1、BRITISH STANDARD BS3483-C3: 1982 ISO787-4: 1981 Methods for Testing pigments for paints Part C3: Determination of acidity or alkalinity of the aqueous extract ISO title: General methods of test for pigments and extenders Part4: Determination of acidity or alkalinity of the aqueous extract This Part
2、should be read in conjunction with the General Introduction to BS3483 issued separately. UDC 667.622:543.241.056BS3483-C3:1982 This BritishStandard, having been prepared under the directionof the Pigments, Paintsand Varnishes StandardsCommittee, waspublished under the authorityof the Board ofBSIandc
3、omes into effect on 30November1982 BSI12-1999 First published March1974 First revision November1982 The following BSI references relate to the work on this standard: Committee reference PVC/1 Draft for comment 80/50280 DC ISBN 0 580 12940 3 Amendments issued since publication Amd. No. Date of issue
4、CommentsBS3483-C3:1982 BSI 12-1999 i Contents Page National foreword ii 0 Introduction 1 1 Scope and field of application 1 2 References 1 3 Reagents 1 4 Apparatus 1 5 Sampling 1 6 Procedure 1 7 Expression of results 2 8 Test report 2 Publications referred to Inside back coverBS3483-C3:1982 ii BSI 1
5、2-1999 National foreword This revision of Part C3 of BS3483 has been prepared under the direction of the Pigments, Paints and Varnishes Standards Committee. It is identical with ISO787-4 “General methods of test for pigments and extenders Part4: Determination of acidity or alkalinity of the aqueous
6、extract” published in1981 by the International Organization for Standardization (ISO). This Part of BS3483 supersedes BS3483-C3:1974 which is withdrawn. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a BritishStandard without devi
7、ation. Some terminology and certain conventions are not identical with those used in BritishStandards; attention is especially drawn to the following. The comma has been used throughout as a decimal marker. In BritishStandards it is current practice to use a full point on the baseline as the decimal
8、 marker. Wherever the words “This part of ISO787” and “International Standard” appear, referring to this standard, they should be read as “This Part of BS3483” and “BritishStandard” respectively. The Technical Committee has reviewed the provisions of ISO/R385, to which reference is made in the text,
9、 and has decided that they are acceptable for use in conjunction with this standard. A related BritishStandard for ISO/R385 was BS846:1962 1) . Additional information. In6.2.3 of ISO787-4:1981, it is stated that the procedure (clause6) is to be repeated if the results of the duplicate determinations
10、 differ by more than5% of the higher value. In implementing this standard in the United Kingdom, it is recommended that, if repeat determinations are necessary, wherever possible both the sampling (clause5) and the procedure (clause6) should be repeated. 2) A British Standard does not purport to inc
11、lude all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance 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, page
12、si andii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Cross-references International Standard Corresponding BritishStandard
13、BS3483 Methods for testing pigments for paints ISO787-3:1979 Part C1:1980 Determination of matter soluble in water (hot extraction method) (Identical) ISO787-8:1979 Part C2:1980 Determination of matter soluble in water (cold extraction method) (Identical) ISO842:1974 BS4726:1971 Method for sampling
14、raw materials for paints and varnishes (Technically equivalent) 1) Now withdrawn, having been superseded by BS846:1980 “Specification for burettes”. 2) This change has been reported to the ISO in a proposal to amend the International Standard.BS3483-C3:1982 BSI 12-1999 1 0 Introduction This document
15、 is a part of ISO787, General methods of test for pigments and extenders. 1 Scope and field of application This part of ISO787 specifies a general method of test for determining the acidity or alkalinity of the aqueous extract of a sample of pigment or extender. NOTEWhen this general method is appli
16、cable to a given pigment or extender, only a cross-reference to it should be included in the International Standard relating to that pigment or extender, with a note of any detailed modification which may be needed in view of the special properties of the material in question. Only when this general
17、 method is not applicable to a particular material should a special method for determination of acidity or alkalinity be specified. 2 References ISO/R385, Burettes. ISO787, General methods of test for pigments and extenders Part3: Determination of matter soluble in water Hot extraction method Part8:
18、 Determination of matter soluble in water Cold extraction method. ISO842, Raw materials for paints and varnishes Sampling. 3 Reagents During the analysis use only reagents of recognized analytical grade and only distilled water or water of at least equivalent purity. 3.1 Hydrochloric acid, standard
19、volumetric solution, c(HCl)=0,05mol/l. 3.2 Sodium hydroxide, standard volumetric solution, c(NaOH)=0,05mol/l, or potassium hydroxide, standard volumetric solution, c(KOH)=0,05mol/l. For method A: 3.3 Methyl red indicator,1g/l solution in60% (V/V) ethanol. 4 Apparatus Ordinary laboratory apparatus an
20、d 4.1 Burette, of capacity50ml, complying with the requirements of ISO/R385. For method B: 4.2 pH measuring device, capable of measurement to0,1unit, calibrated against buffer solutions of known pH value at the temperature of the test. 5 Sampling Take a representative sample of the material to be te
21、sted as described in ISO842. 6 Procedure Carry out the determination in duplicate. 6.1 Test solution Follow the procedure specified in ISO787-3, to the stage of obtaining a perfectly clear filtrate. NOTEIf agreed or specified, the procedure described in ISO787-8 (cold extraction method) may be follo
22、wed. In this case, the period of stirring should be reduced to5min. 6.2 Determination NOTEIf the filtrate is coloured the use of the indicator(6.2.1) is not suitable. The potentiometric method(6.2.2) should be used. 6.2.1 With indicator solution (method A) Add5 drops of the methyl red indicator(3.3)
23、 to100ml of the test solution(6.1). If the solution is orange, consider it as being neutral. If the solution is yellow (alkaline), titrate it with the hydrochloric acid solution(3.1) to an orange end-point. If the solution is red (acid), titrate it with the sodium or potassium hydroxide solution(3.2
24、) to an orange end-point. NOTEBy agreement between the parties, another colour indicator can be used. 6.2.2 Potentiometric determination (method B) Take100ml of the test solution(6.1), insert the electrodes of the pH measuring device and read the pH value. If the pH value is between4 and8, consider
25、the solution as being neutral. If the pH value is more than8 (alkaline), titrate the solution with the hydrochloric acid solution(3.1) to a pH value just less than8. If the pH value is less than4 (acid), titrate the solution with the sodium or potassium hydroxide solution(3.2) to a pH value just mor
26、e than4. 6.2.3 Repeat determinations 3) If the results of the duplicate determinations differ by more than5% of the higher value, the procedure (clause6) should be repeated. 3) See the paragraph headed “Additional information” in the national foreword.BS3483-C3:1982 2 BSI 12-1999 7 Expression of res
27、ults 7.1 Calculation Calculate the acidity (alkalinity) by the equation where A is the acidity (alkalinity) expressed as millilitres of0,1mol/l alkali (hydrochloric acid) solution required to neutralise the extract of100g of product; m is the mass, in grams, of the sample taken to prepare the test s
28、olution(6.1); V is the volume, in millilitres, of the sodium or potassium hydroxide solution(3.2) or hydrochloric acid solution(3.1). If the extract is neutral, report the result as “neutral”. For titrimetric measurements report the mean of the two determinations. 7.2 Precision No precision data are
29、 currently available. 8 Test report The test report shall contain at least the following information: a) the type and identification of the product tested; b) a reference to this International Standard (ISO787-4); c) the result of the test as indicated in clause7; d) any deviation, by agreement or o
30、therwise, from the procedure specified; e) the date of the test. A V 2,5 100 2 m - = 125 V m - =BS3483-C3:1982 BSI 12-1999 Publications referred to See the national foreword.BS3483-C3: 1982 ISO787-4: 1981 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent
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