Flow, level & control
ULTRA-LOW FLOW ULTRASONIC FLOW METER
The ultra-low flowmeter target was to investigate the feasibility of developing an ultrasonic device operating at lower flow rates than any other ultrasonic
Fig 7. Ultra Low Flow Meter Prototype with 1/16” tube connections
devices currently known to us. The target was 0.2 to 20 ml/minute which is ten times lower than existing Titan devices. The production aim was to incorporate this range into our next generation Atrato range. The design principle has a compromise of velocity in the flow measurement tube and length of the tube. Increasing both, increases the time-of-flight difference of the ultrasonic wave travelling in both directions. Increasing velocity requires small bore for low flows which suffer from attenuation of signal and interference of background noise; whilst lengthening the tube makes the response of the meter much lower and suffer from loss of flow measurement signal strength. Prototyping of a variety of configurations, together with additional novel design aspects, becomes a crucial part of development in these advanced technical breakthroughs. The graph in Fig 8. above displays the results obtained from the fifth evolution of the ultralow flowmeter. The 0.2ml/min target was easily achieved, and flow readings were possible down to 50 microlitres per minute under laboratory conditions. The result provided confidence to meet the 200 microlitres per minute target for the final device when set for production.
Development work continues to optimise the flowmeter design based on the best accuracy available at reasonable response times. Novel engineering of the flow sensor element has enabled subsequent designs to improve the flow response time by a factor of 50, whilst maintaining accurate readings. The chart in Fig 9. illustrates the results of two measurement tube flow range designs, meeting ±1.0 per cent + 0.04ml/min accuracy with raw measurement. Calibration linear correction is expected to improve on these results for later designs.
CLAMP-ON ULTRASONIC FLOW METER In response to a customer’s requirement for flow measurement in a disposable medical tube - specifically involving smallbore silicone tubing for plasma-type fluids delivered by peristaltic pumps - Titan developed prototypes to meet their specifications. Initial designs based on Titan’s Metraflow flowmeter were created using their proprietary knowledge and 3D printing capability to offer practical prototypes for the customer to test in-situ. The prototypes were also fitted with the customer’s tubing to test the feasibility of a clamped unit. Utilising the new ultra-low flow calibration rigs enabled quick assessments to be performed on water in Titan’s in-house facilities.
Fig 12. Multiple tube replacement variation in calibration at the ultra-low flow region
Fig 13. Batch dispensing variation at different dispense volumes and flow rates
Fig 10. 3D printed clamp-on prototype with clamp sensor over silicone tube and separate display
of system. Accurate and reliable dispensing measurement is a key area in the medical flow industry and again, initial trials of multiple dose scenarios enabled by the new calibration rig design, could be tested. The graph above (Fig 13.) shows some of the results of dispensing multiple times at different flow rates and total volume dispensed. Even at very low dosing of less than 1ml volume, the repeatability is within 5 per cent at all flow rates - again a very encouraging result. Working with OEM partners, Titan is developing this meter design for multiple tube sizes and materials with a focus on the medical and biopharmaceutical markets, where dosing or flow monitoring is required.
CONCLUSIONS
This complex project demonstrates Titan’s in-house expertise in exploring practical resolutions to overcome limitations in R&D and expand our breakthrough technology.
Fig 8. Example calibration 0.05 to 20ml/min flow range
Fig 11. Initial calibration silicone tube 5-400ml min @ ±2% linearity
Fig 9. Two prototypes of ultra-low flow ultrasonic meters. Accuracy of ±1% + 0.04ml/min without linear correction implemented. Measuring reliably down to 0.15ml/min.
Instrumentation Monthly January 2026
The basic linearity of initial designs proved to be quite acceptable with a typical linearity of ±2 per cent over the flow range of 5 to 400ml/min (see Fig 11.). For such a system to operate practically in the field, it must be reliable and repeatable even when tubing is continuously removed and refitted into the housing. Initial testing gave a variation between multiple tubes of about ±2 per cent and only became more variable at the very low flow end as the noise level increased in the ultrasonic flow signal (Fig 12.).
Apart from flow monitoring, volume dosing is the other key technical challenge for this type
By developing in-house capability for accurate and versatile meter calibration and testing, Titan can quickly advance the process from prototype to verified product. In-house proprietary software allows for rapid testing of multiple scenarios encountered by our customers, helping ensure processes are optimised.
The calibration rig design principles will enable Titan to develop and build advanced tools tailored to customer-specific needs. Future developments include novel fluid test units and fully temperature-controlled systems, supporting the creation of cutting-edge products for both universal applications and OEM-specific solutions in the global market.
Titan Enterprises
flowmeters.co.uk 21
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