1. Water Meter Management
Production, DMA and domestic meters

2. Contents
Introduction Generalities Production meters Bulk water meters Domestic water meters

3. 1. Introduction
Water metering

4. Introduction
Water meters are devises that are installed in a water pipe to measure the flow that goes through that pipe
Knowing the quantity of water that is produced and distrubuted to different places and customers helps a water company to keep its account and make financial as well as technical analysis
Water meters can measure flow based on different methods. For exmple mechanic or electro-magnetic
It is important that water meters are sized, installed and maintained correctly, so that they will work well
introduction

5. DMA and bulk water meters Domestic revenue meters
Introduction
In this workshop we will look at:
Selecting the right type of flow meter
Sizing the flow meter
Installing the flow meter
We will consider:
Production Meters
DMA and bulk water meters
Domestic revenue meters
introduction

6. Velocity profiles, general meter installation
2. Generalities
Velocity profiles, general meter installation

7. Velocity Profiles
All flow meters are only accurate if the water has a uniform Velocity Profile around the pipe’s centre axis:
Upstream fittings have a bad effect on the profile, some fittings have a worse effect than others (e.g. butterfly valve)
The fittings cause ‘swirl’ in the water which causes the meter to either under (-) or over (+) read the flow
Some types of meter are less effected by turbulent flow than others (electro- magnetic meters are better than mechanical)
Turbulent flow can be avoided by keeping a straight pipe before and after the meter (no bends or fittings). All manufacturers state a minimum upstream and downstream straight pipe lengths from the meter
Average velocity at 1/8 diameter
generalities

8. Distorting Velocity Profiles
Swirl caused by two bends in different planes
Turbulence caused by bend or obstruction
generalities

9. General Advice on Meter Installation
Comply with manufacturers recommended minimum upstream and downstream straight pipe lengths from the meter
Install the meter in the correct direction of flow
Avoid fitting insertion and ultrasonic clamp-on meters on the top of the pipe where trapped air can distort the reading
Ensure the pipe is always full of water

10. Meter Accuracy Curve
generalities

11. Water meter maintenance
Water meters can get clogged, break or wear due to dirty water. They can also age with time. For optimal benefit and use of water meters it is important to regularly inspect all types of water meters, clean and calibrate them
generalities

12. Insertion, elector-magnetic and clamp-on meters and their installation
3. Production Meters
Insertion, elector-magnetic and clamp-on meters and their installation

13. Production Meters – Common Types
Production meters are large flow meters that are usually located:
On the outlet of water treatment works
On trunk / carrier mains / large diameter pipes
Generally there are three types:
Insertion
Electro-magnetic
Ultra-sonic 2 3 1
Production meters

14. Production Meters – Insertion meter
Specification
Value
Flow range
0 to 10 m/s
Accuracy
± 2%
Pipe Size
Up to 8,000 mm
Easy to install and use
For permanent or temporary installation
Economical way of measuring flow - especially in large diameter pipes
Useful for surveying and network analysis, flow profiling or bulk meter calibration application
Can be inserted and moved under pressure
Can be used with any pulse/4-20mA data logger
Easily damaged
Production meters

15. Insertion Meter – Installation
Mean Axial velocity at 1/8 Diameter
Centre Line Velocity Factored Must be First Calculated
Production meters

16. Insertion Meter – Installation
Type of Upstream Disturbance
Minimum Upstream Straight Length for Mean Axial Velocity Method
Minimum Upstream Straight Length for Pipe Centre Line Method
90o elbow or bend 50 25
Multiple co-planar bends
Multiple non co-planar bends 80
Fully opened butterfly valve 45
Fully open gate valve 30 15
Production meters

17. Production Meters – Electro-magnetic
Specification
Value
Flow range
? m/s
Accuracy
± 1 %
Pipe Size
up to 2,600 mm
Example manufacturers are ABB, Elster, Siemens and Badger Meter
Usually AC powered
Full bore meter with no moving parts – not easily damaged
Can be buried
Production meters

18. Electro-Magnetic – Installation
Production meters

19. Production Meters – Ultrasonic clamp-on
Specification
Value
Flow range
? m/s
Accuracy
± 1 %
Pipe Size
Up to to 7,600 mm
Example manufacturers are Panametrics, Micronics and Siemens
Battery or AC powered, not suitable for permanent installation
Full bore meter with no moving parts – not easily damaged
Very useful for checking the accuracy of other meters
Easy target for theft
Essential that pipe material and lining is known
Production meters

20. Production Meters – Summary
Issue
Insertion Meter
Electro-Magnetic Meter
Clamp-On Ultrasonic Meter
Cost
Cheapest for larger pipes
Medium
Expensive
Irregular Velocity Profile
Significant effect on accuracy – long sections of straight pipe required
Small effect on accuracy
Medium effect on accuracy (though still significant)
Security
Must be installed in locked chamber
Can be buried
Accuracy
Better than ± 2%
Better than ± 1%
Ease of Installation
Very easy – can be done without pipe shut-off
Requires pipe shut-off
Pipe Size
Up to 8,000 mm
Up to 2,600 mm
Up to 7,600 mm
Reliability
High, but easily damaged
High
Power AC
Flow Ratio
1 : 100
1 : 1500
1 : 400
Production meters

21. Electro-magnetic and mechanical meters and their installation
4. Bulk Water Meters
Electro-magnetic and mechanical meters and their installation

22. Bulk Water Meters DMA and bulk water meters are usually located:
On the in- and outlet pipes of District Meter Areas (DMAs)
On supply pipes to large commercial customers
Generally there are two types of bulk water meters:
Electro-magnetic
Mechanical 1 2
Bulk water meters

23. DMA Meters – Electro-Magnetic
Specification
Value
Accuracy
± 1%
Meter Sizes
15 to 600 mm
E.g. ABB AquaMaster S EM
Battery or AC powered
Meter also contains a data logger
Flow data automatically sent by SMS message to PMAC database
Usual to send 1 SMS/day – equal to 48 x 15 minute readings
Ability to use greater resolution for step-testing etc
Also (as an option) records and transmits pressure
Automatically transmits alarm signals on failure
Bulk water meters

24. Electro-Magnetic Meter – Installation
Can be buried
Great care must be taken in bonding the meter to the pipes
Recommend the transmitter kiosk is ventilated and cooled by solar powered / battery fan
Refer to manufacturer’s Installation Manual
Bulk water meters

25. Electro-Magnetic Meter – Installation
Bulk water meters

26. Electro-Magnetic Meter – Installation
Bulk water meters

27. Electro-Magnetic Meter – Installation
Bulk water meters

28. DMA Meters – Mechanical
Specification
Value
Accuracy
± 2%
Meter Sizes
40 to 500 mm
Traditionally used as DMA meters – now being replaced by EM meters
No power required
Beware of pressure drop caused by meter
Can be damaged by poor quality water
Strainer requires regular cleaning
Now also becoming available with SMS capability
Available as a combination meter to capture both low and high flows
Bulk water meters

29. DMA Meters – Mechanical
Many types on the market, including:
Velocity meters (e.g. single and multi-jet)
Volumetric meters (e.g. piston and rotary)
Woltmann meters
Single jet meter
Volumetric meter
Woltmann meter
Bulk water meters

30. Mechanical Meters – Installation
Installed in a chamber
Usually on a bypass arrangement to easily allow maintenance and replacement
Minimum 10D and 5D upstream and downstream straight length pipe
Bulk water meters

31. Production and DMA Meter Sizing
The correct meter size is critical for accurate flow measurement
As a general rule, install the next size down from the pipe diameter
Refer to manufacturer's sizing tables and software
Bulk water meters

32. Meter Size Example
What is the correct meter size for a DMA inlet flow of:
Minimum flow = 50 m3/hour
Nominal flow = 200 m3/hour
Maximum flow = 300 m3/hour
Meter Size
50 m3/hour
200 m3/hour
300 m3/hour
Minimum
40 mm
80 mm
100 mm
Maximum
200 mm
400 mm
450 mm
Pressure Drop Across the Flow Meter
Meter Size
50 m3/hour
200 m3/hour
300 m3/hour
100 mm
0.5 metres
7.6 metres
17 metres
150 mm
0.1 metres
1.5 metres
3.4 metres
200 mm
0.02 metres
0.4 metres
0.85 metres
Bulk water meters

33. Bulk Water Meters – Summary
Issue
AquaMaster Electro-Magnetic Meter
Mechanical Meter
Cost
Expensive
Cheap
Irregular Velocity Profile
Small effect on accuracy
Large effect on accuracy
Orientation
No effect
Must be horizontal
Security
Can be buried
Must be installed in chamber
Accuracy
Better than ± 1%
Better than ± 2%
Ease of Installation
Requires pipe shut-off
Requires pipe shut-off, bypass, strainer and chamber
Pipe Size
Up to 600 mm
Up to 500 mm
Reliability
High
Damaged by poor quality water
Power
AC or battery
No power required
Flow Ratio
1 : 1000
1 : 400
Bulk water meters

34. 3. Domestic Water meter

35. Domestic Meters – Common Types
Domestic meters are usually located as revenue meters on the supply to:
Houses and apartments
Small commercial premises
Generally, there are two types of domestic meters:
Mechanical
Ultrasonic 1 2
Domestic water meter

36. Domestic Meters – Installation
10 X pipe diameter in length
Domestic water meter

37. Domestic Meters – Installation
The meters are designed only for use with clean water, a strainer is recommended upstream of the meter. The strainer should be installed at least 10 x diameter of straight pipe before the meter, to avoid turbulent flow.
Domestic water meter

38. Domestic Meters – Accuracy
Water meters come in different varieties: Class A (cheapest, least accurate), B, C and D (most expensive, most accurate ), each with their own price and accuracy.
Meter Class
Q nominal
Q min
Class B
1.5 m3/hour
30 litres/hour
Class C
15 litres/hour
Class D
11.25 litres/hour
Class B is very commonly used for domestic water users. However, Class B water meters are not advised for consumption below 0,02 m3/h for they will have a deviation in accuracy over 5%. Class B water meters over DN40 consumption below 0,3 m3/h will not be accurately measured.
Domestic water meter

39. Domestic Meters – Sizing
Accuracy curve of a meter compared to an accuracy range
Water meters should be sized between transitional flow Qt (the point at which the meter is accurate) and nominal flow Qn (everyday flow)
A water meter receiving the maximum flow for more then 1-2 minutes will be damaged
At low flows, the meter is not accurate. Minimum flow is the flow required to operate and record on the meter
Never use maximum flow as a basis for sizing the meter
Domestic water meter

40. Domestic Meters – Specifications
Domestic water meter

41. Domestic Meters – Testing
Domestic water meter

42. 4. Meter Management for NRW Reduction

43. Water meters and NRW
The state and use (or non-use) of water meters plays a large role in NRW. Mainly through:
Illegal consumption
Meter by-passes and tampering
Meter inaccuracies
Volume under-recorded by revenue meter due to its condition or wrong sizing or installation
NRW reduction

44. Meter tampering
Meter tampering is customers illegally altering the revenue meter so that it under-reads. Common methods are:
Inserting a pin or needle to stop the totaliser moving
Blocking the meter inlet or chamber
Placing a powerful magnet to break the magnetic coupling of impellors and gears
Reversing the meter
Temporary removal of the meter
Hitting the meter hard – some meters now come with an impact warning system
Cutting or damaging the impellor
To complete the water balance, we have to identify the reduced consumption of these tampered meters
NRW reduction

45. Examples of meter tampering
NRW reduction

46. Revenue Meter Errors
Almost all meter errors result in them under-reading: the meters will read less than the actual water volume being consumed. Consequently, a proportion of the consumed water is not billed to the customer – loss in revenue
Meter errors can be caused by:
Incorrect sizing
Their class
Their condition:
Age
Water quality
Maintenance regime
Incorrect installation
Meter tampering
NRW reduction

47. Meter installation
NRW reduction

48. Meter sampling
Meter sampling surveys can be organised to find out issues with water meters caused by:
Meter size
Meter age
Meter maintenance
Meter installation
Meter errors can be caused by:
Find out the ages of the customer water meters. Organise regular sessions to test (old) water meters, either with portable meters or by doing a bucket test.Bucket test
Random survey
Age survey
NRW reduction