The moisture contents (MC) of wood as well as the air humidity (EMC) are important values when drying lumber, no matter if in kilns or in an air drying yard. Many key players in the wood drying industry rely on a probe based system. This type of system, where readings for MC and EMC are based on the electrical resistance of wood and wafers, provides the best compromise in accuracy, user-friendliness and cost.

The technology for placing the measuring circuitry in the hostile environment of a kiln was not available in the past. For that reason, long Teflon coated cables were needed to connect the sensors (MC probes driven into the wood and EMC wafer holders) to the measuring device located outside of the kiln. These long cables reduce the accuracy of the readings because the sensitive, low-level analog signals being carried can easily be distorted by leakage currents along the cable (especially at the connectors) or by interference from electromagnetic noise (generated by fan motors, variable speed drives, etc.). The cables are also cumbersome for the kiln operator when loading and unloading the kiln as well as easily damaged when entering the kiln during the drying process.

With the introduction of the Wireless Probe System (WPS), patent pending, the sensor cables become obsolete, thus eliminating the problems described above. The sensors, probes for MC and wafers for EMC, remain the same.

WPS Applications

The wireless probe system can be used for many applications due to its flexible design and easy interfacing to standard equipment. The system is ideal for replacing in-kiln wiring for less maintenance. For open air drying, any number of transmitters can be used to monitor the entire yard from a PC using standard tools like Microsoft Access. Forced-air drying sheds, drying yards, and pre-dryers can now be easily monitored from one central location. Anywhere accurate moisture and temperature monitoring is needed without the hassle of cables, the WPS can be used.