BS ISO 15906-2007 Carbonaceous materials for the production of aluminium - Baked anodes - Determination of the air permeability《铝生产用碳素材料 焙烧阳极 透气率测定》.pdf

1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58aluminium Baked anodes Determination of the air permeability ICS 71.100.10Carbonaceous materials fo

2、r the production of BRITISH STANDARDBS ISO 15906:2007BS ISO 15906:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 June 2007 BSI 2007ISBN 978 0 580 52939 9Amendments issued since publicationAmd. No. Date Commentscontract. Users are resp

3、onsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 15906:2007.The UK participation in its preparation was entrusted to Technical Committee

4、 CII/24, Raw materials for the aluminium industry.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a Reference numberISO 15906:2007(E)INTERNATIONAL STANDARD ISO15906First edi

5、tion2007-05-01Carbonaceous materials for the production of aluminium Baked anodes Determination of the air permeability Produits carbons utiliss pour la production de laluminium Anodes cuites Dtermination de la permabilit lair BS ISO 15906:2007ii iiiForeword ISO (the International Organization for S

6、tandardization) 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 subject for which a technical committee has been established has the ri

7、ght 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) on all matters of electrotechnical standardization. Internationa

8、l 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 committees are circulated to the member bodies for voting. Publication as

9、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 held responsible for identifying any or all such patent rights. ISO

10、 15906 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary aluminium. BS ISO 15906:2007iv Introduction Anode performance in aluminium reduction cells can be partially characterized by the measurement of the gas permeability. Higher permeability allows attack and c

11、onsumption of the anode by air and C02, thus shortening the life and overall performance of the anode. BS ISO 15906:20071Carbonaceous materials for the production of aluminium Baked anodes Determination of the air permeability 1 Scope This International Standard describes a method for the measuremen

12、t of the air permeability of baked anodes, by determining the resistance to airflow of a specimen of specified volume at room temperature, within the range of air permeability between 0,01 nPm (nanoperms) and 10 nPm. “Green” anodes are considered to be impermeable to gas. Therefore, this test is mos

13、t applicable to “baked” carbon material. NOTE This method can also be used for measuring other carbon materials (e.g. microporous carbon materials), but precision statements are not available for other carbon materials. 2 Normative references The following referenced documents are indispensable for

14、the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 8007-2:1999, Carbonaceous materials used in the production of aluminium Sampling plans and sampling fr

15、om individual units Part 2: Prebaked anodes 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 sample portion of carbon from a baked anode 3.2 test specimen article prepared from a sample 4 Principle The air permeability of a sample is determine

16、d by a comparative method. The time necessary to draw a specified volume of air through the test specimen is measured. This time is compared to the time necessary to draw a specified volume of air through a standard with known air permeability. This comparison yields the air permeability of the samp

17、le material. 5 Apparatus 5.1 Callipers, with 0,01 mm reading precision. BS ISO 15906:20072 5.2 Air permeability unit equipped as in 5.2.1 to 5.2.3. 5.2.1 Membrane vacuum pump, with an inlet to generate vacuum down to 100 mbar, and an outlet to generate high pressure up to 4 bar. The maximum flow rat

18、e has to reach 25 l/min. 5.2.2 Permeability cell, as shown in Figure 1. The cell is designed to ensure an airtight sealing around the periphery of the sample. A rubber tube is forced as a seal against the cylindrical test specimen by means of compressed air. The porous filter-paper and the sponge-ru

19、bber protect the vacuum pump from particles and/or dust from the sample. 5.2.3 U-tube manometer, with light fork sensors as shown in Figure 2. The U-tube is directly linked with the vacuum pump and is placed parallel to the permeability cell. It has a working length of 220 mm, an internal diameter o

20、f 16 mm 1 mm and an external diameter of 20 mm. It is filled to the equilibrium mark with a non-volatile, non-hygroscopic liquid of low viscosity and density, such as dibutylphtalate or a light-grade mineral oil. Thereby, the vacuum and the air volume flowing through the test specimen can easily be

21、measured by following the oil level inside the U-tube. There are three light fork sensors. The lowest one (sensor 3) is located at 145 mm below the mark line of equilibrium. The two other sensors are located at 30 mm (sensor 1) and at 80 mm (sensor 2) below the equilibrium mark. The connection to th

22、e vacuum pump can be closed by a valve, which then leads to a decrease of the vacuum by air flowing through the test specimen due to its air permeability. BS ISO 15906:20073Dimensions in millimetres Key 1 test specimen 2 rubber tube 3 porous filter-paper 4 rubber sponge 5 movable clamping device 6 s

23、tationary piston 7 plastic hose 8 compressed air intake 9 vacuum system Figure 1 Permeability cell BS ISO 15906:20074 Dimensions in millimetres Key 1 proximity sensor 1 2 proximity sensor 2 3 proximity sensor 3 4 mark line of equilibrium 5 air inlet 6 vacuum system Figure 2 U-tube manometer BS ISO 1

24、5906:200755.3 Standards with known air permeability, high-precision capillaries with known air permeability suitable for calibrating the air permeability unit.1)A range of permeability values for this standard of between 1 and 2 nPm is appropriate. The capillaries are mounted in a holder which fits

25、onto the cell clamping device (50 mm diameter) of the air permeability unit, see Figure 3. A proper seal guarantees that there is no air leakage between the capillary and the metallic holder. Dimensions in millimetres Key 1 capillary 2 holder 3 screw cap 4 seal Figure 3 Standard with known air perme

26、ability 5.4 Impermeable disc, having the same dimensions as the test specimen. 1) Standards with known air permeability can be certified from the Netherlands Measurements Institute, NMI, in Dordrecht, The Netherlands. BS ISO 15906:20076 6 Sampling and preparation of test specimens 6.1 Prepare sample

27、s taken as defined in ISO 8007-2:1999 in the shape of a cylinder. 6.2 Select, at random, one representative core. Cut at least 20 mm from the outermost end of the core. Discard this portion. 6.3 Carefully cut a 20 mm portion from the adjacent area of the core. Blow any dust or particulate off the 20

28、 mm section and dry it in an oven at 110 C for 4 h. 6.4 Measure the height at four points, 90 apart, on the periphery of the circular end faces, to the nearest 0,01 mm, using the callipers (5.1). Make two sets of diameter measurements, to the nearest 0,01 mm, using the callipers (5.1). Each set shal

29、l consist of four measurements, one at each end and two at intermediate points along an axial line. These sets shall lie at 90 to each other. Determine the mean length and the mean of each of the two sets of diameter measurements. 6.5 The diameter of the test specimen shall be 50 mm 0,4 mm, and the

30、height of the test specimen shall be 20 mm with the two faces parallel within 0,05 mm. 7 Calibration and standardization Calibrate the apparatus by measuring the air permeability of a suitable standard (5.3) according to the procedure given in Clause 8. 8 Procedure 8.1 Check all connections, make su

31、re they are airtight and verify that there are no leaks by performing a leak check using the impermeable disc (5.4). 8.2 Place either the calibration standard (5.3) or test specimen (Clause 6), in the test apparatus and expand the rubber tube to ensure an airtight seal. 8.3 Evacuate the system until

32、 the liquid in the U-tube reaches the sensor 3. Then close the connection to the vacuum tube, using the valve, so causing a decrease of the vacuum by air flowing through the standard or test specimen due to its air permeability. When the liquid level reaches sensor 2, record the time. When the liqui

33、d level reaches sensor 1, record the time again and calculate the time difference between sensors 2 and 1. 9 Calculation of results 9.1 Determination of the calibration factor fcby using the standard of known air permeability (5.3) Calculate the calibration factor fcaccording to Equation (1). ccc196

34、320ftD= (1) where fcis the calibration factor; tcis the time difference, in s; Dcis the air permeability of the standard, in nPm; BS ISO 15906:200771963 corresponds to the cross-sectional surface area of a 50 mm diameter test specimen, to be tested later; 20 corresponds to the nominal height of the

35、test specimen. 9.2 Determination of the air permeability Dsof the test specimen Calculate the air permeability Dsof the sample according to Equation (2). cssssf hDtA= (2) where Dsis the air permeability of the sample, expressed in nPm; tsis the time difference, in s; hsis the height of the test spec

36、imen, in mm; Asis the cross-sectional surface area of the test specimen, in mm2. 10 Precision and bias 10.1 General Precision statements are valid for anode samples in the range 0,7 nPm to 3,4 nPm. 10.2 Repeatability According to document ISO/TC 47/SC 7 N 1369: r = 0,06 (nPm) 10.3 Reproducibility Ac

37、cording to document ISO/TC 47/SC 7 N 1369: R = 0,04X(nPm) + 0,09 (nPm) where X is the material average. 11 Test report The test report shall include the following information: a) a reference to this International Standard; b) the names of the producer and customer; c) the number and reference markin

38、g of the batches; d) the date and place of test; e) the test results. BS ISO 15906:2007BS ISO BSI389 Chiswick High RoadLondonW4 4AL15906:2007BSI British Standards InstitutionBSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Euro

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