wood moisture sensors and signal generated

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Anonymous

What sensor can I use to measure wood moisture content of timber in a closed drying kiln and connect to a telemecanique plc for control purposes? Temperature range is 100 degree celcius.
 
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Trevor Ousey \(List\)

Once you get over 100 degrees using resistance is not effective. We tried using a system from Wagner (US) around 10 years ago, wth limited success, connected to a Basic module on a TI545. One of the more current systems in use is using loadcells and monitoring the weight during drying.
 
Been awhile since I was in the wood products industry But I do recall our Kiln operators using a handheld device and they would drive a two probe sensor into random boards to get an idea of the moisture content of the kiln charge, I think it was developed by Moore. I would imagine you would have to have several sets of sensors strategically placed in the load to assure a statistically viable read though. Are you using humidity measurement in the kiln? That is how I remember we would monitor the progress of the kiln schedule.

Good luck, Mike
 
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Troy Hammerbeck

Sensor Tech has been doing online moisture for over 25 years. They make complete online moisture profiling systems for kiln balance and control. Check out their website: http://sensortech.com. In the meantime if you have any questions call Pete Naiden who is the national sales manager for Sensor Tech/ Moist Tech. (203)685-8710
 
There are on the market some pin-type moisture meter developed for wood drying kilns.

We produces a moisture measuremets board and all other parts of the kiln control system. http://www.cet-electronics.com

Our moisture measuremet board has an insulated RS485 interface and implements the modbus protocol. Wood moisture measures are temperature compensed, the precision is very good under 90ºC, over they get a less precise due to rapid changing of the conduction working principle (near 100ºC almost all water-cellulose bounds are broken).
 
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