Available in 0.5 through 2” models, the Type-21a Seat Support Technology (SST) has a precision-machined PVC ball with center provisions to support PTFE seats from zero to 100 percent of capable flow. The ball valve produces equal percentage flow characteristics for fine throttling. The valve requires directional installation and comes equipped with a flow direction label. Manually operated ball valves include a zero-to-100-degrees indicator plate and an indicator line on the handle, which doubles as a carrier-adjustment tool. An ISO 5211 top flange bolt pattern and integrally molded base pad for panel mounting are standard. The valve body is PVC with either EPDM or FKM O-rings. Socket, threaded and flanged end connections are offered for the ball valves. Options include electric or pneumatic actuation with 4 to 20mA control, stem extension and 2” square operating nut.