Last edited by Julrajas
Thursday, July 9, 2020 | History

2 edition of Use of the equilibrium moisture content principle in the kiln drying of Douglas fir found in the catalog.

Use of the equilibrium moisture content principle in the kiln drying of Douglas fir

Merle Stephen Lowden

Use of the equilibrium moisture content principle in the kiln drying of Douglas fir

by Merle Stephen Lowden

  • 263 Want to read
  • 35 Currently reading

Published .
Written in English

    Subjects:
  • Lumber -- Drying.,
  • Douglas fir -- Drying.

  • Edition Notes

    Statementby Merle Stephen Lowden.
    The Physical Object
    Pagination77 leaves, bound :
    Number of Pages77
    ID Numbers
    Open LibraryOL14341627M

      The moisture content was about 19% on the Douglas fir we used. I assembled it two weeks after I got it home and then flattened it with jack plane and jointer plane. I suppose if the moisture change is a slow enough, the drying stresses can dissipate without any major checking, etc. Its hard to believe the wood was at 60% after 13 years, but Dry wood, on the other hand, absorbs moisture from a humid atmosphere; the moisture content of wood also may be increased by wetting with liquid water. If wet wood is put into place, it eventually dries to a moisture content in equilibrium with the surrounding air -- the equilibrium moisture content (EMC). This drying is accompanied by

    Fremont Sawmill Kiln Drying Project, July The kiln schedule used at Fremont Sawmill for 7/4 juniper lumber and was adapted and altered slightly from a schedule developed by Mike Milota at OSU for the "Drying Western Juniper" project. Target moisture content was 8 to 10 percent, however the lumber exited the kiln at 10 to 12 percent In the case of the Canadian studies of RfV-drying of mm thick softwood, the efficiency appeared to be much higher. From an initially green (fresh from the saw) moisture content to a final of 15%, a use of kWh/kg of water (or MJ/kg) was reported, providing for a high efficiency of 70%.?script=sci_arttext&pid=SX

    Drying of sample seaweed in GVRHSD reduced the moisture content from about % to % in 4 days at average solar radiation of about W/m{sup 2} and mass flow rate about kg/s. Generally the plots of drying rate need more smoothing compared moisture content data. Special cares is needed at low drying rates and moisture :// Air Drying Lumber at WOODWEB's Knowledge Base. Find articles on predicting shrinkage, controlling checking, moisture content and wood movement, moisture content oven tests, high value wood, moisture meter accuracy, drying wood in a tent, promoting blue stain and spalting, and much ://


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Use of the equilibrium moisture content principle in the kiln drying of Douglas fir by Merle Stephen Lowden Download PDF EPUB FB2

At ° C. the equilibrium moisture content is 7 percent. In figure 63 is shown an example of conditions in a superheated-vapor kiln during the drying of 1-inch spruce from a moisture content of 30 to 8 percent in 6 hours.

The initial tem-perature of the wood was 68° F. Dur-ing the first 11/ 2 hours the relative humidity rose to 85 percent Use of the equilibrium moisture content principle in the kiln drying of Douglas fir.

Abstract. Graduation date: Year: OAI identifier: oai: Provided by: [email protected] Suggested articles. To submit an update or takedown An instrument, known as a sliver machine, has been developed to indicate equilibrium-moisture-content conditions.

Its use is described in a study of the variations in the equilibrium moisture content at different levels within a lumber storage shed and, for purposes of comparison, outdoors. It is concluded that lumber, kiln-dried to a per-cent.

moisture content and stored   The process of kiln drying will harden the lignin (the stuff between the cell walls in wood) and set it in place. While the wood will still take on moisture and expel it, the cell walls are not as flexible and thus the wood will not move as dramatically. In essence, kiln drying reduces the wood’s ability to move making it more :// Moisture content and schedules.

Kiln drying allows for a final predetermined moisture content, usually the equilibrium moisture content Equilibrium moisture content (EMC): The moisture content at which wood neither gains nor loses moisture when surrounded by air at a given relative humidity and temperature.

(EMC) for the intended ://   Boiling will decrease drying time an average of up to 50%. For example, a non-boiled piece may take 6 months to air dry. A boiled piece of the same timber will typically reach EMC (equilibrium moisture content) in three months or less. EMC is defined as the point at which the moisture content in the timber is at equilibrium with the   % is the accepted moisture content of kiln dried lumber here in North America.

But over in Europe where the climate is wetter, % is the normal kiln dried range. This may not seem like a huge difference, especially if you plan to use the lumber for an exterior application and since its moisture content will rise to match the local ://   difference in moisture content, the greater the drying stresses.

If the drying stresses become too great, they can exceed the strength of the wood and cause surface and internal cracks. Many kiln schedules are based on average moisture content of the wood because it indi-cates the difference in moisture content between the For processing the timber should be stable, with the correct moisture content, an even moisture profile and minimal residual stress.

Storage. Moisture content of timber should not move outside the range for its intended use. The moisture content of dried timber will reach equilibrium with the ambient conditions of the surrounding ://   Vacuum drying of wood is not a new technology.

A US patent for a “Process for Drying Timber” was issued inin which timber is placed inside an airtight vessel and, after a long heating period, “air and vapor are quickly removed until a more or less perfect vacuum is cycle of heating-vacuum is repeated until the timber is dried to the required As drying continues, cell walls get smaller and the wood starts to shrink – something of particular interest to woodworkers.

Eventually a balance is reached and moisture movement stops. This is the equilibrium moisture content (EMC) of a piece of wood, and this is what wood has been searching for ever since it was cut from the ://   MC = the wood’s moisture content; The EMC (equilibrium moisture content) of the location where the wood is at the moment or the location of where the wood is going to be used = the MC that the wood will eventually attain if it’s placed in that location.

If this is confusing, don’t worry. The chart below will clear things ://   Use the Delmhorst Kil-Mo-Trol, a remote probe system that measures the moisture content of lumber during the drying process. Resistance probes or contact pins are located at various "stations" throughout the lumber packages to monitor shell and core or core only moisture content ://   Proper drying and storage of lumber minimizes problems associated with lumber shrinkage and warping.

A minimum recommendation calls for using “surface dry” lumber with a maximum 19 percent MC. In uses where shrinkage is critical, specifications may call for “KD,” which is kiln-dried lumber with a maximum moisture content of 15 ://   Full Article.

Modeling the Air-drying Rate of Chinese Larch Lumber. Jun Hua, a, * Lin Ju, a Liping Cai, b and Sheldon Q. Shi b To help protect the environment and reduce energy consumption in the wood industry, air-drying has been used to pre-dry lumber to about 30% moisture :// The use of the algorithm for calculating the dispersion of the final moisture content of sawn-timber obtained as a result of the drying kinetics system – the stochastic model process with random   equilibrium moisture content of wood is 4.

5 percent, and at " C. (" F.) it is only 3 percent Kollman regards these conditions as too severe and recommends a maximum temperature of * C (* F.) In this case, the equilibrium moisture content is about 5 5 per-cent. He, as well as Egriez (1), considers a range of * to C'   Above 30 crack-extension force also increased with increases in moisture content, but at lower temperatures there was a slight decrease over the hygroscopic range of moisture contents [5, 6].

The frac- ture toughness of balsa wood was studied by Wu[7], who determined K,c and K,ic and who also developed an empirical criterion for fracture in   In most practical circumstances, the easiest way to check the moisture content of a piece of wood is to simply use a moisture meter.

But it’s a good practice to understand what the moisture meter reading actually represents, and to recognize that readings above % MC are possible, (and in the case of many lightweight species in their green A large number of test data is collected, such as stress and/or strain versus time, moisture content versus time, density, elastic modulus before and after drying etc.

The experiments are carried. A woodworker gets advice on the feasibility of maintaining wood at 25% moisture content for use in drying operations. January 8, Moisture Content of Western Red Cedar A stable wood that is typically serves exterior uses, Western Red Cedar is usually delivered at about 12% moisture content.

But you can find it drier than that. J   ture, and the difference between the initial moisture content of the wood and the eventual equilibrium moisture content for the environment. The relationship between equilibrium moisture content, relative humidity, and temperature is generally independent of species and is shown in Table Table Moisture content of wood in equilibrium   Cupping, bowing, twisting, those types of wood movement are related to changes in moisture content.

The best way to avoid those troubles is to use wood that is at the in service moisture content. Kiln dried construction lumber is dried to 19%, in service the equilibrium moisture content is generally closer to %.?topic=