Q: What is the COSP flow model in a Doppler radar flowmeter?

The COSP flow model is the composite calculation model used by the HZ-KSLF multi-band Doppler radar flowmeter to convert surface velocity into cross-sectional mean velocity. Radar measures the surface velocity at one point on the water surface, while flow calculation requires the mean velocity over the whole wetted cross-section. The conversion between the two varies with channel shape and water level, which is the dominant source of error in non-contact gauging. The COSP model corrects the conversion in real time using three inputs: channel geometry (width and side slope for rectangular, trapezoidal or compound sections), the wetted area corresponding to the live water level, and multiple velocity samples from multi-point measurement. Instead of a fixed velocity coefficient K (0.85-0.95), the model applies a conversion that adapts to actual conditions. On sites with large water-level swings or irregular sections, flow accuracy typically improves from ±5% to about ±2%. Multi-band operation (24 GHz / 10 GHz) supplies several velocity samples for fitting the velocity distribution Pairs with the visual fusion radar level gauge, or uses the integrated level channel, for real-time water level Section parameters and model configuration can be updated remotely via EC32/EC60 series RTUs The more regular the section and the longer the straight reach, the more stable the COSP correction. For more information, please visit our product pages or contact our technical team.

Question 1

Can LGF-PA66 and EC32 RTU provide solar-powered remote metering where irrigation pipelines have no mains electricity?

Accepted Answer

Most irrigation pipe metering points sit out in the fields with no mains power and no wired network. The LGF-PA66 draws very little power, and together with the low-power mode of the Hero V9 EC32 RTU and a solar supply it becomes a fully off-grid remote metering terminal that reports over 4G or NB-IoT.

System layout: the solar panel charges the battery through the EC32 RTU's built-in charge controller, and the RTU samples the LGF-PA66's 4-20 mA or RS485 (Modbus RTU) signals at a set interval, uploading instantaneous and totalized flow. Size the panel and battery from local solar irradiance and the longest expected run of overcast days; for off-grid sites choose a low-power RTU such as the EC32. Keep the controller and battery in a weatherproof enclosure and use low-temperature batteries in northern winters.

Installation notes:

Check 4G coverage at the site first; in weak-signal areas switch to NB-IoT or fit an external antenna.
The LGF-PA66 sensor and converter are both IP68-rated, so the meter can live in a field valve pit — just seal the cable gland properly.
Accuracy matches mains-powered sites: ±0.5%（DN50-100） of reading, with the platform comparing daily totals and alarming on missing reports.

The same arrangement suits volumetric water charging, water-rights trading and irrigation fee billing — no site visits for meter reading. For more information, please visit our product page or contact our technical team.

Question 2

Are Doppler radar flowmeters accurate in sediment-laden rivers?

Accepted Answer

Yes, it stays accurate. A Doppler radar flowmeter measures non-contact: the radar beam is reflected from above the water surface and never touches the flow, so sediment, suspended solids and weeds do not enter the measurement chain. This avoids the problem of ultrasonic instruments, whose acoustic signal is scattered by suspended particles in the water.

The HZ-KSLF multi-band Doppler radar flowmeter has been used on Yellow River irrigation main canals, high-turbidity tailwater and debris-flow channels. Surface velocity is derived from the microwave return of surface micro-roughness; turbidity does not degrade the signal, and because the device is mounted above the channel it cannot be buried by silt or worn by abrasive flow.

Sediment, floating debris and weeds do not affect measurement — no cleaning maintenance
A wide range of 0.03-15 m/s handles the velocity swings of sediment-laden flow
With EC32/EC60 series RTUs and solar power, suited to long-term unmanned field deployment

One boundary case to note: heavily aerated flow (rapids, drop structures) degrades the return signal, so cross-check against a stage-discharge rating curve at those sites. For more information, please visit our product pages or contact our technical team.

Question 3

How to pick the gauging section for a Doppler radar flowmeter?

Accepted Answer

The choice of gauging section determines how well an HZ-KSLF multi-band Doppler radar flowmeter performs. The rule of thumb: calm water surface, regular cross-section, single flow regime.

Straight reach: at least 5 channel widths upstream and 3 widths downstream of the gauging point; avoid bends, gates, drops and confluences
Section shape: prefer regular rectangular or trapezoidal sections with a stable level-area relationship; avoid sudden contractions, expansions or heavy sediment deposits
Flow regime: avoid backwater, ponded zones and strong turbulence downstream of bridge piers, where the surface-to-mean velocity relationship is unstable
Mounting position: install the radar above the centreline of the section, looking vertically down, tilt within 5°

Where the site cannot meet the straight-reach requirement, the COSP model's multi-point sampling plus field calibration can compensate, though accuracy will be lower than on a regular section. Before finalising the site, measure the channel width, side slope and bed slope, then set the mounting height — 2-15 m above the water surface is recommended. For more information, please visit our product pages or contact our technical team.

Question 4

Can a Doppler radar flowmeter measure flow when rivers freeze over?

Accepted Answer

The instrument itself is no problem in winter, but ice-cover data needs special handling. The HZ-KSLF multi-band Doppler radar flowmeter operates from -40°C to +70°C with IP68 protection; the antenna radome and electronics run reliably in severe northern cold, and snow or low temperature alone does not cause failures.

The point to understand: radar waves cannot penetrate ice. Once a river freezes, the reflecting surface changes from water to ice, and the measured surface velocity no longer represents the flow beneath the ice. Fed directly into the flow calculation it produces bias. Conditions are worst during early-winter drifting ice and spring break-up, when the reflecting surface is unstable.

Three common engineering practices:

Tag ice-period flow data and switch to the stage-discharge (Q-H) rating curve for estimation
Apply an ice-period correction factor, then re-calibrate after break-up to resume automatic gauging
Irrigation channels drained for the winter are unaffected and can remain in continuous monitoring

Do one manual comparison before and after the ice season and store the correction parameters in the EC60 series RTU configuration. For more information, please visit our product pages or contact our technical team.

Question 5

Can one radar flowmeter measure level, velocity and flow together?

Accepted Answer

Yes. The HZ-KSLF multi-band Doppler radar flowmeter measures water level and velocity in a single unit and computes flow rate internally from the stored channel-section parameters. One device outputs three values — water level, velocity and flow — so a second instrument does not need to be mounted.

Water level is measured by radar ranging to millimetre-level accuracy; velocity is derived from the Doppler shift over a range of 0.03-15 m/s; flow follows Q=K×V×A, where the wetted area A is computed in real time from the measured level and the configured section. A single device on one mounting bracket, paired with an EC32 series RTU and solar power, forms a complete open-channel gauging station for irrigation canals, urban drainage and small rivers.

Three parameters from one device — fewer mounting points and less civil work
Section parameters are remotely configurable — no hardware change after channel modification
For sites that need higher level accuracy, a visual fusion radar level gauge can be added as a second-channel check

For more information, please visit our product pages or contact our technical team.

Question 6

What is the COSP flow model in a Doppler radar flowmeter?

Accepted Answer

The COSP flow model is the composite calculation model used by the HZ-KSLF multi-band Doppler radar flowmeter to convert surface velocity into cross-sectional mean velocity. Radar measures the surface velocity at one point on the water surface, while flow calculation requires the mean velocity over the whole wetted cross-section. The conversion between the two varies with channel shape and water level, which is the dominant source of error in non-contact gauging.

The COSP model corrects the conversion in real time using three inputs: channel geometry (width and side slope for rectangular, trapezoidal or compound sections), the wetted area corresponding to the live water level, and multiple velocity samples from multi-point measurement. Instead of a fixed velocity coefficient K (0.85-0.95), the model applies a conversion that adapts to actual conditions. On sites with large water-level swings or irregular sections, flow accuracy typically improves from ±5% to about ±2%.

Multi-band operation (24 GHz / 10 GHz) supplies several velocity samples for fitting the velocity distribution
Pairs with the visual fusion radar level gauge, or uses the integrated level channel, for real-time water level
Section parameters and model configuration can be updated remotely via EC32/EC60 series RTUs

The more regular the section and the longer the straight reach, the more stable the COSP correction. For more information, please visit our product pages or contact our technical team.

Question 7

Is LGF-PA66 safe for drinking water pipelines?

Accepted Answer

The LGF-PA66 is designed for drinking water service. All wetted materials comply with GB/T 17219 (Safety Evaluation Standard for Equipment and Protective Materials in Drinking Water Transmission and Distribution). Neither the PTFE liner nor the PA66 body leaches harmful substances into the water.

The smooth PTFE liner resists scale build-up and biofilm, meeting long-term hygiene requirements for potable water. Typical installation points: municipal trunk-line metering, secondary water supply pump rooms, DMA district metering nodes, and rural centralised water supply intakes.

Paired with an EC32 RTU, the LGF-PA66 forms a low-power monitoring terminal with 4G/NB-IoT upload — ideal for valve pits without mains power. For utility billing, select the 0.5 or 0.2 accuracy class as required; periodic verification follows the JJG 1033 regulation.

For more information, please visit our product pages or contact our technical team.

Question 8

LGF-PA66 in cold climates: minimum operating temperature?

Accepted Answer

PA66 is rated for continuous service from −40 °C to +80 °C, and the LGF-PA66 is engineered for outdoor winters in northern China. The glass-fibre-reinforced composite keeps good impact toughness at −40 °C with no brittle-fracture risk, and its low thermal contraction keeps flange seals reliable.

Compared with metal bodies, PA66 conducts heat far more slowly, so under identical insulation the media inside the measuring tube freezes less easily. Field reference: LGF-PA66 units installed above ground in Heilongjiang and Inner Mongolia rural water supply projects run normally through winter.

Two notes: below −40 °C, or whenever the media may freeze, add insulation wrapping or heat tracing; liner and seal temperature ratings must match the body — confirm the configuration with our technical team for extreme conditions.

For more information, please visit our product pages or contact our technical team.

Question 9

Does the LGF-PA66 insulated body need grounding rings?

Accepted Answer

Conventional stainless steel electromagnetic flowmeters have conductive bodies, so grounding rings are often required to stabilise the zero point in low-conductivity media. The LGF-PA66 body is made of insulating composite, so the meter tube wall plays no part in the electrical circuit — no grounding rings needed, saving both parts and installation time.

The insulating body brings two extra benefits:

No stray-current pickup from the pipeline, better zero stability.
No electrochemical attack on the body, long-term accuracy retention.

Grounding for the LGF-PA66 focuses on the electrode signal reference and the cable shield: connect the converter ground terminal to the instrument earth system with resistance ≤ 4 Ω. In heavy stray-current sites such as arc-furnace workshops, add grounding electrodes on the upstream and downstream straight pipe sections.

For more information, please visit our product pages or contact our technical team.

Question 10

LGF-PA66 corrosion resistance: seawater and high-chloride water?

Accepted Answer

PA66 (polyamide 66) offers excellent chemical stability, and the LGF-PA66 body has no electrochemical corrosion at all — the decisive edge over 304/316 stainless steel. Stainless bodies are prone to pitting in seawater, high-salinity groundwater and de-icing salt environments; the PA66 body is immune.

PA66 also resists dilute acids, dilute alkalis, salt solutions and oils, and is insoluble in common solvents at room temperature. Proven field cases include coastal seawater-intrusion monitoring wells, high-salinity wastewater metering in chemical parks, and road sprinkler systems exposed to de-icing salts in cold regions.

One limitation: PA66 has poor resistance to strong oxidising acids such as concentrated sulfuric and nitric acid. For those media, consult our technical team before selection and consider Hastelloy or titanium electrode options.

For more information, please visit our product pages or contact our technical team.

Question 11

How much lighter is the LGF-PA66 flowmeter than stainless steel?

Accepted Answer

The LGF-PA66 uses aviation-grade PA66 composite with a density of about 1.14 g/cm³ — roughly one seventh of 304 stainless steel (7.93 g/cm³). A DN100 LGF-PA66 body weighs around 3.5 kg, while a comparable stainless steel electromagnetic flowmeter typically exceeds 18 kg.

In practice this means one technician can carry the meter into a valve pit and set it in place without lifting gear or a second worker. For retrofit projects, elevated pipework and cramped meter chambers, the weight saving translates directly into lower installation cost.

Flange dimensions follow GB/T 9119, so bolt patterns match existing pipe flanges — no adapters when replacing old meters.
The PA66 body has inherent vibration damping; no extra damping pads are needed on pump discharge lines.

For more information, please visit our product pages or contact our technical team.

Question 12

Which verification regulations apply to electromagnetic flow meters? Does the LGF-PA66 need periodic verification for fiscal metering?

Accepted Answer

In China, electromagnetic flow meters are verified under JJG 1033, the national verification regulation for electromagnetic flow meters. Meters used for fiscal (trade settlement) purposes fall under mandatory verification performed by legal metrology institutes; internal process metering can follow the calibration route with a CNAS calibration certificate.

Key points in practice:

Verification interval: fiscal meters are typically verified every 2 years (subject to local metrology authority requirements); process meters are recommended for calibration every 2–3 years.
Method: wet verification on a standard rig (gravimetric or master-meter method). Sizes up to DN300 are sent to the lab; larger bores can be field-verified against a master meter.
Pass criteria: judged against the meter's stated accuracy class — the LGF-PA66 leaves the factory verified at the ±0.5%（DN50-100） class, passing if indication errors stay within ±0.5%（DN50-100）.

Every LGF-PA66 is individually flow-calibrated before shipment, with a certificate listing indication error at each flow point — usable as the baseline record for initial verification. For fiscal metering points, specify “fiscal use + accuracy class” at order time so the factory certificate aligns with later mandatory verification. At points equipped with an EC32 RTU, the platform retains the full data history, keeping any gap during off-site verification traceable.

For more details, please visit our product pages or contact our technical team.

Question 13

Electromagnetic vs. ultrasonic flow meters for DMA district metering — how does the LGF-PA66 compare with clamp-on ultrasonic?

Accepted Answer

A DMA district metering point must answer two questions: how much water was supplied by day, and how much leaked away at night. Night-flow analysis demands excellent low-velocity stability — exactly where the two technologies diverge.

Principle and accuracy: the LGF-PA66 measures full-bore volumetric flow by Faraday's law at ±0.5%（DN50-100）, independent of flow velocity — it stays stable even below 0.1 m/s at night. Clamp-on ultrasonic infers flow from transit-time differences and is affected by pipe scale, linings, and air bubbles; field accuracy typically wanders between ±1% and ±3%.
Installation: clamp-on ultrasonic needs no pipe cutting or shutdown — good for temporary checks and leakage surveys. The LGF-PA66 requires a line break to install, but once in it serves as a long-term fiscal meter; at one-third the weight of a stainless meter it is easy to set in a chamber.
Long-term stability: the electromagnetic meter has no moving parts and tolerates scaling (periodic electrode cleaning suffices), with small drift over a 10-year cycle; ultrasonic transducers age and coupling gel dries out, both shifting the data.

The common field pattern: use the LGF-PA66 as the settlement-grade district meter with an EC32 RTU uploading 4G data every 15 minutes, and use portable clamp-on ultrasonic for network surveys and suspected-leak localization. They complement rather than replace each other; on tight budgets, clamp-on can bridge small branch lines below DN50 first.

For more details, please visit our product pages or contact our technical team.

Question 14

What conductivity does an electromagnetic flow meter require? What is the minimum conductivity the LGF-PA66 can measure?

Accepted Answer

An electromagnetic flow meter can only measure conductive liquids — by principle, the medium itself acts as the moving conductor that cuts magnetic field lines. The LGF-PA66's lower limit is 5 μS/cm; below that the induced signal is too weak for stable measurement.

Reference values for common waters:

Municipal tap water: 200–800 μS/cm — far above the limit; the ideal medium for electromagnetic meters.
River and reservoir raw water: 100–500 μS/cm — measures normally.
Domestic sewage and industrial wastewater: typically above 1000 μS/cm — ample signal.
Seawater: ~50,000 μS/cm — LGF-PA66 with Hastelloy electrodes is the standard configuration.
Pure, deionized, or distilled water: 0.1–5 μS/cm — below the limit; electromagnetic meters cannot be used and another principle is required.

When site conductivity sits near the limit (5–20 μS/cm), choose the split-mount version to keep the signal cable short, and run a zero calibration with a flooded pipe before commissioning. The LGF-PA66's wide conductivity window lets one meter cover media from raw water to seawater while holding ±0.5%（DN50-100） accuracy. If the medium's conductivity is unknown, measure a sample with a portable conductivity meter — that beats any rule of thumb.

For more details, please visit our product pages or contact our technical team.

Question 15

Can an IP68 electromagnetic flow meter stay submerged long-term? What matters for installation in flooded valve chambers?

Accepted Answer

IP68 does not mean “splash-proof” — it means “no water ingress under continuous immersion.” Both the sensor and transmitter of the LGF-PA66 are designed to IP68 and can operate submerged for long periods in valve and metering chambers, which is exactly the typical duty for municipal network metering points.

Three things decide success in submerged service:

Whole-unit sealing: the LGF-PA66 body is one-piece injection molded with no welds, and the terminal chamber is sealed. Standard duty covers immersion up to 1 m; for deeper or permanent deep-water installation, state it at order time and the meter ships with deep-water sealing.
Cable joints are the weak link: sensor-to-transmitter signal cables and transmitter-to-RTU communication cables must be jointed in waterproof boxes or resin-potted. Field experience shows ~90% of immersion failures happen at joints, not in the meter itself.
Chamber drainage and ventilation: provide a gravel drainage layer at the chamber bottom so silt does not bury the meter; where possible add a level switch to alarm on excessive flooding.

The EC32 RTU is also IP68-rated and can be installed in the same chamber, sending data over 4G/NB-IoT with no mains cabling — solar plus battery is sufficient. Inspecting joint seals before the rainy season is the cheapest insurance you can buy.

For more details, please visit our product pages or contact our technical team.

Frequently Asked Questions

Can LGF-PA66 and EC32 RTU provide solar-powered remote metering where irrigation pipelines have no mains electricity?

Are Doppler radar flowmeters accurate in sediment-laden rivers?

How to pick the gauging section for a Doppler radar flowmeter?

Can a Doppler radar flowmeter measure flow when rivers freeze over?

Can one radar flowmeter measure level, velocity and flow together?

What is the COSP flow model in a Doppler radar flowmeter?

Is LGF-PA66 safe for drinking water pipelines?

LGF-PA66 in cold climates: minimum operating temperature?

Does the LGF-PA66 insulated body need grounding rings?

LGF-PA66 corrosion resistance: seawater and high-chloride water?

How much lighter is the LGF-PA66 flowmeter than stainless steel?

Which verification regulations apply to electromagnetic flow meters? Does the LGF-PA66 need periodic verification for fiscal metering?

Electromagnetic vs. ultrasonic flow meters for DMA district metering — how does the LGF-PA66 compare with clamp-on ultrasonic?

What conductivity does an electromagnetic flow meter require? What is the minimum conductivity the LGF-PA66 can measure?

Can an IP68 electromagnetic flow meter stay submerged long-term? What matters for installation in flooded valve chambers?

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