Water & Wastewater Flow Measurement
Water and wastewater facilities require flow measurement throughout the complete process: raw-water abstraction, well maintenance, water treatment, chemical dosing, drinking-water distribution, wastewater collection, plant influent, aeration, sludge handling, partially filled pipes, open channels, digester gas, treated effluent and water reuse.
No single flowmeter technology is ideal for every application. Selection depends on whether the pipe is completely full or partially filled, liquid conductivity, suspended solids and entrained bubbles, pipe material and size, required accuracy, available power, chemical compatibility, accessibility and whether the customer wants an intrusive or non-intrusive installation.
SmartMeasurement Technology Selection Philosophy
Where an existing full pipe can be measured successfully from the outside, SmartMeasurement generally favors a non-intrusive ALSONIC clamp-on ultrasonic solution. The transducers mount on the outside of the pipe, so there is no need to cut or drill the pipe, interrupt the process, create a potential leakage point or expose a sensor to the liquid.
Electromagnetic flowmeters remain important for permanent inline measurement of conductive liquids, particularly difficult sludge and wastewater applications, and ALMAGPF is specifically designed for partially filled closed pipes.
Important: Selecting the Correct ALSONIC Clamp-On Family
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ALSONIC-DSP and ALSONIC-DSPPL – Clean Through Very Dirty Liquids
The ALSONIC-DSP permanent-mount and ALSONIC-DSPPL portable flowmeters are SmartMeasurement’s advanced transit-time clamp-on ultrasonic products. They are designed for applications ranging from clean liquids to liquids containing high concentrations of suspended particles or entrained bubbles.
The DSP family can measure liquids containing up to 30% suspended particles/bubbles. This is an important distinction in water and wastewater applications because the same technology can be applied to clean water, raw water and much dirtier liquids without penetrating the pipe.
| Primary recommendation | ALSONIC-DSP for permanent, non-intrusive measurement of clean through dirty liquids. |
| Alternative / special use | ALSONIC-DSPPL when portability, troubleshooting, surveys or meter verification are required. |
| Selection note | Use the DSP family when solids/bubbles may be significant or process cleanliness can vary. |
ALSONIC-FX and ALSONIC-PL – Economical Solutions for Virtually Clean Liquids
The ALSONIC-FX permanent-mount and ALSONIC-PL portable flowmeters are economical clamp-on transit-time instruments intended for clean or virtually clean liquids with only low concentrations of suspended particles or entrained bubbles.
These products are excellent for clean-water applications where the advanced dirty-liquid capability of the DSP family is not required. They should not be presented as equivalent to DSP/DSPPL for difficult wastewater.
| Primary recommendation | ALSONIC-FX for economical permanent measurement of virtually clean liquids. |
| Alternative / special use | ALSONIC-PL for economical portable measurement of virtually clean liquids. |
| Selection note | For dirty water or uncertain/variable solids and bubble concentrations, move to DSP/DSPPL. |
Quick ALSONIC Selection
| Liquid condition | Permanent | Portable | Key distinction |
|---|---|---|---|
| Clean / virtually clean | ALSONIC-FX | ALSONIC-PL | Economical transit-time solution |
| Clean through very dirty | ALSONIC-DSP | ALSONIC-DSPPL | Up to 30% particles/bubbles |
Raw Water and Water Supply Applications
Raw Water and Water Abstraction
Water is abstracted from wells, rivers, reservoirs and other sources for drinking water, industrial use and irrigation. Raw water may contain sediment, suspended solids and entrained air, while many abstraction installations already have large piping in place that is undesirable to cut or modify.
For existing full pipes, a non-intrusive ALSONIC clamp-on meter should be considered first. ALSONIC-DSP is preferred where suspended particles or bubbles may be significant or variable. ALSONIC-FX is an economical option where the water is virtually clean.
Where a permanent inline meter is desired and the liquid is conductive, ALMAGWP provides an unobstructed electromagnetic measuring tube with no moving parts. Liner and electrode materials should be selected according to water chemistry and abrasion.
| Primary recommendation | ALSONIC-DSP for dirty/variable raw water; ALSONIC-FX for virtually clean raw water. |
| Alternative / special use | ALMAGWP when a permanent inline electromagnetic meter is preferred. |
| Selection note | Portable surveys: DSPPL for dirty/variable water; PL for virtually clean water. |
Water Well Regeneration and Maintenance
Well rehabilitation and regeneration frequently occur at remote locations where external power is unavailable. Contractors may need to document water extracted from a well and water discharged during cleaning, flushing or chemical regeneration.
ALMAGBAT is a strong permanent or skid-mounted battery-powered electromagnetic solution where the pipe can accommodate an inline meter. For temporary work on existing piping, ALSONIC-DSPPL provides a completely non-intrusive portable solution and is particularly useful when water quality changes during cleaning. For virtually clean water, ALSONIC-PL provides a lower-cost portable alternative.
| Primary recommendation | ALMAGBAT for battery-powered inline measurement. |
| Alternative / special use | ALSONIC-DSPPL for portable non-intrusive measurement; ALSONIC-PL where the water is virtually clean. |
Water Distribution Networks
Municipal distribution networks experience wide variations between minimum nighttime demand and peak daytime flow. Flow measurement is used for network balancing, district metering, leakage studies, pump optimization and water accounting.
ALMAGWP and ALMAGBAT are appropriate permanent electromagnetic solutions where an inline meter is desired. For retrofit installations, flow surveys and verification of existing meters, clamp-on ultrasonic measurement avoids pipe cutting and service interruption.
| Primary recommendation | ALMAGWP or ALMAGBAT for permanent inline network metering. |
| Alternative / special use | ALSONIC-FX/PL for clean-water retrofit and surveys; DSP/DSPPL where water quality may contain more solids/bubbles. |
Drinking Water
Drinking water is generally well suited to electromagnetic and transit-time ultrasonic measurement. ALMAGWP and ALMAGBAT provide obstruction-free inline measurement with no moving measuring components, while ALSONIC-FX and ALSONIC-PL provide economical non-intrusive measurement for virtually clean water.
Potable-water approvals must be confirmed for the specific project and meter configuration. Certifications such as NSF/ANSI/CAN 61, WRAS, ACS or other local approvals should never be assumed solely from the liner material.
Pressure Filtration and Water Treatment
Pressure filters remove suspended particles and contaminants during water treatment. ALMAGWP provides permanent inline electromagnetic measurement without moving parts. On existing piping where shutdown or modification is undesirable, ALSONIC-DSP can be used when solids or bubbles are present, while ALSONIC-FX is appropriate for virtually clean water.
Pumping and Booster Stations
Pump and booster stations require flow information for pump control, energy optimization, balancing and performance verification. Clamp-on ultrasonic measurement is especially attractive in existing stations because it can be installed without cutting the pipe.
| Primary recommendation | ALSONIC-FX for clean-water permanent clamp-on measurement; ALSONIC-DSP where solids/bubbles may be present. |
| Alternative / special use | ALMAGWP for permanent inline electromagnetic measurement; DSPPL/PL for portable pump testing and verification. |
Chemical Treatment and Dosing
Corrosion Control, pH Adjustment and Disinfection
Treatment plants dose chemicals for pH adjustment, corrosion control, coagulation and disinfection. Meter selection must consider both required accuracy and chemical compatibility of every wetted component.
For conductive chemicals, appropriately configured electromagnetic flowmeters can provide accurate volumetric measurement without moving parts. For applications requiring direct mass measurement, ALCM Coriolis flowmeters may be preferred. Chemical concentration and temperature must be reviewed before selecting liner, electrode and other wetted materials.
Ferric Chloride and Coagulant Measurement
Ferric chloride and other coagulants can be highly corrosive. Electromagnetic meters are suitable when the chemical is conductive, but the liner and electrode materials must be selected for the actual chemical concentration and temperature. PTFE is commonly considered for aggressive chemical service, while electrode material must be selected separately for compatibility.
Methanol and Carbon-Source Dosing
Methanol or other external carbon sources may be added during biological nitrogen-removal processes. The ALCM Coriolis mass flowmeter is well suited where direct mass flow, density and temperature measurement are valuable. For conductive alternative carbon-source chemicals where direct mass measurement is unnecessary, an appropriately sized electromagnetic meter may provide a more economical solution.
Wastewater Treatment Applications
Wastewater Plant Influent
Untreated wastewater can contain suspended solids, grit, organic material, bubbles and debris. For existing full pipes, ALSONIC-DSP provides a non-intrusive option capable of handling liquids with high particle/bubble concentrations without cutting or drilling the pipe.
Where a permanent inline meter is desired, ALMAGWP is particularly well suited to conductive wastewater because it has no moving measuring parts and an unobstructed bore. If the influent pipe does not remain full, the application must instead be treated as partially filled pipe measurement.
| Primary recommendation | ALSONIC-DSP for non-intrusive full-pipe wastewater measurement. |
| Alternative / special use | ALMAGWP for permanent inline electromagnetic measurement. |
| Selection note | If the closed pipe is partially filled, use ALMAGPF instead. |
Return Activated Sludge (RAS), Waste Activated Sludge (WAS) and Sludge Transfer
ALSONIC-DSP clamp-on ultrasonic installation for return-slurry / wastewater service
RAS, WAS and sludge lines can contain high concentrations of suspended solids and entrained gas. ALMAGWP remains a strong inline choice for completely full conductive sludge pipes. Where a non-intrusive installation is desired and ultrasonic conditions are suitable, ALSONIC-DSP should be evaluated because its advanced signal processing is designed for clean through very dirty liquids with up to 30% particles/bubbles.
Correct sizing remains important in sludge service so adequate velocity is maintained while the overall piping system avoids unnecessary pressure loss.
Partially Filled Closed Pipes
Wastewater, Sewage and Sludge in Partially Filled Closed Pipes
A conventional full-pipe electromagnetic meter or full-pipe clamp-on ultrasonic meter assumes the pipe is completely filled. When a closed sewer, drainage line, wastewater pipe or sludge pipe operates partially full, the wetted cross-sectional area changes continuously with liquid level.
The SmartMeasurement ALMAGPF is designed specifically for this condition. It combines electromagnetic velocity measurement with ultrasonic liquid-level measurement to provide continuous area-velocity flow measurement in a partially filled closed pipe.
ALMAGPF should replace the older concept of using an insertion magnetic meter plus a separate level transmitter for this application. It is a dedicated partially filled pipe system and is particularly suited to wastewater, sewage, sludge, drainage and stormwater piping.
- Partially filled wastewater and sewage pipes
- Partially filled sludge pipes
- Gravity sewers and combined sewers
- Drainage and stormwater piping
- Industrial wastewater discharge
- Surge and overflow monitoring
| Primary recommendation | ALMAGPF – dedicated electromagnetic area-velocity measurement for partially filled closed pipes. |
| Selection note | Do not recommend ALMAGIS for this application. |
Open Channel Flow Measurement
Simple Non-Contact Open Channel Measurement – ALSONIC-RAVM
ALSONIC-RAVM non-contact radar installation above an open channel
The ALSONIC-RAVM provides a simple, completely non-contact solution for open-channel flow measurement. Radar measures the surface velocity while a separate level measurement determines the flowing cross-sectional area. Because the velocity sensor is mounted above the liquid, there is no contact with wastewater, sediment or debris.
RAVM is preferred when ease of installation and non-contact measurement are the main priorities. Because it measures surface velocity rather than profiling velocity through the channel depth, applications requiring higher flow-measurement accuracy should consider the ALSONIC-AVM.
| Primary recommendation | ALSONIC-RAVM for simple, completely non-contact open-channel measurement using surface velocity + level. |
| Alternative / special use | ALSONIC-AVM where higher accuracy requires multi-path velocity profiling through the channel depth. |
Higher-Accuracy Open Channel Velocity Profiling – ALSONIC-AVM
Where engineers require higher flow-measurement accuracy, the velocity distribution through the depth of the channel must be considered. The ALSONIC-AVM uses multiple ultrasonic acoustic paths positioned at different depths to profile velocity within the flowing cross-section. This provides a more representative average velocity for calculating flow and makes AVM the preferred SmartMeasurement solution when accuracy requires multi-depth velocity profiling.
ALSONIC-AVM open-channel installation for multi-path velocity profiling
Sewer Monitoring – ALSONIC-SAVM
The ALSONIC-SAVM is dedicated to sewer monitoring applications where flow conditions can vary from very low nighttime flow to high storm flow and even full-pipe conditions. Its multi-path ultrasonic velocity measurement and level measurement are designed for the difficult hydraulic conditions found in sanitary and combined sewers, including infiltration and inflow (I/I) monitoring.
Primary recommendation: ALSONIC-SAVM for sewer monitoring where extreme changes in level and velocity, very low flow, sediment, or transition to full-pipe conditions make conventional sewer flow measurement difficult. By applying the transit-time cross correlation technology, the system can measure the wide variations in sewage flow rates typically seen over the course of a day – from the lowest flow velocity at midnight, which is almost zero to the highest velocity of 10 m/sec with heavy stormwater (Figure 6). Even under these harsh conditions, an accuracy level of 2% is maintained.
ALSONIC-SAVM four-path sensor arrangement for sewer monitoring
Aeration, Digester Gas and Biogas
Aeration Air Flow Measurement
Aeration is one of the major energy consumers in a wastewater treatment facility. ATMF thermal mass flowmeters provide direct gas mass-flow measurement for blower headers, branch lines and aeration zones without requiring separate pressure and temperature transmitters to calculate standardized flow.
When airflow measurement is integrated with dissolved-oxygen control, blower controls and variable-frequency drives, plant operators can better distribute air and optimize aeration energy while maintaining biological treatment requirements.
Digester Gas and Biogas Measurement
Anaerobic digestion produces biogas containing primarily methane and carbon dioxide together with water vapor and smaller concentrations of other gases. Biogas may be used in boilers, engines, combined heat and power systems or sent to a flare.
ATMF thermal mass flowmeters provide direct mass-flow measurement with very low permanent pressure loss and no moving measuring components. Gas composition, moisture, condensate and contaminants must still be evaluated because they can influence thermal mass measurement and sensor condition.
Landfill Gas and Cogeneration
Landfill gas presents similar challenges: low pressure, moisture, particulates and variable composition. ATMF thermal mass flowmeters are suitable for collection headers, flare monitoring and gas supplied to energy-recovery systems where low pressure loss and wide turndown are important.
Treated Effluent and Water Reuse
Following biological treatment, clarification and filtration, treated wastewater must often be measured before discharge or reuse. The correct technology depends primarily on whether the flow is in a full pipe, a partially filled closed pipe or an open channel.
| Primary recommendation | Full pipe: ALSONIC-FX for virtually clean effluent, ALSONIC-DSP where solids/bubbles remain, or ALMAGWP for inline electromagnetic measurement. |
| Alternative / special use | Partially filled closed pipe: ALMAGPF. Open channel: ALSONIC-RAVM or ALSONIC-AVM. |
| Selection note | Portable verification: ALSONIC-PL for virtually clean liquid; ALSONIC-DSPPL for clean through dirty liquid. |
SmartMeasurement Water & Wastewater Technology Selection Guide
| Application | Recommended product | Why |
|---|---|---|
| Virtually clean liquid – permanent clamp-on | ALSONIC-FX | Economical, non-intrusive |
| Virtually clean liquid – portable | ALSONIC-PL | Economical portable clamp-on |
| Clean through very dirty liquid – permanent clamp-on | ALSONIC-DSP | Up to 30% particles/bubbles |
| Clean through very dirty liquid – portable | ALSONIC-DSPPL | Up to 30% particles/bubbles; surveys/verification |
| Conductive full pipe – inline | ALMAGWP | Permanent full-bore electromagnetic measurement |
| Remote conductive water – no external power | ALMAGBAT | Battery-powered electromagnetic measurement |
| Partially filled closed pipe | ALMAGPF | Velocity + level area-velocity measurement |
| Open channel – simple non-contact measurement | ALSONIC-RAVM | Surface velocity + level; no contact with liquid |
| Open channel – higher accuracy / velocity profiling | ALSONIC-AVM | Multi-path velocity profiling through channel depth |
| Sewer monitoring – extreme/variable flow | ALSONIC-SAVM | Multi-path sewer monitoring from very low flow through full-pipe storm conditions |
| Aeration air / biogas / landfill gas | ATMF | Thermal mass flow |
| Precision chemical mass flow | ALCM | Coriolis mass flow, density and temperature |
