ARCHIVESHISTORIQUES
DELACOMMISSION
COLLECTION RELIEEDES
DOCUMENTS "COM"
COM(77)495
Vol.1977/0157

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COMMISSION OFTHEEUROPEAN COMMUNITIES
COM(77 )495final .
Brussels ,18October ,1977
.v Proposal fora
■ : COUNCIL DIRECTIVE
ontheapproximation ofthelaws oftheMember States
.relating to . ■ ■,
HOT-WATER METERS "
(submitted totheCouncil bytheCommission )
CCM(77 )495final .

EXPLANATORY MEMORANDUM
1.Genera L
ThisdirectivehasbeendrawnupinpursuanceofArticle100ofthe
TreatyandoftheCouncilDirectiveof26July1971ontheapproximation
ofthelawsoftheMemberStatesrelatingtocommonprovisionsforboth
measuringinstruments andmethodsofmetrological inspection (1).
Itisaimedatguaranteeing theaccesstotheentireCommonMarketofhot
watermeterswhichsatisfytheprescriptions ofthisDirective.
Itisalsodesignedtopreventthecreationofnewobstaclesthroughthe
introduction ofdifferentlaws,regulations oradministrative provisions
MemberStateswhichsofarhavenonationallegislation onthesubject.
Acomparative studyoftherulesapplicable tohot-watermetershas
revealeddifferences inthetechnicalspecifications forconstruction
anduse,aswellasintheclassesofaccuracyandthemethodsof
inspection towhichthesemetersaresubjectbeforetheycanbemarketed
andputtouse.
Asthepresentnationallawsarejustified bythelegitimate wishto
protecttheconsumerandtheuser,theharmonization oftheselaws
hasemergedastheonlylikelymeansofovercoming thedifficulties
causedbythediscrepancies ,andofcreatingtheconditions necessary
fortheestablishment ofthecommonmarket.
Furthermore ,theharmonization ofthelawsrelatingtohot-watermeters
isinlinewiththegeneralpolicyofaimedattherationaluseof
energytowhichnotonlythenineMemberStatesbutalsothemajority
ofindustrialized countries arecommitted .
Theriseinthepriceofoiloverthelastfewyearshasledmostof
thesecountriestoreviewtheirconsumption forecastswithaviewto
cuttingdownexpenditure .Effortshavebeenmadeinmostbranchesof
industryeithertocutdownconsumption ortorationalize theuseof
energy.
Atthesametime,demographic developments ,urbanization ,advancesin
hygieneandlife-style andfinallytheprocessofindustrialization
havebeendemandingevergreaterquantitiesofwater,andinparticular
ofhotwater.
Althoughformanyyearsthelocaldistribution services,bothpublic
andprivate,wereabletoadoptvaryingcriteriaforthesupplyoftheir
customers,thetimehascomewhenthiskindoflaxityisnolongerper­
mitted,sincepresent–daymarketconditions havemadehotwatera
costlyproduct.
Moreover,theeffortstoprotecttheconsumerthathavebeenundertaken
overthepastfewyearshaveresultedinmostoftheMemberStates
exercisingstrictercontroloverthequantitiesofwaterusedbyhaving
metersinstalled oneachconsumer'spremises.
(1)O.J.N°L202of6September1971,page1.

-2-
ALLtheseconsiderations underlinetheimportanceofharmonization ,
which,apartfromfurtheringthemainobjectivesoftheCounciLwith
regardtothefreemovementofgoodsandgreaterprotectionforthe
consumer,wiLLaLsoenabLebettercantroLtobeexercisedoverthe
energyconsumed.
OncethisdirectivehasbeenadoptedbytheCounciL,theCommission
wiLLbeabLetoputforwardaproposaLinconnectionwiththermal
energymeters,theneedforwhichisbeingfeLtevermoreacutely.
Since,inmostcases,thehot-watermeterscoveredbythisproposal
areoneofthemaincomponentsofthermalenergymeters,thework
ofharmonizing theLatterwillbefacilitated bythefactthatthe
hot-watermeterswillalreadyhavebeenharmonized whenthedirective
onthermalenergymetersisadopted.
2.Structureofthedirective
LikemostofthedirectivesalreadyadoptedbytheCouncilinthe
measuringinstrumentssector,thisdirectivecomprisesalegal
instrument andatechnical annex.
Thespecifications containedintheannexdefinethemainconceptsto
beemployed,andlistallthecharacteristics whichhot-watermeters
mustpossessandtheteststheymustsuccessfully undergobeforethey
canmovefreelywithintheCommunity.
3.Harmonization solution
Asinmostofthespecialdirectivesinthisfield,theharmonization
solutionthathasbeenadoptedistheoneknownas"optional".This
solutionispermitted,alongwith"total"harmonization ,bytheCouncil
Directiveof26July1971relatingtocommonprovisionsforbothmea­
suringinstruments andmethodsofmetrological control.
Untilsuchtimeasthemainnon-technical provisions havebeen
harmonized-especiallythoserelatingtotheuseofhot-watermeters
andtheinspectioncharges-thesolutionoftotalharmonization isli­
kelytoraiseseriousproblems.
Optionalharmonization meansthathot-watermetersconformingtothis
directivecouldbemarketedfreelybetweenMemberStatesandwithin
MemberStatesinthesamewayasmetersthatcomplywithnational
requirements canbemarketedintheparticularStateconcerned.
4.Consultation oftheParliament andtheEconomicandSocialCommittee
Theopinionofthesetwobodiesisrequiredundertheprovisionsof
Article100(2).ForsomeMemberStates,theimplementation ofthe
provisionsofthedirectivewillrequireanamendmenttotheirnational
laws.

THECOUNCIL OFTHEEUROPEAN COMMUNITIES ,
Having regard totheTreaty establishing theEuropean Economic Community ,
and inparticular Article 100thereof ,
Having regard totheproposal from theCommission ,
Having regard totheopinion ofthe European Parliament (1),
Having regard totheopinion oftheEconomic andSocial Committee (2),
Whereas intheMember States theconstruction andthemethods ofinspecting
hot-water meters are subject tomandatory provisions which differ from one
Member State toanother and consequently hinder trade insuch instruments ;
whereas itistherefore necessary toapproximate these provisions ;
Whereas Council Directive -71/316/EEC of26July 1971 onthe appro­
ximation ofthe laws oftheMember States relating tocommon provisions
forboth measuring instruments andmethods ofmetrological control (3),as
amended ,bytheActofAccession (4),laid down theESCpattern approval and
EEC initial verification procedures ;whereas ,inaccordance with that Dir­
ective ,there should helaid down thetechnical requirements relating to
thedesign andfunctioning which hot-water meters must satisfy inorder to
befreely imported ,marketed andused ,after inspection and theaffixing of
theappropriate signs andmarks ,
HAS ADOPTED THIS DIRECTIVE :
Article 1
This Directive shall apply tohot-water meters intended forthecontinuous
determination ofthevolume ofhot-water passing through them .Such meters
shall beprovided with ameasuring device linked toanindicating device .
Forthepurpose ofthis Regulation ,hotwater shall bewater ,thetempera ---
ture ofwhich exceeds 30°C but does not exceed 90°C .
Article 2
Hot-water meters towhich theEECmarks and signs maybeaffixed are des­
cribed inthe Annex tothis Directive .
They shall besubject toEECpattern approval andshall besubmitted for
EEC initial verification .
Article 3
NoMember State mayrefuse ,prohibit orrestrict theplacing onthemarket
orentry intoservice ofhot-water meters bearing theEECpattern approval
andtheEECinitial verification mark ,onthegrounds oftheir metrological
properties . ./...
(1)O.J. N°C,
(2)O.J. N°C,
(3)O.J. N°L202,6.9.1971 ,p.l
C4)O.J. N°L73,27.3.1972 ,p.14

Article4
1„MemberStatesshall "bringintoforcethelaws,regulations and
administrative provisions neededinordertocomplywiththis
Directivewithin18monthsofitsnotification andshallforthwith
informtheCommission thereof.
2.Furthermore ,afternotification ofthisDirective ,
MemberStatesshallensurethattheCommissionisinformed,in
timeforittosubmititscomments,ofanydraftlaws,regulations
administrative provisionswhichtheyintend ,toadoptinthefield
coveredbythisDirective.
Article5
ThisDirectiveisaddressedtotheMemberStates.
DoneatBrussels,

ANNEX
TERMINOLOGY ANDDEFINITIONS
1.0ThisAnnexappliesonlytohot-watermetersbasedonadirect^
mechanicalprocessinvolvingtheuseofvolumetricchamberswith
mobilewallsortheactionofthevelocityofthewateronthe
rotationrateofamovingpart(turbine,impelleretc.)
1.1.Flowrate.
Theflowrateisthevolumeofwaterpassingthroughthemeter
perunitoftime.
1.2.Volumedelivered.
Thevolumedeliveredisthetotalvolumeofwaterwhichhas
passedthroughthemeterinagiventime.
1.3.Maximumflowrate(Q).
Themaximumflowrate,Qisthehighestflowrateatwhichthemax
metercanfunctionoverlimitedperiodswithoutdamage,and
withoutexceedingthemaximumpermissibleerrorsandthemaximum
permissiblevalueforlossofpressure.
1.4.Nominalflowrate(Q)
Thenominalflowrate,Qn,isequaltohalfthemaximumflowrat
QItisexpressedincubicmetresperhourandisusedto
max
designatethemeter.
Atthenominalflowrate,Q,themetershouldbeabletofunction
innormaluse,i.e.,incontinuousandintermittentoperating
conditions,withoutexceedingthemaximumpermissibleerrors.
1.5.Minimumflowrate(Q.).
Theminimumflowrate,Qmin,istheflowrateabovewhichthe
metermustnotexceedthemaximumpermissibleerrors,andis
fixedasafunctionofQ
1.6.Flowraterange.
Theflowraterangeofawatermeterisboundedbythemaximum
andminimumflowrates,G>maxandQ^.Itisdividedintotwo
regions,termedupperandlower,withdifferentmaximumpermissi­
bleerrors.
1.7.Transitionalflowrate(Qt).
Thetransitionalflowrate,Qt,istheflowratewhichdividesthe
upperandlowerregionsoftheflowrangeandtherateatwhich
themaximumpermissibleerrorsbecomediscontinuous .

"»4~
1.8.Maximumpermissible error.
Themaximumpermissibleerroristhelimitoftheerrorpermitted
bythisDirectiveforEECpatternapprovalandEECinitial
verification ofawatermeter.
1.9.Lossofpressure.
Lossofpressuremeansthelosswithiscausedbythepresence
ofthewatermeterintheconduit.
II.METROLOGICAL CHARACTERISTICS
2.1.Maximumpermissible errors.
Themaximumerrorpermittedinthelowerregion,fromQ.mm
inclusivetoQnon-inclusive,is_+5/..
Themaximum *errorpermittedintheupperregion,from
inclusivetoQinclusive,is+3%.max –
2.2.Metrological classes.
Hot-watermetersaredividedaccordingtothevaluesofQ.andmin
definedabove,intothefourmetrological classesinthe
followingtable:
Classes––
; Q
! 0
<15m3/h">15m/h
Class .0
ValueofQ.min
ValueofQ0,08Q'n
0,15Q'n0,16Q'n
0,30Q'n
1
ClassA
ValueofQ.min
'ValueofQ0,04Qη
0,10Q'ni
0,08Qn
0,20Qη
ClassB
ValueofQ.
min
ValueofQ0,02Qη
0,08Q'n0,04Q'n
0,15Q'n
ClassC
ValueofQ. i
min j
ValueofG> ;0,01Q'n
0,06Q'n0,02Qn
0,10Q |n î
./...

-5-
/ III .TECHNOLOGICAL CHARACTERISTICS
3.1 .Construction –General provisions .
Themeters must beconstructed insuch away asto :
(1)give long service andguarantee proof against fraud ,
(2)conform with theprovisions ofthis Directive ,under
normal conditions ofuse .
Where meters may besubjected toanaccidental reversal of
flow they must becapable ofwithstanding itwithout any
deterioration orchange intheir metrological properties ,
and atthe same time should record such areversal .
3.2 .Materials .
Thewater meter must bemade ofmaterials ofadequate strength
and stability forthepurpose forwhich the water meter istobe
used .Itmust beconstructed throughout ofmaterials which are
resistant tointernal and normal external corrosion and ifne­
cessary beprotected bysome suitable surface treatment .Water
temperature variations within thetemperature range 0°-110° C
must not adversely affect thematerials used inthe construction
ofthe water meter .
3.3 .Soundness -pressure tightness andtemperature resistance .
Ameter must beable towithstand constantly -without defects
initsfunctioning ,leakage ,seepage through thewalls orperma­
nent deformation -acontinuous water temperature of90° Cand the
pressure forwhich itisdesigned ,termed themaximum operating
pressure .Theminimum value forthis pressure is10bars .
3.4 .Loss ofpressure .
Loss ofpressure through themeter isdetermined byEECpattern
approval tests ,andmust notexceed 0.25 bars atthenominal
flowrate and one atthemaximum flowrate .
Onthebasis ofthetest results meters aredivided into one of
four groups with thefollowing maximum values forpressure loss :
1,0.6,0.3and0.1bars .Therelevant value must beindicated
inthe EECpattern approval certificate .
3.5 .Indicating mechanisms .
Theindicator must allow ,bysimple juxtaposition ofitsvarious
constituent elements ,areliable ,easy andunambiguous reading of
thevolume ofwater measured ,expressed incubic metres .Thevolu­
memust begiven either by :
(a)theposition ofoneormore pointers oncircular scales ;
(b)reading off arowofin-line consecutive digits inoneormore
apertures ;
(c)acombination ofthese two systems .

~6~
Acubicmetreanditsmultiplesareindicatedinblack,and
sub-multiples ofacubicmetreinred.
Theactualorapparentheightofthedigitsmustnotbelessthan
4mm.
Ondigitalindicators (types(b)and(c))visibledisplacement
ofalldigitsmustbeupwardsinvalue.Theadvanceofany
givendigitalunitmustbecompletedwhilethedigitofthe
immediately nextlowervaluedescribesthelasttenthofits
course.
Therollershowingthedigitsofthelowestvaluemaymovecon­
tinuouslyinthecaseoftype(c).Thewholenumberofcubic
metresmustbeclearlyindicated.
Indicatorswithpointers(types(a)and(c)shouldrotateina
clockwisedirection.Thevalueincubicmetresforeachscale
divisionshouldbeexpressedas10,wherenisapositiveor
negativewholenumberorzero,therebyestablishing asystemof
consecutive decades.Datasuchasthefollowingshouldbeshown
neareachpartofthescale:x1000-x100-x10-x1-
x0.1-x0.01-x0.001..
Inbothcases(dialanddigitalindicators ):
-theunitsymbolm^shouldbeshowneitheronthedialorin
theimmediatevicinityofthedigitalindication;
-thefastest-moving visiblegraduatedelement-themonitoring
element(thescaleintervalofwhichisknownasthe'verifi­
cationscaleinterval')-shouldmovecontinuously .Thismoni­
toringelementmaybepermanentormaybefittedtemporarily
byaddingdetachableparts.Thesepartsmustnothaveany
significant influenceonthemetrological propertiesofthe
meter.
Thelengthoftheverification scaleintervalshouldbenotless
than1mmandnotmorethan5mm.Thescaleshallconsist:
-eitheroflinesofequalthicknessnotexceedingonequarter
ofthedistancebetweentheaxesoftwoconsecutive linesand
differingonlyinlength;
-orofcontrasting bandsofaconstantwidthequaltothelength
ofthescaledivision.
However,until19June1981:
.(a)thedownwardmovementofdigitswillbepermitted,this
movementbeingindicatedbyanarrow;
(b)thelengthofthescaledivisionmaybe0.8mm.
3.6.Numberoffiguresintheverification scaledivisionandtheir
values.
Itmustbepossiblefortheindicatingdevicetorecordavolume,
expressedincubicmetres,corresponding toatleast1999hours'
operationatthenominalflowrate,withoutreturningtozero.
Thesizeoftheverification scaledivisionmustbebasedonthe
formula1x10nor2x10nor5x10n.Duringverification,it
mustbesmallenoughtoensureameasurementinaccuracyofnot
morethan0.5%(allowingforapossiblereadingerrorofnot

-7*
morethanhalftheLengthofthesmallestscaledivision)and
smallenoughsothatattheminimumflowratethetestdoesnot
takemorethan1h30.
Asupplementary device(star,discwithareference mark,etc)
maybeaddedinordertoshowthemovementofthemeasuring
devicebeforethisjDecomes clearlyvisibleontheindicator.
3.7.Adjustingdevice.
Themetersmaybefittedwithanadjustingdevicewithwhichitis
possibletoaltertherelationship betweenthevolumeindicated
andthevolumeactuallypassed.Thisdeviceiscompulsoryfor
meterswhichusetheactionofthevelocityofthewateronthe
rotationofamovingpart.
3.8.Accelerating device.
Theuseofanaccelerating deviceforincreasing thespeedofthe
meterbelowQ.isprohibited ,mm
3.9.Additional devices.
Metersmayincludeapulse-generating deviceprovidedthatthe
devicedoesnotappreciably affecttheirmetrological properties .
Thepatternapprovalcertificate mayprovidefortheaddition
ofspecialfixedordetachable devicestopermitautomatic
verification ofthemeters.

-8-
IV.MARKSANDINSCRIPTIONS
4.1.Identification inscriptions .
ALLmetersmusthavecLearLyandindeliblyinscribeduponthem
thefoLLowingitemsofinformation,whichmaybeeithergrouped
togetherorenteredatseparatepointsonthecasing,theindi­
catordiaLorthedatapLate:
(a)themanufacturer'snameortradenameorhistrademark;
(b)themetroLogicaL cLassandnominaLfLowrate Qincubic
metresperhour;
(c)theyearofmanufacture andtheindividualproduction number;
(d)oneortwoarrowsshowingthedirectionoffLow;
Ce)theEECpatternapprovaLmark;
(f)themaximumoperatingpressureinbars,wherethismay
exceed10bars;
(g)themaximumoperatingtemperature intheform:90°C;
(h)theLetter'V1or'H*ifthemetercanoperateproperLyonLy
intheverticaL(V)orhorizontaL (H)position.
4.2.Positioning ofverification marks.
SpacefortheEECverification marksshouLdbeprovidedonan
essentiaLpart(normaLLythemetercasing),whichisvisibLe
withoutdismantling .
4.3.SeaLmg.
Metersmustbefittedwithprotectivedeviceswhichcanbe
seaLedinsuchawayastoensure,bothbeforeandafter
instalLation,thatneitherthemeteritseLfnoritsadjusting
devicecanbedismantledoralteredwithoutdamagingthepro­
tectivedevices.

-o-
V.EECPATTERNAPPROVAL.
5.1.Procédure.
TheEECpatternapprovalprocedurewillbecarriedoutinaccor­
dancewithDirective N°71/316/EEC.
5.2.Patterntests.
Whenithasbeenascertained fromtheapplicationfilethatthe
patternconformstotheprovisionsofthisDirective,laboratory
testswillbecarriedoutonanumberofinstruments underthe
followingconditions :
5.2.1.Numberofmeterstobetested.
Thenumberofmeterstobesubmittedbythemanufacturer isas
showninthefollowingtable:
Nominalflowrate,Q,m/h Numberofmeters
Under1.5 10
Notlessthan1.5
butlessthan15 3
Notlessthan15 2
Dependingonhowthetestsprogress,additional specimenmeters
mayberequired.
5.2.2.Pressure.
Forthemetrological tests(item5.2.4.),thepressureatthe
meteroutletshouldbesufficiently hightopreventcavitation.
5.2.3.Testequipment.
Ingeneral,metersshallbetestedindividually and,inallcases,
insuchawayastodemonstrateaccuratelytheindividual
characteristics ofeach.
Themetrological serviceoftheMemberStateshalltakethe
necessarystepstoensurethatthemaximumrelativeinaccuracy
inmeasuringthevolumeofwaterdelivereddoesnotexceed
0,3%afterallowanceismadeforthevariouscausesoferrorin
installation .
Themaximumpermissibleinaccuracyis5%inthecaseofmeasure­
mentofpressureand2.5%inthecaseofmeasurementoflossof
pressure.
Duringeachtest,therelativevariationintheflowratesmustnot
exceed2.5%betweenQ.andQ.and5%betweenQandQm.mint imax
Themaximumpermissibleinaccuracyinthemeasurementoftempera­
tureis1°C.
Theequipmentmustbeapprovedbythemetrologicalserviceofthe
MemberStateconcernednomatterwherethesetestsarecarriedout.
5.2.4.Testprocédure.
Thetestscomprisethefollowingoperations,carriedoutinthe
ordershown:
(1)pressuretightnesstest;
•/•■■

-10-
(2)determination oftheerrorcurvesonthebasisofthe
flowratebyascertaining theeffectofthepressureand
temperature andtakingintoaccountthenormalinstallation
conditionsforthistypeofmeter(straightsectionsof
pipingupstreamanddownstreamofthemeter,constrictions ,
obstacles,etc)stipulated bythemanufacturer ;
(3)determination ofpressurelosses;
(4)accelerated endurancetest;
(5)athermalshockresistancetest|ormeterswithanominalflowrate Qofnotmorethan10m/h.
n
Thepressuretightnesstestisconductedintwopartsat
85(+5)°C:
(a)eachmetershouldbeabletowithstand,without
leakageorseepagethroughthewalls,apressureof
16barsor1.6timesthemaximumoperatingpressure,
appliedforaperiodof15minutes(seeitem4.1(f));
(b)eachmetershouldbeabletowithstand,withoutany
damageorblockage,apressureof20barsortwicethe
maximumoperatingpressure,appliedforaperiodofone
minute(seeitem4.1(f)).
Theresultsoftests(2)and(3)shouldprovideasuffi­
cientnumberofpointstoenablethecurvestobeplotted
accurately throughout theoperating range.
Theaccelerated endurancetestistobecarriedoutas
follows :
Nominal
flowrate
ofmeterTestflowrate
and
temperature'Type
of
testNumber
of
inter­
ruptionsDuration
of
pausesPenod
ofopé­
ration
attest
flowrateDurationof
start-up
and
rundown
(sec.)
Q^10m/hQ
n
and
(50+5)°Cdis~
conti­
nuous100000 15s15s0,015(Q)*n
minimum 1s
Q
max
and
(85_+5)°C
iconti­
nuous 100h
Q^1.0m/hI
Q
n
and
(50+5)°Cconti­
nuous
500h
Q
max
and
(85+5)°Cconti­
nuous
200h
ι
*(Q)isanumberequaltothevalueofQexpressedinm/h.n n

-11-
Beforethefirsttestandoncompletionofeachtestseriesthe
measuringerrorsmustbedetermined,asaminimumrequirement,
atthefollowingflowrates :
Q.–Q-0.5Q-Qmint nmax
Ineachtest,thevolumeofwaterpassedthroughthemetermust
besufficienttorotatethepointerortherollerontheveri­
ficationscalethroughoneormorecompleterevolutions and
toeliminatetheeffectsofcyclicdistortion.
Thethermalshockresistancetestshallbecarriedoutat
25cyclesasfollows:
Watertemperature Q Duration
90°C Q I8min.
max
0 1-2min.
15°C Q 8min.
max
0 1-2min.
5.2.5.ConditionsforEECpatternapproval.
Awatermeterpatternshallbeapprovedif:
(a)itconformswiththeadministrative ,technicaland
metrological provisionsofthisDirectiveanditsAnnex;
Cb)tests1,2and3listedinitem5.2.4.showthatitcon­
formswithPartsIIandIIIofthisAnnexasregards
metrological andtechnological characteristics ;
(c)afterthethermalshockresistancetestandaftereach
accelerated endurancetest,novariationinrelationto
theinitialcurvegreaterthan1.5%betweenandQor
greaterthan3%betweenQ.andQ.hasbeenobserved.3 mint
TheEECpatternapprovalcertificate maylaydownrulesof
equivalenceenablinginitialverification tobecarriedout
withcoldwater.

-12-
EEC INITIAL VERIFICATION .
6.1 . Verification methods .
EECinitial verification will becarried out inaplace approved
bythemetrological service oftheMember State .
The layout ofthe premises andthe test equipment should besuch
that verification may becarried out insafe ,reliable condi­
tions ,and with noloss oftime for theperson responsible for
the control .Theprovisions ofitem 5.2.3 .must becomplied
with ,except with respect totemperatures inthe event ofthe
tests being carried out with cold water inaccordance with such
provisions asmay belaid down inthe EECpattern approval
certificate .Arrangements may bemade atthe test centre to
enable the meters tobetested inseries .The exit pressure
ofall themeters should always besufficient toprevent
cavitation and special measures may berequired toprevent
interference between meters .
f
Thecomplete unit may include automatic devices ,by-pass valves ,
flow-restri ctors ,etc.,provided that each test circuit between
themeters tobeverified andthe control tanks isclearly
defined and that itispossible toverify atany time its
internal pressure absorption .
Any type ofwater supply system may beused ,but ifseveral
test circuits areoperated inparallel ,there should beno
interference incompatible with theprovisions ofitem 5.2.3 .
Ifacontrol tank isdivided into several chambers ,the sepa­
rating walls should besufficiently rigid toensure that the
volume ofachamber does notvary bymore than 0.2% according
towhether the adjacent chambers are full orempty .
6.2 . Inspection operations .
Themeters must conform toanapproved pattern .
Conformity with this pattern may beverified byarandom
sample inspection ofthevarious components during manufacture
andassembly orbyopening one ofthemeters submitted .
Verification includes aleak-tightness test ,which may carried
outwith cold water ,andanaccuracy test normally conducted
with hot water atatemperature of50°C (+50°C )atatleast
three flowrates :
(a)between 0.9 Q and Q ;max max
(b)between and1.1Q^;
(c)between Q .and 1.1 Q ..min min

-13-
WheretheEECpatternapprovalcertificate permits,initialverification
ofahot-watermetermaybecarriedoutwithcoldwaterinaccordancewith
theprocedures laiddowninthecertificate .
Morespecifically ,thelattermayincrease,reduceand/orre-setthemaxi­
mumpermissible errorstoallowfortheeffectofthetemperature and
pressureofthewateronthemeasuredresults.Forthesamereason,itmay,
forthepurposeoftheinitialverification tests,specifydifferentvalues
®+-anc'fromthoselaiddownforthemeteringofhotwater.HiIFtL illaX
Duringtheleak-tightness test,carriedoutforoneminuteat1.6times
themaximumoperatingpressure,theremustbenoleakageorseepage
throughthewallsofthemeters.
Iftheaccuracytestsconsistincomparingthemeterindicatorreading
againstthatofthereferencestandard,thevolumeofwaterpassedthrough
themeterineachtestshouldbesufficient torotatethepointerorroller
ontheverification scalethroughacompleteseriesofrevolutions and
shouldbesuchthatperiodicerrorsarenegligible .Anyotherinspection
procedure maybeused,onconditionthatitisprovidedforinthepattern
approvalcertificate andgivesanaccuracyofmeasurement atleastequiva­
lenttothatassuredbytheforegoingrule.
Thefirstoftheaccuracytestsinvolvesthedetermination ofpressureloss,
whichshouldbelessthanthevalueindicatedintheEECpatternapproval
certificate .
Themaximumpermissible errorsareasshowninitem2.1.
Ifalltheerrorsarefoundtolieinonedirection,thewatermetershall
beadjustedsothatnotalltheerrorsexceedone-halfofthemaximum
permissible error,insofarastheEECpatternapprovalcertificate doesnot
laydownspecialprovisions onthesubject.