Paddle Flow Switch - LFS Series. The LFS range of flow switches are paddle devices that are mounted vertically through a socket or upstand process connection. Electrical connections are made within the housing, which has a screw on sealed lid and cable gland. A choice of paddle sizes is supplied with each switch. Higher temperature versions are designated by "H" in the part number. Features and Benefits. Stainless steel SS 304 paddle. G3/4"" or 1""NPT mounting plug thread. Aluminium alloy housing or DIN 43650 plug. Maximum operating pressure 20 bar. Operating pressure up to 150°C (H versions)