The Smart III RF Moisture Probe, both on-line and continuous, answers the industry need for instantaneous, non-destructive moisture measurement in storage and in-process silos. The RF (radio frequency) probe typically installs near the bottom of a vertical silo near the point of product discharge. Multiple probes can be installed top, middle, and bottom of the silo should measurement of moisture gradients be desired. The probes can be manufactured in various lengths from 6 inches to 48 inches to accommodate facility requirements. The probes are ¾ inches in diameter and easily install in a ¾ inch NPT flange welded to the side of the silo. The probes simply screw into the flange and are then connected via two short cables to a separate oscillator box mounted within 15 feet of the probe.
The probe operates using the capacitance principle wherein the tip of the probe acts as one plate of a capacitor while the barrel of the probe acts as a second plate. The radio frequency field is then transmitted via a low AC volt signal from the tip of the probe across a 1-inch wide insulator to the barrel of the probe. Typical field penetration is about 3 inches. The insulator can be Teflon or ceramic depending on the temperature of the product within the silo. Teflon insulators are good up to 200 deg. F, while ceramic insulators would be appropriate for product up to 482 deg. F.
The Model Smart III RF Probe readout console offers a variety of output signals including 4-20ma, Ethernet IP, a low voltage signal, Profibus, Profinet, Devicenet, etc. When connected to the plants PLC or DCS, automatic moisture control is possible thereby providing instant moisture correction with minimum operator interface. Charting capability and unlimited calibration tables (up to 7 points each) are built in to the readout console. Software is Windows based, so any future needed updates can be easily downloaded. Output smoothing and loss of product alarms are also included. High and low moisture alarms are provided from the PLC using the SMART III console signal output.