Domestic water meters

​In 2015 APLMF agreed to summarise the test procedures used in each APLMF training course and then to survey its members to validate the test procedures and to provide some quality control. The validated test procedures will be later used to develop eLearning modules. 

The summary test procedures are provided to guide economies wishing to follow OIML recommendations. They contain abbreviated terms and formulae which are defined in the relevant OIML recommendation.

Information relating to Domestic water meters:
SUMMARY OF TEST PROCEDURES USED TO VERIFY DOMESTIC WATER METERS
  • These test procedures are based on OIML R 49 - Updated 20-06-02
​Test Name
​Procedures Description
TEST SET-UP










































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​
  • All meters are verified by an appropriately authorised laboratory prior to installation. Imported meters are either individually tested or batch tested. 
  • Meters are pattern/type approved and are marked accordingly.
  • Water meters of the same size and series can be tested in groups as long there is no significant interaction between the meters. 
  • Test meters in the same position indicted on its markings (V/H). If there are no markings test in the horizontal position.
  • No supplementary device is attached to meters during testing unless they cannot be removed.
  • All filtration systems on the test rig are clean, operational and maintained.
  • Water temperature is maintained at 20°C ±10°C  Note:  This is for T30 and T50 temperature class water meters (i.e. cold-water meters)
Influence factors – ranges are maintained
  • Ambient temperature is between 15°C and 25°C.
  • Ambient humidity is between 45% and 75%.
  • Atmospheric pressure is between 86 kPa and 106 kPa.
  • Outlet gauge pressure is between 0.03 MPa and 1 MPa
  • Control excessive vibrations
Batch Testing
  • Batches comprise water meters of the same pattern, manufactured in the same location. 
  • Samples are selected at random using an acceptable batch sampling system such as that described the Australian Standard AS 1199.1 or ISO2859
Determine flowrates used for testing
  • Each meter is marked with flowrate Q3 and a ratio. Use these values to calculate flow rates for Q1 and Q2.
  • Q1 = Q3 divided by the ratio
  • Q2 = Q1 multiplied by 1.6
Meters are tested once at the following flowrates:
  • between Q1 and 1.1 Q1;
  • between Q2 and 1.1 Q2;
  • between 0.9 Q3 and Q3;
  • for combination meters, between 
    1.05 Qx2 and 1.15 Qx2 For value of Q see R49-2 Section 7.4.3.2
Determine the minimum quantity of water required for testing
  • Use a test volume appropriate to maintain the measurement uncertainty as quoted for the laboratory.
  • When verifying a water meter, the expanded uncertainty in the determination of the reference quantity (i.e. volume) shall not exceed one-third of the applicable maximum permissible error (MPE).
  • Note: A spreadsheet can be generated that can be used before each test. Enter the resolution of the meter and the uncertainty of the laboratory to calculate the amount of water required for testing. Use a larger tank or run the system for longer to lowers the uncertainty value.
CONDITIONING THE SYSTEM
  • Install the meters in the test rig either singly or in groups.
  • Conduct a dummy run to remove air and to pressurise the system.
  • Open the valve allowing water to flow through the meters.
  • Ensure the pressure is constant and free of pulsations.
  • Ensure the test rig is free of leaks.
  • Ensure flow rate can be maintained at a constant value during each test.
  • Ensure influence factors are within the permitted ranges.
​STATIC PRESSURE







​
  • The purpose of this test is to ensure each meter can meet the pressure requirement of 1.6 X MAP.
  • Connect the meter to the test system.
  • Open the valve and allow water to run through the meter.
  • Bring the system up to the pressure required.
  • Allow the system to run for 1 min monitoring the pressure gauge.
  • Note: Test can be carried for individual meters or groups of meters. This will depend on the quality of the test rig. If pressure cannot be maintained the problem could be in the rig.
​ACCURACY
  • Close the valve that controls water flow through the meters.
  • Record the flowrates required for testing.
  • Select the first flowrate Q1. 
  • Record the initial reading on all meters (m3).
  • Note: water meters may also provide a volume indication in other units of volume, such as litres (L), kilolitres (kL) or megalitres (ML). 
  • Open the valve to allow water to flow through the meters
  • Run the required volume through the meters.
  • Close the valve allowing water to flow through the meters.
  • Record the final reading on all meters (m3).
  • For each meter subtract the initial reading from the final reading to determine the indicated volume VI.
  • Read the actual volume VA from the calibrated reference device.
  • Calculate the relative error using:
    {(VI – VA) ÷ VA} X 100
    Repeat this procedure for each flowrate required
  • The errors shall not exceed the MPEs given in Table 1.
  • Table 1. MPEs for water meters
Accuracy class           Flow rate range
                                     Q1 ≤ Q < Q2             Q2 ≤ Q ≤ Q4
Class 1                         ±3%                          ±1%
Class 2                         ±5%                           ±2%
  • If all the errors for a water meter have the same sign, at least one of the errors shall not exceed one half of the MPE.
  • Note: A batch is verified when all samples tested meet the acceptance criteria within the sample plan.
  • Apply the verification mark to meters that meet these requirements.
SUMMARY OF ECONOMY REPORTS
MEDEA (Project APLMF1): Course on Pattern Approval and Verification of Water Meters, Sepang, Malaysia 12-14 September 2017
​Economy
​Legislation
SI
​MPE used
Inspector or 3rd party
​Verification periods
Bhutan
No
Yes
N/A
N/A
No
Cambodia
Yes
Yes
N/A
N/A
N/A
​Fiji
Yes
Yes
​±5% domestic, 1% high flow
Inspector
5 years
Malaysia
Yes
Yes
​I±3%, ±1%
II±5%, ±2%
Both
7-9 years
​Mongolia
Yes
Yes
​±5%, ±2%
3rd party
2yr company
5yr home 
​Myanmar
Yes
Yes
No
No
None
Nepal
No
Yes
N/A
Gov acengy
N/A
​​Papua New Guinea
No
Yes
N/A
3rd party
N/A
​Philippines​
Yes
Yes
​±5%, ±2% 
3rd party
5-7 years
Thailand
Yes
Yes
​±5%, ±2%
3rd party licence
5 years
​Uzbekistan​
Yes
Yes
​±5%, ±2%
3rd party
6 years
​Vietnam
Yes
Yes
​±5%, ±2%
3rd party
5 years
Economy
​OIML compliant
​Type approval
Issues
Other
Bhutan
?
No
No Act , no PA, no local manufacturers, no regional offices
​Water meters not verified at all
Cambodia
Yes*
Yes
Lack of facilities, technical assistance, budget
*Work with STAMEQ Vietnam
Have water meter test bench
​Fiji
Yes
Yes
​More training
More staff 
Has high/low flow water meter testing beds
Malaysia
Yes
Yes
​Lack awareness re legal metrology 
​Installed meters not approved
​Mongolia
-
Yes
Training
Technical for over 150mm
Lack of budget
No magnetic protection currently use Qn,
Qt, Qmin flows for
testing
​Myanmar
No
No
​Need training 
Advice to make regulations
​ Moving towards
ISO/IEC 17025
compliance
​Nepal
No
No
No initial or annual
verification
performed 
​Has Act, Rules,
use India, PTB for
traceability of lab
​​​Papua New Guinea
Not clear
No
Need regulation
​ Trying to move
towards ISO/IEC
17025
compliance,Use
NMI Australia for
traceability
​Philippines
Yes
Use model approval not based on OIML 
Upgrade facilities
​Want to establish a national training centre 
​Thailand
Yes
No
​Limit knowledge Limit knowledge,
ISO/IEC 17025
certified under old
edition
​Want a training centre to ensure skills are maintained
​Uzbekistan​​
Yes
No
​Ensure water
meters conform to
standards
​ Use ISO 4064
​Vietnam
Yes
Yes
​ More training
​Conducts training for verifiers
SURVEY RESULTS ON ADOPTING THE DOMESTIC WATER METERS TEST PROCEDURES