BS EN 321-2002 pdf download.Wood-based panels DEtermination of moisture resistance under cyclic test conditions.
This BS EN 321 specifies a test method for the determination of the moisture resistance of woodbased panels under cyclic test conditions.
2 NormatIve references
This European Standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies (including amendments).
EN 310, Wood based panels — Determination of modulus of elasticity in bending and of bending strength.
EN 317, Particieboards and fibreboards — Determiria lion of slllng in thickness after immersion in water.
EN 319, Particleboards and fibreboards — Determination of tensile strength perpendicular to the plane of the board.
EN 325, Wood based panels — Determination of dimensions of test pieces.
EN 326-1, Wood based panels — Sampling, cutting and inspection — Part 1: Sampling arid cutting of test pieces
and expression of test results.
3 Principle
Test pieces are exposed to three cycles, each comprising immersion in water, freezing, and drying at elevated temperature. After cyclic treatment, the test pieces are then reconditioned and their swelling in thickness and residual strength determined.
4 Apparatus
4.1 Water bath
A water bath which shall maintain water at a temperature of (20 ± 1) °C.
4.2 Freezing cabinet
A freezing cabinet which shall be capable of maintaining a temperature of between- 12 C and- 25 °C. It shall also be capable of regaining this temperature within 1 h after inserting the test pieces,
4.3 Drying cabinet
6 Procedure
6.1 Treatment of the test pieces
The foHowing sequence of operations shall be camed out:
6.1.1 InItial conditioning and measurement
1) Condition the test pieces in accordance with 5.3.
2) Determine the dimensions of the test pieces in accordance with EN 325.
6.1.2 Cyclic treatment
6.1.2.1 First cycle
3) Immerse the test pieces in the water bath which shall contain fresh water of pH (7 ± 1) and be at a tempera- hire of (20 ± 1) °C.
The test pieces shall be placed standing on one edge (one long edge in the case of the bending test pieces) and shall be separated from each other, and from the bottom and sides of the water bath by at least 15 mm. The upper edges of test pieces shall be covered by (25 ± 5) mm of water throughout the immersion penod.
The immersion period shall be (70 ± 1) h.
4) Remove the test pieces from the water bath. Allow the surface water to drain off for a few minutes and then place the test pieces in the freezing cabinet which shall be at a temperature between- 12 °C and – 25 °C.
The test pieces shall be placed standing on the same edge as when immersed, and shall be separated from each other by at least 15 mm.
The freezing period shall be (24 ± 1) h.
5) Remove the test pieces from the freezing cabinet and immediately place them in the drying cabinet which shall be at a temperature of (70 ± 2) °C.
The test pieces shall be placed standing on the same edges as when immersed and frozen, and shalt be separated from each other by at least 15 mm. The total volume of the test pieces shall not exceed 10 % of the internal volume of the drying cabinet.
Belore standing them in the water bath, the test pieces shall be inverted to stand on its opposite edge. The test pieces shall be separated from each other and from the bottom arid sides of the bath by at least 15 mm. The upper edges of test pieces shall be covered by (25 ± 5) mm of water throughout the immersion period.
The immersion period shall be (70 ± 1) h.
8) Remove the test pieces from the water bath. Allow the surface water to drain oft for a few minutes and then place the test pieces in the freezing cabinet which shall be at a temperature between – 12 °C and – 25 °C.
The test pieces shall be placed standing on the same edges as when immersed (7), and shall be separated from each other by at least 15 mm,
The freezing period shall be (24 ± 1) h.
9) Remove the test pieces from the freezing cabinet and immediately place them in the drying cabinet which shall be at a temperature of (70 ± 2) °C.
The test pieces shall be placed standing on the same edge as when immersed (7) and frozen (8), and shall be separated from each other by at least 15 mm. The total volume of the test pieces shall not exceed 10 % of the internal volume of the drying cabinet.
The drying period shall be (70 ± 1) h.
10) Remove the test pieces from the drying cabinet and place them in a room with a temperature of (20 ± 5) °C.
The test piece shall be placed on the same edge as when immersed (7), frozen (8) and dried (9). and shall be separated from each other by at least 15 mm.
The cooling period shall be for (4 ± 0,5) Ii.
6.1.2.3 Third cycle
11) At the end of the cooling period immerse the test pieces again in the water bath which shall contain fresh water of pH = (7 ± 1) and be at a temperature of (20 ± 1) °C.
Before standing them in the water bath, the test pieces shall be inverted to stand on its opposite edge (I.e. each test piece shall be standing on the same edge as during the initial immersion period described in 3). The test pieces shall be separated from each other and from the bottom arid sides of the bath by at least 15 mm. The upper edges of test pieces shall be covered by (25 ± 5) mm of water throughout the immersion period.
The immersion period shall be (70 ± 1) h.
12) Remove the test pieces from the water bath. Allow the surface water to drain off for a few minutes and then place the test pieces in the freezing cabinet which shall be at a temperature between – 12 °C and – 25 0C.BS EN 321-2002 pdf download.