ASTM_D_726_-_94_2003.pdf

Designation:D 726 94(Reapproved 2003)An American National StandardStandard Test Method forResistance of Nonporous Paper to Passage of Air1This standard is issued under the fixed designation D 726;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the resis-tance of nonporous paper to the passage of air.This test methodcannot be used in those cases where the paper cannot beclamped securely against surface and edge leakage,such as,crepe or corrugated papers.1.2 This test method is applicable to papers that permit thepassage of up to 25 mL of air/0.785 in.2in 15 s,and in general,to papers not sufficiently porous to be tested by TAPPI methodsT460 and T536.NOTE1For testing pourous and semiporous paper,refer to TAPPIT460,and T536,respectively.Since the three methods(D 726,T460,andT536)do not give the same results,it is recommended that a specificmethod be agreed upon in specifications covering paper between the sellerand the purchaser,and that the method be chosen to conform to theprinciple range.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D 585 Practice for Sampling and Accepting a Single Lot ofPaper,Paperboard,Fiberboard,and Related ProductsD 685 Practice for Conditioning Paper and Paper Productsfor TestingE 122 Practice for Choice of Sample Size to Estimate aMeasure of Quality for a Lot or Process2.2TAPPI Standards:T 460 Air Resistance of Paper3T 536 Resistance of paper to passage of air(HP Method)33.Significance and Use3.1 The air resistance of paper can be used as an indirectindication of such variables as degree of beating,absorbency(penetration of oil,water,etc.),apparent specific gravity,filtering efficiency for liquids or gasses,etc.It is influenced byboth the internal structure and the surface finish.Internalstructure is controlled largely by type and length of fiber,degree of hydration,orientation,and compaction.Surfacefinish is governed by the degree of wet pressing,types of feltsused in manufacture,and primarily,calendering,as well as bythe presence or absence of coating.Air resistance is furthergreatly influenced by the type and amount of filler,sizing,etc.The air resistance of coated papers is generally so high as to beof doubtful significance.While the measurement of air resis-tance is a useful control test for machine production,due to thenumber and complexity of factors outlined above,carefuljudgment with a consideration for end-product use shouldgovern the adoption of specification limits for air resistance.3.2 In insulating papers,air resistance can be used as acriterion in predicting dielectric strength and absorbency,inuncoated printing papers it can be used as an indication ofrotogravure ink absorption,and in filter papers it can foretellthe performance in filtering liquids or gasses.4.Apparatus4.1 Fig.1 shows the dimensions,design,and assembly ofthe apparatus,which consists essentially of a clamping devicefor the test specimen,a stopcock,a 100-mL buret,and aleveling bulb with tube mounted on a board for attachment toa wall or upright stand.4.2 The gasket shall consist of a thin,elastic,oil-resistant,nonoxidizing material,having a smooth surface.4It shall beheld in position with a water-insoluble synthetic rubber-basecold-setting adhesive.The calibrated portion of the scale shallbe 24 612in.(610 6 13 mm).5.Calibration of Apparatus5.1 With the stopcock open and no specimen over theorifice,place the leveling bulb in the lower support.Addsufficient distilled water to the level in the bulb so that it is1This test method is under the jurisdiction of ASTM Committee D06 on Paperand Paper Products and is the direct responsibility of Subcommittee D06.92 on TestMethods.Current edition approved April 15,1994.Published June 1994.Originallypublished as D 726 43 T.Last previous edition D 726 58(1971).2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from the Technical Association of the Pulp and Paper Industry,Technology Park/Atlanta,P.O.Box 105113,Atlanta,GA 30348.4Thiokol gasket,grade ST,polished plate molded,116in.(0.8 mm)in thickness,50 to 60 Durometer hardness,is a satisfactory gasket material.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.about three-fourths full,and adjust the