Non-invasive Microwave Sensors for the Monitoring of the state of Liquids Used in the Polyurethane Industry

A dynamic microwave sensor system able to monitor compositional changes of the basic liquids used in the polyurethane industry (polyol and isocyanate) was designed, installed in the production line and tested. These liquids are continuously flowing into hermetic pipes and its desirable properties are gradually degraded in time. The sensor provides online information about the state of the liquids by means of microwave non-invasive measurements. This information can be used in real-time non-destructive quality control processes. The sensor technology described here can be used for the monitoring of other liquids used in chemical industry.