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Kiln Drying Studies on 5 Cm Planks of Thirty Timber Species.

M. A. Sattar
Director (Ex.)
Seasoning & Timber Physics Division, Bangladesh Forest Research Institute, Chittagong.

Y. A. Talukdar
Seasoning & Timber Physics Division, Bangladesh Forest Research Institute, Chittagong.

Abstract/ Executive Summary:

The applicability of kiln drying schedules developed earlier were verified for 5 cm thick planks of thirty indigenous hardwood species. A series of charges were kiln dried covering the entire specific gravity range under four classes. It was found that the kiln schedules developed earlier for thinner stocks were equally effective in drying thicker ones. Five cm thick planks of different species having similar specific gravity range in different classes may, therefore, conveniently be kiln dried using the recommended schedules.

Keywords: Applicability, Kiln drying, Specific gravity

Location: BFIDC timber depot at Kaptai

Start Date: 00-00-0000

End Date: 00-00-0000

Program Area: Postharvest and Agro-processing

Commodity: Tree

Objectives:

To verify the applicability of these schedules for thicker planks with a view to recommending appropriate kiln drying schedules.

Methodology:

Thirty indigenous timber species of different specific gravity ranges were used. Green timber of each species in the form of log was procured from the BFIDC timber depot at Kaptai. These logs were converted into 5 cm ´ 20 cm ´ 2.5 m dimension planks.Six full-length representative boards, three from flat-sawn and three from quarter-sawn planks were taken as test samples for each charge. Moisture sections were cut from each sample and the initial moisture contents were determined by the oven drying method. From another set, specific gravity of the species were determined based on green volume. The sample boards were end-coated with bituminous paint and their initial weights were also taken. Based on the initial moisture contents and weights, calculated oven-dry weights were found out for each sample board. During the subsequent process of drying, the daily moisture loss data were computed by simply weighing the samples.

A force-draft compartment type kiln was used for the drying. The selection of schedules was done, in the first instance, from the schedules developed for 3.2 cm thick lumber (1980) representing the specific gravity class determined by actual measurement. Then, schedules of higher specific gravity classes were tried. The schedules which offered the fastest drying rate with minimum drying degrades were considered to be the appropriate ones. The kiln schedules used are shown in the text.

Source of Information: Bano Biggyan Patrika, Jan-July 1985 : 14 (1 & 2), 18-25

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Drying time from green condition to 12 percent moisture content level were recorded for each species. The observed drying co-efficient were determined from the regressions of the rate of moisture loss on moisture content. The estimated drying co-efficient were found out with the help of the drying equation. Drying degrade, on completion of drying, was assessed visually. These are presented in the text. Based on all these data, appropriate kiln drying schedules for 5 cm thick lumber are recommended.

Knowledge Management: Journal