Flow, level & control
of Titan’s ultrasonic flow measurement technology created the demand for ultra-low flow calibration:
Extending the Atrato Ultrasonic Flowmeter Range – Targeting flows >10× lower than the current minimum flow rate, with measurement capability down to 0.2 ml/ min or below. This would offer a competitive volumetric alternative to existing thermal lowflow devices.
Clamp-On Ultrasonic Flowmeter with Disposable Tubing – Designed to measure small batches of medical-grade fluids in a low-cost disposable tube. Potential applications include dialysis equipment and bolus delivery monitoring, where accuracy, sterility, and affordability are critical.
Both projects required calibration systems capable of extremely smooth, stable, and repeatable flow delivery. Direct integration of calibrator feedback into the control system was also essential. Full automation would also allow the rigs to perform complex flow profiles and transient tests while logging detailed performance data.
SUMMARY OF CONCLUSION For these development projects, the team designed hardware and software to produce smooth-flow, fully automatic calibration rigs, with a total flow range of 0.0054ml/min to 4l/min calibration capability and calculated uncertainty of 0.1 per cent. The software allows for multiple scenarios of operation, from long-term flow stability to short batch dispensing to be assessed with new meter designs. With the newly designed calibration rigs we were able to take concept designs for very low flow measurement using current ultrasonic knowledge and prove the effectiveness for flows down to 0.1ml/min at accuracies of ±1 per cent + 0.02ml/min.
In addition, the prototype designs for a clamp-on meter for use with silicone tubing on blood type liquids, were also proven to be reliable for flows of 5 to 400ml/min with linearity of ±2 per cent. With the versatile nature of the new calibration designs, meters were tested for linearity, repeatability, batch dispensing at multiple volumes and flow rates, as well as long-term calibration drift.
PROBLEM: LIMITING FACTORS Commercial low-flow calibrators with the required accuracy and versatility were not available, and bespoke systems proved prohibitively expensive. Building on prior experience with motorised piston systems, Titan therefore committed to developing next-generation low-flow calibration rigs in-house. Based on previous work with ball screw driven piston systems, one of the main issues encountered was the method to ensure accurate measurement
Instrumentation Monthly January 2026 Fig 3. Chart showing Flow Cycling of original design versus new design as measured by Atrato® flowmeter
Fig 4. Example Mass Calibration report on the new Piston Prover Calibrators
Fig 5. Low flow calibration rig design with liquid on piston side of cylinder to improve the resolution at very low flows: 0.0054 to 10 ml/min (0.324-600ml/h)
of the piston movement, coupled with smooth, reliable delivery. The commercial piston provers used controlled pneumatic or hydraulic feed and relied on linear encoder to measure the
progress of the piston. Complex and expensive as this method is, it inherently provided a good, measurable liquid flow. By moving to a mechanical threaded driver, reliance on the thread rotation and
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