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1、BRITISH STANDARD BS 3482-6: 1991 Methods of test for Desiccants Part 6: Determination of adsorptive capacity NOTEIt is recommended that this Part be read in conjunction with BS 3482-1 “Sampling, and preparation and storage of test samples” which is issued separately. Licensed Copy: sheffieldun sheff
2、ieldun, na, Wed Nov 29 07:32:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3482-6:1991 This British Standard, having been prepared under the direction of the Chemicals Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 31 July 1991 BSI 06
3、-1999 The following BSI references relate to the work on this standard: Committee reference CIC/2 Draft for comment 90/55566 DC ISBN 0 580 19702 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Chemicals Standards Policy Committee (CIC/
4、-) to Technical Committee CIC/2, upon which the following bodies were represented: Chemical Industries Association Ministry of Defence Royal Society of Chemistry Society of British Aerospace Companies Limited Society of Environmental Engineers Amendments issued since publication Amd. No.DateComments
5、 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:32:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3482-6:1991 BSI 06-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Method A. Determination at 50 % relative humidity1 3Method B. Determination at 11 % relat
6、ive humidity2 Figure 1 Diagrammatical representation of apparatus required for adsorptive capacity determination3 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:32:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3482-6:1991 ii BSI 06-1999 Forew
7、ord This Part of BS 3482 has been prepared under the direction of the Chemicals Standards Policy Committee. This revision of BS 3482 comprises Part 1, which describes procedures for sampling and preparation and storage of test samples and a number of Parts describing methods of test for desiccants.
8、This revision supersedes BS 3482:1962 which is withdrawn. It differs from BS 3482:1962 in that individual methods have been published in separate Parts and have been generally updated. Some additional methods not included in BS 3482:1962 have also been incorporated. This Part of BS 3482 also superse
9、des the methods given in Appendix F of BS 2540:1960, Appendix F of BS 2541:1960 and Appendix E of BS 3523:1962 which are withdrawn. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Com
10、pliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may h
11、ave had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:32:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3482-6:1991 BSI 06-19991 1 Scope This Part of BS 3482 describes two methods for the
12、determination of the adsorptive capacity of desiccants, method A at 50 % relative humidity and method B at 11 % relative humidity. NOTE 1The desiccant product standards specify which of the methods is to be used. NOTE 2The titles of the publications referred to in this standard are listed on the ins
13、ide back page. 2 Method A. Determination at 50 % relative humidity 2.1 Principle Air at 25 C and 50 % relative humidity is passed through a column of desiccant of known mass until no further increase in mass is observed. The mass gained is expressed as a percentage of the original mass. 2.2 Reagents
14、 2.2.1 General. Use only reagents of recognized analytical grade and water complying with grade 3 of BS 3978. 2.2.2 Calcium nitrate saturated solution 2.2.3 Calcium nitrate, solid 2.3 Apparatus 2.3.1 Ordinary laboratory apparatus and the following are required. 2.3.2 Air pumping apparatus NOTE 1The
15、items described in 2.3.2.1 to 2.3.2.9 comprise the air pumping apparatus. NOTE 2A suitable apparatus is illustrated in Figure 1. 2.3.2.1 Circulating pump, capable of pumping air at the rate of 2 L/min. 2.3.2.2 Flow meter, capable of measuring flow of air at a rate of at least 2 L/min. 2.3.2.3 Heat e
16、xchange coil, of sufficient length and efficiency to ensure that air leaving the pump is brought to the bath temperature before entering the bubbler. 2.3.2.4 Bubbler, about 250 mL capacity, fitted with a thermometer. 2.3.2.5 Spray catch bottle, about 250 mL capacity, containing a glass wool filter.
17、2.3.2.6 Tube with side arm, fitted with a thermometer for checking the temperature of the air entering the adsorption tubes. 2.3.2.7 Two adsorption tubes, 150 mm in length and of 14 mm internal diameter, with stoppers. 2.3.2.8 Tubes, of flexible plastics, forming leak-proof joints with the items des
18、cribed in 2.3.2.1 to 2.3.2.7. NOTEThe joints should be tested before the determination by applying a 0.1 % (m/m) solution of sodium dodecyl sulphate to the joints not immersed in water and operating the pump (2.3.2.1). The absence of visible bubbles indicates leak-proofness. 2.3.2.9 Thermometers, ca
19、pable of indicating 25 C to an accuracy of 0.2 C, complying with BS 593. 2.3.3 Water bath, capable of being maintained at 25 0.2 C, of size sufficient to contain the items described in 2.3.2.3 to 2.3.2.9. 2.3.4 Desiccator, containing anhydrous phosphorus pentoxide. 2.4 Preparation of the test sample
20、 Prepare at least 50 g of dried sample from the laboratory sample by the method described in BS 3482-1. 2.5 Procedure 2.5.1 Test portions Take approximately 25 g of the test sample (2.4) and dry further at the specified temperature until the loss in mass after successive periods of 1 h is less than
21、0.010 g. Cool in the desiccator (2.3.4). Remove the sample from the desiccator and immediately weigh 10 g of sample, to the nearest 0.001 g, into each of the two stoppered adsorption tubes (2.3.2.7), which have previously been weighed to the nearest 0.001 g. 2.5.2 Moisture adsorption Approximately h
22、alf fill the bubbler (2.3.2.4) with the saturated calcium nitrate solution (2.2.2) adding a little of the solid calcium nitrate (2.2.3) to excess. Quickly assemble the air pumping apparatus (2.3.2) and the water bath (2.3.3) as shown in Figure 1 taking care with the underwater connections to ensure
23、that they are leak-proof. Maintain the temperature of the water bath at 25 2 C. Adjust the air flow from the pump (2.3.2.1) so that each stoppered adsorption tube (2.3.2.7) receives air at a rate of approximately 1 L/min, as measured by the flow meter (2.3.2.2). 2.5.3 Determination At intervals, rem
24、ove the adsorption tubes, wipe them dry and reweigh each tube and its contents to the nearest 0.001 g. Continue to pass air, and repeat this process until no further increase in the masses of the tubes and their contents is observed. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:32:53 GM
25、T+00:00 2006, Uncontrolled Copy, (c) BSI BS 3482-6:1991 2 BSI 06-1999 2.6 Calculation and expression of results Calculate the increase in mass of each tube and express the adsorptive capacity at 50 % relative humidity as a percentage by mass of the test portion in each tube from the following expres
26、sion: where Calculate the mean of the two determinations as the adsorptive capacity of the sample. Invalidate two values that differ by more than 0.5 % (absolute). 2.7 Test report The test report shall include the following information. a) A complete identification of the sample. b) A reference to t
27、his British Standard method, i.e. method A of BS 3482-6:1991. c) The results, expressed in accordance with 2.6. d) Any unusual features noted during the determination. 3 Method B. Determination at 11 % relative humidity 3.1 Principle Air at 25 C and 11 % relative humidity is passed through a column
28、of desiccant of known mass until no further increase in mass is observed. The mass gained is expressed as a percentage of the original mass. 3.2 Reagents 3.2.1 General. Use only reagents of recognized analytical grade. 3.2.2 Lithium chloride, saturated solution. 3.2.3 Lithium chloride, solid. 3.3 Ap
29、paratus The apparatus described in 2.3 is required. 3.4 Preparation of the test sample Prepare at least 50 g of dried sample from the laboratory sample by the method described in BS 3482-1. 3.5 Procedure 3.5.1 Test portions Follow the procedure described in 2.5.1. 3.5.2 Moisture adsorption Follow th
30、e procedure described in 2.5.2, substituting “lithium chloride saturated solution (3.2.2)” for “calcium nitrate saturated solution (2.2.2)” and “solid lithium chloride (3.2.3)” for “solid calcium chloride (2.2.3)”. 3.5.3 Determination Follow the procedure described in 2.5.3. 3.6 Calculation and expr
31、ession of results Calculate the increase in mass of each tube and express the adsorptive capacity at 11 % relative humidity as a percentage by mass of the test portion in each tube from the following expression: where Calculate the mean of the two determinations as the adsorptive capacity of the sam
32、ple. Invalidate two values that differ by more than 0.5 % (absolute). 3.7 Test report The test report shall include the following information. a) A complete identification of the sample. b) A reference to this British Standard method, i.e. method B of BS 3482-6:1991. c) The results, expressed in acc
33、ordance with 3.6. d) Any unusual features noted during the determination. m1is the mass of the dried test portion (2.5.1) (in g); m2is the initial mass of the test portion and adsorption tube (2.5.1) (in g); m3is the final mass of the test portion and absorption tube (2.5.3) (in g). m3m2() m1 - -100
34、 m1is the mass of the dried test portion (3.5.1) (in g); m1is the initial mass of the test portion and adsorption tube (3.5.1) (in g); m1is the final mass of the test portion and adsorption tube (3.5.3) (in g). m3m2() m1 - -100 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:32:53 GMT+00:0
35、0 2006, Uncontrolled Copy, (c) BSI BS 3482-6:1991 BSI 06-19993 Figure 1 Diagrammatical representation of apparatus required for adsorptive capacity determination Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:32:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: sheffiel
36、dun sheffieldun, na, Wed Nov 29 07:32:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3482-6:1991 BSI 06-1999 Publication(s) referred to BS 593, Specification for laboratory thermometers. BS 3482, Methods of test for desiccants. BS 3482-1, Sampling, and preparation and storage of samples. BS 3978,
37、Specification for water for laboratory use. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:32:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3482-6: 1991 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for prepa
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