1971L0318 — EN — 11.04.1978 — 002.001 — 1
This document is meant purely as a documentation tool and the institutions do not assume any liability for its contents
►B COUNCILDIRECTIVE
of26July1971
ontheapproximationofthelawsoftheMember Statesrelatingtogasvolumemeters
(71/318/EEC)
(OJ L 202, 6.9.1971, p. 21)
Amended by:
Official Journal
No page date
►M1Commission Directive 74/331/EEC of 12 June 1974 L 189 9 12.7.1974
►M2Commission Directive 78/365/EEC of 31 March1978 L 104 26 18.4.1978
▼B
COUNCILDIRECTIVE
of26July1971
on the approximationof the lawsofthe Member States relating to
gasvolumemeters
(71/318/EEC)
THE COUNCIL OF THE EUROPEAN COMMUNITIES,
Having regard to the Treaty establishing the European Economic
Community, and in particular Article 100 thereof;
Having regard to the proposal from the Commission;Having regard to the Opinion of the European Parliament(
1);
Having regard to the Opinion of the Economic and Social
Committee(2);
Whereas in the Member States the construction and methods of control
of gas volume meters are subject to mandatory provisions which differfrom one Member State to another and consequently hinder trade insuch instruments; whereas it is therefore necessary to approximate
these provisions;
Whereas the Council Directive of 26 July 1971(
3) on the approxima-
tion of the laws of the Member States relating to provisions both formeasuring instruments and methods of metrological control has laiddown the EEC type approval and EEC initial verification procedures;
whereas, in accordance with that Directive, the technical requirements
for the design and functioning of gas volume meters should be laiddown;
HAS ADOPTED THIS DIRECTIVE:
Article 1
This Directive applies to the following gas volume meters:
1. Volumetric meters:
— meters withdeformable walls;
— meters withrotary pistons.
2. Non-volumetric meters:
— turbine meters.
Article 2
Those meters which may bear EEC marks and symbols are described in
the Annex to this Directive. They shall be subject to EEC type
approval and shall be submitted to EEC initial verification.
Article 3
No Member State may refuse, prohibit, or restrict the placing on the
market or entry into service of gas volume meters bearing the EEC
type approval symbol and the EEC initial verification mark.
Article 4
1. Member States shall put into force the laws, regulations and
administrative provisions needed in order to comply withth is Directivewithin eighteen months of its notification, and shall forthwith informthe Commission thereof.1971L0318 — EN — 11.04.1978 — 002.001 — 2
(1) OJ No C 65, 5.6.1970, p. 30.
(2) OJ No C 131, 29.10.1970, p. 7.
(3) OJ No L 202, 6.9.1971, p. 1.
▼B
2. Member States shall ensure that the texts of the main provisions
of national law which they adopt in the field covered by this Directiveare communicated to the Commission.
Article 5
This Directive is addressed to the Member States.1971L0318 — EN — 11.04.1978 — 002.001 — 3
▼B
ANNEX
CHAPTER I
A.DEFINITIONOFCERTAINTERMSUSEDINTHEANNEX
1.Rangeofload
The range of load of a gas meter is bounded by the maximum flow Qmaxand
the minimum flow Qmin.
2.Cyclicvolumeofavolumetric meter
‘Cyclic volume V of a volumetric meter’ means the volume of gas corre-
sponding to a cycle of operation of the meter, that is to say to the whole of
the movements of the moving components of the meter at the end of which
all these components except the indicator and the intermediate transmissions
return, for the first time, to their original position.
It is calculated by multiplying the value of the volume represented by a
complete revolution of the test element, by the transmission ratio of the
measuring device to the index counter.
3.Operatingpressureandreference pressure
3.1.Operating pressure
The operating pressure of a gas meter is the difference between the pres-
sure of the gas at the inlet of the meter and the atmospheric pressure.
3.2.Reference pressure
The reference pressure prof a gas meter is the gas pressure to which the
indicated volume of gas is related.
The pressure tapping for measuring the reference pressure is laid down
in Chapter III.
4.Pressureabsorption
The pressure absorption of a gas meter is the difference between the pres-
sures measured at the inlet and outlet of the meter during the flow of a gas.
5.Outputdriveconstant
The constant of an output drive is the value of the volume represented by a
complete turn of the shaft of this drive; this value is calculated by multi-
plying the value of the volume represented by a complete turn of the test
element by the transmission ratio of the index counter to this shaft.
B.GENERALPROVISIONSFORGASVOLUMEMETERS
1.General
1.1. Chapter I of this Annex lays down the general provisions which must
be satisfied by all gas volume meters covered by Article 1 of this
Directive.
1.2. Chapters II and III of this Annex lay down the special provisions
relating to the meters concerned.
2.Construction
2.1.Materials
The meters must be manufactured of solid materials with low internal
stresses, which change little with age, and which are sufficiently resis-
tant to corrosion and attack by the various gases which are normally
distributed or by any of their condensates.
2.2.Soundness of meters
The cases of meters must be gas-tight at the maximum operating pres-
sure.
2.3.Protection against interference
The meters must be so constructed that any interference which could
affect the accuracy of measurement is impossible without damaging
the verification marks or protective seals.1971L0318 — EN — 11.04.1978 — 002.001 — 4
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2.4.Direction of gas flow
For meters whose indicating devices function positively only for one
direction of flow, this direction must be indicated by an arrow.
This arrow is not required if the direction of gas flow is fixed by the
construction.
2.5.Metrological properties
At a flow equal to Qmaxa meter must be able to operate continuously
for the time laid down in Chapter II of III without any change in its
metrological performance beyond the limits specified in those chapters.
3.Additionaldevices
3.1. Gas volume meters may be fitted with:
(a) prepayment devices;
(b) integral pulse generators the outlets of which must bear an indica-
tion of the value of one pulse in the form:
‘1 imp. /wedgeq…m3(or dm3)’ or
‘1 m3/wedgeq… imp.’.
These additional devices, where fitted, are regarded as forming an inte-
gral part of the meter; they should be connected to the gas volume
meter at the time of EEC initial verification. There are no separate
requirements regarding their effects on the measuring properties of the
meters.
3.2. Gas meters may be fitted with output drive shafts which should be
taken to include drive shafts or other facilities for operating detachable
additional devices. The torque which the gas meters are required to
produce in order to drive the additional devices fitted must not bring
about any changes in the meter indication greater than the values speci-
fied in Sections II.5.2.1 and III.5.2.1.
3.2.1. If there is only one drive shaft, it must be characterized by an
indication of its constant in the form ‘1 tr /wedgeq…m3(or dm3)’,
of the maximum permissible torque in the form ‘Mmax=…
N.mm’ and of the direction of rotation.
3.2.2. If there are several drive shafts, each shaft must be characterized
by the letter M with subscript in the form ‘M1;M2;…Mn’, as
well as by an indication of its constant in the form ‘1 tr /wedgeq…m3
(or dm3)’ and of the direction of rotation.
The following formula must appear on the meter, preferably on
the data plate:
k1M1+k2M2+…+knMn≤A N.mm,
in which:
A represents the numerical value of the maximum permissible
torque applied to the drive shaft with the highest constant, where
the torque is applied only to this shaft; this shaft must be char-
acterized by the symbol M1;
ki(i = 1; 2; … n) represents a numerical value determined as
follows:
ki¼C1
Ci;
Mi(i = 1; 2; … n) represents the torque applied to the drive
shaft characterized by the symbol Mi;
Ci(i = 1; 2; … n) represents the constant for the drive shaft
characterized by the symbol Mi.
3.2.3. The extremity of the drive shafts must be protected by means of
a sealed cap or by means of a sealed connection between any
additional device and the meter.
3.2.4. The connection between the measuring device and the inter-
mediate gearing must not be broken or altered if a torque equal
to three times the permissible torque as laid down in Sections
I.B.3.2.1 and I.B.3.2.2 is applied.1971L0318 — EN — 11.04.1978 — 002.001 — 5
▼M2
▼B
4.Inscriptions
4.1. Each meter must bear the following inscriptions, either on the dial
plate or on a special data plate or divided between the two:
(a) the EEC type-approval mark;
(b) the identification mark or name of the manufacturer;
(c) the number and year of manufacture of the meter;
(d) the size designation of the meter: this has the form of a capital G
followed by a number which is laid down in Chapter II or III;
(e) the maximum flow expressed as: Qmax…m3/h;
(f) the minimum flow expressed as: Qmin…m3/h(or dm3/h);
(g) the maximum operating pressure expressed as: pmax… MPa (or kPa
or Pa or bar or mbar);
(h) for volumetric meters, the nominal value of the cyclic volume
expressed as: V…m3(or dm3);
(i) where appropriate, the inscriptions mentioned in Sections I.B.3.1
and I.B.3.2; these inscriptions may, however, be made on other
plates or on the meter itself.
These inscriptions must be clearly visible, easily legible and indelible
under the normal conditions of use of the meter.
4.2. The metrological service which issues the type approval may decide
the cases in which the nature of the gas must also be specified on the
badge plate.
4.3. The meter may also carry the commercial designation, a special series
number, the name of the gas distributor, a mark indicating that it
conforms to a European standard, and an indication relating to any
repairs made. Unless specially authorised, any other indication or
inscription is prohibited.
5.Counterandtestelement
5.1.Counter
5.1.1. The counters must be in the form of drums; however, the last
element may be excepted from this rule. The drums must be
calibrated in cubic metres or decimal multiples or submultiples
of the cubic metre. The symbol m3must be marked on the index
plate.
5.1.1.1. The drums indicating the submultiples of the cubic
metre if provided must be clearly distinguishable from
the other drums, and separated from them by a clearly
marked decimal point.
5.1.1.2. In cases in which the last drum is figured in decimal
multiples of a cubic metre, the index plate must be
marked witheith er:
(a) one or more fixed zero's as appropriate after the last
drum; or
(b) the indication ‘× 10, × 100, × 1000 etc.’ in such a
way that the reading is always made in cubic
metres.
5.1.2. The counter must have sufficient numbered drums to be able to
indicate within one unit of the last drum, the volume passed
during an operating period of one thousand hours at maximum
flow rate.
5.2.Test element
5.2.1. Meters must be designed in such a way that checking can be
done with sufficient accuracy. For this purpose they must incor-
porate in their design an integral test unit or arrangements
permitting the connection of a portable test unit.
5.2.2. The integral test element may be the last element of the counter
in one of the two following forms:
(a) a continuously revolving drum carrying a graduated scale;1971L0318 — EN — 11.04.1978 — 002.001 — 6
▼M2
▼B
▼B
(b) a pointer passing over a fixed dial having a graduated scale
or a disc carrying a graduated scale moving past a fixed
reference mark.
5.2.3. On the graduated scales of these test elements the unit of the
graduations must be indicated clearly and unambiguously in m3
or decimal submultiples of the m3; the beginning of the scale
must be indicated by the figure zero.
5.2.3.1. The interval between scale divisions must be constant
throughout the scale and not less than 1 millimetre.
5.2.3.2. The value of the scale divisions must be in the form
1×1 0n,2×1 0n,o r5×1 0nm3, n being a whole positive
or negative number or zero.
5.2.3.3. The graduation lines must be fine and uniform. In cases
in which the division is of the form 1 × 10nor 2 × 10n
m3, all the lines representing multiples of 5, and in the
case of a division of the form 5 × 10nm3, all the lines
representing multiples of 2, must be distinguished by a
greater length.
5.2.4.►M1The pointer or the reference mark must be sufficiently
thin to permit certain and easy reading.
The test element may have a removable reference mark and be
of a size sufficient to permit photo-electric scanning. The refer-
ence mark must not conceal the graduation; if necessary, it may
replace the figure 0. It must not interfere with the accuracy of
reading. ◄
5.3.Diameters of drums and dials
The diameters of drums must be at least 16 millimetres.
The diameter of the graduated scales mentioned in Chapter I B 5.2.2. b
must be at least 32 millimetres.
5.4.Reading of the counter
The counter must be so designed that it can be read by simple juxtapo-
sition of the figures.
5.5.Advance of figures
The advance by one figure at any part of the index must be completed
whilst the figure of the immediately next lower range describes the last
tenthof its course.
5.6.Removal of the counter
Meters must be so designed that the counter may be removed easily
during examination.
6.Maximumpermissibleerrors
6.1. The measuring errors are expressed as a relative value by the ratio, as a
percentage, of the difference between the volume indicated and the
volume actually passed by the meter, to the latter volume.
6.2. These errors relate to the measurement of volumes of air having a
reference density of 1·2 kg/m3. Under normal atmospheric conditions
the ambient air in a test laboratory may be considered to satisfy this
condition.
6.3. The maximum permissible errors are specified in Chapters II and III;
they are valid for the authorised direction of flow.
7.Pressureabsorption
7.1.Maximum permissible values
The maximum permissible values of pressure absorption are specified
in Chapters II and III.
8.Applicationofverification marksandseals
8.1.Purpose
The application of EEC verification marks and seals on a gas meter
certifies solely that the meter meets the requirements of the present
Directive.1971L0318 — EN — 11.04.1978 — 002.001 — 7
▼B
8.2.Location
8.2.1. The locations of the marks must be chosen in such a way that
dismantling of the part sealed will involve destruction of the
marks.
8.2.2. When the inscriptions mentioned in item 4.1. of Chapter I B are
on a special badge plate, one of the marks should be fixed in
such a manner that it is damaged if the special plate is removed.
8.2.3. Locations should be provided for verification marks or seals:
(a) on all plates bearing an inscription required by this Annex;
(b) on all parts of the meter which cannot otherwise be
protected against interference liable to:
— affect or alter the indication on the indicating device of
the meter,
— alter or break the connection between the measuring
device and the indicating device,
— remove or displace metrologically important parts of the
meter.
9.EECtype-approvalandEECinitialverification
EEC type-approval and EEC initial verification of gas volume meters shall
be carried out in accordance with the requirements of the Council Directive
of 26 July 1971 on the approximation of the laws of the Member States
relating to common provisions for bothmeasuring instruments and meth ods
of metrological control.
9.1.EEC type-approval
9.1.1. Applications for EEC type-approval for gas meters must be
accompanied by the following documents:
— a description of the meter giving the technical characteristics
and the principle of its operation,
— a perspective drawing or photograph of the meter,— a nomenclature of parts witha description of th e constituent
materials of suchparts,
— an assembly drawing withidentification of th e component
parts listed in the nomenclature,
— a dimensioned drawing,
— a plan showing the location of verification marks and seals,— a plan of the indicating device, with adjustment mechanisms,— a dimensioned drawing of metrologically important compo-
nents,
— a plan of the dial plate and of the inscriptions arrangements,
— where appropriate, a plan of the additional devices referred
to in Section I.B.3.1,
— where appropriate, a table setting out the characteristics of
the drive shafts (Section I.B.3.2),
— a list of the documents submitted,— a declaration specifying that the meters manufactured in
conformity with the type meet the requirements for safety,
particularly those concerning the maximum operating pres-
sure as indicated on the data plates.
9.1.2. The following particulars shall appear on the EEC type-approval
certificate:
— the name and address of the person to whom the EEC type-
approval certificate is issued,
— the type and/or commercial designation,— the principal technical and metrological characteristics, such
as the minimum flow, maximum operating pressure, nominal
internal diameter of the connecting pieces and, in the case of
volumetric gas meters, the nominal value of the cyclic
volume,
— the EEC type-approval mark,
— the period of validity of the EEC type-approval,
— in the case of meters equipped with drive shafts:
(a) the characteristics of the shaft as set out in Section
I.B.3.2.1 (where there is only one drive shaft),1971L0318 — EN — 11.04.1978 — 002.001 — 8
▼M2
▼M2
(b) the characteristics of each shaft and the formula given in
Section I.B.3.2.2 (where there are two or more drive
shafts),
— information on the location of EEC type-approval marks,
EEC initial verification marks and seals (where appropriate,
in the form of photographs or drawings),
— a list of the documents accompanying the EEC type-
approval certificate,
— any special comments.
9.2.EEC initial verification
9.2.1. Gas meters submitted for EEC initial verification shall be in
working order.
EEC initial verification is no guarantee of the proper functioning
or accuracy of reading of any additional devices as referred to in
Sections I.B.3.1 and I.B.3.2 which may be connected to the
meter.
No EEC verification marks or EEC seals shall be affixed to such
additional devices.
10.Verificationmarksandseals
Meters having undergone successfully the verification tests:
— shall be provided with a verification mark;
— shall receive seals in the locations provided for the protection of certain
components against interference liable to affect the meter characteristics.
CHAPTER II
PROVISIONS RELATING TO GAS VOLUME METERS WITH
DEFORMABLEWALLS
1.Fieldofapplication
The present Chapter applies, together with the provisions of Chapter I, to gas
meters in which the measurement of gas passed through is effected by means
of measuring chambers with deformable walls.
2.Rangeofcapacityanddesignation
2.1. The following table gives the authorised values for maximum flow, the
upper limits of the corresponding minimum flows, and the minimum
values of cyclic volumes, corresponding to the designation (G) of the
meters:
GQmax
m3/hQmin
m3/h
(Maximum
value)V
dm3
(Minimum value)
1·6 2·5 0·016 0·7
2·5 4 0·025 1·2
4 6 0·040 2·0
6 10 0·060 3·5
10 16 0·100 6·0
16 25 0·160 10
25 40 0·250 1840 65 0·400 30
65 100 0·650 55
100 160 1·000 100
160 250 1·600 200
250 400 2·500 400
400 650 4·000 900
650 1000 6·500 20001971L0318 — EN — 11.04.1978 — 002.001 — 9
▼B
▼B
2.2. If for a type of meter the value of Qminis lower than the number given in
the table of item 2.1 of this Chapter, the numerical value of this Qminmust be expressed by a number in column 3 of this table or by adecimal submultiple of this number.
2.3. Meters having a cyclic volume less than the value given in the table of
item 2.1 of this Chapter may be approved provided that the model satis-
fies the requirements of the endurance test mentioned in this connection
in item 7.2.5 of this Chapter.
3.Detailsofconstruction
3.1. For each of the meters the difference between the calculated value of
the cyclic volume V and the value of this volume specified on the meter
must not exceed 5% of the latter.
3.2. Meters G 1·6 to G 6 inclusive may be provided witha device to prevent
operation of the counter when the gas flows in a non-authorised direc-
tion.
4.Testelement
4.1. For meters G 1·6 to G 6 inclusive the test element is manufactured as
indicated in item 5.2.2 of Chapter I. For meters G 10 to G 650 inclusive
the test element is:
— either manufactured as in item 5.2.2 of Chapter I;
— or is detachable.
4.2. When the test element is manufactured as in item 5.2.2 of Chapter I B
the value of the scale division of the element and its graduation must
satisfy the requirements of the type as shown in the following table:
Designation of meterMaximum
value of the
scaleFigured in
G 1·6 to G 6 inc. 0·2 dm31d m3
G 10 to G 65 inc. 2 dm310 dm3
G 100 to G 650 inc. 20 dm3100 dm3
4.3. For meters of which the test element is manufactured as in item 5.2.2 of
Chapter I B, the typical deviation for a series of at least thirty successive
measurements, carried out at a flow of the order of 0·1 Qmax, and under
the same conditions, of a volume of air specified below must exceed the
values in the following table:
Designation of meterVolume of
air to be
measuredMaximum
permissible
typical devia-
tion
G 1·6 to G 4 inc. 20 V 0·2 dm3
G 6 10 V 0·2 dm3
G 10 to G 65 inc. 10 V 2 dm3
G 100 to G 650 inc. 5 V 20 dm3
The volume of air to be measured may be replaced by the volume which
corresponds approximately with a whole number of revolutions of the
test element.
5.Maximumpermissibleerrors
5.1.General Provisions
5.1.1. The maximum permissible errors, positive or negative, are given
in the following table:
Flow QMaximum permissible
error in EEC initial verifi-
cation
Qmin≤Q< 2 Qmin3%1971L0318 — EN — 11.04.1978 — 002.001 — 10
▼M1
▼B
▼B
Flow QMaximum permissible
error in EEC initial verifi-
cation
2Qmin≤Q≤ Qmax2%
5.1.2. In EEC initial verification the errors for a meter for flows Q
between 2 Qminand Qmaxmust not all exceed 1% if they are all
of the same sign.
5.2.Special provisions
5.2.1. When the maximum torques indicated on the gas meter pursuant
to Sections I.B.3.2.1 and I.B.3.2.2 are applied to the drive shafts,
the indication of the gas meter at Qminmust not vary by more than
0·5 %.
6.Pressureabsorption
6.1.Total pressure absorption
The total pressure absorption with a flow of air of density 1·2 kg/m3at a
flow rate equal to Qmaxmust not exceed on average:
Designation of meterMaximum permissible value
of average total pressure
absorption in EEC initial veri-
fication
N/m2mbar
G 1·6 to G 10 inc. 200 2
G 16 to G 40 inc. 300 3G 65 to G 650 inc. 400 4
6.2.Mechanical pressure absorption
The mechanical pressure absorption, that is to say the absorption of
pressure witha flow of air of density 1·2 kg/m
3at a flow between Qminand 2 Qminmust not exceed:
Designation of meterMaximum permissible value
of mechanical pressure
absorption in EEC initial veri-
fication
N/m2mbar
G 1·6 to G 40 inc. 60 0·6
G 65 to G 650 inc. 100 1·0
The above values relate to the maximum of the mechanical pressure
absorption.
6.3.Special provisions
6.3.1. For meters for which the operating pressure exceeds 0·1 MPa
(1 bar) the provisions of Section II.6.2 regarding mechanical pres-
sure absorption shall apply, but the total pressure absorption of
these meters as referred to in Section II.6.1 shall not be taken
into consideration.
6.3.2. The fitting of additional devices must not cause the mechanical
pressure absorption of the gas meters to increase by more than
20 Pa (0·2 mbar).
7.EECtypeapproval
7.1. As well as the type sample the applicant must place initially at the
disposal of the competent authority two to six further sample meters
manufactured in accordance withth e type sample.1971L0318 — EN — 11.04.1978 — 002.001 — 11
▼M2
▼B
▼M2
▼B
▼B
The number is to be spread over several G sizes at the request of the
competent authority if the application for approval covers meters of
different sizes.
If the results of the tests are not wholly satisfactory further sample
meters may be called for.
7.1.1. A derogation from this provision may be allowed in that these
sample meters be placed at the disposal of the competent
authority at a later date. However, the decision regarding type
approval will not be taken until all samples have been fully
examined.
7.1.2. The sample meters shall remain the property of the applicant and
will be returned to him after type approval has been granted.
7.2.The examination
7.2.1. The type sample and the sample meters must satisfy the require-
ments of Chapter I and items 2, 3, 4, 5 and 6 of this Chapter.
7.2.2. In addition, over the range, the difference between the maximum
and the minimum of errors as a function of the flow rate Q must
not exceed 3% for eachmeter.
7.2.3. The type sample and the sample meters shall be subjected to an
endurance test. This test is carried out:
7.2.3.1. For meters G 1·6 to G 10 inclusive: at the maximum
meter capacities and withair: h owever, for meters on
which the badge plate specifies the gas to be metered,
the test may be effected wholly or partly with this gas.
7.2.3.2. For meters G 16 to G 650 inclusive: so far as possible at
the maximum capacity of the meter with air or with gas.
7.2.4. The duration of the endurance test for meters of which the cyclic
volume is equal to or greater than the values mentioned in the
Table of item 2.1 of this Chapter shall be:
7.2.4.1. For meters G 1·6 to G 10 inclusive: 1000 hrs. The test
may be interrupted but must be completed within sixty
days.
7.2.4.2. For meters G 16 to G 650 inclusive: suchth at eachmeter
will measure a volume of air or of gas corresponding to
an operation of 1000 hrs at the maximum output of the
meter; the test must be completed within the six-month
period.
7.2.5. For meters of which the cyclic volume is less than the values
specified in the table of item 2.1 of this Chapter, the duration of
the endurance test must be of a duration of 2000 hrs and must be
carried out on a greater number of meters than that specified in
item 7.1 of this Chapter, according to the description of the meter
and its general characteristics.
7.2.6. After the endurance test, the meters (with the exception, at most,
of one of them if the tests are carried out on a minimum of three
meters) must satisfy the following requirements:
(a) over the flow range the difference between the maximum and
minimum errors as a function of the flow Q must not exceed
a value of 4% for eachmeter;
(b) the error values must not differ by more than 1·5% of the
initial corresponding values;
For the Qmin rate this error applies only to variations in the
negative sense;
(c) the mechanical pressure drop must not have increased by
more than 20 N/m2(0·2 millibars).
7.2.7. In the case of meters with one or more drive shafts, at least three
meters of eachG size must be tested withair at a density of
1·2 kg/m3(see Section I.B.6.2) for compliance withth e require-
ments of Section I.B.3.2.4 and of Sections II.5.2.1 and II.6.3.2.
In the case of meters with several drive shafts, the test must be
carried out on the shaft which gives the most unfavourable result.1971L0318 — EN — 11.04.1978 — 002.001 — 12
▼M1
▼M2
▼M2
For meters of the same G size, the lowest torque value obtained
in the tests shall be used as the maximum permissible torque
value.
Where a type embraces meters of various G sizes, the torque test
need only be carried out on meters of the smallest G size,
provided that the same torque is specified for the larger meters
and that the drive shaft of the latter has the same or a greater
constant.
7.3.Modification of a model already approved
If the request for approval concerns a modification to a model already
approved, the metrology service which approved the primary model
shall decide, according to the nature of the modification, whether and
to what extent the provisions of items 7.1, 7.2.3, 7.2.4 and 7.2.5 of this
Chapter are applicable.
8.EECinitialverification
8.1.Accuracy tests
A meter is considered to satisfy the requirements concerning maximum
permissible errors if these requirements are met at the following flow
rates:
(a) at a flow rate of Qmin;
(b) at a flow rate of the order of /onefifthQmax;
(c) at a flow rate of Qmax.
If the examination is conducted under different conditions, the guaran-
tees must be at least equal to those obtained by the tests mentioned
above.
CHAPTER III
PROVISIONSCONCERNINGGASMETERSWITH ROTARYPISTONS
ORTURBINES
1.Fieldofapplication
The present Chapter applies, together with the provisions of Chapter I, to:
1.1.Rotary piston gas meters
— in which the measurement of gas passed is effected by means of
measuring chambers with rotary walls.
1.2.Turbine gas meters
— in which the axial flow of gas rotates a turbine wheel and the
number of revolutions of the wheel represents the volume of gas
passed.
2.Rangeofcapacities
2.1. Gas volume meters shall have only the ranges shown in the following
G designa-
tionQmax(m3/h)Range
Small Medium Large
Qmin(m3/h)
16 25 5 2·5 1·3
25 40 8 4 2
40 65 13 6 3
65 100 20 10 5
100 160 32 16 8
160 250 50 25 13
250 400 80 40 20
400 650 130 65 321971L0318 — EN — 11.04.1978 — 002.001 — 13
▼B
▼M1
▼B
▼M2
▼M2
G designa-
tionQmax(m3/h)Range
Small Medium Large
Qmin(m3/h)
650 1 000 200 100 50
1 000 1 600 320 160 80
and decimal multiples of the last five lines.
3.Detailsofconstruction
3.1.Rotary Piston Meters
3.1.1. Meters should include upstream and downstream static pressure
tappings of 3 to 5 millimetre diameter to permit measurement of
the pressure drop: the pressure measured upstream will constitute
the reference pressure.
3.1.2. The meters may incorporate a manual arrangement for turning the
pistons provided that it cannot be used in such a way as to inter-
fere with the correct operation of the meter.
3.1.3. The bearings of the shafts of the rotary pistons of meters of sizes
G160 and above may be constructed in sucha way as to provide
access to them without breaking the protective seals.
3.2.Turbine Meters
3.2.1. The meters must incorporate a pressure tapping permitting, if
necessary indirectly, the determination of the pressure immedi-
ately upstream of the turbine wheel as a reference pressure.
3.2.1.1. If there is a device for throttling the gas flow upstream
of the rotor, the meter may incorporate, as well as the
pressure tapping required by item 3.2.1 of this Chapter,
another pressure tapping immediately before the throttle
to permit determination of the pressure drop across the
throttling device.
3.3.Pressure Tappings
3.3.1. These pressure tappings must be provided with means for closing
them.
3.3.2. The pressure tappings for the reference pressure must be clearly
and indelibly marked ‘pr’ and the pressure tapping should be indi-
cated as ‘p’.
4.Testelement
4.1. In accordance with the provisions of Section I.B.5.2.2 (a) and (b) the
scale unit of the test element must not exceed the following values:
for G 16 to G 65 inclusive 0·002 m3
for G 100 to G 650 inclusive 0·02 m3
for G 1 000 to G 6 500 inclusive 0·2 m3
for G 10000 and over 2·0 m3
4.2. The interval between numbers on the scale of the test element must not
exceed:
for G 16 to G 65 inclusive 0·01 m3
for G 100 to G 650 inclusive 0·1 m3
for G 1 000 to G 6 500 inclusive 1·0 m3
for G 10000 and over 10·0 m31971L0318 — EN — 11.04.1978 — 002.001 — 14
▼B
▼M2
▼M2
5.Maximumpermissibleerrors
5.1.General provisions
5.1.1. The maximum permissible errors, positive and negative, are given
in the following table:
Flow QMaximum permissible error
in EEC initial verification
Qmin≤Q < 0·2 Qmax2%
0·2 Qmax≤Q≤Qmax1%
5.1.2. The errors must not all exceed half the maximum permissible
error if they are all of the same sign.
5.2.Special provisions
5.2.1. When the maximum torques indicated on the gas volume meter
pursuant to Sections I.B.3.2.1 and I.B.3.2.2 are applied to the
drive shafts, the indication of the gas volume meter at Qminmust
not vary by more than the values given in the following table:
QminVariations in indication at
Qmin
0·05 Qmax1%
0·1 Qmax0·5 %
0·2 Qmax0·25 %
6.EECtypeapproval
6.1. As well as the type sample, the applicant must place initially at the
disposal of the competent authority two to six sample meters manufac-
tured in accordance withth e type sample.
At the request of the competent authority this number shall be spread
over several G sizes in the case of a request for approval covering
meters of different sizes.
If the results of the tests are not wholly satisfactory supplementary
samples may be called for.
6.1.1. A derogation from this provision may be allowed in that these
sample meters may be placed at the disposal of the competent
authority at a later date. However, the decision regarding type
approval will not be taken until all samples have been fully
examined.
6.1.2. The sample meters shall remain the property of the applicant and
be returned to him after type approval has been granted.
6.2.Examination
6.2.1. The examination will include in particular the determination of
the errors of each meter, by a test with air of density 1·2 kg/m3.
Eachtest result sh all be taken into separate consideration.
6.2.1.1. The error curve of each of the meters must remain within
the band given by the limits of the maximum permissible
errors of EEC initial verifications over the range of flow
rates for which approval is requested.
6.2.1.2. The difference between the maximum value and
minimum value of the errors for each of the meters
must not exceed 1% over the range from 0·5 Qmaxto
Qmax.
6.2.2. The meters shall then be subjected to an endurance test with air
or gas.1971L0318 — EN — 11.04.1978 — 002.001 — 15
▼B
▼B
6.2.2.1. So far as possible the endurance test shall be carried out
at the maximum capacity of the meter. The period of
operation shall be such that each meter measures a
volume of air or gas corresponding to operation for
1000 hrs at its maximum capacity, without this total
period of test exceeding six months.
6.2.2.2. After this endurance test, the meters shall be examined
again withair of density 1·2 kg/m3using the same stan-
dard equipment as in the test referred to in item 6.2.1 of
this Chapter.
Under these test conditions:
(a) The values of the errors determined at the flows
specified in item 7.1 of this Chapter for each meter
(with the exception of not more than one) should
not differ by more than 1% from the errors found in
the test referred to in item 6.2.1 of this Chapter;
(b) the difference between the maximum value and the
minimum value of the error curve should not exceed,
for each of the meters (with the exception of not
more than one) 1·5% over the range 0·5 Qmaxto Qmax.
6.2.3. Meters withdrive sh afts
6.2.3.1. In the case of meters with one or more drive shafts, at
least three meters of each G size must be tested with air
at a density of 1·2 kg/m3(see Section I.B.6.2) for compli-
ance withth e requirements of Sections I.B.3.2.4 and
III.5.2.1.
In the case of meters with several drive shafts, the test
must be carried out on the shaft which gives the most
unfavourable result.
For meters of the same G size, the lowest torque value
obtained in the tests shall be used as the maximum
permissible torque value.
Where a type embraces meters of various G sizes, the
torque test need only be carried out on meters of the
smallest G size, provided that the same torque is speci-
fied for the larger meters and that the output shaft of
the latter has the same or a greater constant.
6.2.3.2. In the case of meters with several values for Qmin, only
the test described in Section III.6.2.3.1 for the smallest
Qminvalue need be carried out. The permissible torques
for the other flow ranges may be calculated from this
test result.
Conversion to other Qminvalues is governed by the
following rules:
(a) where the flow is constant, the variation in the error
is proportional to the torque;
(b) where the torque is constant, the variation in the
error for rotary-piston meters is inversely propor-
tional to the flow and for turbine meters it is
inversely proportional to the square of the flow.
7.EECinitialverification
7.1.Accuracy tests
A meter is considered to satisfy the requirements concerning the
maximum permissible errors if the requirements are met at the following
flow rates:
(a) For rotary piston meters:
Qmin, 1·5 Qmin, 0·25 Qmax, 0·5 Qmaxand Qmax;1971L0318 — EN — 11.04.1978 — 002.001 — 16
▼M2
▼B
▼M1
(b) For turbine meters:
Qmin, 1·5 Qmin, 2·5 Qmin, 0·25 Qmax, 0·5 Qmax and Qmax.
If the examination is conducted under different conditions, the guaran-
tees must be at least equal to those obtained by the tests mentionedabove.
7.2. The values specified in item 7.1 of this Chapter may be varied by ±5%.1971L0318 — EN — 11.04.1978 — 002.001 — 17
▼B