dehumidification kiln drying schedules

Share sensitive information only on official, secure websites. Heat comes primarily from an integral dehumidification unit that also removes . The first thing to consider when designing a shed kiln is size. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. USDA, 1991) . I opted not to install a true vapor barrier between the framing and sheetrock, because of potential condensation and mold issues with sheds constructed this way. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. Just walk out to the shed kiln and grab what you need from your custom-dried supply. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. KD150 Series dehumidifier pdf manual download. I have been reading & studying kiln schedules for years too. Low temperatures can be used for an extra safety margin on greener lumber. /Filter /JBIG2Decode The order was 540 board feet (BF) of 5/4 white oak. I also wrapped the shed with Tyvek HomeWrap. Share. With a well-designed dehumidification kiln, hardwood lumber can be dried for mere pennies per board foot. The first load was started with 60% and this load was started with 78%. Determine the equalization settings and conditioning settings, as required. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. This will allow the heater to cycle on and off automatically, according to the kiln operator's setting. Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation, Air-Drying and Kiln-Drying Methods for Wide Plank Flooring, Drying lumber - selecting the best method. Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. However, you may need more cycles depending on the species, moisture content, and size of the timber. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. This kicker board will help distribute the airflow more evenly through all layers of lumber. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. For equalizing, use an EMC 2% below the target MC at a dry-bulb of 170 F. For conditioning, use an EMC 4% above the target MC at a dry-bulb of 180 F. Professor Gene Wengert is Extension Specialist in Wood Processing at the Department of Forestry, University of Wisconsin-Madison. Dehumidification drying system. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. Make sure the total amp draw is well within the limit of your electrical circuit. 0000001208 00000 n I had these custom cut and I air dried them outside under a tarp for 6 to 18 months (depending on which load they came in on) and then I kiln dried them in a Nyle dehumidification kiln for 3 months. 158 p. Dry kiln schedules for commercial woods : temperate and tropical. I chose double wall construction with 1/2 sheathing, and 1/2 T1-11 siding. Our approach was to build and operate a small dehumidification dry kiln. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Diy dehumidifier kiln time table. For a kiln temperature of 140 F, sterilization takes three to five hours. It can be constructed in any style, with architectural features that match or complement an existing home. I either use some cedar 3 x 5, or 4 x 4 stock. _0e`bd\ p@ 3. 0000002827 00000 n But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. A household dehumidifier (DH) removes moisture from the kiln chamber. Place the one inch sections in an oven 215F to 218F (102C to 103C) and dry - usually 18 to 36 hours depending on the oven. You can download the paper by clicking the button above. Maderas. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. This can create internal stress in the lumber that is released when sawing. These kilns will typically hold several thousand board foot of lumber. How do I convert from the standard kiln schedules in the USDA's "Dry Kiln Schedules for Commercial Woods" and "Drying Hardwood Lumber" to an SDR-type schedule? Always avoid conditions that add moisture back to the lumber, especially during start-up. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. Basically the idea seems to be to maintain a constant temperature, and . The approach described in the article where you try to keep the water leaving at a steady rate is fine. I guess I am thinking that while I am seeing the wood's MC and the kiln's RH drop smoothly, the fact that the temperature jumps around a bit may mean that the drying rates are hard to control, hence my loss of horse chestnut. I found that brackets for mounting rigid metal electrical conduit work best. %PDF-1.6 % My four main baffles consist of sheets of 1" Styrofoam insulation. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. Lay down the bead of caulking before raising the walls. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. Select 3/4" conduit brackets for hanging baffles on 1/2" galvanized pipe. For 4/4 hard maple, with an initial temperature of 90F and an initial relative humidity of 81%, the SDR was given as .0061 pints per hour per board foot. Two-by-four material sawn from young trees, thinnings, and stem tops contains a significant proportion of juvenile wood and is particularly notorious for warp. Lock Go to the second letter designation (the MC Class Designation) and find the corresponding MC ranges in the table below. Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . Dehumidification Kilns (Sawing and Drying Forum) Official websites use .gov In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . Place a sticker at each end, and every 16" along the stack for 4/4 stock. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. /Width 1628 Evaluation of kiln-drying schedules for wild cherry wood (Cerasus avium), Model to assess energy consumption in industrial lumber kilns, Mathematical modelling and experimental investigation of dehumidifier drying of radiata pine timber, A survey of Bolivian lumber drying operations, Warp reduction of SYP lumber by restrained drying, Western Juniper Drying Project Summaries, 1993-96, Vacuum contact drying kinetics of Jack pine wood and its influence on mechanical properties: industrial applications, Kiln drying behavior of lumber from ten fast-growth plantation species in Costa Rica, Effect of fire-retardant treatment and redrying on the mechanical properties of Douglas-fir and aspen plywood, Properties of Douglas-Fir and Aspen Plywood, A numerical study on the influence of the bond-line diffusivity on moisture-related stresses and deformations of three-layered spruce cross-laminates, Error in Estimates of the Moisture Content of White Oak Kiln Sample Boards, Green Kerfing Treatment for Improving Softwood Lumber Drying: A Review, A comparison of kiln-drying schedules and quality outcomes for 4/4-thickness black cherry lumber sawn from small-diameter logs, A comparison of kiln-drying schedules and quality outcomes in 4/4-thickness black cherry lumber sawn from small-diameter logs, Data bank for short-length red oak lumber, Hardwood lumber widths and grades used by the furniture and cabinet industries: Results of a 14-mill survey, Lumber and veneer recovery from intensively managed young-growth Douglas-fir, WOOD-FRAME HOUSE CONSTRUCTION U.S. DEPARTMENT OF AGRICULTURE FOREST SERVICBAGRICULTURE HANDBOOK NO. Place a 16 board on the floor behind the stack, tilted to a 45 angle. High Temperature Kiln Drying Systems (160F) Loads up to 350,000 BF; Pull up to 20,000 pounds of water daily; Use standard drying schedule; Precision temperature and RH . Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . In a professional DH kiln, the final climate for oak is 120F and <40>t over-dry it at that rate. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I won't use the auxiliary heater. For single-stack kilns, stationary fans are adequate. Understand how kiln performance must be modified to permit the use of custom schedules for specific product applications; Be able to modify existing conventional kiln schedules to dry products in dehumidifier kilns; Recognize degrades common to various species, including hardwoods, and modify handling practices to minimize these With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. An anemometer confirms that your effort constructing baffles was worthwhile. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). Sorry, preview is currently unavailable. The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. If severe enough, the lumber can develop honeycomb cracks throughout. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). This procedure is discussed in a following section. A kiln schedule is a set of temperatures and humidities that are used during kiln operation.

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