Dielectric Moisture Measurement
Sensortech’s ST-2200A Moisture Measurement and Control System is designed for continuous monitoring of moisture composition in harsh environments where extreme temperatures, severe vibration, and excessive dust or debris typically exclude the use of other methods of moisture measurement.
The ST-2200A uses a proprietary Radio Frequency Dielectric Measurement to analyze the moisture composition of your product. In contrast to the surface measurement techniques of Near Infrared Reflectance (NIR) and Thermal Imaging technologies, the RF energy deeply penetrates the product minimizing the influence of moisture distribution.
Sensortech produces more than 40 RF sensor styles to satisfy most manufacturing locations and requirements. The ST-2200A provides an advanced level of stability, repeatability and precision measurement regardless of environment and product complexity.
The product passes over the sensor where the moisture measurement is taken. The open-frame minimizes buildup of debris by allowing product to fall through it and is commonly used for applications having extreme temperatures, excessive vibration, or other harsh environments. Typically used between conveying belts or rollers and In-Kiln locations.
The product glides on the sealed Teﬂon or ceramic surface of the sensor where the moisture measurement is taken. The sensor is ﬁxed in place using the ﬂange-mount and is placed in critical points throughout your production process. Performs well in high vibration environments and is ideally suited for granular or powdered products. Typically used in bins, hoppers, planar (sloping/horizontal) surfaces and conveyor drop-off points.
The product passes underneath the sensor where the moisture measurement is taken. The sled hangs from hinged arms allowing it to maintain a parallel position to the conveyor and to level the product for consistent measurement. Other varieties of Sled Sensors include the Skid-Plate Sensor that has a smooth abrasion-proof surface designed to have a gentle impact on sensitive products. Typically used on conveyors (sloping/horizontal).
The product ﬂows through the pipeline where the moisture measurement is taken. The Application Interface is made up of a pipe with an attached sensor that is integrated into the pipeline framework of the production process. A variation of the pipeline sensor is the coaxial pipeline sensor which features a center electrode providing a uniform radial field through the product to the pipe wall. An optional heater jacket ensures that the product does not solidify. Typically used with production processes manufacturing fluids, pastes, and confectionery applications.
The product enters a sampling tray or chamber where the moisture measurement it taken. A digital output of the Processor Unit is used to control the fill and purge method of sampling. Common types of Sampling Sensors include a Piston-Purge and Air-Purge Application Interface that uses different techniques of sampling the product. Sampling Sensors can be found in production processes where a small sample is taken from a large flow of product or where it is not possible to maintain a reasonably constant ﬂow of product over the sensor.
Central Components of the ST-2200A
Application Interface (RF Sensor)
The RF Sensor (Antenna) provides the source of the Radio Frequency Dielectric Measurement using on of over forty adapted housings suited to your specific application.
A NEMA12 rated metal enclosure contains the moisture measurement and RF switching electronics that is used to collect the signal received from the Application Interface (RF Sensor). It is housed separately from the Application Interface allowing the ST-2200A to operate in harsh environments including temperatures up to 1000°F (540°C).
Particular applications requiring high sensitivity will use an Application Interface housing having an Attached Sensor Electronics enclosure. These Application Interfaces combine the RF Sensor with the Sensor Electronics to form a single component of the ST-2200A
Processor Unit (Signal Processor)
An intelligent measurement and control unit that connects to the Sensor Electronics and provides moisture measurements via serial communication protocols (RS-232/485), 4-20mA outputs and the front panel LED display.
Controller / PLC (User Defined)
Your existing control system receives the serial communication from the Processor Unit. This communication provides a critical moisture measurement variable that can be used to make appropriate adjustments to your production process.