• • • SENSORS & SENSING SYSTEMS • • •
HOW AN EASY-TO-USE SENSOR MODULE CAN BRING FLOW INTELLIGENCE TO CONSUMER AND
INDUSTRIAL EQUIPMENT BY ANDREAS BLOCHERER, PRODUCT MANAGER, SCIOSENSE C
offee shops are tasked with the job of drawing the exact dose of water required to produce the full richness of a perfect
cup of espresso. For a pub or bar it is about serving exactly a pint of beer so that the customer gets no more and no less than they paid for. For the industrial process control engineer, the requirement is to know exactly when a filter has cleaned its rated volume of water and is due for replacement. In these brewing, dispensing and filtering applications, accurate flow sensing can substantially increase the value of equipment or machinery. Traditional electromechanical technology for flow sensing has, however, been a pain point for system design engineers, causing performance and reliability headaches which have proved difficult to eradicate.
12 ELECTRICAL ENGINEERING • MAY 2026
Pure electronic sensing using ultrasonic technology eliminates the moving parts from a flow sensor assembly, and provides an escape route from the problems with traditional flow sensors. When first introduced, ultrasonic sensor ICs posed a considerable integration challenge which generally restricted their use to the manufacturers of specialist measurement equipment. But now successive generations of complete off-the-shelf ultrasonic flow sensing modules, which provide a simple measurement interface to any microcontroller, have made accurate, reliable ultrasonic flow sensing a valid option for non-specialist designers of any type of equipment which can benefit from flow rate measurement.
Stuck with traditional
turbine-based flow sensors Flow sensing has traditionally been performed with a simple electromechanical assembly: a length of tubing with turbines inside is positioned inline with the flow. The speed of rotation of the turbines can be converted to a measurement of flow rate. Over time, the flow rate measurements
can be integrated to provide an absolute measurement of the volume of liquid which has passed through the sensor.
This method of sensing flow provides a simple measurement interface to an external logic device such as a microcontroller or programmable logic controller (PLC). But equipment manufacturers have to take account of serious drawbacks which can limit the sensor’s usefulness, or even make the sensor inoperable. The problems stem from inherent mechanical characteristics of the turbine or wheel in the assembly.
The first problem is that a turbine has friction which creates inertia: at low flow rates, the force of the flow will be insufficient to overcome the turbine’s inertia, and so the turbine will fail to rotate. As a result, a low flow rate will be registered as zero flow. Part of the value of many applications for flow sensing is the ability to measure leakage, in other words, a fault condition in which the flow is continuous, but at a much lower rate than in normal operation. In this case, an electromechanical flow sensor will be able to measure normal flow, but will likely fail to alert the operator to leakage.
electricalengineeringmagazine.co.uk
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