Gas ls transferred from the bulk
<torageto tfe s-oGgecyi:nderonooad tl-e
lesl bFncf throLgl Ja-iols vatves and
frdngs. The _igh pressureso,eno.d,/aive
attachedto Lheregliatoris heldshuti| the
db5erceof elect4ccur-ercusudrlysLppriec
whenthe vehicjeis switchedon. The po!,ve.
supply onboardlhe test bench provides
eleclrc cLrrent at suitablevolts to Lhe
solefioidcoii to enablelhe High Pressure
Solenoid
Vaiveto openallowingnaturaigas
lo erter dle 'i.sr sBge of p.essure
aeduction, Pressurd and temperature
sensilg are dore before a_d after t"q
pressurerequlatingstage,Theseptessure
and temperatlres€nsorswill help anallze
tl-e conditjonswrthil fle -egLlarordufl-g
operauon.The outlet of the relu{ator js
equippedwitjr a flow meter and a pressure
sensorlo anailze the effectsof variousflow
obtainedwid] a helpof variablevalve.The
nacuraigas is Suopried
to $e moco.cycte
or
anyvehicleundertest.
Nomenclafure:
6 = deflection,inches
n = numberof activecoils
G = Torsional
modulusof elasticity
Lbf/sq.in.
R= springrate,lbf/in.of deflection,
fs = max.shenrsb-ess,
lq/ sq.in.
T = Torque,lbr/ in.
W = Load,lbr
D = lvlean
coiidia.in.
n = 22/7 for dris sort of work.
Reference:
1. l,lartinPhilipKng Ik Piau,arlkefli
Yaacob,
ZulkifliAMui Flajid,Rahmnnt
l"lohsin:
"Development
of NaturalGas
l4otorcyclein Malalsia"G€sex2000,
C-onference
and Exhibitjon,Pattaya,
Thailand,11-14ss€ptefiber2OOO.
2. 0r. ZulkefliYaacob,
ZulkifliAbdul
ltajid,
FlartinPhiiipKng Ik Piau:"A Studyon
Exhaust
Ernission,
Performance
andLubricating
Oil",JordanIntemational
Glem.Eng.
Conference
III, Amman
, )atdan,27-29
3. ZLrikifli
AMul lvlajid,ZulkefliYaacob,
lvlartinPhilipKingIk Pia!: "Naturdlcas
plotorcycleErnission",
International
Conference
& Exhibition
on NaturalGas
Vehjcle,Yokohama,
lapan,17-20'
October2000.
4. Heenan,
J.5. (1996)."FuelSystem
P.esslreControlImprovesNGV
Perforrnance,"
SAETechnical
Paper960851.
5- Whitehouse,
R.C.(1993)"Thevalveand
aciu€toruser'srnanual",
The8fltish
ValveandActLrator
iqanufacturers
Association.
llechanicalEngtneering
Publicatjons
Limited.
6. FloydD, .1ury.(1972)."Fundamental
of
GasPressure
Regulation",
Technical
I4onograph
27, Fisher
ControlsCompany.
7. FloydD, Jury,(1973)."Flrdamentalof
l]]ree-l4odeControllers",
Technrcal
Monograph
28, Fisher
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Materialfor highTemperature".
Pg31+
318,SpringDesign
andApplication,
llccraw-Hill.
9. B€ck'4ith,
l.B./ (1961)"FlatSpring
l4ate.ialCo$ and StressFacors"Pg
122,SpringDesignandApplication,
IVcGraw
Hill.
10. Diilon,C.P./(1995)"Corrosion
Resistance
of Stainless
Steels",Ivarcel
Dekkef,Inc.
11. SAEHS795"Flanualon Designand
Application
of HelicalandSpiral
_
Sprjngs".1990.
12. Warring,R.H.(197:)."SpfingDesign
and Caicuiation",
lvlodel& Allied
Umited.
Pubiications
13. Carlson,H. (1980)."Springs:
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P.H.,Carstlllen,W. E.
(1997)"Compressible
FluidRow"
14cGraw-Hill.
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H. K., l'4alalasekera,
W.
(1995)"An Introduction
to
Fl-id Dynan;cs,
Computational
The
FiniteVo{umelvlethod"
PrenticeHall.
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(1989)"Ther.noph)sical
Properties
of
Mathrna''
I D6\/< ahrm
Vo..1B,
No.2.
O6F nlE
17. Cain,T, (1988)"SpringDesign&
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WorkhoppracticeSeries
Number19.ArgusBooks
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18. Eakin,C.T.,(1961)"Highrc perdture
pg 77-gt, Sprng
Creepof coiiSprings,,.
Designand
ApplicEtjon,
ivlccfaw-Hill.
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C.R.H.,(1961)"properliesof
Springtvtaterials
andAllowable
Working
Stresses",
Pg310-313,Spinq Design
andAppllcation,
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VesselCode
Sedrion
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American
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anq
lvlaterial
Requircments
for f4etric
'Externally
Threaded
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23. A 563N1.2003.
"Standard
Specjfication
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24. Standard
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NaiuralGas
(CNG)Vehicular
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NFPA
(NationalFireProtection
Associatio|
)
52-1984