Water Meter Overview Travis Smith

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

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

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

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

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

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)

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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

Flow in a Pipe

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.

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.

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

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

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

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

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

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

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

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

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.

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

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

Pressure Loss

Fire Service

Fixture Usage

Consumption by Type

Register Dials

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