The SSV series stream selector system delivers a representative sample from multiple sample streams to a single analyzer. These modular assemblies are ANSI/ISA 76.00.02 compatible and accommodate multiple process streams in a limited amount of space. Each stream is controlled by a double-block and bleed (DBB) module to eliminate cross contamination and maintain sample integrity. Based on a modular technology concept, these valves house double-block, bleed and actuation functions within a single, compact module to reduce total space needed to perform sample stream selection and overall installation time. As system requirements change, modules can be added or removed.