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Tech Update

Moisture Measuring Equipment

by Tech Update Editor: Helen Johnson

In the manufacture of dimensional lumber and other wood products, moisture content monitoring is the key to a number of vital aspects of product and mill management, and profitability. Moisture content (MC) measurements are an important quality control tool that ensures the final product meets specifications required by end users. As well, dimensional lumber mills are vulnerable to product liability claims when the MC of a shipment exceeds standards. Lumber drying management is contingent upon MC monitoring, especially final MC. Product liability prevention, lumber drying management and grade recovery are all contingent upon this technology.

Wagner Electronic Products:  Wagner makes state of the art MC technology available in four product lines encompassing the needs of dimensional lumber production. Inline MC monitoring and management is accomplished with the System 750M, using the latest Electromagnetic Wave Technology. The system offers three high and one low level 24V DC outputs with user adjustable MC set points and preset high and low levels. The 750D inline continuous MC detection system detects wet boards prior to planning. System 750D146 is a linear (end to end) tech_update_1.jpg (2708 bytes)configuration with one non contact sensor and System 750D220 is a transverse configuration with three (and optionally up to six) sensors. Inkiln high limit MC setpoint detection is accomplished with the Model 987, which can determine when a stack of lumber is at the target MC, once the timber charge is less than 24 per cent. Using a resistance measurement method, the Model 987 samples more boards than the traditional "nail" system. Fillet sensors contact the surface of each board within a stack layer, which are then connected to a small PLC. Inkiln "hot checking" is accomplished with the Model L612/L712 combination. The L612 digital recording moisture meter takes up to 5,000 separate readings and stores them in up to 200 organized groups for comparison of average MC, standard deviation and minimum/maximum MC. The nonvolatile memory stores the readings even when the batteries are removed. Each L612 comes with a PC compatible software package, StatPac, for archiving and report generation. General purpose "spot checking" is accomplished with the quick scanning Model L6013.

Lignomat: The Lignomat Inline Moisture Meter tracks and analyzes each piece of processed lumber using dual frequencies for accuracy regardless of density changes between species. With a repetition accuracy of +/0.5 per cent wood moisture or better, it has been designed to allow the use of 18, 21 and 28inch moisture measuring heads, each measuring MC from six to 27 per cent (maximum fibre saturation). Once completed, species calibration can be recalled when required. Board width is measured to accurately calculate MC and any combination, wet or dry, can be rejected. Output signals are 120 or 240 VAC and can trigger a PLC, spray system or dropout gate. Equipped with online diagnostics for rapid troubleshooting and repair, the system includes one to six moisture measuring heads, one to six moisture sensor controllers, a rotary encoder, photo eye, limit switches, operator interface and control processor. Lignomat has also implemented a spot/streak feature that allows rejection of a board if one head reads at or above a set value or if consecutive measuring heads read at or above a set value. Lignomat also offers a Host PC that is connected to the moisture meter via Ethernet. The PC enables the generation of MC reports, setting up charges to be loaded into the moisture meter at the operator interface and setting up species calibration from an office

Delmhorst Instrument Co.: Delmhorst Instrument's R2000 Wood Moisture Meter calculates and displays the accumulated average of highest readings and measures the percentage of MC over the range of 6 to 60 per cent. Features include: builtin individual species and temperature corrections, memory for up to 100 readings and a user changeable setpoint with audio to alert for a preselected percentage of MC. Delmhorst's pintype moisture meters provide reliable readings in lumber production, drying and all phases of manufacturing, the company says, and accurately measure the difference between surface and core moisture, while giving an estimate of the average MC and the range of MC.

Northern Milltech Inc.:  Northern Milltech offers the MCPro 1000 transverse sawmill moisture density sorting system for increased grade recovery, tech_update_2.jpg (4597 bytes)optimized drying times, decreased trim loss and maximized returns. The electronic based sensing system injects an electric field into the wood from both faces, giving accurate readings. Using both moisture and density to calculate wet readings, the system processes more than 200 pieces per minute, accepts multiple thicknesses of any species and can process frozen wood. Eight, full contact sensor heads, single pass calibration, auto temperature and humidity correction and a full function program are among its other features. The system can be easily configured and interfaced with sawmill sorter lines, says the company. The MCPro 2000 planer inline moisture sensor uses electronic based, full contact sensing rolls and offers automatic adjustment for temperature and humidity, full diagnostic functions for lumber testing and a paint marking system. The MCPro 2000 handles line speeds in excess of 2,000 ft/min, while shift reports give real time and printed information on overall MC characteristics. It interfaces with the MCPro 3000 bundle tracking database system, which allocates bar codes to bundles for scanning and database tabulation of MC results.

MSC Moisture Systems:  MSC Moisture Systems offers the SpectraQuad near infrared (NIR) process analyzer for online moisture and constituent measurement. Incorporating patented QuadraBeam optical system technology, the SpectraQuad integrates the measurement sensor tech_update_3.jpg (4775 bytes)and the traditional processor control unit into a single standalone package, providing a high performance, cost effective analyzer system to measure and control moisture in wood chips and wood products. The non contacting, nondestructive system interfaces with Windows 95/98 or NT software and many sensors can be monitored from a single computer using instrument monitor software. SpectraQuad is available with a range of dedicated operator interfaces, ranging from a display of measured value to a full access control station with keypad and highresolution graphics. NIR technology can also be used to measure resin content in board manufacturing. The combination of accurate, realtime, online process NIR measurements can be used for closedloop control, providing improved product and reduced costs, the company says.

MPB Lamsor Inc./MPB Technologies Inc.:  MPB Lamsor, a subsidiary of MPB Technologies Inc., has developed the AquaViewer, a noncontact moisture sensor for wood products that is based on radiometric measurements combined with specially designed imaging technology. The AquaViewer displays and analyzes the MC distribution of wood products in real time, with the biggest advantage of the new moisture imager being that it provides information on the MC of the entire piece. In addition, it is capable of providing information on longitudinal and vertical gradients, recognizing local MC irregularities, such as wet spots, and recognizing sapwood from heartwood. Moisture content measurements for each piece are based on the simultaneous use of 76,800 miniature detectors.

As a result, the user is provided with new tools, such as sorting by MC mean values in combination with MC gradients. Designed specifically for online applications, it provides twodimensional readings on MC and colour mapping of MC distribution. The system can be interfaced with any control system and has the flexibility to make decisions based on average MC of the product or statistics on the moisture distribution within the product.

Grecon Inc.:  The GreCon IR Moisture Meter monitors product MC online for assured quality panel production. Online monitoring after the chip or fibre dryer, or at the blender or forming station provides measured values of moist, dry or glued material without the delay of taking samples. Immediate adjustments can be made to optimize production in the drying process. A multiprocessor control console is integrated into visualization PC so production data can be stored, printed or saved for future comparisons and reference. Rejects, waste and raw material usage are reduced for increased profits and total quality assurance, says GreCon. The IR Moisture Meter uses a noncontact near infrared measuring principle and eliminates rejects due to poor MC. Unaffected by light or product height, it offers realtime monitoring for immediate adjustments to production. Multiple measuring heads can be integrated into a single processor while noncontact measurement prevents product damage. The meter displays data in user-friendly windows with charts and graphs for visual reference and is compatible with Windows 95 and 3.x software with Standard NetDDE interface (Wonderware).



This page last modified on Monday, November 03, 2003