BS ISO 1136:2015 pdf download – Wool — Determination of mean diameter of fibres — Air permeability method

BS ISO 1136:2015 pdf download – Wool — Determination of mean diameter of fibres — Air permeability method 7.1.3 Selection of specimens The specimens shall be taken from different places in the laboratory sample. In the case of balls of sliver, the laboratory sample shall be made up of pieces of sliver from both inside and outside the ball. 7.1.4 Specimen mass For the constant flow method, the specimen mass shall be 1,5 g ± 0,002 g. For the constant pressure method, the specimen mass shall be 2,5 g ± 0,004 g. 7.1.5 Preparation For slivers with cut ends, the specimen shall be prepared by cutting off with scissors a length to give as nearly as possible the specimen mass and then making up to the exact mass by adding shorter cut lengths or portions. For slivers with pulled ends, about five hand draws shall be removed and discarded and the specimens weighed out by taking several successive hand draws. These two methods of sampling give the same results if carried out properly. 7.2 Opened sliver 7.2.1 Cleaning The laboratory sample should weigh not less than 10 g, and if it is known to have an oil content not exceeding 1,0 %, the test specimen may be taken from it without cleaning. Otherwise, the sample should first be degreased by rinsing it well in two baths each of about 200 ml of petroleum ether before conditioning. 7.2.2 Preparation Take from the sample 10 g to 20 g of sliver and deparallelize using a Shirley Analyser or another method to give the laboratory sample. Pre-condition (see 6.1) and condition the laboratory sample. For the Shirley Analyser, cut the sliver into lengths of 15 mm to 20 mm before deparallelizing. Other methods may refer to Shirley Analyser. Laboratories can, according to their own conditions, develop their own method. 7.2.3 Number of specimens Unless otherwise specified, test a minimum of two specimens, and measurements per test specimen two times. 7.2.4 Selection of specimens Passing the cut sliver through a Shirley Analyser or other methods thoroughly blends the fibres. Test specimens need not, therefore, be made up from pinches of fibre from different parts of the prepared laboratory sample. 7.2.5 Specimen mass For the constant flow method, the specimen mass shall be 1,5 ± 0,002 g. For the constant pressure method, the specimen mass shall be 2,5 g ± 0,004 g. 8 Procedure 8.1...