SC valves select one of 4 to 16 dead-ended streams. The selected stream flows from the outlet to a sample valve, pressure sensor, detector, column, etc. SC valves are similar to the SD configuration in that regard, but instead of being dead-ended as in the SD valves, the non-selected streams flow to a common outlet.
Low pressure SC selectors are made of Nitronic 60, with a rotor made of Valco E, a polyaryletherketone/PTFE composite. Valves are rated from 100 to 200 psi gas and 75° to 200°C, depending on the fitting size and number of positions.
Valves can be actuated manually or automated with pneumatic or electric actuators. GC valves usually require a standoff - an extension between the valve and actuator which allows the valve to be mounted in the heated zone while the actuator or handle remains outside at ambient temperature. Standoffs are available in lengths of 2", 3" 4", and 6".