In modern, production-related analytics, online processes are becoming more important than traditional laboratory methods. The latter, that is still dominant particularly in the chemical industry, allows a complete analysis of all selected parameters. However, analysis tools are not directly connected with the production process. This method is therefore called off-line analysis.
Off-line technology is characterized by the fact that samples are taken discontinuously. Analysis time in the laboratory may take hours before having the results.
Laboratory analysis provides greater flexibility in the choice of methods than online analysis. Another advantage is the fact that samples with unknown components can be analysed successfully.
Negative effects result from the greater expenditure of human labour and from the delay between sampling and results, which can last between hours and days. Further disadvantages are the discontinuous equipment utilization and the high cost of the required laboratory tools.
In contrast, online process systems are directly and continuously connected with the production process. The entire analytical process takes place automatically without interruption. Measuring parameters are obtained within seconds or minutes.
This constant and immediate monitoring of relevant process parameters permit fast reactions to changes in the production process and increases the safety of workers, the plants and the environment. It also supports process optimisation and helps to enhance product quality. Thereby it contributes significantly to the increase of efficiency and to the reduction of costs.
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Schematic comparison between online and off-line techniques

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