Type  63FL in flanged design have a directly acting and external medium operated type of control  and need compressed air from 4 to 10 bar for switching. They have a simple  and solid design and quick reaction times. They can also be used for dirty, aggressive and highly viscous mediums. High  quality valves, very suitable for large series plants thanks to their variable design. In order to avoid water hammer effects, just select the option "valve closes against the media" .