Asia-Pacific
Legal Metrology
Forum
OIML R 49-1
Water meters intended for the metering of cold
potable water and hot water meters
APEC/APLMF Training Courses
in Legal Metrology
September 23 – 26, 2008
Hanoi, Vietnam
Water Meter Standards
“Water
meter as a measurement device may be
subject to international or national standards.”
International Standards
{
Major International Standards:
{
International Organization of Legal Metrology
(OIML)
z
z
z
{
International Standards Organization (ISO)
z
z
z
{
OIML R49-1
OIML R49-2
OIML R49-3
ISO 4064 Part 1
ISO 4064 Part 2
ISO 4064 Part 3
EC 51/2003 Legislation (MID)
z
Annex MI-001
International Standards
{
Major International Standards (cont.):
o Comite Europeén de Normalisation (CEN)
• EN 14154-1
• EN 14154-2
• EN 14154-3
o American Water Work Association (AWWA)
•
•
•
•
•
•
•
•
AWWA C 700 (PD Meters)
AWWA C 701 (Turbine Meters)
AWWA C 702 (Compound Meters)
AWWA C 703 (Fire Service Meters)
AWWA C 708 (Multi-Jet Meters)
AWWA C 712 (Fluidic Oscillator Meters)
AWWA C 713 (Single-Jet Meters)
AWWA M6 (Meters- Selection, Installation, Testing and
Maintenance)
National Standards
{
Examples of National Standards:
z
NMI 49-1 (Australia)
z
NIST Handbook 44, Section 3.36 (USA)
z
BS 5728 (United Kingdom)
z
z
Draft Weights and Measures Regulation, Division XIV
(Canada)
National Measurement Law (Japan)
OIML R 49-1
Scope
{
Applies to all water meters used to meter the actual volume of
cold potable water and hot water flowing through a fully charged,
closed conduit
{
Water meters shall indicate the integrated volume
{
Pattern approval and initial verification
{
Includes ancillary devices
OIML R 49-1
History
{
{
{
{
The original version of OIML R 49 was published in 1977
The second version was published in 2000. Many changes in this
document
The 2003 edition was an amended edition of the 2000 document
with the following changes:
z
z
z
{
{
criteria of acceptance for the endurance test
Annex A and the bibliography were amended (update of the standards)
the terminology used has been harmonized with the VIML (2000)
The 2006 edition is a revision of the 2003 version with the
inclusion of R 72 (hot water meters) and combination meters
The United Kingdom had been the secretariat of OIML TC8/SC5
since it’s inception.
OIML R 49-1
Current Developments
{
{
{
Harmonization of OIML R 49-1, OIML R 49-2 & OIML R 49-3
Document with ISO 4064 and EN 14154 Documents
Working Group met in London – June, 2008
Proposed changes would need to be ratified by CIML (Target Date
October 2009)
OIML R 49-1
Selected Terminology
2.1.1 Water meter
An instrument intended to measure continuously, memorize and
display the volume of water passing through the meter at
metering conditions.
Water meter will include a measurement transducer (flow sensor),
calculator and indicating device.
OIML R 49-1
Selected Terminology
2.1.12 Meter for two constant partners
Meter permanently installed and only used for deliveries from one
supplier to one customer.
2.2.1
Actual volume (Va)
Total volume of water passing through the water meter.
2.2.2
Indicated volume (Vi)
Volume of water indicated by the meter.
OIML R 49-1
Selected Terminology
2.2.3
Primary indication
Indication (displayed, printed or memorized) which is subject to
legal metrological control.
2.2.4
Error (of indication)
Indicated volume minus the actual volume.
2.2.5
Relative error (of indication)
Error (of indication) divided by the actual volume.
OIML R 49-1
Selected Terminology
2.2.6
Maximum permissible error (mpe)
Extreme values of the relative error (of indication) of a water
meter permitted by this Recommendation.
2.2.7
Intrinsic error
Error (of indication) of a water meter determined under reference
conditions.
2.2.8
Initial intrinsic error
Intrinsic error of a water meter as determined prior to all
performance tests.
OIML R 49-1
Selected Terminology
2.2.11 Durability
Capability of the water meter to maintain its performance
characteristics over a period of use.
2.2.14 Verification scale interval
Lowest value scale division of the first element of an indicating
device.
OIML R 49-1
Selected Terminology
2.2.15
Resolution (of an indicating device)
Smallest difference between indications of an indicating
device that can be meaningfully distinguished For a digital
device, this is the change in the indication when the least
significant digit changes by one step.
OIML R 49-1
Selected Terminology
2.3.1
Flowrate (Q)
Quotient of the actual volume of water passing through the water
meter and the time taken for this volume to pass through the
water meter.
2.3.2
Permanent flowrate (Q3)
Highest flowrate within the rated operating conditions, at which
the water meter is required to operate in a satisfactory manner
within the maximum permissible error.
2.3.3
Overload flowrate (Q4)
Highest flowrate at which a water meter is required to operate,
for a short period of time, within its maximum permissible error,
whilst maintaining its metrological performance when it is
subsequently operated within its rated operating conditions.
OIML R 49-1
Selected Terminology
2.3.4
Transitional flowrate (Q2)
Flowrate between Q3 and Q1, that divides the flowrate range into two
zones, the upper flowrate zone and the lower flowrate zone, each
characterized by its own maximum permissible error.
2.3.5
Minimum flowrate (Q1)
Lowest flowrate at which the water meter is required to operate within
the maximum permissible error.
2.3.6
Combination meter changeover flowrate (Qx)
{
Change-over flowrate Qx1 is when flow stops in the larger meter with
decreasing flowrate.
{
Change-over flowrate Qx2 is when flow starts in the larger meter with
increasing flowrate.
OIML R 49-1
Selected Terminology
2.3.7
Minimum and maximum admissible temperature
(mAT and MAT)
Minimum and maximum water temperatures that a water meter
can withstand permanently, within its rated operating conditions,
without deterioration of its metrological performance. mAT and
MAT are respectively the lower and upper of the rated operating
conditions (ROC).
2.3.8
Maximum admissible pressure (MAP)
Maximum internal pressure that a water meter can withstand
permanently, within its rated operating conditions, without
deterioration of its metrological performance.
OIML R 49-1
Selected Terminology
2.3.9
Working temperature (Tw)
Average water temperature in the pipe measured upstream and
downstream of the water meter.
2.3.10 Working pressure (Pw)
Average water pressure in the pipe measured upstream and
downstream of the water meter.
2.3.11 Pressure loss (∆ p)
Pressure loss, at a given flowrate, caused by the presence of the
water meter in the pipeline.
OIML R 49-1
Selected Terminology
2.4.4
Rated operating conditions (ROC)
Conditions of use for which the errors (of indication) of the water
meter are required to be within the maximum permissible errors.
2.4.7
Performance test
Test intended to verify whether the water meter is capable of
accomplishing its intended functions.
2.4.8
Endurance test
Test intended to verify whether the water meter is able to
maintain its performance characteristics over a period of use.
OIML R 49-1
Q Values
3.1.1 The flowrate characteristics of a water meter shall be defined
by the values of Q1, Q2, Q3, and Q4.
3.1.2 A water meter shall be designated by the numerical value of
Q3 in m3/h and the ratio Q3 / Q1.
3.1.3 The value of Q3 shall be chosen from the following list: (Q3
expressed in m3/h)
1
10
100
1 000
1.6
16
160
1 600
2.5
25
250
2 500
4
40
400
4 000
Note: The list may be extended to higher or lower values in the series.
{
..\APLMF Training File\preferred numbers.doc
6.3
63
630
6 300
OIML R 49-1
Q Ratios
3.1.4 The value
following list:
10
31.5
100
315
of the ratio Q3 / Q1 shall be chosen from the
12.5
40
125
400
16
50
160
500
20
63
200
630
25
80
250
800
Note: The list may be extended to higher values in the series.
3.1.5 The ratio Q2 / Q1 shall be 1.6.
z until 30 April, 2009, Q2 / Q1 may also be 2.5, or 4, or 6.3,
provided that Q3 / Q2 > 5.
3.1.6 The ratio Q4 / Q3 shall be 1.25.
Classification Comparison
Old classification system - 15 mm meter
Class A
Class B
Class C
Class D
Qmax (qs)
3.0 m3/h
3.0 m3/h
3.0 m3/h
3.0 m3/h
Qn (qp)
1.5 m3/h
1.5 m3/h
1.5 m3/h
1.5 m3/h
Qt
150 l/h
120 l/h
22.5 l/h
17.25 l/h
Qmin
60 l/h
30 l/h
15 l/h
11.25 l/h
New classification system – q3 = 1.6 m3/h
q3/q1 = 20
q3/q1 = 80
q3/q1 = 100
q3/q1 = 200
Q4
2.0 m3/h
2.0 m3/h
2.0 m3/h
2.0 m3/h
Q3
1.6 m3/h
1.6 m3/h
1.6 m3/h
1.6 m3/h
Q2
128 l/h
32 l/h
25.6 l/h
12.8 l/h
Q1
80 l/h
20 l/h
16 l/h
8 l/h
OIML R 49-1
Accuracy Classes & MPE
3.2 Water meters shall be designed and manufactured such that
their errors (of indication) do not exceed the mpe.
{
{
These requirements shall be met durably.
Water meters shall be designated as either accuracy class 1 or
accuracy class 2.
OIML R 49-1
Accuracy Class 1 Meters
3.2.1 The maximum permissible error for the upper flowrate zone
(Q2 ≤ Q ≤ Q4) is ± 1 %, for temperatures from 0.1 °C to 30
°C, and ± 2 % for temperatures greater than 30 °C.
{
{
{
The maximum permissible error for the lower flowrate zone (Q1
≤ Q < Q2) is ± 3 %.
Accuracy class 1 designation shall be applied only to water
meters with Q3 ≥ 100 m3/h.
Note: Class 1 meters not common for customer billing
OIML R 49-1
Accuracy Class 2 Meters
3.2.2 The maximum permissible error for the upper flowrate zone
(Q2 ≤ Q ≤ Q4) is ± 2 %, for temperatures from 0.1°C to 30 °C,
and ± 3 % for temperatures greater than 30 °C.
{
{
The maximum permissible error for the lower flowrate zone (Q1
≤ Q < Q2) is ± 5 %.
Accuracy class 2 designation shall be applied to all water meters
with Q3 < 100 m3/h and may be applied to water meters with
values of Q3 ≥ 100 m3/h.
OIML R 49-1
Meter Accuracy Curve
OIML R 49-1
Temperature Classes (3.2.3)
Class
mAT(◦c)
mAT(◦c)
Reference Conditions (◦c)
T 30
0.1
30
20
T 50
0.1
50
20
T 70
0.1
70
20 and 50
T 90
0.1
90
20 and 50
T 130
0.1
130
20 and 50
T 180
0.1
180
20 and 50
T 30/70
30
70
50
T 30/90
30
90
50
T 30/130
30
130
50
T 30/180
30
180
50
Note: Water temperature measured at the inlet of the meter
OIML R 49-1
Reverse Flow
3.2.6 The manufacturer shall specify whether or not the
water meter is designed to measure reverse flow.
{
{
If a meter is designed to measure reverse flow, the actual volume
passed during reverse flow shall either be subtracted from the
indicated volume or the meter shall record it separately. The
applicable mpe shall be met both for forward and reverse flow.
If a meter is not designed to measure reverse flow, the meter
shall either prevent reverse flow, or it shall withstand accidental
reverse flow without deterioration or change in its metrological
properties for forward flow.
OIML R 49-1
Metrological Requirements
3.2.7 The requirements relating to the maximum permissible errors
shall be met for all temperature and pressure variations occurring
within the rated operating conditions of the water meter.
3.2.8 The water meter totalization shall not change when the
flowrate is zero.
OIML R 49-1
In-Service mpe
3.2.9 The maximum permissible errors of a water meter while in
service shall be twice the maximum permissible errors given in
3.2.1 or 3.2.2. (Section may be revoked in future revisions to OIML R
49-1).
Country
Re-verification In-service
Sampling
Germany
mpeu ± 2 %
mpel ± 5 %
mpeu ± 4 %
mpel ± 10 %
mpeu ± 3 %
mpel ± 8 %
Australia
mpeu ± 4.0 %
mpel n/a
mpeu ± 4 %
mpel ± 10 %
n/a
United Kingdom
mpeu ± 2.5 %
mpel ± 6.0 %
n/a
n/a
Canada*
mpeu ± 2 %
mpel ± 5 %
mpeu ± 4 %
mpel ± 10 %
tbd
Note: Canada is developing in-service and sampling mpe
OIML R 49-1
Metrological Requirements
3.3.2 Adjustment device
{
{
{
{
A device incorporated in the meter.
Only allows the error curve to be shifted generally parallel to
itself.
Object is bring errors (of indication) within the maximum
permissible errors.
Can be electronic or mechanical.
OIML R 49-1
Metrological Requirements
3.3.3 Correction device
{
{
{
{
{
Connected to or incorporated in the meter.
Automatically corrects the volume at metering conditions, by
taking into account the flowrate and/or the characteristics of the
water to be measured (e.g. temperature and pressure).
In normal operation, non-corrected volume is not displayed.
The correction device shall not allow the correction of a preestimated drift, for example in relation to time or volume.
Correction devices shall not be used for adjusting the errors (of
indication) of a water meter to values other than as close as
practical to zero, even when these values are within the
maximum permissible errors.
OIML R 49-1
Metrological Requirements
3.3.5 Electronic indicating device
{
The continuous display of volume during the period of
measurement is not mandatory.
3.3.6 Ancillary devices (OIML R 117 (6))
{
{
{
{
Zero-setting device
Price indicating device
Printing or memory device
Pre-setting or self-service device
OIML R 49-1
Water Meters Equipped
with Electronic Devices
4.1 General Requirements
4.1.1 Water meters with electronic devices shall be
designed and manufactured such that significant faults do
not occur when they are exposed to disturbances specified
in A.6.
{
z
z
z
z
z
z
Dry heat
Cold
Damp heat, cyclic
Power voltage variation
DC batteries
Vibration
z
z
z
z
z
Mechanical Shock
Short time power reduction
Bursts
Electrostatic discharge
EMC susceptibility
OIML R 49-1
Water Meters Equipped
with Electronic Devices
4.1.2 Checking facilities
{
{
Only required when the delivered volume of water is prepaid by
the customer and cannot be confirmed by the supplier
Not required for meters that are used for non-resettable
measurements between two constant partners
OIML R 49-1
Water Meters Equipped
with Electronic Devices
4.1.5 Display and Blanking
{
The meter shall provide visual checking of the entire display
z
Each step shall be in the following sequence:
{
{
z
Display all the elements (ex. “eights test”)
Blank all the elements (ex. “blank test”)
Each step of the sequence shall last at least one second.
OIML R 49-1
Water Meters Equipped
with Electronic Devices
4.2 Power Supply Display and Blanking
{
Three types of power supplies may be used alone or in
combination
z
z
z
External power supply
Non-replaceable battery
Replaceable battery
OIML R 49-1
Technical Requirements
5.1 Materials and Construction
{
Adequate strength and durability
{
Not adversely affected by water temperature variations
{
Shall be non-toxic, non-contaminating and biologically inert
{
{
Resistant to internal and external corrosion (parts can be coated,
ex. Epoxy)
Indicating device shall be protected by a transparent window
OIML R 49-1
Technical Requirements
5.1 Materials and Construction (cont.)
{
Shall incorporate devices for elimination of condensation (register)
Example
z
Hermetically seal the capsule with a dry atmosphere such as nitrogen
z
Coat the window with a hydrophilic coating so that condensation
spreads over the surface rather that forming small droplets which
make the indicating device unreadable
z
Install a wiping device
z
Fill the indicating device with a clear/clean liquid
z
Use wet dial techniques
OIML R 49-1
Technical Requirements
5.4 Rated Operating Conditions
Flow Rate Range
Q1 to Q3 inclusive
Ambient Temperature Range
+ 5 o C to + 55 o C
Water Temperature Range
Table 1 – Clause 3.2.3
Ambient Relative Humidity
0 % to 100 % (exceptions)
Working Pressure Range
(meters w/dia. < 500 mm)
0.03 MPa to at least 1 MPa
Working Pressure Range
(meters w/dia. ≥ 500 mm)
0.03 MPa to at least 0.6 MPa
OIML R 49-1
Technical Requirements
5.5 Pressure Loss
{
{
{
{
Pressure Loss through the water meter shall not be greater than
0.063 MPa between Q1 and Q3
Value includes pressure loss if water meter has an integral
strainer
Pressure loss may exceed 0.063 MPa at flow rates > Q3
Note: Maximum Pressure loss on combination meters may be
found at Qx1 or Qx2
OIML R 49-1
Technical Requirements
5.6 Marks and Inscriptions
{
The water meter shall contain information that is:
{
Clearly and indelibly marked
{
Either grouped or distributed
{
Can be located:
z
z
z
z
on
on
on
on
the casing
the indicating device dial
an identification plate
the meter cover if it is not detachable
OIML R 49-1
Technical Requirements
5.6 Marks and Inscriptions
{
The water meter shall be marked with the following
information:
(a)
Unit of measurement: cubic metre (see 5.7.1.2);
(b)
Accuracy class, where it differs from accuracy class 2;
(c)
Numerical value of Q3, the ratio Q1/Q3, and the ratio Q2/Q1 where
it differs from 1.6;
(d)
Type approval sign according to national regulations;
(e)
Name or trademark of the manufacturer;
(f)
Year of manufacture and serial number (as near as possible to the
indicating device);
OIML R 49-1
Technical Requirements
5.6 Marks and Inscriptions (cont.)
{
The water meter shall be marked with the following
information:
(g)
Direction of flow (shown on both sides of the body; or on one side
only provided the direction of flow arrow will be easily visible under
all circumstances);
(h)
Maximum admissible pressure (MAP) if it exceeds 1 MPa
(i)
Letter V or H, if the meter can only be operated in the vertical or
horizontal position;
(j)
The temperature class in table 1 when it differs from T30; and
(k)
The manufacturer may indicate the maximum pressure loss.
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
Shall provide an indication of the indicated volume
{
z
z
z
Easily read
Reliable
Unambiguous
{
Shall include visual means of testing and calibration
{
May include additional elements for testing or calibration
{
Indicated volume shall be expressed in cubic metres
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
Shall be able to record the indicated volume in cubic metres
corresponding to at least 1 600 hours (rounded value) of operation
at Q3 without passing through zero.
Q3m3/h
Indicating range (minimum values)
m3
Q3 ≤ 6.3
9,999
6.3 < Q3 ≤ 63
99,999
63 < Q3 ≤ 630
999,999
630 < Q3 ≤ 6,300
9,999,999
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
Black used to indicate the cubic metre and its multiples
{
Red used to indicate sub-multiples of a cubic metre
{
{
Applied to either pointers, indexes, numbers, wheels, discs,
dials or to the aperture frames
Other means may be used for electronic water meters,
provided there is no ambiguity in distinguishing between the
primary indication and alternative displays, e.g. sub-multiples
for verification and testing
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
{
{
{
Rotational movement of the pointers or circular scales shall be
clockwise
Linear movement of pointers or scales shall be left to right
Movement of numbered roller indicators (drums) shall be
upwards
The apparent height of the digits shall be at least 4 mm
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
A water meter may include supplementary devices
z
z
z
Which may be permanently incorporated or added
temporarily
Used to detect movement of the flow sensor before this is
clearly visible on the indicating device
Where national regulations permit, the device may be used
for testing and verification and for remote reading of the
water meter, provided that other means guarantee the
satisfactory operation of the water meter
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
Resolution of the indicating device
z
The sub-divisions of the verification scale shall be small
enough to ensure that the resolution error of the indicating
device does not exceed 0.25 % for accuracy class 1 meters,
and 0.5 % for accuracy class 2 meters, of the actual volume
passed during 1 hour 30 minutes at the minimum flowrate
Q1.
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
Resolution of the indicating device
Example #1: Class 2 meter, Q3 = 4 m3/h, Q3/Q1 = 200
Q1 = Q3/200 = 4/200 = 0.02 m3/h
Volume required = 0.02 m3/h x 1.5 h (90 min) = 0.03 m3
Max Resolution = 0.03 x 0.5% = 0.00015 m3
Need to use 0.0001 m3 (only 1, 2 or 5 X 10n is permitted)
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
Resolution of the indicating device
Example #2: Class 2 meter, Q3 = 4 m3/h, Q3/Q1 = 100
Q1 = Q3/100 = 4/100 = 0.04 m3/h
Volume required = 0.04 m3/h x 1.5 h (90 min) = 0.06 m3
Max Resolution = 0.06 x 0.5% = 0.0003 m3
Can use 0.0002 m3 (only 1, 2 or 5 X 10n is permitted)
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
Resolution of the indicating device
Example #3: Class 2 meter, Q3 = 2.5 m3/h, Q3/Q1 = 100
Q1 = Q3/100 = 2.5/100 = 0.025 m3/h
Volume required = 0.025 m3/h x 1.5 h (90 min) = 0.0375 m3
Max Resolution = 0.03 x 0.5% = 0.0001875 m3
Need to use 0.0001 m3 (only 1, 2 or 5 X 10n is permitted)
OIML R 49-1
Technical Requirements
5.7 Indicating Devices
{
Resolution of the indicating device
Example #
Q3
m3/h
Q3/Q1
1
4 m3/h
200
0.1 litre
2
4 m3/h
100
0.2 litre
3
2.5 m3/h
100
0.1 litre
Maximum
Resolution
OIML R 49-1
Technical Requirements
5.8 Verification Marks and Protection Devices
{
A place shall be provided for affixing the main verification mark
{
Shall be visible without dismantling the meter
OIML R 49-1
Technical Requirements
5.8 Verification Marks and Protection Devices
{
Water Meters shall include protections devices
z
Sealable
z
Prevent dismantling or modifications of the meter
z
Prevent adjustments to calibration or corrections devices
z
Sealing can be before or after correct installation of the
water meter
OIML R 49-1
Metrological Controls (6.0)
{
Reference conditions
{
Type Approval
{
Initial Verifications
OIML R 49-1
Reference Conditions
6.1 Reference Conditions
{
All influence quantities, except for the influence quantity being
tested, shall be held to the following values during type
evaluation tests on a water meter:
Flowrate:
0.7 x (Q2 + Q3) ± 0.03 x (Q2 + Q3);
Water temperature:
Within ± 5 °C of reference value(s) of Table 1
Ambient temperature:
(20 ± 5) °C
Ambient relative humidity
(60 ± 15) %;
Ambient atmospheric pressure
86 kPa to 106 kPa [0.86 to 1.06 bar].
OIML R 49-1
Type Approval
6.2 Type Approval
{
External Evaluation
{
Sample Size
{
Accuracy Tests – flowrates
{
Pass/Fail Criteria
{
Angle of Orientation (if applicable)
{
Static Pressure Test
OIML R 49-1
Type Approval
6.2 Type Approval (cont.)
{
Pressure Loss
{
Endurance Tests
{
Static Magnetic Field Test
{
Documentation
{
Type Approval Certificates
{
Modifications of an Approved Type
{
Special Tests for Electronic Devices
OIML R 49-1
Initial Verification
6.3 Initial Verification
{
May be tested in series
{
Accuracy Test - flowrates
{
Pass/Fail Criteria
OIML R 49-1
Test Method and
Test Report Format (7.0)
7.1 Test Method
{
The methods of examination and testing described in OIML R
49-2 shall apply to type approval and verification of a water
meter.
“Water meters intended for the metering of cold potable
water and hot water, Part 2: Test methods”
OIML R 49-1
Test Method and
Test Report Format (7.0)
7.1 Test Method
z
Annex A shall apply to water meters with electronic devices
z
Expanded uncertainty:
{
shall not exceed 1/5 of mpe for Type Approvals
{
shall not exceed 1/3 of mpe for Initial Verifications
{
{
estimated according to Guide to the Expression of Measurement
(GUM) with a coverage factor, K=2
Error due to resolution of meter under test shall not exceed the
values given in 5.7.4.2.3
OIML R 49-1
Test Method and
Test Report Format (7.0)
7.2 Test Report
{
The results of type approval and initial verification
examinations should be presented in the format given
according to OIML R 49-3.
“water meters intended for the metering of cold potable
water and hot water, Part 3: Test Report Format’
Asia-Pacific
Legal Metrology
Forum
OIML R 49-1
Water meters intended for the metering of cold potable
water and hot water meters
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