1、BRITISH STANDARD BS 4258-12: 1982 ISO 4285:1977 Methods of test for Phosphoric acid (orthophosphoric acid) for industrial use Part 12: Guide to sampling techniques ISO title: Phosphoric acid for industrial useGuide to sampling techniques UDC 661.634.2:543.05BS4258-12:1982 This British Standard, havi
2、ng been prepared under the directionof the Chemicals Standards Committee, was published under the authorityofthe Board of BSIon 30November1982 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference CIC/25 Draft for comment75/53887 DC ISBN 0 580 13078 9 Coop
3、erating organizations The Chemicals Standards Committee, under whose direction this BritishStandard was prepared, consists of representatives from the followingGovernment departments and scientific and industrial organizations: Association of Fatty Acid Distillers British Tar Industry Association Ch
4、emical Industries Association* Chemical Society, Analytical Division Department of Health and Social Security Department of Industry, Chemicals and Textiles Division Department of Industry, Laboratory of the Government Chemist* Fertiliser Manufacturers Association Ltd.* Hydrocarbon Solvents Associat
5、ion Ministry of Agriculture, Fisheries and Food Ministry of Defence National Sulphuric Acid Association Paintmakers Association of Great Britain Ltd. Royal Institute of Public Health and Hygiene Soap and Detergent Industry Association Standardization of Tar Products Tests Committee The organizations
6、 marked with an asterisk in the above list, together with thefollowing, were directly represented on the committee entrusted with thepreparation of this British Standard: British Pharmacopoeia Commission Campden Food Preservation Research Association Flour Milling and Baking Research Association Ins
7、titute of Metal Finishing Institution of Water Engineers and Scientists National Association of Soft Drinks Manufacturers Society of Chemical Industry Textile Institute Coopted member Amendments issued since publication Amd. No. Date of issue CommentsBS4258-12:1982 BSI 08-1999 i Contents Page Cooper
8、ating organizations Inside front cover National foreword ii 1 Scope 1 2 Field of application 1 3 References 1 4 Means of delivery 1 5 Apparatus 1 6 Procedure 1 7 Sampling report 3 Annex ISO publications relating to phosphoric acid for industrial use 4 Publications referred to Inside back coverBS4258
9、-12:1982 ii BSI 08-1999 National foreword This British Standard has been prepared under the direction of the Chemical Standards Committee in order to provide methods of test for phosphoric acid. This Part is identical with ISO4285 “Phosphoric acid for industrial useGuide to sampling techniques” publ
10、ished in1977 by the International Organization for Standardization (ISO). For some years the UK has participated in the work of preparing methods of test for phosphoric acid for industrial use, organized by subcommittee6 (formerly Working Group7) “Phosphoric acid and condensed phosphates” of Technic
11、al Committee47 “Chemistry” of ISO. As international agreement is reached on the methods, it is proposed to publish them as Parts of this British Standard. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without d
12、eviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. Cross-references. The
13、Technical Committee has reviewed the provisions of ISO683-XIII:1974 and ISO3165:1976, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. However, ISO683-XIII is related to BS1449 “Steel plate, sheet and strip” Part2:1975 “Stain
14、less and heat resisting steel plate, sheet and strip” and ISO3165 is related to BS5309 “Methods for sampling chemical products” Part1:1976 “Introduction and general principles”. ISO . . . . “Chemical productsSampling techniques for mobile liquids and mobile liquids derived from solids” has not yet b
15、een published. Until it is available, guidance can be found in BS5309 “Methods of sampling chemical products” Part3 “Sampling of liquids”. The ISO publications relating to phosphoric acid for industrial use, which are listed in the Annex, correspond to Parts of this British Standard as follows. ISO
16、publication Part of BS4258 ISO848 No equivalent (seeISO3707) ISO849 Part2 Determination of iron content (Technically equivalent) ISO2997 Part3 Determination of sulphate content (Technically equivalent) ISO3359 Part6 Determination of arsenic content (Identical) ISO3360 Part4 Determination of fluorine
17、 content (Technically equivalent) ISO3361 Part5 Determination of silica content (Technically equivalent) ISO3706 Part7 Determination of total phosphorus (V) oxide content:Quinoline phosphomolybdate gravimetric method (Technically equivalent) ISO3707 Part8 Determination of calcium content (flame atom
18、ic absorption method) (Identical) ISO3708 Part9 Determination of chloride content (Technically equivalent) ISO3709 Part10 Determination of oxides of nitrogen content (Identical) ISO4285 Part12 Guide to sampling techniques (Identical)BS4258-12:1982 BSI 08-1999 iii Textual errors. When adopting the te
19、xt of the International Standard, the errors given below were discovered. They have been marked in the text and have been reported to ISO in a proposal to amend the text of the International Standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of
20、 British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Clause reference Textual change Clause4 In line4, “1000ml” should be “1000l”. Clause5.1.2 In line4 of the note, insert “some” before “phosph
21、oricacids”. Summary of pages This document comprises a front cover, an inside front cover, pagesi toiv, pages1to4, 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
22、 inside front cover.iv blankBS4258-12:1982 BSI 08-1999 1 1 Scope This International Standard is a guide to sampling techniques concerning the procedure to be followed and the precautions to be observed for the taking, the preparation and the storage of samples from a delivery of phosphoric acid for
23、industrial use, with a view to assessing its quality. 2 Field of application This guide to sampling techniques applies to orthophosphoric and polyphosphoric acids prepared by thermal and by wet processes, as well as to crystallized phosphoric acids. The sampling of wet-process acids is particularly
24、difficult because of the frequent presence of a more or less copious precipitate that is not easy to disperse into a suspension. 3 References ISO683-XIII, Heat-treated steels, alloy steels and free-cutting steelsPart13: Wrought stainless steels. ISO3165, Sampling of chemical products for industrial
25、useSafety in sampling. ISO. . ., Chemical productsSampling techniques for mobile liquids and mobile liquids derived from solids 1) . 4 Means of delivery Phosphoric acids are generally delivered in large containers or mobile tanks (trucks, wagons, tankers) each of which may form a batch, and, morerar
26、ely, in smaller containers (forexample,capacity less than1000ml 2) ). 5 Apparatus 5.1 For sampling 5.1.1 Sampler or weighted bottle, of stainless steel complying with the requirements of grade20a of ISO683-XIII (seeISO . . .). 5.1.2 Containers, of plastics (polyethylene, polypropylene, polystyrene)
27、when the acids are at a temperature below50 C but of stainless steel, complying with the requirements of grade20a of ISO683-XIII, when the acids are at a temperature above50 C. The caps of plastics containers shall not contain metal inserts. NOTEThe use of glass flasks for the taking and storage of
28、samples is not recommended. They can cause the formation of films that adhere to the walls and form fluorosilicates by attack of the glass by the hydrofluoric acid present in phosphoric acids 2) . 5.2 For mixing in the delivery container Among the available means for mixing, those with the greatest
29、chances of success are the following: 5.2.1 Mechanical stirrer (for example, propeller type), in the case of small delivery containers. 5.2.2 Stirring system by air bubbling or closed-circuit pumping, in the case of large containers and tanks. NOTE 1The air-bubbling system is the simplest and most p
30、ractical and may, furthermore, be adapted to the shape of the reservoir by the use of spargers. It may, however, possibly result in the removal of hydrogen fluoride and fluorosilicate gas from the liquid, or vary the water content. Closed-circuit pumping, provided that the output of the pump is high
31、 enough, is undoubtedly the most effective. NOTE 2The mechanical stirrer and the air lance should be of acid-resistant stainless steel or be plastics coated. For assaying high strength acids, use dry air. If closed-circuit pumping is the method selected, it should be remembered that strong phosphori
32、c acids crystallize at temperature of up to28 C; facilities should, therefore, be available to drain and wash out lines and pumps. 5.3 Other equipment (for crystallized acids) 5.3.1 Suitable heating system: immersion heaters, heating jackets, etc. Take care when using immersion heaters, steam coils
33、and jackets as a significant degree of corrosion always occurs if the surface temperature exceeds80 C. Furthermore, the temperature of significant attack is decreased considerably if halides are present. The use of hot water through acid-resistant steel coils is recommended. 6 Procedure 6.1 Safety m
34、easures WARNING Carry out the different operations for the sampling of phosphoric acid with all safety precautions. In particular,the wearing of protective gogglesand anti-acid gloves is mandatory. SeealsoISO3165. 6.2 Sampling of thermal-process acids As these acids are normally free from deposits,
35、their sampling does not present any special difficulties. Follow the general techniques specified in ISO . . . 1) In preparation. 2) Seenational foreword for details of textual errors.BS4258-12:1982 2 BSI 08-1999 6.3 Sampling of wet-process acids These acids generally contain a precipitate which inc
36、reases with time and which consists chiefly of calcium sulphate (gypsum), fluorosilicates and phosphates (of calcium, iron, aluminium, etc.). The sampling is difficult: it depends on the strength of the acid, on the storage time (if the acid is “old”, the precipitate may be copious and more or less
37、agglomerated), and on the size of the containers (stirring is more difficult in large containers). The usual technique consists in stirring, in the most effective manner possible, the acid to be sampled, so as to place any precipitate completely into suspension (complete mixing may, in certain cases
38、, require8h) and if possible, carrying out sampling while maintaining the stirring. 6.3.1 Case of large containers and mobile tanks This is the most frequent case. The batch or the consignment may consist of a single container. Sampling may be carried out, by agreement between the interested parties
39、, during either the filling or the emptying of each container. 6.3.1.1 SAMPLING 6.3.1.1.1 After filling or before emptying Stir the contents of the container by the most effective means available (see5.2) and maintain the stirring during the sampling. Take the samples as provided for in the sampling
40、 plan 3) , using the sampler or the weighted bottle (see5.1) and following the method specified in ISO ., depending on the shape of the container. In general, depending on the size of the container, its shape and the locations of the openings, take one or more series of three primary samplesat the b
41、ottom, mid-height and surfaceby the procedure specified in ISO . . . 6.3.1.1.2 During transfer It is particularly advantageous and useful to take the sample during the filling or emptying of the delivery container, because, by this means, a more representative sample is generally obtained. Stir the
42、product upstream of the transfer piping, that is in the storage tank during filling of the container, or in the container itself during emptying. In general, take three primary samples, at the beginning, half-way through, and at the end of transfer. For this purpose, proceed as follows: Connect the
43、tanker hose to the inlet valve at flangeA. Close drain valve C and open inlet valve B. Start the tanker pump. When a sample is required, switch off the tanker pump, and quickly close valveB. Then open valve C (this valve is normally used to drain the inlet line) and take a sample of acid. 6.3.1.1.3
44、In all cases Collect the various samples quantitatively (without loss of precipitate) in the plastics or stainless steel containers(5.1.2). If possible, avoid the storage ofsamples of any acid containing significant (greaterthan100mg/kg) levels of halide ions in stainless steel containers. 6.3.1.2 P
45、REPARATION OF REPRESENTATIVE SAMPLES FROM THE CONTAINER (THE CONTAINER CONTENTS) AND FROM THE BULK SAMPLES Proceed as indicated in ISO . . ., but take particular care to mix each primary sample as thoroughly as possible before combining them in suitable proportions. When samples have been taken duri
46、ng transfer, the masses mixed shall be proportional to the rate of flow. NOTEIf the samples are to be analysed separately, do not mix them but store them individually as partial samples. Prepare and store the samples in the plastics containers(5.1.2). 6.3.1.3 PREPARATION OF LABORATORY SAMPLES Mix th
47、e bulk sample (which may be the container sample in the case of a single container) as thoroughly as possible and take the required number of portions of suitable volume, following the sampling plan, so that each laboratory concerned receives one assay sample, on which other determinations may also
48、be carried out, one sample for other determinations, 3) The sampling plan depends on the particular characteristics of the acid to be sampled, and should be drawn up on statistical bases, amongst others, in conformity with International Standards at present under study.BS4258-12:1982 BSI 08-1999 3 a
49、nd so that one or more additional samples may be kept in case of dispute. Treat all these samples in such a way as to give a solution in which any precipitate has been completely dissolved by a suitable method. Store the samples in the plastics containers(5.1.2). 6.3.2 Case of smaller containers (for example of capacity less than1000l) Mix the contents of the containers to be sampled. If a precipitate is present that cannot be dispersed by stirring (a particularly unfavourable possibility), it may be possible to determine the proportion of sediment a
