BS-4443-6-1991.pdf

BRITISH STANDARD BS 4443-6: 1991 Incorporating Amendment No. 1 Methods of test for Flexible cellular materials Part 6: Method 14. Preparation of water extract Method 15. Determination of tear strength Method 16. Determination of air flow value Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 08:48:59 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4443-6:1991 This British Standard, having been prepared under the direction of the Plastics and Rubber Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 31 May 1991 © BSI 06-1999 First published December 1980 Second edition May 1991 The following BSI references relate to the work on this standard: Committee reference PRM/24 Draft for comment 90/37852 DC ISBN 0 580 19569 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/24, upon which the following bodies were represented: British Plastics Federation British Railways Board British Rigid Urethane Foam Manufacturers Association British Rubber Manufacturers Association Department of the Environment (Building Research Establishment) Furniture Industry Research Association Furniture, Timber and Allied Trades Union Ministry of Defence National Bed Federation Limited Phenolic Foam Manufacturers Association RAPRA Technology Ltd. Society of British Aerospace Companies Limited Society of Motor Manufacturers and Traders Limited Amendments issued since publication Amd. No.DateComments 8867December 1995 Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 08:48:59 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4443-6:1991 © BSI 06-1999i Contents Page Committees responsibleInside front cover Forewordii Section 1. General 1.1Scope1 1.2Definition1 Section 2. Method 14. Preparation of water extract 2.1General2 2.2Preparation of test portion2 2.3Method 14A. Boiling water extraction2 2.4Method 14B. Hot water extraction2 2.5Test report3 Section 3. Method 15. Determination of tear strength Section 4. Method 16. Determination of air flow value 4.1General5 4.2Apparatus5 4.3Checking for leaks in an apparatus using an air pressure less than atmospheric pressure5 4.4Test specimen5 4.5Number of test specimens5 4.6Conditioning and test conditions5 4.7Procedure7 4.8Test report7 Figure 3 Air flow apparatus: schematic diagram when using air pressure less than atmospheric pressure6 Figure 4 Air flow apparatus: schematic diagram when using air pressure greater than atmospheric pressure6 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 08:48:59 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4443-6:1991 ii © BSI 06-1999 Foreword This Part of BS 4443 has been prepared under the direction of the Plastics and Rubber Standards Policy Committee. It is a revision of BS 4443-6:1980 which is withdrawn. It comprises methods for the preparation of water extract, and the determination of tear strength and air flow value of flexible cellular materials of polymeric origin. Attention is drawn to BS 4443-1, BS 4443-2, BS 4443-3, BS 4443-4, BS 4443-5 and BS 4443-7. Part 1 comprises methods for the measurement of dimensions, apparent density, tensile strength and elongation at break, compression stress-strain characteristics and compression set. Part 2 comprises a method for the determination of indentation hardness. Part 3 comprises methods for the determination of creep and dynamic cushioning performance. Part 4 comprises methods for the determination of solvent swelling, humidity ageing and heat ageing. Part 5 comprises a constant load pounding test, whilst Part 7 describes a tear test for materials with an integral skin. Two methods for the preparation of water extract are described: a) extraction with boiling water, derived from BS 903-F9 (now withdrawn); b) extraction with hot water, derived from method 406 (now withdrawn) of BS 2782:1970. Tests on the water extracts are of importance for materials that are liable to be in contact with explosives, or to be used in the packaging industry where corrosivity may be of importance. Tests on water extract may also be necessary where the material is liable to be in contact with foodstuffs and other cases where there is a risk of toxic hazards. Air flow values may be used to determine the effect on the cellular structure of formulation and production variables. In this edition the conditioning clause has been updated in line with the recently revised Parts 1, 2, 3, 4, 5 and 7. Method 15 for the determination of tear strength is related to ISO 8067:1989 and method 16 for the determination of air flow value is related to ISO 7231:1984. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 08:48:59 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4443-6:1991 © BSI 06-19991 Section 1. General 1.1 Scope This Part of BS 4443 describes three methods of test that apply to flexible cellular products of polymeric origin: preparation of water extract, determination of tear strength and determination of air flow value. The method for determining tear strength is not applicable to products with an integral skin. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 1.2 Definition air flow value the volume of air, in litres per second, under standard conditions, required to maintain a constant pressure differential of 125 Pa across a flexible foam test specimen of standardized dimensions when tested in accordance with method 16 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 08:48:59 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4443-6:1991 2 © BSI 06-1999 Section 2. Method 14. Preparation of water extract 2.1 General The water-soluble contents of the test sample are extracted either by boiling in a flask with water or by shaking in a flask with hot water. After cooling, the resultant solution is either decanted or pipetted for analysis, as required. NOTEBecause certain factors (e.g. extraction temperature and time, size of test specimen and surface area) are known to influence the test results, the procedures have been laid down precisely in methods 14A and 14B. The water extract may be used for any of the following determinations: pH value; electrical resistivity; free acid, free alkali, chloride, sulphate, ammonium salts or total water-soluble content. The methods described are not comparable because extraction with hot water is less severe than extraction with boiling water, and hot water is used where boiling water might cause partial hydrolysis, as in the case of some polyester based polyurethane foams. Therefore unless otherwise specified in the material specification the hot water method is the preferred method. 2.2 Preparation of test portion The test portion shall be in the form of small, approximately cube-shaped specimens, the side of which shall measure between 3 mm and 5 mm, to ensure a large surface area. It shall be obtained by removing the original surface of the sample to eliminate contamination due to handling, and then subdividing the sample in such a way as to avoid recontamination. Hot wire cutting is not permitted. The approximate average size of the specimens into which the sample is cut shall be recorded. For tests that are intended to be comparable, the size range of the specimens shall be approximately the same. 2.3 Method 14A. Boiling water extraction 2.3.1 Reagents 2.3.1.1 Soda lime, of recognized analytical grade quality self-indicating, particle size range such that it is retained by a sieve of nominal aperture size 0.71 mm and passes through a sieve of nominal aperture size 3.35 mm (see BS 410). 2.3.1.2 Water, complying with BS 3978. 2.3.2 Apparatus 2.3.2.1 Laboratory balance, capable of weighing to an accuracy of ± 0.1 g. 2.3.2.2 Borosilicate glass flask, of at least 500 mL capacity, having a ground neck complying with the requirements of BS 572. 2.3.2.3 Reflux condenser, with a ground glass inlet and outlet to fit the neck of the borosilicate glass flask (2.3.2.2) and the carbon dioxide guard tube (2.3.2.4) respectively. 2.3.2.4 Carbon dioxide guard tube, fitted with a ground glass joint, to fit the reflux condenser outlet. 2.3.2.5 Ground glass stopper, to fit the neck of the borosilicate glass flask (2.3.2.2). 2.3.2.6 Filter funnel 2.3.3 Procedure Weigh on the laboratory balance (2.3.2.1) between 5 g and 15 g (depending on the number of tests to be carried out) of the test specimen to an accuracy of ± 0.1 g. Record this quantity as the mass of the test portion. Place the test portion in the borosilicate glass flask (2.3.2.2) and add to it 20 times its mass of water (2.3.1.2). Fit the reflux condenser (2.3.2.3) to the flask and fit the carbon dioxide guard tube (2.3.2.4), previously packed with soda lime (2.3.1.1) at the outlet end of the condenser. Heat the flask until the water boils, and continue boiling for 1 h. Remove the flask from the heat source, replace the condenser by the ground glass stopper (2.3.2.5) and allow the contents to cool to room temperature. Remove any suspended solid material by filtration. Rapidly decant or pipette aliquot portions of the water extract as required for analysis. NOTESome determinations, e.g. of pH value, have to be carried out within a short time of preparing the extract. 2.4 Method 14B. Hot water extraction 2.4.1 Reagents 2.4.1.1 Water, complying with BS 3978. 2.4.2 Apparatus 2.4.2.1 Laboratory balance, capable of weighing to an accuracy of ± 0.1 g. 2.4.2.2 Borosilicate glass flask, 250 mL capacity. 2.4.2.3 Filter funnel 2.4.2.4 Ground glass stopper, to fit the neck of the borosilicate glass flask (2.4.2.2). Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 08:48:59 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4443-6:1991 © BSI 06-19993 2.4.3 Procedure Weigh on the laboratory balance (2.4.2.1) between 5 g and 15 g (depending on the number of tests to be carried out) of the test specimen to an accuracy of ± 0.1 g. Record this quantity as the mass of the test portion. Place the test portion in the borosilicate glass flask (2.4.2.2) and add to it 40 times its mass of boiling water (2.4.1.1). Immediately insert the ground glass stopper (2.4.2.4) in the flask and shake it vigorously until the material is thoroughly wetted. Allow the flask to stand at room temperature for 1 h, with occasional shaking. If, at the end of the 1 h period, the flask has not cooled to room temperature, rapidly cool it. Remove any suspended solid material by filtration. Rapidly decant or pipette aliquot portions of the water extract as required for analysis. NOTESome determinations, e.g. of pH value, have to be carried out within a short time of preparing the extract. 2.5 Test report The test report shall include the following information: a) a description of the material; b) the approximate average dimensions of the specimens comprising the test portion; c) the results of determinations carried out on the water extract, indicating, where necessary, the analytical method used and expressing the result relative to the mass of the test portion; d) the number and date of this British Standard and the method of preparing the water extract, i.e. method 14A or 14B of BS 4443-6:1991. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 08:48:59 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4443-6:1991 4 © BSI 06-1999 Section 3. Method 15. Determination of tear strength Superseded by BS EN ISO 8067:1995. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 08:48:59 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4443-6:1991 © BSI 06-19995 Section 4. Method 16. Determination of air flow value 4.1 General This method describes the procedure for determining the air flow value of flexible cellular materials. Air flow values may be used to determine the effect on the cellular structure of formulation and production variables. The test consists of creating a specific constant air pressure differential across a standard flexible foam specimen. The rate of flow of air required to maintain this pressure differential is the air flow value. As a result the method is not suitable for specimens with an integral skin. NOTEThis method is related to ISO 7231:1984. 4.2 Apparatus 4.2.1 Test specimen mounting and pressure chamber, consisting of a chamber 140 mm in diameter × 150 mm depth (Figure 3) or 75 mm in diameter × 1 000 mm length (Figure 4), each incorporating a test specimen mounting and fittings for the manometer and exhaust. The test specimen cavity shall be 50 ± 0.05 mm × 50 ± 0.05 mm × 25 ± 0.05 mm. The test specimen shall be supported by suitable means, e.g. by the use of vanes, wires or perforated support. This support shall provide a minimum open proportion of 70 % of the test specimen face in contact with the support, evenly distributed over the test specimen face. Manometer connections shall be as shown in Figure 3 and Figure 4. 4.2.2 Manometer, calibrated and suitable for use in the pressure range of up to 250 Pa, to an accuracy of ± 2 %. NOTEThe use of an inclined manometer with 2 Pa graduations is recommended. A level mounted on the manometer is essential to ensure that the proper degree of inclination from the horizontal is maintained. Traps to prevent manometer liquid being drawn into the chamber by accidental excess pressure changes shall be provided. A plunger in the fluid reservoir is used to set the zero point after levelling the manometer. 4.2.3 Flowmeters, low pressure-drop, accurate to ± 2 %. NOTEAir flowmeters with at least 250 mm scales are recommended; flowmeters in the range 0 L/min to 600 L/min will cover a wide variety of cellular materials. 4.2.4 Air supply, such that the pressure difference across the test specimen is either greater or less than atmospheric pressure. The air flow shall be adjustable, e.g. by use of a combination of valve restriction and blower speed. NOTEThe air supply may be provided from a compressed air line or by using an exhaust blower vacuum pump. Valves shall be fitted (see Figure 3 and Figure 4) to ensure that the pressure drop across the test specimen is constant at any given flow rate. 4.3 Checking for leaks in an apparatus using an air pressure less than atmospheric pressure (see Figure 3) Check the apparatus for leaks in the foll