BS EN ISO 4674-1:2016 pdf download
BS EN ISO 4674-1:2016 pdf download.Rubber- or plastics-coated fabrics — Determination of tear resistance Part 1: Constant rate of tear methods.
7.2 Procedure
Adjust the test machine to give a rate of jaw traverse of (100 i 10) mm/nun, and select the appropriate load capacity range. Engage and zero the autographic recorder. Adjust the jaw separation to 100 mm.
Clamp the tongue of the test piece centrally and symmetrically in the jaw so that the line BC is just visible, as illustrated In Figure3. Clamp the legs of the test piece symmetrically in the other paw of the machine so that the lines AB and CD are just visible and the legs of the test piece are parallel to the tearing force.
Set the test machine in motion at the specified rate of traverse and stop the test after 60mm of the test piece has been torn, i.e. at the termination line.
Observe if the tear does not proceed along the direction of force and whether any threads slip out from the fabric rather than being torn. The test Is to be considered correct If no slippage occurs In the jaws. no delamination takes place between coating and base fabric during the test and the tear proceeded and was completed along the direction of application of the force. Other results shall be rejected unless otherwise they are judged to be useful information at the users’ discretion and to be recorded as an informative value in the test report.
When testing on wet test pieces is required, remove the test piece from the water (in accordance with the last paragraph in 7.1). press it tightly between two sheets niblotting paper and immediately carry out the test as described above.
If three or more test pieces have to be rejected, consider the method as unsuitable.
In this case, and if the test has been performed with normal test pieces, the tear resistance may be assessed either by using another method, e.g. ISO 4674’2, or by re’tcsting by the present method using large test pieces as described in Annex B.
7.3 Calculation and expression of results
7.3.1 Trace with a series of delinite peaks
7.3.1.1 Manual evaluation of tear forces from the chart recording AmiezA gives an example of a calculation,
Divide the tear trace, beginning with the first peak and ending with the last, into four equal subsections (see AnnexA). Do not use the first subsection for the calculation. From each of the remaining three subsections, select and note the two highest and the two lowest peaks. A peak for calculation Is 10 % drop in force as defined in 11.
If the evaluation of peaks derived from dense fabrics with large numbers of threads per centimetre is to be done from the chart recording manually, the speed of the chart paper should prefer-ably be set to 2:1 in relation to the tearing speed.
For each test piece. calculate the arithmetIc mean of the 12 peak values obtained. In Newtons. If required, record the minimum and maximum peak force from the three subsections for each test piece.
For manual evaluations, a limited number of selected peaks Is chosen to keep calculation time within acceptable limits. For calculations including all peaks, the electronic evaluation method (see 7.3.L2) is recommended.
From the mean calculated for each test piece, calculate the overall arithmetic mean of the tear force, in Newtons, for each direction tested and round It to two significant flgures
If required, calculate the coefficient of variation to the nearest 0.1 % and the 95% confidence limits of the mean values calculated for each direction (In accordance with ISO 2602).
7.3.1.2 CalculatIon using an electronic device Annex A gives an example of a calculation.
Divide the tear trace, beginning with the first peak and ending with the last. into four equal subsections (see Annex A). Do not use the first subsection for the calculation. From each of the remaining three sLibsections, record all peaks. A peak for calculation is characterized by at least a 10 % drop in force as defined in 11.
For each test piece, calculate the arithmetic mean using all the peaks recorded.
From the mean calculated for each test piece, calculate the overall arithmetic mean of the tear force, in Newtons, for each direction tested and round It to two significant figures.
If required, calculate the coefficient of variation to the nearest 0,1 % and the 95% confidence limits of the mean values calculated for each direction (In accordance with ISO 2602).
