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Hawaiian Ranch Reclaims Old Wood: Lignomat Wireless System Enables Company to Monitor Lumber Drying Process in Solar Kiln

Lignomat Enables Company to Monitor Lumber Drying

By Diane M. Calabrese
Date Posted: 8/1/2007


KEALAKEKUA, Hawaii — Great ideas are as much a part of the Aloha State as gorgeous vistas. Consider the way the Hokukano Ranch adds value to wood reclaimed from slash piles and windfall.

            Many of the slash piles are three or four decades old, but Hokukano Ranch processes these salvaged logs, 2 inches to 36 inches in diameter, into kiln-dried lumber and finished components for furniture, cabinets and flooring.

            Hokukano Ranch, which spans 23,000 acres, is part of a larger, multi-state enterprise owned by Island Land Management. It is located on the island of Hawaii.

            Hokukano Ranch occupies land with a history of lumber and sugar cane production. Most of the wood in slash piles is Acacia koa, which has the common name koa. Windfall consists largely of the endemic species ohia (Metrosideros polymorpha, in the myrtle family). Sandalwood, eucalyptus, sugi pine (Japanese cedar) are represented, too.

            There is enough wood in slash piles and from windfall to keep the company busy for eight or nine years without cutting standing timber, estimated Clark Allred, wood products manager for Hokukano Ranch.

            Wood reclamation started 18 months ago. After the koa piles are reclaimed for lumber and flooring, the acreage will be reforested. Ohia, one of the world’s hardest woods, is processed into lumber for cabinets and material for decorative posts. Its branches are used for rustic chairs and tables.

            Currently, the market for Hokukano Ranch wood products is Hawaii, but that is expected to change. Expanding to other markets will depend on the company’s ability to supply dry lumber.

            Hokukano Ranch designed its own dry kiln — a solar kiln. “It will dry up to 15,000 board feet in a month,” said Clark. The kiln has seven bays, each with a capacity of about 2,000 board feet. The kiln has an auxiliary fan and a household dehumidifier for use under challenging dew point conditions.

            Drying schedules vary from bay to bay with species. Koa and ohia generally are dried to 8% moisture content; for flooring material the target is 9%-10%.

            Some wood has a moisture content of 60%-70% before drying, and dry rot across the years complicates measurements.

            Finding a reliable, easy way to monitor the drying process was important. “We did a lot of research,” said Clark. The company chose monitors from Lignomat.

            “There’s a lot of neat equipment out there,” said Clark, “but this (Lignomat) fit best” with the operations at Hokukano Ranch. “We’ll actually be able to monitor each pallet of lumber.”

            The Lignomat wireless monitoring system had been in use for six months when Clark talked with TimberLine in June. Lumber is stacked on pallets and then placed in the kiln. A wireless probe is put in the middle of the lumber on each pallet. Because each probe has a unique identifier code, the information it records can be relayed to a computer and viewed and stored by corresponding stack. (Lignomat also offers hand-held devices to access the information.)

            The Lignomat wireless moisture recording system helps ensure the optimum drying time for green lumber. It also provides information about how the kiln is functioning, which will contribute to improvements in the design of the next generation of solar kilns — three of them.

            With the Lignomat wireless system, said Clark, it’s possible to “monitor the pallets anywhere in the yard or kiln from one station.”

            The Lignomat wireless monitor system documents and displays conditions in almost any environment where moisture content, humidity, air temperatures or core temperatures of a material are needed. With its wireless technology and the ability to transmit data in digital format, sensors can be placed anywhere without the need for cumbersome wires. It also improves accuracy because electrical ‘noise’ can corrupt analog data, resulting in false readings.

            Hokukano Ranch chose the Ligno­mat’s wireless monitor for several reasons, according to Lignomat. One was the sensors may be placed anywhere without restriction from cumbersome wires. Also, the sensors are directly interchangeable with Lignomat kiln control systems, which will make it easy and less expensive to upgrade to a kiln control system in the future. Other benefits include the capability to trouble-shoot the drying process and kiln structural modifications, ease of operation, and the ability to monitor moisture content of different species in the same kiln charge.

            The kiln operator monitors the operations with a basic off-the-shelf personal computer and software provided by Lignomat. Readings for moisture content, at specified time intervals, are recorded and saved; they can be accessed and printed any time.

            The Lignomat wireless monitor system is used in dry kilns, air drying operations, and laboratory testing chambers. When used to monitor air drying, The Lignomat system can increase uniformity in the drying process by grouping lumber with a lower moisture content deviation; drying time for drier lumber is reduced.

            Lignomat tested wood samples provided by Hokukano Ranch in order to develop moisture content calibrations for each wood species, which makes the drying process and monitoring system more accurate. The company provides the testing service for all customers.

            Five full-time employees and two contractors work in the wood processing operations at Hokukano Ranch, which has 21 full-time employees. The sawmill is equipped with a Wood-Mizer LT70 portable band sawmill and edger; they produce lumber and flooring blanks. In another building, a Wood-Mizer five-head moulder forms the tongue and groove for the flooring.

            Reclaiming the wood is relatively simple, but drying wood that has been exposed to the elements for as many as 40 years is not. Dry rot, species differences and high humidity complicate drying schedules.

            “The ability to set moisture content for each type of wood” is a critical part of the process, said Clark. Lignomat has “been willing to help” at each juncture. “We can send them samples and they give us the variances,” explained Clark.

            (For more information about Ligno­mat, call (800) 227-2105 or e-mail sales@lignomat.com.)




 






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