1、 Reference numberISO 8791-3:2005(E)ISO 2005INTERNATIONAL STANDARD ISO8791-3Second edition2005-02-15Paper and board Determination of roughness/smoothness (air leak methods) Part 3: Sheffield method Papier et carton Dtermination de la rugosit/du liss (mthodes du dbit dair) Partie 3: Mthode Sheffield C
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7、Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reservedCopyright International Organization for Standardization Reproduced by IHS under license with ISO Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-I
8、SO 8791-3:2005(E) ISO 2005 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle . 2 5 Apparatus 2 6 Sampling 4 7 Conditioning 4 8 Preparation of test pieces 4 9 Calibration . 4 9.1 Variable-area flow-measuring dev
9、ice 4 9.2 Electronic flow-measuring device. 4 10 Procedure 4 10.1 Test atmosphere . 4 10.2 Determination of roughness 5 11 Calculation and expression of results 5 12 Test report . 5 Annex A (normative) Care and maintenance of test instrument with variable-area flowmeters . 6 Annex B (normative) Cali
10、bration of flowmeters 7 Annex C (informative) Conversion table 11 Bibliography . 12 Copyright International Organization for Standardization Reproduced by IHS under license with ISO Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO 8791-3:2005(E) iv ISO 2005 All
11、rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subjec
12、t for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC)
13、 on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committee
14、s are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be he
15、ld responsible for identifying any or all such patent rights. ISO 8791-3 was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee SC 2, Test methods and quality specifications for paper and board. This second edition cancels and replaces the first edition (ISO 8791-3:1990),
16、 which has been technically revised. ISO 8791 consists of the following parts, under the general title Paper and board Determination of roughness/smoothness (air leak methods): Part 1: General method Part 2: Bendtsen method Part 3: Sheffield method Part 4: Print-surf method Copyright International O
17、rganization for Standardization Reproduced by IHS under license with ISO Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO 8791-3:2005(E) ISO 2005 All rights reserved vIntroduction This part of ISO 8791 describes one of several methods of determining the roughnes
18、s of paper and board by an air leak method. Since these methods are based on different geometrical designs and since they use different air pressures and subject the test piece to different clamping pressures, they give different numerical results. General requirements for such tests are described i
19、n ISO 8791-11. Copyright International Organization for Standardization Reproduced by IHS under license with ISO Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright International Organization for Standardization Reproduced by IHS under license with ISO Not fo
20、r ResaleNo reproduction or networking permitted without license from IHS-,-,-INTERNATIONAL STANDARD ISO 8791-3:2005(E) ISO 2005 All rights reserved 1Paper and board Determination of roughness/smoothness (air leak methods) Part 3: Sheffield method 1 Scope This part of ISO 8791 specifies a method for
21、the determination of the roughness of paper and board using the Sheffield apparatus. The method is applicable to papers and boards which have Sheffield roughness values between 10 and about 3 000 ml/min. It is not suitable for soft papers which allow the lands of the test head to indent the surface,
22、 or for high air-permeance papers which allow a significant flow of air through the sheet, or for papers which will not lie flat during the test. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition c
23、ited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 186, Paper and board Sampling to determine average quality ISO 187, Paper, board and pulps Standard atmosphere for conditioning and testing and procedure for monitoring the atm
24、osphere and conditioning of samples 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 Sheffield roughness rate at which air flows between flat circular lands and the surface of a sheet of paper or board under specified conditions NOTE 1 The rou
25、ghness is expressed in millilitres per minute. NOTE 2 The Sheffield unit is not defined, since it has been found that the scale units (Sheffield units) on different instruments can correspond to different air flows, and there is no precise physical definition. This part of ISO 8791 requires that the
26、 flowmeters be calibrated to give a flow rate in millilitres per minute. Copyright International Organization for Standardization Reproduced by IHS under license with ISO Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO 8791-3:2005(E) 2 ISO 2005 All rights reser
27、ved4 Principle A test piece is clamped between a flat plate and two flat concentric annular lands. Air is supplied at a specified pressure to the space between the two lands and the rate of air flow between the lands and the test piece is measured. The air flow rate is a measure of the roughness of
28、the test piece. 5 Apparatus The apparatus, an example of which is shown in Figure 1, shall consist of an air supply, an air pressure control and air flow measuring device, a test assembly which houses a flat plate, a measuring head fitted with test lands, and a mechanical device for bringing the lan
29、ds into contact with the flat plate under a defined load. Key 1 air supply 2 pressure regulator 3 flow-measuring device 4 flow impedance 5 test assembly 6 test piece 7 flat plate Figure 1 Example of Sheffield apparatus 5.1 Air supply, free of water, oil and other contaminants, at a pressure of 420 k
30、Pa to 950 kPa. A small compressor using laboratory air is preferred to external compressed air. 5.2 Pressure regulating device, consisting of a primary regulator to reduce the pressure to between 205 kPa and 210 kPa and a further regulator to adjust the pressure at the measuring head to 10,3 kPa (va
31、riable-area flowmeters) or 9,85 kPa (electronic flowmeters). 5.3 Pressure manometer, with a range from 0 to 20 kPa to enable the air pressure at the measuring head to be set to the specified pressure within 2 % of the nominal value. 5.4 Flow-measuring device, of either a variable-area or an electron
32、ic type. The air flow shall be measurable to an accuracy of 5 % of the measured value. 5.4.1 Variable-area flow-measuring device, consisting of three variable-area flowmeters each having a tapered glass column containing a metering float suspended by the air flow in the column (see 3 in the Bibliogr
33、aphy). The three columns shall be chosen such that they enable measurement to be made on a continuous scale of flow rate from 10 ml/min to 3 000 ml/min, with some overlap of scales between columns. Copyright International Organization for Standardization Reproduced by IHS under license with ISO Not
34、for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO 8791-3:2005(E) ISO 2005 All rights reserved 3Each column shall be provided with a means of adjusting the flow rate (float-position knob) and a means of span calibration (calibrating knob). This type of instrument shal
35、l operate at a supply pressure of 10,3 kPa. At air flow rates greater than 1 200 ml/min, the pressure drop in the Sheffield system is substantial and, to ensure reproducibility of results, it is necessary that the tubing used to connect the flowmeter to the measuring head be carefully controlled wit
36、h a length of 1,50 m 0,01 m and an internal diameter of 6,25 mm 0,25 mm. For the same reason, openings in valves and other fittings on the instrument must not be changed from those provided by the instrument manufacturer. 5.4.2 Electronic flow-measuring device, for measuring the air flow to the test
37、 assembly (measuring head). The inlet pressure to the measurement device shall be controlled at 9,85 kPa. NOTE The 9,85 kPa pressure is the typical pressure measured downstream of variable-area flow tubes that have been calibrated using the zero and span adjustment air bleeds to atmosphere. 5.5 Test
38、 assembly 5.5.1 The measuring head, together with a dead weight, shall have a mass of 1 640 g 2 g, shall have two concentric annular lands made of, or coated with, a corrosion-resistant material and be designed to contact the test piece. The annular lands shall have a total area of 97 mm2 3 mm2; eac
39、h land shall have a width of 0,380 0,010 mm. The outer diameters of the outer and inner lands shall be 47,70 mm 0,03 mm and 34,37 mm 0,03 mm, respectively. The test assembly, an example of which is shown in Figure 2, shall include a detachable measuring head mounted so that it can be brought into co
40、ntact with a test piece placed on an optically flat plate. Dimensions in millimetres Figure 2 Example of test assembly The measuring head shall be connected to the air supply with an airtight seal and the air shall be fed into the gap between the two measuring lands through a narrow hole bored throu
41、gh the material of the measuring head. This can act as impedance in the measurement air line, see Figure 1 (4). The central space inside the inner land shall be vented to the atmosphere. The test assembly shall have a suitable coupling through which the chosen flowmeter is connected to the tube lead
42、ing to the measuring head. The tube connecting the measuring head to the instrument, and the tube connectors, have internal diameters that provide resistance to the air flow. Alteration of these components from those provided by the manufacturer may change the calibration and operation of the instru
43、ment. 5.5.2 The flat plate is usually glass and shall be free from surface flaws. The measuring lands shall be machined and the supporting plate shall be sufficiently flat so that, when the measuring lands are in contact with the plate in the absence of any test piece, the air flow rate does not exc
44、eed 10 ml/min. Copyright International Organization for Standardization Reproduced by IHS under license with ISO Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO 8791-3:2005(E) 4 ISO 2005 All rights reserved5.6 Calibration plate device, if the instrument employs
45、 an electronic flow-measuring device, the plate device will enable the test assembly to be connected to an external calibration system (see Clause 9 and Annex B). NOTE 1 Although this calibration plate is necessary only with electronic devices, it can also be used in instruments incorporating a vari
46、able-area flow-measuring device. NOTE 2 Sheffield reference surface masters are available to check orifices for contamination and measuring heads for wear or damage, but these are not specified by this part of ISO 8791. 6 Sampling Sampling is not included in this part of ISO 8791. If the mean qualit
47、y of a lot is to be determined, sampling shall be in accordance with ISO 186. If the tests are made on another type of sample, make sure that the test pieces taken are representative of the sample received. 7 Conditioning Condition the samples in accordance with ISO 187. 8 Preparation of test pieces
48、 Cut at least 10 test pieces, each at least 100 mm 100 mm for each surface to be tested, and identify the two sides (e.g. side one and side two). The test pieces shall be free from watermarks, creases, wrinkles, rubber marks, and other defects. Do not handle that part of the test piece which will be
49、come the test area. 9 Calibration 9.1 Variable-area flow-measuring device Calibrate the instrument against an external flow-measuring device as described in B.1, and prepare a calibration graph or chart as described in B.2. Calibrate the instrument sufficiently frequently to ensure that the reading doe
