1971L0318 — EN — 21.06.1974 — 001.001 — 1
This document is meant purely as a documentation tool and the institutions do not assume any liability for its contents
►B COUNCIL DIRECTIVE
of 26July 1971
on the approximation of the laws of the Member States relating to gas volume meters
(71/318/EEC)
(OJ L 202, 6.9.1971, p. 21)
Amended by:
Official Journal
No page date
►M1 Commission Directive 74/331/EEC of 12 June 1974 L 189 9 12.7.1974
▼B
COUNCIL DIRECTIVE
of 26July 1971
on the approximation of the laws of the Member States relating to
gas volume meters
(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 differ
from one Member State to another and consequently hinder trade in such
instruments; whereas it is therefore necessary to approximate theseprovisions;
Whereas the Council Directive of 26 July 1971 (
3) on the approximation
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 requirementsfor the design and functioning of gas volume meters should be laid
down;
HAS ADOPTED THIS DIRECTIVE:
Article 1
This Directive applies to the following gas volume meters:
1. Volumetric meters:
— meters with deformable walls;
— meters with rotary 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 typeapproval 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 with this Directivewithin eighteen months of its notification, and shall forthwith inform theCommission thereof.1971L0318 — EN — 21.06.1974 — 001.001 — 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 Directive arecommunicated to the Commission.
Article 5
This Directive is addressed to the Member States.1971L0318 — EN — 21.06.1974 — 001.001 — 3
▼B
ANNEX
CHAPTER I
A.DEFINITION OF CERTAIN TERMS USED IN THE ANNEX
1.Range of load
The range of load of a gas meter is bounded by the maximum flow Qmaxand
the minimum flow Qmin.
2.Cyclic volume of a volumetric meter
‘Cyclic volume V of a volumetric meter’ means the volume of gas
corresponding 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.Operating pressure and reference pressure
3.1.Operating pressure
The operating pressure of a gas meter is the difference between the
pressure 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.Pressure absorption
The pressure absorption of a gas meter is the difference between the pressures
measured at the inlet and outlet of the meter during the flow of a gas.
5.Output drive constant
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 multiplying
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.GENERAL PROVISIONS FOR GAS VOLUME METERS
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
resistant 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
pressure.
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.
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.1971L0318 — EN — 21.06.1974 — 001.001 — 4
▼B
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.Additional devices
3.1. Meters may be fitted with additional devices (for correction, recording,
supplementary indication etc); their addition is subject to the EEC type
approval procedure.
3.2. Meters may be fitted with output drives to operate a detachable
indicator, a pre-payment device, or any other complementary or
additional device.
3.2.1. When these controls are not used, the free end of the drive must
be protected by a plug or similar arrangement which can be
sealed.
3.2.2. In the case when this output drive is a shaft, it must carry an
indication of the value of its constant in the form: ‘1 rev /wedgeq…m3’
(or dm3).
3.3. Meters may be fitted with integral pulse generators.
The outlets for these generators should bear an indication of the
corresponding value for one pulse in the form: ‘1 pulse /wedgeq…m3’ (or
dm3).
4.Inscriptions
4.1. Each meter must carry, grouped together either on the dial plate of the
indicating device or on a special badge plate, the following inscriptions:
(a) the number of the type approval of the meter
(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 and 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… MN/m2(or N/m2), or Pmax… bar (or … mbar)
(h) for volumetric meters, the nominal value of the cyclic volume
expressed as:
V=…m3(or dm3).
These inscriptions must be directly 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.Counter and test element
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.1971L0318 — EN — 21.06.1974 — 001.001 — 5
▼B
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 with either:
(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 incorporate
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;
(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 × 10nm3,
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 reference
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
juxtaposition 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
tenth of its course.
5.6.Removal of the counter
Meters must be so designed that the counter may be removed easily
during examination.1971L0318 — EN — 21.06.1974 — 001.001 — 6
▼B
6.Maximum permissible errors
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.Pressure absorption
7.1.Maximum permissible values
The maximum permissible values of pressure absorption are specified in
Chapters II and III.
8.Application of verification marks and seals
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.
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 sealing:
(a) on all plates carrying an inscription required by the present
Annex;
(b) on all parts of the casing which cannot otherwise be protected
against interference liable to affect the accuracy of measure-
ment.
9.EEC Type approval and initial verification
9.1.EEC Type approval
9.1.1 The request for type approval of a meter must include the
following documents, accompanying the type submitted:
— a description of the meter for which approval is requested;
— a drawing in perspective or a photograph of this meter;
— a plan of the assembly of the complete meter, supplemented if
necessary by detailed drawings;
— a parts list and all other information considered necessary by
the metrology services concerned;
— a plan showing the locations for verification marks and for
protective seals;
— a declaration specifying that the meters manufactured in
conformity with the type meet the requirements for safety,
particularly those concerning the maximum operating pressure
as indicated on the badge plate.
9.2.EEC Initial verification
9.2.1. Meters submitted for the EEC initial verification shall be in
working order. If the meters are to be used with additional
devices operated by output drives, these accessories must have
been connected during the examination unless a later connection
has been expressly authorised.
10.Verification marks and seals
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.1971L0318 — EN — 21.06.1974 — 001.001 — 7
▼B
CHAPTER II
PROVISIONS RELATING TO GAS VOLUME METERS WITH
DEFORMABLE WALLS
1.Field of application
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.Range of capacity and designation
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 18
40 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 2000
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 a decimal
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
satisfies the requirements of the endurance test mentioned in this
connection in item 7.2.5 of this Chapter.
3.Details of construction
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 with a device to prevent
operation of the counter when the gas flows in a non-authorised direction.
4.Test element
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:1971L0318 — EN — 21.06.1974 — 001.001 — 8
▼B
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.Maximum permissible errors
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 veri-
fication
Qmin≤Q< 2 Qmin3%
2Qmin≤Q≤ Qmax2%
5.1.2. In EEC initial verification the errors for a meter for flows Q between
2Qminand Qmaxmust not all exceed 1% if they are all of the same sign.
6.Pressure absorption
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 3
G 65 to G 650 inc. 400 41971L0318 — EN — 21.06.1974 — 001.001 — 9
▼M1
▼B
▼B
6.2.Mechanical pressure absorption
The mechanical pressure absorption, that is to say the absorption of
pressure with a flow of air of density 1·2 kg/m3at a flow between Qminand
2Qminmust 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 provision
For meters for which the operating pressure exceeds 0·1 MN/m2(1 bar)
the provisions of item 6.2 of this Chapter regarding the mechanical
pressure absorption apply, but the total pressure absorption mentioned in
item 6.1 of this Chapter of these meters is not taken into consideration.
7.EEC type approval
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 with the type sample.
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
requirements 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 each meter.
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 with air: however, 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: such that each meter
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.1971L0318 — EN — 21.06.1974 — 001.001 — 10
▼B
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 each meter;
(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).
7.3.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.EEC initial verification
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 guarantees
must be at least equal to those obtained by the tests mentioned above.
CHAPTER III
PROVISIONS CONCERNING GAS METERS WITH ROTARY PISTONS
OR TURBINES
1.Field of application
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.Range of capacities
2.1. Gas meters shall have only the ranges shown in the following table which
correspond to their designation(G):
G Qmax m3/hRange of capacities
small medium large
Qmin m2/h
25 40 8 4 21971L0318 — EN — 21.06.1974 — 001.001 — 11
▼M1
▼B
▼M1
▼B
▼M1
▼M1
G Qmax m3/hRange of capacities
small medium large
Qmin m2/h
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 32
650 1 000 200 100 50
1 000 1 600 320 160 80
and decimal multiples of the last five lines.
3.Details of construction
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 interfere
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 such a 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 immediately
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
indicated as ‘p’.
4.Test element
4.1. In applying the provisions of item 5.1.1.2 (a) and (b) of Chapter I B, the
maximum value of the scale unit of the test element must be:
for G 40 and G 65 0·002m3
for G 100 and G 650 and intermediate sizes 0·02m3
for G 1 000 and G 6 500 and intermediate sizes 0·2m3
for G 10 000 and above 2·0m3
4.2. The scale of the test element must be numbered:
for G 40 and G 65, every 0·01m3
for G 100 and G 650 and intermediate
sizes, every 0·1m31971L0318 — EN — 21.06.1974 — 001.001 — 12
▼B
▼B
for G 1 000 and G 6 500 and intermediate
sizes, every 1·0m3
for G 10 000 and above, every 10·0m3
5.Maximum permissible errors
5.1. The maximum permissible errors, positive and negative, are given in the
following table:
Flow Q m3/hMaximum permissible error in
EEC initial verification
Qmin≤Q < 0·2 Qmax2%
0·2 Qmax≤Q≤Qmax1%
5.2. The errors must not all exceed half the maximum permissible error if they
are all of the same sign.
6.EEC type approval
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
manufactured in accordance with the 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. Each
test result shall 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.
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 with air of density 1·2 kg/m3using the same
standard 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;1971L0318 — EN — 21.06.1974 — 001.001 — 13
▼B
(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.
7.EEC initial verification
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;
(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 guarantees
must be at least equal to those obtained by the tests mentioned above.
7.2. The values specified in item 7.1 of this Chapter may be varied by ±5%.1971L0318 — EN — 21.06.1974 — 001.001 — 14
▼M1
▼B