FSVPLC Inline Flow Switch. The FSVPLC can be used to control some other equipment or process via a PLC. If used in a pumped system, the device has to be fitted in the pipe above the pump. The FSVPLC gives a closed contact signal to the PLC once the flow rate exceeds 0.6 L/min or 3.0 L/min, depending on version. Features and Benefits. Signal level output to PLC. 0.6 L/min or 3.0 L/min turn on flow rate. Automatic shut down on flow stop. G1"" pipe connection