For many medical and laboratory uses, however, verification of liquid flow is paramount, and incorporating sensors or electronics to validate the execution of functions such as valve switching can complicate design.
The answer, developed by Bürkert, lies in a suite of algorithms that can monitor the induced current within its electrodynamic Whisper valves. A range of diagnostic functions detects faults for immediate and preventative maintenance, and provides a boost in process intelligence.
In a dialysis machine, precise timing and positioning of each valve is critical in maintaining controlled, sterile, and safe therapy. If a valve cannot open, either blood or dialysate flow may be restricted, leading to reduced toxin removal and potentially causing pressure build-up.
Alternatively, if a valve fails to close, fluid may leak or flow in the wrong direction, risking contamination. This scenario can thus easily be related to various medical appliances in which the controlled flow of liquid is an intrinsic part of point-of-care procedures.
In a laboratory setup, the result may not be as immediately crucial; however, the deviation in valve actuation results in inaccurate flow, thereby returning wrong results or wastage of the sample. Since the liquid volume is usually at the microlitre level, it could take a while to identify the errors.
Be it medical or laboratory applications, poorly performing valves might be due to a variety of reasons such as mechanical wear and tear, clogging, or crystallisation of the media. Whatever the cause, identification, diagnosis, and maintenance need to happen quickly.
Across these applications, there is a need for a solenoid valve that can switch rapidly and handle high pressures to keep safety and sterility. These are combined with a very low level of operational noise essential for the patient settings, while this feature is important in the lab; thus, the name ‘whisper valve'.
Typically these valves are analogue with no means of monitoring if or how they were actuated. A 24‑volt signal can be supplied but this doesn't provide feedback on whether the valve's opening or closing rate are performing as required.
Diagnostic devices such as flow meters or photoelectric sensors can be installed downstream but aside from adding cost and footprint their integration complicates device design.
Now a new development for valves with electrodynamic actuators, for instance, Bürkert Whisper Valves, offers a diagnostic variant in which the valve serves as the sensor.
A valve with an electrodynamic actuator possesses a coil arranged in a magnetic field. Once electrical current passes through the coil, it provokes the Lorentz force, which shifts the coil to realise precise and fast motion of opening or closing the valve.
When voltage is applied to the coil, it draws raw, ohmic current, but this does not convey enough information about valve switching status. However, the coil moving within the magnetic field under the Lorentz force induces an additional current.
Analysing this induced current-which in the end provides a wider scale and more precise measurement of valve stroke-allows the system to interpret the actual motion of the valve and, ultimately, its switching status and factors influencing its switching behavior.
A decisive advantage of this new possibility is simplicity of integration. Instead of requiring additional third‑party sensors or electronics for data acquisition, the ValveInsight solution from Bürkert uses a set of algorithms that are made available open source on the developer platform GitHub.
By integrating the algorithms into existing electronics, manufacturers of devices and processes can quickly add more intelligence to their products. Depending on the functional OEM equipment requirements, several algorithms for switching detection and/or switching time monitoring are available.
Valve switching detection is another major function that assures whether or not the valve has completely switched. The induction current curve against a known profile for an entire stroke is interrupted at this point. Therefore, immediate switching anomaly detection would, for instance, be able to detect blocked valves.
Thereafter, it confers process safety in highly critical applications inside a medical setting or reduces lab wastage or even lab downtime. This capability also adds key data for documentation purposes, essential to pharmaceutical production.
Monitoring of switching time is also possible. In critical dosing applications, evaluation of the deviation from the speed curve can determine problems with the valve or with changing environmental conditions. While switching detection provides immediate identification of blockages, switching time monitoring can be vital to detecting developing issues that alert for preventive maintenance.
These algorithms can also be trained according to particular application requirements. For example, it could be developed to identify empty tanks, whereby a customised algorithm detects air in the valve, adding redundancy to tank‑level monitoring.
The algorithm could also be taught to understand normal state conditions, thereby recognising deviations caused by factors such as changing liquid viscosity, feed rate or back pressure.
This functionality is integrated into Bürkert's Whisper Valve design. While OEM customers are given full access to the suite of ValveInsight algorithms, allowing them to try out and develop custom solutions if needed, this can also be fully supported by Bürkert's flow‑control engineering expertise.
While GitHub provides complete resources to get the most from ValveInsight, an Evaluation Kit allows users with the hardware to quickly get up and running. The Evaluation Kit enables current measurement, voltage measurement, valve switching circuits, and a controller to execute the algorithm.
Users can also test the standard switching detection algorithm with a blockable valve directly on the controller or use their own controller with the measurement circuits provided with the Evaluation Kit electronics.
When precision and reliability in liquid handling are critical for an application, a closed‑loop solution that adds feedback on valve performance is necessary. While ValveInsight adds this layer of security, its diagnostic capabilities can offer a number of benefits whose algorithms can be explored for tailored needs. What's more, tapping into these insights is possible without major redesign of an OEM's existing equipment.
In medical fields like dialysis and other fluid-dependent treatments, this means safer, more reliable therapy with fewer risks of contamination and malfunction.
In laboratories dealing with liquid volumes in the microliter range, that means more reliable dosing, less sample waste, and more accurate results.
In pharmaceutical production and in-vitro diagnostics, this allows for easy documentation and quality assurance due to data logging and immediate fault detection.
Learn more about Valve Diagnostics
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