EN 434-1994 pdf download.Resilient floor coverings Determination of dimensional stability and curling after exposure to heat.
This EN 434 specifies a method for determining the dimensional stability and curling of a resilient floor covering on exposure to heat.
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. EN 428, Resilient floor coverings — Determination of overall thickness.
3 Principle
3.1 For dimensional stability, the relative variation of the distance between marks previously made on the test piece after heat treatment under specified conditions is determined.
3.2 For curling, the vertical deformation appearing in a test piece after specified heat treatment is measured.
4 Apparatus
4.1 A thermostatically-controlled ventilated oven, where the temperature throughout shall be (80 ± 2) °C and the radiation from the heating element shall not reach the test pieces or support places directly.
4.2 Solid metal support plates, ground and covered with a film of polytetrafluoroethylene.
The shapes and dimensions of 4.1 and 4.2 shall be such that:
— curling shall be measured without removing the test pieces from the support plates;
— the clearance between the plates and the vertical walls of the oven shall be not less than 50 mm;
— the vertical clearance between the support plates and between the plates and the oven shall be not less than 100 mm.
4.3 An optical bench., range 200 mm and
precision ± 0,02 mm.
4.4 A pillar-mounted micrometer, or other device, accurate to at least 0,1 mm.
Take a representative sample from the available material.
Before cutting the test pieces, lay out the sample in sheet form as flat as possible and mark the machine direction. In the case of tiles, remove these from the packaging and lay them out.
Take three test pieces at equal distances from the sample, the distance between the outer edge of the sample and the nearest edge of the test piece being at least 100 mm, each of approximate dimensions (225 to 250) mm square, their edges being parallel or transverse to the direction of manufacture. On each test piece, approximately 20 mm from the edges. scribe four lengths, two in each direction, at a distance of (200 ± 1) mm, and measure these on an optical bench (see Figure 1).
Place each test piece on a support plate. If present, measure the initial curling before carrying out the test.
7 Procedure
Carry out the tests on the day of the initial length measurement. At least 1 h after the marks for the dimensional variation measurements have been made, measure the vertical distance between the support plate and the visible surface of the test piece in four places around the edge, usually the corners. where the distance is greatest. Carry out the measurements with the pillar-mounted micrometer. Store the test pieces for 360 mm in the oven, which has previously been stabilized at (80 ± 2) °C. Remove the metal plates bearing the test pieces from the oven. Allow these to cool and recondition at a temperature of (23 ± 2) °C and relative humidity (50 ± 5) % for a further 24 h, unless otherwise specified for the product.
NOTE The reconditioning period for all cork floor coverings should he 7 days.
After reconditioning, take the following measurements:
a) dimensional variations, i.e. the new distance of each scribed length; and
b) curling. i.e. the maximum vertical distances on each edge, usually at the corners.
8 Calculation and expression of results
8.1 Dimensional stability
For each of the test directions, record the variations for the six length measurements (two readings from three test pieces). Calculate the relative variation related to the initial lengths.EN 434-1994 pdf download.