dehumidification kiln drying schedules

Hardwood kiln drying schedules typically keep the dry bulb temperature below 80 C (176 F). I decided on a dehumidification kiln after reading an article in Fine Woodworking (1991). For the best experience on our site, be sure to turn on Javascript in your browser. 0000001417 00000 n Additionally, I have been underwhelmed by the performance of solar-operated fans. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. To hang the baffles, simply attach hooks to the plywood frame. January 27, 2007. This Blue&White Ginger Jar is a stunning piece of porcelain and pottery, expertly handcrafted with natural variations in each piece. 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 Rocky Mountain . Q,kjifT33P[! Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. I have been reading & studying kiln schedules for years too. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. This will allow the DH to drain automatically without you needing to enter the kiln. Thus, a drying program can be adapted according to the characteristics of the kiln load, e.g., species, dimensions, and moisture content. After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. of this publication is to make available to dry kiln operators and others interested in kiln-drying wood, kiln schedules that are completely assembled and written out for ready reference and easy use. Go to the second number designation (the wet-bulb depression designation) and find the corresponding depressions in the table below. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. Choosing a Kiln Schedule I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. To accommodate the floor insulation, blocking between joists is oriented horizontally instead of the normal vertical position. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. November 1, 2020. Formulating a Kiln Schedule . Kiln Systems. 1. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) Add to my manuals. The velocity through the load is assumed to be between 275 and 350 fpm, except for the white woods (including maple, ash, basswood, hackberry) where higher velocities (up to 600 fpm) are desired and acceptable. /ColorSpace /DeviceGray Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. . Vacuum Kiln Drying. I then manually rotate the fan boxes halfway through the drying cycle. Ignoring for a moment the merits of a homebrew DH kiln versus a Nyle, I was curious to see that rather than referencing the standard kiln schedules (e.g. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. 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. 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. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. Basically the idea seems to be to maintain a constant temperature, and to keep lowering the humidistat to maintain the SDR until the moisture content gets to the desired level. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. Enter the email address you signed up with and we'll email you a reset link. I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. 73. . In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. Chinese, Korean or Japanese kilns have an arch roof. In larger kilns, the heater may be needed in the latter part of the drying cycle. An Overview. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. Additionally, a 12 air plenum is required between the walls and stacks of lumber. For DH kilns, use the same RH, but lower the temperature to the typical operating temperature for the compressor; raise temperature to steam values when convenient and possible. txN.a!HQ)FmCw~{B1Aq_!+zN#+j For a kiln temperature of 140 F, sterilization takes three to five hours. Remote operation and networking is optional. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. The second most common type of drying is called dehumidification drying. The stickers are uniform in size and usually 3/4" or 1" square. In exchange for building the shed myself, I wound up with a shed of higher quality, with more features. HWn8gXA N,[mKJr2"Ec9,t By. 0000000591 00000 n Construction of a kiln chamber is very similar to building a small house. At the planer mill, warped 2 by 4's represent a significant loss in value. %%EOF By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. Dehumidification kilns from Nyle Systems in Brewer, Maine. A maximum 45 F depression often produces better lumber. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. in the kiln to dry specific wood products at a satisfactory rate without causing objectionable drying defects. Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. 301 0 obj <>stream On this order alone, I saved over $1,300 by drying the lumber myself. Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). 0 \ Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. 0000002827 00000 n https://www.fs.usda.gov/research/treesearch/9635, International Institute of Tropical Forestry, Eastern Forest Environmental Threat Assessment Center, Northern Institute of Applied Climate Science, Western Wildland Environmental Threat Assessment Center, conventional-temperature (< 180 F) schedules, elevated-temperature (180-212 F) schedules, R. Sidney Boone, Charles J. Kozlik, Paul J. Bois, Eugene M. Wengert. (Sawing and Drying Forum) Once the lumber is sterilized, it is ready for the conditioning phase. )f7haRoMRhib5Sd|-=RBkBBN r-hzf+1\IFgk;v]3_, KxL$9oL "Qw#"BFGfk}>cT2g yP K|7@N*v9!Wy9jB. op(y"X)Fz"q]fQC/ha>7=k_p}}^VXQmj e'2fyXQ{~23X^H1,d>Hq|^KQ*cN=yF%z. Sears Canada 70 Pint Dehumidifier. Check your local building codes for regionally specific requirements and electrical permits. Bring your moisture meter to confirm. It uses a simple humidistat to control the dehumidifier, and a remote bulb thermostat to control the heater, which is a couple of light bulbs. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Place some sample boards in the stack that will be easy to pull out for moisture testing later. They are easy to use and give you precision control over your drying. %PDF-1.4 % In this paper, the effective schedules were further investigated for longer culm parts treated with boron. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. A low temperature heat treatment chamber and/or dehumidification kiln is identified as operating between approximately 43C (110F) and 56C (133F) for an extended period during the kiln drying cycle. Ciencia y Tecnologia, Duygu Kocaefe, Ayhan Aytin, The Bolivian secondary forest products industry has experienced substantial growth during the last 10 years. Vote. Kiln drying is almost always essential for wood intended for interior uses. This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. Another common sticker size is 1 x 2, and these work fine as well. Another great option is to convert an existing shed or outbuilding to a lumber kiln. Soon the DH won't show much water collected in the tray. 906 0 obj << /Linearized 1 /O 908 /H [ 710 498 ] /L 501020 /E 6532 /N 45 /T 482781 >> endobj xref 906 12 0000000016 00000 n Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. USDA, 1991) . A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. Looking at the cost-benefit analysis of a shed kiln can be enlightening. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. I recommend a 2 x 3 sliding window with bug screen. Staggering the seams between the sheathing and siding layers helps avoid air infiltration. Frequently, the lumber has already air-dried for several years in a barn or outbuilding. Manufacturer guarantees/warranties for power tools, CNC and laser products will supersede the Rockler Guarantee if these items are damaged or defective. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. %PDF-1.5 Typical dehumidification kiln (FPL 1999 p. 12-10). This makes lightweight baffles that can be easily moved and repositioned. endstream endobj 283 0 obj <>/Metadata 40 0 R/OCProperties<>/OCGs[294 0 R]>>/Outlines 53 0 R/PageLayout/SinglePage/Pages 280 0 R/StructTreeRoot 72 0 R/Type/Catalog>> endobj 284 0 obj <>/Font<>/Properties<>/XObject<>>>/Rotate 0/StructParents 0/Tabs/S/Type/Page>> endobj 285 0 obj <>stream

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