Valco Selectors

Selectors (multiposition valves) step incrementally through continuous revolutions, instead of switching back and forth like two position valves. (Selectors step bi-directionally with microelectric and universal actuators.) The preload design allows the rotor to be inspected or replaced without taking the valve off the actuator. Valves ordered with a microelectric actuator are permanently aligned.

Valco selectors are available in five lower pressure flowpaths typically used in gas chromatography applications, and two high pressure flowpaths suitable for high performance liquid chromatography.

Flowpath configurations

SD: Dead-ended

SD valves select one of 4 to 16 dead-ended streams, directing it through the valve outlet to a sample valve, pressure sensor, detector, column, etc. The same configuration can also direct one stream to a number of outlets for fraction collection.

SC: Common outlet

SC selectors are similar to SDs. They select one of 4 to 16 streams, with the selected stream flowing from the valve outlet to a sample valve, pressure sensor, detector, column, etc. The non-selected streams flow to a common outlet, instead of being dead-ended as in the SD model.

SF: Flow-through

SD and SC valves select and isolate one of 4 to 16 streams, with the remainder dead-ended in the SD and flowing to a common outlet in the SC. The SF selector is similar, but carries the evolution a step further with the non-selected streams flowing through individual outlets.

ST: Trapping

ST selectors are used for multi-column, multi-sample, or multi-trap operations, and are available for use with 4 to 16 loops, or positions. Valves can be ordered with matched loops already installed.

STF: Trapping flow-through

The STF selector is a variation of the ST flowpath, with the single difference that the non-selected streams are returned to their own vents or sources rather than being dead-ended or trapped as they are in the standard ST configuration.

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