The ball check valves with integrated sight glass CSF are used for monitoring the flow in pipelines where a wide range of corrosive and toxic fluids circulate. These valves lined with PFA-fluorine polymer combine the characteristics of the ball check valves and sight glasses offering the advantage of the visual control of the PTFE ball during its moviment. The CSF valves are suitable for connection with flanges according to DIN EN 1092-1 or ANSI B16.5 150/300 class.