Process safety specialist Smith Flow Control has introduced a new series of valve interlocks. The new QLS and GLS interlocks provide a mechanical process management system for potentially hazardous valve operations requiring strict sequential control. A new feature is on-site lock re-coding. This lets plant managers quickly adapt interlocking sequences to changes in process logic. Interlock process control systems are typically used to support “Permit to Work” procedures during safety relief valve changeover, pig trap loading and retrieval, and filter changeover. These new safety devices can be integrated with most quarter-turn and multi-turn valves, up to 3 inches diameter, in ball, plug, gate, butterfly and globe formats. Retro-fitting on operational plant is possible without shut-down, since the interlocks simply replace original hand wheels or levers.