U Series: compact integrated wall-mount for HVAC and building services, up to +90°C. SEGX3: split-type, up to +160°C high-temperature transducer, industrial pipelines. SEGX3M: SEGX3 plus integrated BTU/heat energy metering and M-BUS output. SEGX5: highest accuracy (±0.5% under optimized conditions). U20: battery-powered portable for survey and commissioning. SEGEX3: dedicated heat energy meter for district heating networks.
Understanding the SEGMENsensor Clamp-On Flow Meter Family
Every model in the SEGMENsensor clamp-on flow meter range uses the same fundamental measurement principle: transit-time ultrasonic technology. Two transducers clamp to the outside of an existing pipe and measure the difference in travel time between ultrasonic pulses sent upstream and downstream. This time difference is directly proportional to the average flow velocity of the liquid in the pipe. No pipe cutting. No process shutdown. No contamination risk.
Where the models diverge is in how the transmitter electronics are packaged, the temperature limits of the transducers, what additional calculations they perform on the flow signal, and what output protocols they speak to downstream control and metering systems. Understanding these differences — rather than just comparing datasheets line by line — is the key to specifying the right product for your application.
All models share a common performance baseline: ±1% accuracy, ±0.2% repeatability, DN15–DN6000 pipe diameter range (split-type models start at DN25–DN32), and measurement velocities from ±0.01 m/s to ±15 m/s. All meet CE and RoHS requirements. ISO 9001:2015 quality management is applied across the product range.
Comparison at a Glance
The table below summarizes the six models across the six parameters that matter most for model selection. Use it as a first-pass filter; the per-model sections below provide the technical depth needed to finalize your specification.
| Model | Type | Pipe Range | Max. Pipe Temp. | Key Output | Primary Use Case |
|---|---|---|---|---|---|
| U Series | Integrated wall-mount | DN15–DN6000 | +90°C | 4-20mA, RS485, Pulse | HVAC, BMS, data center cooling |
| SEGX3 | Split-type | DN25–DN6000 | +160°C (HT option) | 4-20mA, RS485, Pulse | Industrial pipelines, high-temperature |
| SEGX3M | Split-type + energy | DN32–DN6000 | +160°C (HT option) | 4-20mA, M-BUS, RS485 | Heat metering, BTU accounting, energy billing |
| SEGX5 | Split-type, high-accuracy | DN25–DN6000 | +160°C (HT option) | 4-20mA, RS485, Pulse | Precision metering, custody transfer verification |
| U20 | Portable handheld | DN15–DN6000 | +90°C | 4-20mA, RS232, USB, SD card | Survey, commissioning, temporary monitoring |
| SEGEX3 | Dedicated energy meter | DN15–DN250 | +90°C | M-BUS, RS485 | District heating, heat cost allocation |
U Series — Integrated Wall-Mount for Building Services
The U series uses an integrated design where the transmitter electronics, OLED display, and keypad are housed in a single wall-mount enclosure that ships with the transducers. This compact integration makes the U series the fastest product to commission on-site: mount the enclosure near the pipe, clamp the transducers, connect the short coaxial leads, and the unit is operational. There is no separate transmitter panel to cable back to.
U series is the right choice for HVAC chilled water systems, condenser water loops, cooling tower circuits, domestic hot water (DHW) monitoring, and data center cooling distribution units (CDUs) where pipe temperatures do not exceed +90°C. The OLED display shows instantaneous flow rate, velocity, total forward/reverse volume, and signal quality — all readable without connecting external software.
- HVAC chilled water and condenser water circuits
- Data center cooling loops and CDU flow balancing
- Building management systems (BMS/DCIM) — 4-20mA or Modbus RTU to controller
- Domestic water and irrigation flow monitoring
- Applications where a single compact unit is preferred over a split-type installation
Available sub-models: U10 (compact), U10S (stainless bracket), U12 (standard), U13 (large-pipe reinforced bracket). See the U series product page or download the U series brochure for dimensional drawings and ordering codes.
SEGX3 Series — Split-Type for Industrial and High-Temperature Pipelines
The SEGX3 is a split-type flow meter: the transmitter enclosure is wall-mounted separately from the transducers, which clamp directly to the pipe and connect via coaxial cable (up to 10 m standard, extended cable available). This split configuration solves a critical industrial problem — the transmitter can be located in a temperature-controlled cabinet or accessible panel room while the transducers themselves operate in harsh environments: high temperatures, outdoor exposure, or vibrating pipe runs.
The standard SEGX3 transducers are rated from -40°C to +90°C pipe surface temperature. The high-temperature (HT) variant extends this to +160°C, covering hot water boiler circuits, thermal oil systems, and steam condensate return lines. The anti-corrosion variant uses 316L stainless steel transducer housings for pipelines carrying aggressive media. The small-pipe variant uses a narrower transducer geometry optimized for DN25–DN100.
SEGX3 uses an LCD display (vs. OLED on U series and SEGX3M). Output signals include 4-20mA, RS485 Modbus RTU, and pulse/relay. The X3DN designation indicates a DN-type transducer connection variant available for specific large-pipe or special installation requirements.
- Industrial process pipelines at temperatures above +90°C
- Hot water boiler return and distribution monitoring
- Thermal oil and heat transfer fluid systems
- Outdoor pipe installations requiring IP67/IP68 transducer sealing
- Pipeline installations where the transmitter must be located remotely from the pipe
SEGX3M Series — Flow + Integrated Heat Energy Metering
The SEGX3M extends the SEGX3 hardware platform with a critical addition: an integrated thermal energy calculator. Two PT100 or PT1000 temperature sensor inputs (supply and return pipe) are processed together with the flow rate measurement to calculate instantaneous heat power (kW or BTU/hr) and cumulative thermal energy (kWh or BTU). The OLED display on the SEGX3M shows both flow and energy data simultaneously.
The addition of M-BUS communication protocol is the other key differentiator. M-BUS (Meter-Bus) is the European standard communications protocol for heat meters, water meters, gas meters, and energy meters — widely used in residential and commercial district heating networks, smart metering infrastructure, and sub-metering systems. If your project integrates with an M-BUS data concentrator or AMR (automatic meter reading) system, the SEGX3M is the correct choice. RS485 Modbus RTU remains available for SCADA/PLC integration.
- District heating and cooling energy metering — any heat meter application
- Data center PUE calculation (IT load vs. cooling energy ratio)
- Chiller plant efficiency monitoring (COP measurement)
- Tenant sub-metering in multi-occupancy buildings
- Industrial heat exchanger efficiency auditing
- Projects requiring M-BUS output for integration with smart metering networks
SEGX5 Series — High-Accuracy Clamp-On Flow Measurement
The SEGX5 is the precision tier of the SEGMENsensor clamp-on range. Where the SEGX3 and SEGX3M achieve ±1.0% accuracy under standard installation conditions, the SEGX5 achieves ±0.5% under optimized conditions: ≥20D upstream straight run, accurately measured pipe outer diameter and wall thickness, and calibrated acoustic sound speed for the pipe material and fluid.
The SEGX5 achieves this by employing wider-angle transducers that sample a broader cross-section of the flow profile, combined with higher-resolution signal processing that reduces sensitivity to turbulence and flow asymmetry. The high-temperature variant covers pipe surfaces up to +160°C, and the AC-powered variant is available for installations where DC power supply is not available. Split-type configuration with LCD display.
- Custody transfer verification and billing-grade flow measurement
- Chemical process dosing where ±1% introduces significant cost errors
- Calibration reference measurements for comparing against inline meters
- High-value fluid monitoring where accuracy margin has direct financial impact
- Semiconductor ultra-pure water (UPW) flow measurement
Both standard and high-temperature transducer variants are available, as are split-type with AC and DC power. The X5 does not currently include M-BUS or energy metering — for ±0.5% accuracy plus heat metering, contact the engineering team for a custom configuration.
U20 — Portable Handheld for Survey and Commissioning
The U20 is the portable field instrument in the SEGMENsensor flow meter range. Battery-operated and IP54-rated, it is designed for engineers and technicians who need to measure flow at multiple points without permanent installation — commissioning a hydronic heating system, balancing HVAC branch circuits, performing energy audits, or comparing measured flow rates at different points in a distribution network.
The U20 measures the same DN15–DN6000 range as the fixed U series, using the same ±1% transit-time technology. The key portable-specific features are: built-in rechargeable battery (8+ hour runtime), SD card slot for continuous data logging to CSV, RS232 and USB interfaces for direct PC download, and a 4-20mA output for temporary connection to test equipment or portable recorders.
- Pre-installation flow surveys to verify flow conditions before ordering permanent meters
- HVAC commissioning and circuit balancing across multiple branch pipes
- Building energy audits — periodic measurements without permanent installation
- Maintenance diagnostics — compare actual vs. expected flow at multiple points
- Rental or loan-instrument applications in OEM service teams
SEGEX3 — BTU Heat Energy Meter for District Heating Networks
The SEGEX3 is purpose-built for heat cost allocation and district heating/cooling energy metering. Unlike the SEGX3M — which is a general-purpose flow meter with energy metering added — the SEGEX3 is optimized specifically as a heat meter: compact enclosure, M-BUS as the primary output, and a simplified setup procedure for heat metering installations. It covers DN15 to DN250 in the standard version, with a large-pipe variant for DN125 to DN6000.
The SEGEX3 accepts two PT100 or PT1000 temperature inputs (supply and return) and calculates and displays heat power (kW), cooling power (kW), cumulative heating energy (kWh/MWh/BTU/GJ), cumulative cooling energy, and total heat hours. RS485 Modbus RTU is also available for systems that do not use M-BUS. IP67 rated for outdoor or wet plant room installations.
- District heating and district cooling networks — residential and commercial
- Heat cost allocation meters in apartment buildings
- Process heat exchanger performance monitoring and billing
- Chilled water plant room metering for cooling energy accounting
Model Selection Guide — Which One Is Right for Your Application?
Use this table to match your application requirements to the right model. If more than one model qualifies, the tie-breaker is usually output protocol (Modbus RTU vs. M-BUS), temperature requirement, or accuracy specification.
| Your Application Requirement | Recommended Model |
|---|---|
| HVAC chilled/hot water — permanent fixed installation, pipe surface ≤90°C | U Series |
| Industrial process pipeline — temperature ≤90°C, split-type preferred | SEGX3 Standard |
| Industrial pipeline — temperature 90°C to 160°C (hot water, thermal oil) | SEGX3 High-Temp |
| Pipe material is aggressive, needs 316L stainless transducer housing | SEGX3 Anti-Corrosion |
| Heat metering / BTU tracking / M-BUS output required | SEGX3M or SEGEX3 |
| Highest possible accuracy (±0.5%) for precision or custody transfer | SEGX5 |
| Portable flow survey or HVAC commissioning | U20 |
| District heating network cost allocation, compact M-BUS heat meter | SEGEX3 |
For OEM applications where none of the standard models exactly fits — different enclosure size, custom output protocol, co-branded labeling, or modified operating range — contact the SEGMENsensor OEM engineering team. Custom configurations are available from MOQ 50 pieces.
Frequently Asked Questions
The SEGX3 is a split-type clamp-on transit-time flow meter measuring volumetric flow rate with 4-20mA, pulse, and RS485 Modbus outputs. The SEGX3M adds integrated energy metering capability: it accepts two PT100 or PT1000 temperature sensor inputs (supply and return lines), calculates BTU or kWh thermal energy in real time, and outputs both flow and energy data via M-BUS and RS485. Choose SEGX3 when you only need flow rate; choose SEGX3M when you need heat metering or energy billing in addition to flow.
Yes. SEGX3, SEGX3M, and SEGX5 all offer high-temperature transducer variants rated for pipe surface temperatures up to +160°C. The standard transducers cover -40°C to +90°C. The U series and U20 portable meter use standard transducers rated to +90°C pipe surface. For hot water boiler circuits, thermal oil systems, or steam condensate return lines with surface temperatures above 90°C, specify the high-temperature transducer option when ordering SEGX3, SEGX3M, or SEGX5.
SEGMENsensor clamp-on transit-time ultrasonic flow meters work on all solid pipe materials that transmit ultrasound: carbon steel, stainless steel (304 and 316L), cast iron, ductile iron, copper, brass, PVC, CPVC, PE, HDPE, PP, ABS, and fiberglass-reinforced plastic. They do not work reliably on concrete-lined pipe (thick liner attenuates the signal), pipes with rubber lining thicker than 6 mm, or heavily corroded pipe with irregular internal surfaces. For any non-standard pipe material, contact the engineering team for a signal feasibility assessment before ordering.
SEGMENsensor clamp-on flow meters offer the following outputs depending on model: 4-20mA analog (all models), pulse/frequency output (all models), RS485 Modbus RTU (SEGX3, SEGX3M, SEGX5, U series), M-BUS (SEGX3M and SEGEX3), RS232 and USB with SD card data logging (U20 portable). Custom OEM outputs including HART, BACnet/IP, KNX, and CANopen are available on minimum order quantities. All models support bidirectional flow measurement and net flow totalizing.
Standard installation requires at least 10 times the pipe diameter (10D) of unobstructed straight pipe upstream and 5D downstream of the measurement point, clear of elbows, tees, valves, reducers, pumps, or other flow disturbances. On DN100 pipe this means 1,000 mm upstream and 500 mm downstream. Near control valves, increase upstream distance to 15D. In constrained spaces where 10D is not available, contact the engineering team for reduced-distance installation guidance — multi-beam or optimized transducer positioning can partially compensate, though accuracy may be reduced.
V-mode (reflect mode) mounts both transducers on the same side of the pipe — the ultrasonic signal crosses the pipe, bounces off the far wall, and returns. V-mode is standard for pipe sizes DN15 to DN300. Z-mode (pass-through mode) mounts the transducers on opposite sides of the pipe so the signal crosses once. Use Z-mode for pipes above DN300, pipes with internal deposits or scale that attenuate a reflected signal, or liquids with high acoustic attenuation. The flow meter display shows signal strength — if V-mode reads below 60%, switch to Z-mode.
Yes. PVC, CPVC, PE, HDPE, and PP pipes are fully compatible with SEGMENsensor clamp-on transit-time flow meters. Plastic pipe typically transmits the ultrasonic signal well, often producing strong signal quality. The key parameters to enter correctly are the plastic pipe's outer diameter, wall thickness, and the material sound speed value (provided in the specification tables). Note that soft plastic pipes that deform under transducer strap pressure should be supported with a rigid backing plate at the measurement point to maintain consistent transducer contact and measurement stability.
A clamp-on flow meter (SEGX3, SEGX5, U series) measures volumetric flow rate and total flow volume only. A BTU or heat energy meter (SEGX3M, SEGEX3) adds thermal energy calculation: it combines the flow rate with the temperature difference between supply and return lines (measured by two PT100 or PT1000 sensors) to calculate heat power (BTU/hr or kW) and cumulative thermal energy (BTU or kWh). Energy meters are required for heat cost allocation, district heating billing, data center PUE calculation, and chiller plant efficiency monitoring. If you only need to know how much liquid flows through the pipe — not how much heat it carries — a standard flow meter is sufficient.