3Wire FBTU2X is a cost-effective wall-mounted ultrasonic flow meter designed for long-term flow measurement and optional BTU / heat energy monitoring.
Using transit-time ultrasonic technology, FBTU2X measures liquid flow accurately and reliably without moving parts. With suitable Pt100 temperature transducers, it can also measure heating or cooling energy in chilled water, hot water and process water systems.
FBTU2X is suitable for industrial plants, commercial buildings, HVAC systems, chilled water systems, process utilities and water distribution applications.


Flow and BTU measurement are important for understanding system performance, utility usage and energy efficiency.
In many facilities, chilled water, cooling water, process water or reclaimed water flow is not measured continuously. This makes it difficult to verify cooling output, detect abnormal flow conditions, calculate BTU, or evaluate system performance.
The system can be selected based on pipe size, liquid type, installation method and site condition.
Provides accurate and stable liquid flow readings using transit-time ultrasonic flow measurement technology.
With suitable Pt100 temperature transducers, FBTU2X can calculate heat energy using flow rate and supply / return temperature difference.
The ultrasonic measurement method has no moving mechanical parts, reducing wear and maintenance requirements.
Clamp-on transducers allow flow measurement without cutting the pipe and without pressure loss.
Suitable for applications where higher stability, permanent installation or wider pipe compatibility is required.
Supports integration with PLC, SCADA, BMS, EMS, IoT gateways and energy monitoring platforms.
Suitable for liquid flow monitoring across chilled water, cooling water, process water, raw water, reclaimed water, plant effluent, potable water, chemical liquid and river water applications.
When paired with Pt100 temperature sensors, FBTU2X can support chilled water BTU monitoring, hot water energy measurement, HVAC energy monitoring and chiller plant performance analysis.
Designed for continuous flow and optional BTU monitoring in industrial, commercial, HVAC and utility applications.
Allows installation without cutting the pipe, without water shutdown and without pressure loss. Suitable for retrofit projects and operating systems.
Provides stable long-term measurement and is suitable for larger pipes or applications where clamp-on installation is not ideal.
Suitable where high accuracy and stable permanent measurement are required. This type normally requires pipe cutting and installation of the meter section.
FBTU2X supports different transducer selections based on pipe size, liquid condition, temperature and installation method.
| Item | FBTU2X Specification |
|---|---|
| Product Type | Wall mounted ultrasonic flow meter |
| Measurement Principle | Transit-time ultrasonic flow measurement |
| Flow / BTU Capability | Flow measurement; optional BTU / heat energy measurement |
| Accuracy | ±1% |
| Display | 2 × 20 character LCD with backlight |
| Signal Output | 4–20 mA output, OCT pulse output, relay output |
| Signal Input | 3-way 4–20 mA input |
| Temperature Input | Supports Pt100 temperature transducer for heat / energy measurement |
| Communication | RS485 serial interface, Modbus support |
| Pipe Diameter | 25–6000 mm |
| Flow Rate | 0 to ±7 m/s |
| Straight Pipe Requirement | Upstream 10D, downstream 5D, 30D from pump |
| Liquid Type | Water, hot water, chilled water, city water, sea water, waste water, sewage, chemicals, plant effluent, beverage, ultra-pure liquids and others |
| Medium Temperature | -30°C to 160°C |
| Converter Operating Temperature | -20°C to 60°C |
| Flow Transducer Operating Temperature | -30°C to 160°C |
| Power Supply | DC 8–36 V or AC 85–264 V optional |
| Power Consumption | 1.5 W |
| Converter Dimension | 132 × 150 × 85 mm |
| Converter Protection | IP67 |
| Transducer Protection | IP68 |
FBTU2X can measure many liquid types. Final application suitability should be checked based on pipe material, liquid condition, temperature, turbidity and installation method.
Chilled water BTU measurement, cooling system performance monitoring and chiller plant performance analysis.
Cooling water, process water, plant utility, reclaimed water and plant effluent flow monitoring.
Supports BTU measurement, cooling load calculation, pump optimisation and abnormal flow detection.
Supports building cooling system analysis, heat exchanger energy tracking and cost centre allocation.
Connect through RS485 / Modbus to automation, monitoring and energy management systems.
Flow and BTU data can be connected to IoT platforms for long-term monitoring and analytics.
FBTU2X can be connected through RS485 / Modbus to IoT gateways and energy management platforms.
When integrated with IoTWatt 4.0, flow and BTU data can be combined with power meter data, temperature readings, equipment status and energy cost data.
Combine BTU output and power input to support chiller efficiency visibility.
Analyse cooling performance, abnormal flow and system behaviour over time.
Support energy audit reporting, savings opportunity identification and performance verification.
The 3Wire FBTU2X Wall Mounted Ultrasonic Flow Meter is a practical and cost-effective solution for long-term liquid flow monitoring and optional BTU / heat energy measurement.
With transit-time ultrasonic measurement, multiple transducer options, RS485 / Modbus communication, optional SD card storage and IP-rated protection, FBTU2X is suitable for industrial, commercial and HVAC applications.
Contact 3Wire / Saturn Pyro for product selection, transducer matching and application support.
Malaysia