ASTM_D_815_-_81_scan.pdf

9009276 0023335 812=Designation:D 81 5-81($1)AMERICAN SOCIETY FOR TESTING A N D MATERIALS 1916 Race St.,Philadelphia,Pa.19103 Reprinted from the Annual Book of ASTM Standards,Copyright ASTM if not listed in the current combined index,will appear in the next edition.Standard Method for Testing COATED FABRlCS-HYDROGEN PERMEABILITY This standard is issued under the fixed designation D S15:the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(E)indicates an editorial change since the last revision or reapproval.1.Scope 1.i This method covers the measurement of the permeability of hydrogen through fabrics coated with rubber or synthetic elastomers.2.Applicable Document 2.1 ASTM Standard D 3040-8 1 Practice for Preparing Statements for Standards Relating to Rubber and Rubber Testing 3.Significance and Use 3.1 This method is intended for quality con-trol of rubberized fabric that is used to manu-facture articles that contain helium.There is a direct relation between the permeability of hy-drogen and helium,with that of hydrogen being approximately twice that of helium.3.2 It may also be used for development and research purposes.4.Apparatus 4.1 The apparatus shall consist of the Cam-bridge fabric permeameter or its equivalent.The essential components,properly assembled for the test as shown in Fig.1,shail comprise the following:4.1.1 Test Plates-Test plates,essentially in two parts,the lower half being the hydrogen chamber and the upper half containing the analysis cell.The specimen to be tested shzll be sandwiched between the iipper and lower plates.The analysis celi is part ofa Wheatstone bridge arrangement,which is contained in the control box.The hydrcpen diffusing into the unalysis celi produces a cxrrent thermal charge in the sensor.This thermal charge causes 3 voltage imbalance in the system that is regis-tered on the galvanometer.4.1.2 Waxing Plate Assembly-A waxing plate assembly as shown in Fig.2,consisting of two metal plates 127.0 stl 1 mm in diameter(125 cm in area)mounted in a holder so that the fabric specimen may be clamped between them with a peripheral ring approximately 8 mm in width exposed for wax coating.4.1.3 Control Box-A control box,essen-tially a Wheatstone bridge,with a standard cell.A 6-V storage battery or any other means of supplying the proper voltage with steady cur-rent to the operating circuit may be used.4.1.4 Galvanometer-A galvanometer cali-brated by the manufacturer to read in litres of hydrogen per square metre per 24 h at a state temperature.5.Test Temperature 5.1 Unless otherwise specified,23 f 2C(73 I 4F)shall be taken as the standard temper-ature for calibration and test.The test shall be conducted at the temperature at which the apparatus is calibrated within a tolerance of 12c(+3.6F).All specimens,equipment,and gases shall be preconditioned at this tempera-ture for 1 h prior to test.A temperature-mea-suring device shall be provided at the back of the lower test plate for measurement of the actual temperature while testing.This methcd is under the jurisdiction of ASTM Com-mittee D-1 I on Rubber and is the direct responsibility of Sibcommittee DI 1.37 on Coated Fabrics and Rubber Thread.Current edition approved Nov.27.1981.Published Jsn-uary 1982.Originally published 3s D 815-44 T.Lasi pre-vioy edition t 8ij-73.-.Annuo!aook o f ASTM Sfandards.Parts 37 and 38.1 NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.9009276 0021336 759 D 815 6.Time Lapse Between Vulcanization and Testing 6.1 For all purposes this minimum time be-tween vulcanization and testing should be i6 h.6.2 For nonproduct tests,the maximum time between vulcanization and testing should be 4 weeks and for evaluations intended to be com-parable,the tests,as far as possible,should be carried out after the same time interval.6.3 For product tests,whenever possible,the time between vulcanization and testing should not exceed 3 months.7.Test Specimens 7.1 The test specimens shaii be accurately cut from the coated fabric in circular form 143-t-2 mm in diameter.Three specimens from each sample shail be tested and the average of the readings taken as the permeability except when a minimum requirement is established,as in testing for compliance with a particular specification,in which case only one test shail be required.If the result of this test is below the specified requirement,two additional spec-imens shail be prepared from the original sam-ple and tested.Should the results of either of these tests be below the specified requirement,the samples shall be considered to have failed to conform to the specifications.8.Preparation of Specimens 8.1 The waxing compound shall be prepared by melting together a mixture of half beeswax and half p