1. Water Meter Overview
Travis Smith

2. Agenda Why do Water Meters Matter?
How does it work : Measurement / Flow Characteristics
Types of Water Meters
Standards and Reference Material

3. Why Do Water Meters Matter
Conservation
If it is not measured it will be wasted.
Equitable use and availability for others
Public Safety
Recover Costs for Clean Water
Lower Loads on Wastewater Facilities
Revenue

4. Why Do Water Meters Matter?
ptlprdapp1/.../Budget/ADV_Archive/FY14/FY14AdoptedBudget.pdf
Why Do Water Meters Matter?
City of Raleigh 2014 budget

5. Why Do Water Meters Matter?
ptlprdapp1/.../Budget/ADV_Archive/FY14/FY14AdoptedBudget.pdf
Why Do Water Meters Matter?
City of Raleigh 2014 budget

6. How does it work Two Measurement Types Velocity Positive Displacement
Flow Characteristics
Parameters
Types of Flow
Challenges with Velocity Measurement

7. Water Consumption Measurement
Displacement of known volume
Flow Rate over a Period Time
Flow (Q) = Velocity (V) x Area (A)
Consumption = Flow (Q) x Time (T)

8. Title

9. Terminology Flow Area Density – Mass Per Unit Volume
Cross Section Area Measurement is Critical. 1/8” deviation in a diameter of a 12” pipe will cause a 2% change in area.
Density – Mass Per Unit Volume
Viscosity – Fluid’s Resistance To Flow
Pressure – Force Per Unit Area
Temperature – Effects Fluid Properties
Electrical Conductivity – Ability to Conduct Electricity
Sonic Velocity/Conductivity - Ability to Transfer Sound and the Speed of Travel

10. Flow in a Pipe

11. Measurement
Accuracy
The percentage of error of the output to the actual value including precision and bias error.
Precision Error
The measurement error. Not correctable. Target a 95% confidence level.
Bias Error
The difference of the measured value the true value. Can be adjusted/filtered. Hole in the piston.

12. Measurement - 2 Repeatability
Ability to provide the same flow calculation value with the same flow.
Linearity
A flowmeter is linear if its readout is a straight line going through the origin when plotted versus the rate of flow.
Range (turn down)
The ratio of maximum to minimum flow measurement capabilities.
Sensitivity
The impact to final flow calculation to each of the variables measured.

13. Velocity Measurement Challenges
Inconsistent Velocity in Part of the Cross Sectional Area
Causes - Valves, Fittings, Obstructions, Precipitation, Corrosion
Measurement Error
Cross Section Area
Parameters
Line of Sight
Water Quality – Hardness, Particulate, Precipitation, Turbidity
Cavitation, Water Hammer

19. Types of Common Water Meters
Positive Displacement
Nutating Disc
Oscillating Piston
Velocity
Electromagnetic
Ultrasonic
Single Jet /Multi Jet
Fluidic Oscillator
Turbine
Propeller
Other Flowmeter
Orifice Plate
Differential Pressure/Venturi
Pitot Tube
Variable Area
Vortex

20. Volume: Nutating Disc
Nutation - n(y)Ü-`tā-shen: Oscillatory movement of a rotating object: wobble
As water moves into the inlet, it forces the disc to wobble on its axis
The calibrated space fills and empties with each nutation
The volume of fluid required to make the disc complete one revolution is known, the total flow through a nutating disc can be calculated by multiplying the number of disc rotations by the known volume of fluid

22. Volume: Oscillating Piston
Oscillate - \ `äs-e-lāt : To move or travel back and forth between two points
The calibrated space fills and empties with each piston oscillation
A chamber that obstructs the water flow and a rotating mechanism allows the passage of fixed- volume amounts
The rate of revolution determines the flow rate

28. Velocity: Single or Multi-jet
Single or multi-jet – measure the speed of water passing through the calibrated measuring chamber
The impeller rotation speed is in relation to the velocity of water flow
Generally have an internal strainer element that can protect the jet ports from getting clogged
Single jet water meters use single input port to create a jet of water against an impeller
Multi-jet meters use multiple ports surrounding an internal chamber, to create multiple jets of water against an impeller

29. Velocity: Multi-jet Multi-jet design Chamber "Multi" - multiple
"jet" - water into chamber
Water enters lower chamber
Impeller rotates
Magnet transfers impeller to register
Water exits upper chamber
Chamber
One moving part in water
Corrosion resistant material
More easily pass suspended solids
Multi-jet meter utilizes same measuring principle as a turbine meter
Measures velocity of water passing through rotor
How it works:
1) Water enters through lower ports of chamber
2) Ports are angled to direct water flow into impeller
3) As water strikes impeller, impeller rotates
4) Water exits through upper chamber ports
5) Magnet in impeller transfers rotations into register
Long life performance achieved through low friction, low wear bearing system
Sapphire jewel in impeller
Tungsten-based titanium ball bearing on shaft
Chamber is precisely molded to size, eliminating the need to calibrate
Other velocity meters require calibration

30. Velocity: Turbine
Turbine meters have a measuring element that does not occupy or severely restrict the entire path of flow
Flow direction is generally straight through the meter, allowing for higher flow rates and less pressure loss than displacement- type meters

31. Velocity: Ultrasonic Ultrasonic
Use an ultrasonic transducer to send ultrasonic sound waves through the fluid to determine the velocity and translate the velocity into measurement of the water volume

32. Velocity: Fluidic Oscillator
Uses a nozzle to create a jet stream of water that flows against one of two diffuser walls. A small portion of the jet is recirculated to flip the oscillator to draw the stream to the other wall. The frequency of the oscillation is portional to the volume of water.

33. Velocity: Magnetic Electromagnetic Measuring Principle:
Begin with a round pipe, then add the rectangular measuring section.
Homogeneous B field: magnetics are strong across the entire cross section of the device and is always perpendicular to the electrodes. As a result, short in/out requirements.
8 – 10 x better signal to noise ratio due to rectangular measuring section – results in better measurements at low flows.
An electrically conductive fluid flows inside an electrically insulating pipe through a magnetic field.
This magnetic field is generated by a current, flowing through a pair of field coils.
Inside of the fluid, a voltage U is generated:
Ui = k • B • D • v
Ui = induced signal voltage
v = mean flow velocity
k = constant factor correcting for geometry
B = magnetic field strength
D = inner diameter
The signal voltage U is picked off by electrodes and is proportional to the mean flow velocity v and thus the flow rate q.
A signal converter is used to amplify the signal voltage, filter it and convert it into signals for totalising, recording and output processing.
Magnetic field:
Parallel pole plates
High homogeneous magnetic field over complete section: B 
High signal contribution over complete section
In case of contraction:
Electrodes far apart: D 
Flow profile disturbances squeezed out
Velocity doubles: v 
Pole plate distance is decreased: B 
High U  Better Signal to Noise Ratio
Electromagnetic Measuring Principle:
Ui (induced signal voltage) = v • k • B • D
v = mean flow velocity
k = constant factor correcting for geometry
B = magnetic field strength
D = inner diameter

34. Volume & Velocity: Compound
Two measuring elements and a check valve to regulate flow between them
Low flow – multi-jet or PD meter
High flow – turbine meter
When the flow rates drop to where the turbine meter cannot measure accurately, a check valve closes to divert water to a smaller meter that can measure the lower flow rates accurately

35. Pressure Loss

36. Fire Service

37. Fixture Usage

38. Consumption by Type

39. Register Dials

40. Reference Materials American Water Works Association
Manual of Water Supply Practices
M33 Flowmeters in Water Supply
M6 Water Meters – Selection, Installation, Testing, and Maintenance
M22 Sizing of Water Service Lines and Meters
Applicable Standards:
C700 – Displacement Type, Bronze Main Case
C701 – Turbine Meters
C702 – Compound Meters
C703 – Fireline Meters
C704 – Propeller Meters
C706 – Direct Read Registers
C707 – Encoder-Type Registers
C708 – Multijet Type
C710 – Displacement Type, Plastic Main Case
C713 – Fluidic Oscillator