Abstract: A valve assembly for controlling fluid flow through at least three flowlines comprises a housing having a cylindrical central cavity with at least three ports opening therethrough, the housing further having at least three conduits for making fluid connection between the flowlines and a corresponding one of the ports. A flow control signal is rotatably mounted within the central cavity having at least three radial bores therethrough and intersecting therein for completing a fluid path between selected ones of the ports. A radial seal is supported by the spool and is configured to prevent fluid migration into the central cavity from non-selected ones of the ports. The spool can be positioned to complete a flowpath between any two or any three of the flowlines while the non-selected flowline is positively sealed. The housing and spool are composed of a non-opaque or transparent material to permit direct observation of the fluid passing therethrough.