However, due to the reference potential of the piping, there is a risk of failure or even electric shock. SMC has therefore expanded its range of flow switches with the LFE-Z series in an insulated version. This eliminates both a voltage potential on the piping and an unwanted current flow within the system.

Whether pressurized cooling water for welding guns, cooling water for metal moulds or water-soluble coolants: flow control is a standard application in the industry. Depending on the design of the installation, external galvanic isolation of the supply voltage can prevent unwanted current flows within the system or a voltage potential on the pipeline - however, this requires more components and increases the cost of the power supply. SMC has therefore expanded its LFE series of flow switches with the LFE-Z series, which solves the problem much more easily thanks to the isolation of the pipe connection from the power supply. At the same time, users benefit from all the existing advantages of the LFE series.

Insulation via two different earthing types

The design of the LFE-Z series electromagnetic circuit breaker creates potential isolation between the supply voltage and the housing/piping in order to solve the problem of voltage potential on the piping or unwanted current flows within the system. Depending on the application, process engineers can use either a positive or negative earth connection without having to take this into account separately in the cabling. Thanks to the absence of external galvanic isolation of the supply voltage, fewer components are required overall - which saves costs.

Even in the isolated version, users can access a nominal flow rate of min. 0.5 (LFE1-Z) to max. 200 l/min (LFE3-Z), depending on the model, at an operating medium temperature of 0 to 85 °C. While the repeat accuracy of the displayed values is ±2% F.S. (full scale) and ±1.5% F.S. at the analog output, the flow direction can also be changed manually after installation. If backflows occur, the flow switch detects them and indicates this as an error message on the 3-color display. The following parameters can be set and displayed: Set value, flow direction, cumulative value, system designation as well as maximum and minimum value.

The compact design of the LFE-Z series with a width of 40 mm and a height of 56 mm ensures that process engineers can also make do with the limited space available. In addition, at around 340 g (LFE1-Z) to a maximum of around 680 g (LFE3-Z), they are lightweights that also enable a slimline machine design.

Thanks to their extensive features, they are suitable for monitoring cooling circuits in welding guns, cooling and lubrication circuits, water circuits in casting molds and many other applications. And thanks to their insulation, they not only protect against breakdowns, but also against electric shocks, thus making an important contribution to greater process and occupational safety.