ASTM_D_1081_-_60_1968_scan.pdf

Designation:D 1081-60(Reapproved 1968)American National Standard J2.20-1971 Approved July 27.1971 By American National Standards Institute Standard Method of Test for EVALUATING PRESSURE SEALING PROPERTIES OF RUBBER AND RUBBER-LIKE MATERIALS1 This Standard is issued under the fixed designation D 1081;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.1.Scope 1.1 This method is primarily for use in eval-uating the sealing properties of rubber or rubber-like material intended particularly for use as gaskets.It is not applicable to material ordinarily classed as hard rubber.2.Apparatus 2.1 IndentorThe indentor tip shall be hemispherical in shape having a diameter of 3.16 to 3.19 mm(0.125 to 0.1255 in.)and an orifice 1.00 to 1.05 mm(0.040 to 0.042 in.)in diameter located as illustrated in Fig.1.The material shall be corrosion resisting steel.The surface of the hemispherical tip shall be free of scratches or surface defects.2.2 Indenting DeviceThe indenting de-vice shall be of a design capable of indenting the specimen a specified amount with an ac-curacy of 0.01 mm(0.0005 in.).A suitable type is illustrated in Fig.2.Specimen and in-dentor may or may not be rotated relative to each other during the indenting operation.2.3 Specimen HolderThe test specimen holder shall consist of two parts,the holder proper and the base.2.3.1 The base may screw into the holder or merely slide into it as indicated in Fig.2.2.3.2 The holder,of a suitable design as illustrated in Fig.2,shall be 28.75 to 28.80 mm(1.132 to 1.134 in.)in internal diameter and shall have an opening 25 0.05 mm(1 0.002 in.)in its upper end.This opening provides a cavity above the specimen to re-tain fluids on the specimen surface to sub-merge the indentor tip.2.4 Air SupplyA compressed air line,a pressure regulator valve,a pressure gage and release vent to release the air after the test,shall be provided as shown in Fig.3.The pressure gage used to determine the sealing pressure shall be capable of measuring the pressure with an accuracy of 0.1 kgf/cm2(2 psi).NOTE 1 If a suitable air supply is not available the use of compressed gas cylinders containing ni-trogen or carbon dioxide will be acceptable.2.5 Initial Leakage Point ApparatusThe apparatus to determine the initial leakage point shall consist of a 0.07-kgf/cm2(1-psi)air supply such as illustrated in Fig.4,which can be taken from the main air supply.2.6 Conditioning ChamberA conditioning air chamber capable of maintaining the speci-fied temperature and of sufficient size to hold the indenting device will be required.The air chamber shall be provided with proper tem-perature control to maintain the specified temperature within a permissible variation of 2 C(3.6 F).Satisfactory circulation of the air shall be secured by means of a fan.3.Test Specimen 3.1 The test specimen shall be a cylindrical 1 This method is under the jurisdiction of ASTM Com-mittee D-U on Rubber and Rubber-Like Materials and is the direct responsibility of Subcommittee D-11.36 on Seals.Current edition effective Sept.19,1960.Originally is-sued 1949.Replaces D 1081-58 T.543 NOTICE:This standard has either been superseded and replaced by a new version or withdrawnContact ASTM International(www.astm.org)for the lastest information#D 1081 disk 12.4 0.4 mm(0.485 0.015 in.)in thickness,cut from the vulcanized rubber part or from a test sample if the part is unsuitable.A sharp,circular die having an inside diame-ter of 28.68 0.02 mm(1.129 0.001 in.)shall be used.In cutting the specimen,the die shall be suitably rotated in a drill press or sim-ilar device and lubricated by means of soapy water,so that a smooth cut surface having square edges is obtained.The cutting pressure shall be kept sufficiently small to avoid cup-ping of the cut surface.3.1.1 When necessary,the specimen thick-ness shall be reduced to the required thick-ness by cutting with a sharp knife and care-fully buffing to size within the permissible tolerance.The buffing shall be done lightly to avoid overheating and care shall be taken to keep the circular faces parallel and at right angles to the axis of the cylinder.3.1.2 If necessary,the test specimen may be made of two pieces essentially equal in thickness.After the indentation,allow the specimen to rest for 30 min prior to the determination of the initial sealing pressure.Use an indentation of 1.59 0.01 mm(0.0625 0.0005 in.)un-less otherwise specified.4.3 Initial Sealing Pressure:4.3.1 Initially adjust the air supply until profuse bubbling occurs,and then decrease it to zero.4.3.2 Then determine the initial sealing pressure of the indented test specimen as that pressure at which the rate of leakage of the air is one bubble in 10 s.Make the pressure measurement with an accuracy of 0.1 kgf/cm2(2 psi).Make the initial leakage point,indentation of test specimen,and initial seal