Low Flow Small Size Ultrasonic Flow Sensor DN8-DN40

The RBFM-MK Series clamp-on flow sensor is special designed for small pipe and ultrasonic low flow rate and Cost-Effective Flow Solutions, it's easily installed, without any pipe modifcation, by simply clamping to theoutside of a pipe, tube or hose. This RBFM-MK series provides stable fow rate measurement regardless of the pipe or liquid. in addition to metal and hard plastic piping can also be supported. This productcan not only measure the flow rates of various liquids such as water, Dl water, oil, chemicals, and high temperatures, and highly viscous liquids, Connecting a concentration sensor and temperaturesensor allows for the centralized management of multiple parameters, helping improve product quality, and decrease costs.

Measuring flow in small pipes with low flow rates can be a complex task fraught with accuracy challenges and technical difficulties. Traditional methods often require invasive installations that disrupt the system and are costly to maintain. Enter the economical clamp-on transit time ultrasonic flowmeters: a non-invasive solution that promises to simplify this challenge. These devices attach externally to the pipe, causing no disruption to the flow, and provide accurate measurements by utilizing ultrasonic waves to calculate fluid velocity. This introduction will guide you through the principles and advantages of using these innovative tools for your low-flow applications.










  • Principle
  • Features
  • Specification
  • Model Selection
  • Applicants
  • Download

RBFM-MK Series Clamp-On Transit Time Ultrasonic Flowmeters for Small Pipes and Low Flowrate Principle:

The operating principle of an ultrasonic flow meter, specifically a transit-time difference flow meter, is fascinating. In this design, paired ultrasonic transmitters and receivers (also called transducers) are mounted opposite each other in the pipe. These transducers then alternately transmit and receive ultrasonic waves, calculating the flow rate based on the difference in transit times.
One of the key aspects of this technology is its accuracy. Unlike other types of flow meters, ultrasonic devices can measure a vast range of velocities, from very slow to very fast flow speeds, all with remarkable precision.

RBFM-MK Series Clamp-On Transit Time Ultrasonic Flowmeters for Small Pipes and Low Flowrate Features:

  • Does not require the measured liquid to be conductive.
  • Available in ¼” – 1-1/2″ (8-40 mm) pipe sizes
  • Will measure a wide range of fluid velocities; 0.3-16.5 f/s (0.1 ~5.0) m/s
  • Outputs include 4-20mA and MODBUS RTU 
  • Suitable pipe materials including stainless steel, carbon steel, copper, PVC, PVDF, polypropylene and HDPE.
  • Accuracy; ±3% of reading
  • Energy and BTU measurement optional
  • NIST traceable calibration certificate
  • Installation does not necessitate pipe cutting or process shutdowns, allowing operation to continue uninterrupted.
  • No moving parts and no pressure loss.
  • Installation could be performed without specialized training, just by an instructional video or step by step diagram.
  • The enclosure is made of PP and fiberglass, ensuring durability in acidic or alkaline environment.



RBFM-MK Series Clamp-On Transit Time Ultrasonic Flowmeters for Small Pipes and Low Flowrate Specification:

Enclosure material PP and F
Mounting screw SS304
Enclosure protection class IP54
Vibration resistance 10 to 55 Hz, double amplitude 1.5 mm, 2 hours in each XYZ axis
Impact resistant 100 m/s2 16 ms pulse, 1000 times each for X Y and Z axis
Models DN10DN15DN20DN25DN32DN40(DN8 can be customized)
Flow range DN10 DN15 DN20
  2-30 LPM 5-60 LPM 10-100 LPM
  DN25 DN32 DN40
  10-150 LPM 20-260 LPM 20-400 LPM
Pipe material Metal /PVC, PP, PE or PVDF rigid plastic pipe (Common examples, if notlisted, please contact the factory for confirmation)
Medium Water, Alcohol, Liquid gasoline, Chemical solvent and other fixed compositionliquid other liquid (Single liquid medium without solid particles or impurities)/Common examples, if not listed, please contact the factory for confirmation
Medium temperature Standard temperature transducers:-10°C-65°C                                                                                   Middle temperature transducers:-10°C-105°
Accuracy < 3% FS.
Response time 0.5s -3s
Power supply 20-28VDC
Electric power 1W
Power and I/O connection M12-A type avation plug (Five-cores)
Output 4-20mA
Communication RS485 Modbus
Display 1.5' OLed display
Keyboard 2 touch buttons
Envronment temperature -10C -60℃℃ (No freezing)
Heat/cool Measuement Yes
Model Selection

RBFM-MK Series Clamp-On Transit Time Ultrasonic Flowmeters for Small Pipes and Low Flowrate Model Selection:

RBFM-MK Model Selection
  Pipe size: DN10-DN40
  10 DN10 OD 12-18mm
15 DN15 OD 18-23mm
20 DN20 OD 23-28mm
25 DN25 OD 28-33mm
32 DN32 OD 33-44mm
40 DN40 OD 44-52mm
8 Please contact the factory
  Temperature Range
1 (-10 to 65°C)
2 (-10 to 105°C)
Model RBFM-MK 20 1  
DN20 (0D 23-28mm) Clamp on ultrasonic flow meter, transducer temperature range -10-65'C,24VDC power supply with 4-20mA and RS485(Modbus) output, cable length 2m.


RBFM-MK Series Clamp-On Transit Time Ultrasonic Flowmeters for Small Pipes and Low Flowrate Applications:

RBFM-MK Series Clamp-On ultrasonic flowmeter capable of measuring small liquid flow rates of ultrapure water, various chemical solutions, etc. without moving parts or sensors.

Suitable for

  • Incorporation into semiconductor manufacturing equipment;
  • Chemical equipment, chemical injection,
  • Ultrapure water, pure water equipment, 
  • Medical equipment,
  • Residential heating system water,
  • HVAC chilled water measurement,
  • Agricultural Climate Control,
  • Boiler water/feed water supplies,
  • Cooling water,
  • etc.


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