Ultrasonic Flowmeter Technology

Ultrasonic Flowmeter - UFM Measurement Principle: Transit Time (or time-of-flight principle) Theory: Signal in the direction of flow travels faster compared to signal against the flow direction The difference in transit time is a measure for the flow velocity A swimmer swims faster with the flow as compared to against the flow The sonic signal does the same … external measurement of internal flow

Clamp-on Ultrasound Flow Meter The average velocity of the entire pipe is measured directly

Shear wave principle – for liquids Pipe wall penetration Multi reflection

Shear Wave Transducer No pipe frequency dependency 4 size transducers covers full pipe range … external measurement of internal flow

Flow profile disturbance Bends, valves, elbows, diffusers, reducers, pumps etc. change the profile of the flow. Certain distances to such flow elements are necessary for an undisturbed flow profile.

Multiple Beams – less straight run Direct Mount 10-5 Reflect Mount 5-2 2 Path – 3-1

Monitoring water networks with ultrasound flow meters Costs of installing inline flow meters Calculating the effects of the water supply interruption: Are there other pipes that lead into the affected area? Are these pipes sufficient to supply the affected area? Or is a bypass required? Planning effort: at least ½ man-day

Monitoring water networks with ultrasound flow meters Costs of installing inline flow meters Informing of the supply interruption Identifying which streets / households are affected Printing the notifications Distributing the notifications

Monitoring water networks with ultrasound flow meters Costs of installing inline flow meters Installation of the flow meter: Shutting off the pipe Cutting the pipe Welding the flanges Installing the flow meter Effort: starting with 6 man-days (3 staff members x 2 days)

Monitoring water networks with ultrasound flow meters Costs of installing inline flow meters Restarting the water supply: Reopening the pipe Flushing the pipe Effort: 1-2 hours

Monitoring water networks with ultrasound flow meters What do the IWA and EPA guidelines mean for a water supplier? Example Richmond (Virginia) If every DMA requires just 2 flow meters (for inflow and outflow) then Richmond would require about 60 flow meters Inline flow meter installation costs (excluding earth works) if IWA and EPA guidelines are followed:

USFM Monitoring water networks with ultrasound flow meters Costs of installing ultrasound flow meters Calculating the effects of the supply interruption: Not necessary Informing of the supply interruption: Not necessary USFM Restarting the water supply: Not necessary

Monitoring water networks with ultrasound flow meters Costs of installing ultrasound flow meters Installation of the flow meter: Shutting of the pipe Cutting the pipe Welding the flanges Determining pipe parameters Installing transducers Connecting the transducers and parameterizing the transmitter Effort: about ½ man-day

Monitoring water networks with ultrasound flow meters Comparison of man-days Work step Minimum man-days inline flow meter Minimum man-days ultrasound flow meter Calculating the effects of the supply interruption ½ day not necessary Informing of the supply interruption ¼ day Installation of the flow meter 6 days Restarting the water supply Summ: 7 days

Monitoring water networks with ultrasound flow meters What do the IWA and EPA guidelines mean for a water supplier? Example Richmond (Virginia) If every DMA requires just 2 flow meters (for inflow and outflow) then Richmond would require about 60 flow meters Inline flow meter installation costs (excluding earth works) if IWA and EPA guidelines are followed: Ultrasound flow meter installation costs (excluding earth works) if IWA and EPA guidelines are followed:

Purchase of flow meters Installation of flow meters Monitoring water networks with ultrasound flow meters Possible bottlenecks in the implementation of the IWA and EPA guidelines Planning of zones Purchase of flow meters Installation of flow meters Staff bottleneck Capital expenditure bottleneck Staff and operational expenditure bottleneck

Monitoring water networks with ultrasound flow meters What is required of a DMA flow meter? Measuring very low flow velocities The flow velocity in pipes DN200 – DN400 is seldom above 1 m/s The minimum night flow velocity is nearly always below 0.2 m/s Nightly changes of flow direction are not seldom

Monitoring water networks with ultrasound flow meters What is required of a DMA flow meter? Extremely robust Must be permanently resistant to groundwater and rainwater Have to withstand the possible strain of being stepped on (during chamber inspections) and the strain during the cleaning of chambers Must withstand the mechanical stress during the burial of the transducers

Monitoring water networks with ultrasound flow meters What is required of a DMA flow meter? Completely maintenance-free No consumable material No wear parts

Monitoring water networks with ultrasound flow meters Extreme low flow measurements with ultrasound Measures extremely low flow rates (down to 0.01 m/s) and is therefore ideally suited for DMA monitoring Cable length of up to 300 m (Transmitter to Transducer) Integrated temperature compensation

Monitoring water networks with ultrasound flow meters Extremely robust design Massive stainless steel mounting Transducers are not directly visible Transducer mounting can only be opened with tools No connections on the IP68 transducer heads

Monitoring water networks with ultrasound flow meters Coupling pads – maintenance free Maintenance-free due to coupling pads No use of coupling paste Instead the high signal strength and the excellent signal evaluation software enable us the use of permanent coupling pads No more Gel fixed units

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