Small-Pipe Ultrasonic Flow Meter (OD 3–12.7 mm)
Clamp-On for Lab, Dosing, and Sub-DN10 Process Lines
Velocity 0.3 to 5 m/s, ±1.0 %, repeatability 0.4 %
24 V DC, 3 W. IP65 transmitter
Modbus RTU, 4-20 mA, OCT (open-collector) pulse
- V-method bounce path doubles the acoustic distance; captures flow on pipes as small as 1/8 inch.
- Velocity floor 0.3 m/s, below the 0.5 m/s floor on larger ultrasonic meters.
- Factory programs pipe material, wall thickness, and OD at order; no field commissioning of the acoustic geometry.
The Small-Pipe Ultrasonic Flow Meter is a clamp-on transit-time instrument for liquid service on pipe outside diameter 3 to 12.7 mm. Two transducers clamp on the outside; the acoustic pulse crosses the wall, bounces off the far inner wall, and returns to the second transducer (V-method). The firmware times the transit difference and returns volumetric flow at ±1.0 %. 24 V DC, 3 W. IP65 transmitter. 5–7 business days from the factory.
Benefits
- Sub-DN10 coverage that larger ultrasonic meters cannot reach. OD 3 to 12.7 mm covers 1/8 inch to 1/2 inch tubing; research lab, dosing pump, OEM lab equipment scale. No pipe cut.
- Velocity floor 0.3 m/s captures slow lab and dosing flow. V-method bounce path doubles the acoustic distance, which improves transit-time resolution at low velocity. Larger ultrasonic meters bottom out at 0.5 m/s.
- Factory programs pipe material, wall thickness, and OD at order. The acoustic time-of-flight calculation depends on these three numbers. Specify the pipe at order; the firmware ships configured.
- ±1.0 % of reading, repeatability 0.4 %. Linearity ±1.0 %. Suits research, OEM verification, and dosing-pump output check. For metrology-grade lab reference, go to a primary-standard calibration instrument.
- 24 V DC, 3 W. Modbus RTU + 4-20 mA + OCT pulse. IP65 transmitter. Pre-configured slave address. Works with lab data-acquisition systems and OEM controllers.
Configure your build.
Specify the pipe outside diameter, material, and wall thickness. The factory programs these three numbers into the firmware before shipment.
Your configuration
PF-UFM-SP-OD12.7-SS-W1.0-MOD-DC
OD 12.7 mm (1/2 inch) stainless steel tubing, 1.0 mm wall, RS-485 Modbus RTU + 4-20 mA + OCT pulse, 24 V DC.
Estimated unit price
$ 550
Request engineering quote
Request datasheet
Applications
🔬
OEM lab equipment integration
Chromatography, dispensing, and bench-top instrument fluid paths on 1/8 to 1/2 inch tubing. Modbus output integrates with the equipment controller.
🧪
Research and pilot-plant flow
Bench-scale reactor inlet, chemical reagent verification, small-batch process monitoring. Velocity floor of 0.3 m/s captures slow lab flow.
💉
Dosing pump output verification
Confirms peristaltic, piston, or diaphragm dosing-pump output on the dosing tubing. Continuous Modbus signal feeds the dosing controller for closed-loop trim.
📏
Metrology calibration reference
Reference instrument for low-flow calibration of dosing pumps and small-bore mechanical meters. Pair with a lab-grade reference for traceability.
Full specifications.
| Measurement principle | Clamp-on transit-time ultrasonic; transducer pair clamps externally on the pipe wall; V-method acoustic path bounces off the far inner wall and back |
|---|---|
| Channels | 1 acoustic path (V-method bidirectional) |
| Pipe outside diameter | 3 to 12.7 mm (sub-DN10 lab and dosing scale; covers 1/8 to 1/2 inch tubing) |
| Nominal diameter | Sub-DN10; the host tubing OD 3 to 12.7 mm is the measured size (see Pipe outside diameter row above) |
| Install style | External clamp-on transducer pair on sub-DN10 host tubing (see Install row below for spacing and coupling-paste detail) |
| Optional BTU pair | Not available on this model; sub-DN10 service is below the typical BTU calorimetry flow range; go to the inline BTU meter for DN15-DN300 heat metering |
| Accuracy | ±1.0 % of reading at velocity 0.3 to 5 m/s |
| Linearity | ±1.0 % |
| Repeatability | 0.4 % |
| Response time | 500 ms |
| Velocity range | 0.1 to 5 m/s operating; accuracy spec ±1.0 % within 0.3 to 5 m/s (lower accuracy floor than the 0.5 m/s on larger ultrasonic meters) |
| Install | External clamp-on transducer pair; no pipe cut; coupling paste plus stainless-steel clamp strap |
| Pipe materials | Stainless steel, PVC / CPVC, PVDF, PEEK, PTFE, copper / brass, borosilicate glass; specify at order so firmware programs the acoustic time-of-flight correctly |
| Pipe materials NOT supported | Soft tubing (silicone, Tygon); wall absorbs the acoustic pulse; go to a different flow technology |
| Output; analog | 4-20 mA, max load 600 ohm |
| Output; digital | RS-485 Modbus RTU |
| Output; other | OCT (open-collector) pulse + high / low alarm; relay 30 V DC at 1 A, switching frequency under 2 Hz |
| Display | LCD 2.4-inch IPS, 320 × 240 resolution, 4-direction rotation; unit selection m³/h, LPM, mL/min, GPM, LPH |
| Power | 24 V DC, 3 W |
| Medium | Single-phase liquid, 100 % pipe-fill; water, aqueous solution, chemical reagent; suspended solids 4 % or less |
| Medium temperature | −10 to +60 deg C (narrower than the −40 to +80 °C ceiling on larger UFM counterparts) |
| Ambient temperature | −10 to +60 deg C operating (transmitter housing rated to same range as medium) |
| Process connection | External clamp-on; no process port on the meter; mounts on sub-DN10 host tubing OD with stainless strap |
| Ingress protection | IP65 transmitter |
| Hazardous area | Not declared on this model |
| Compliance ships standard | Calibration record with each meter (serial number + tested flow range + programmed pipe spec) |
| Lead time | 5–7 business days from factory |
Installation rules.
Small-pipe clamp-on needs careful coupling. Five rules.
- Specify the pipe OD, material, and wall thickness at order. Firmware ships pre-programmed; record the pipe spec on the meter label for swap-out.
- Clean the pipe wall before clamping. Wipe with isopropyl alcohol. Coupling paste fills the air gap; dust or oxide layer adds time-of-flight error.
- Tighten the clamp strap evenly. Over-torque deforms thin-wall tubing and changes the time-of-flight. Hand-tight plus 1/4 turn is the working rule.
- Hold 10D upstream and 5D downstream straight-pipe (D = pipe outside diameter).
- Configure register map and slave address at commissioning. Factory pre-configures from the lab DAQ or OEM controller spec. Record both in the commissioning log.
Frequently asked questions
How does clamp-on ultrasonic work on a small pipe?+
Two transducers clamp on the outside of the pipe at an offset. One transducer fires an acoustic pulse that crosses the pipe wall, bounces off the far inner wall, and returns to the second transducer (V-method). The firmware alternates which transducer is the transmitter and times the upstream and downstream transit difference. The bounce path doubles the acoustic distance through the fluid, which is what makes meaningful timing possible on sub-DN10 pipe where the diameter is otherwise too small.
Why is the velocity floor 0.3 m/s instead of the 0.5 m/s on larger ultrasonic meters?+
Two reasons. The V-method bounce doubles the acoustic distance, which improves the transit-time resolution at low velocity. And the firmware is optimized for the small-pipe / low-flow range rather than the broad industrial range. Below 0.3 m/s the transit-time signal-to-noise ratio drops and accuracy falls outside ±1.0 %.
What pipe materials does the clamp-on work on?+
Most rigid plastics (PVC, PVDF, PEEK, PTFE), stainless steel, copper, brass, and glass tubing in the OD 3 to 12.7 mm range. The factory programs the firmware for the pipe wall thickness, material, and outside diameter at order so the acoustic time-of-flight calculation is correct from commissioning. Soft tubing (silicone, Tygon) is not supported; the wall absorbs the acoustic pulse.
How does it differ from the Standard Clamp-On for larger pipe?+
Pipe size and velocity floor. This meter covers OD 3 to 12.7 mm (sub-DN10 lab and dosing scale) with a velocity floor of 0.3 m/s. The Standard Clamp-On covers DN15 to DN6000 with the broader 0.5 m/s industrial floor and ±0.5 % accuracy on its main range. For 1/4 inch dosing-pump verification, pick this meter; for DN15+ retrofit on plant pipe, pick the Standard Clamp-On.
What ships in the package and what is the lead time?+
The kit ships with the external transducer pair, the transmitter, signal cable (factory-set length), the calibration record (serial number, tested flow range, programmed pipe spec), coupling paste, stainless straps, and a pre-configured Modbus register map and slave address. Lead time is 5 to 7 business days from the factory.
Need help spec’ing the small-pipe meter?
Send the pipe OD, material, wall thickness, and the service liquid. The factory programs these into the firmware before shipment. Lead time 5–7 business days.