BS 4774-1972 Methods of test for chloroform for industrial use《工业用氯仿试验方法》.pdf

1、BRITISH STANDARD BS 4774:1972 Methods of test for Chloroform for industrial useBS4774:1972 This British Standard, having been approved by the ChemicalsIndustry Standards Committee, was published underthe authority of the Executive Board on 26 May 1972 BSI 12-1999 The following BSI references relate

2、to the work on this standard: Committee references CIC/4 and CIC/4/6 Draft for approval 70/32041 ISBN 580 06666 5 Co-operating organizations The Chemicals Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Governme

3、nt departments and scientific and industrial organizations: British Steel Industry Chemical Industries Association* Department of Health and Social Security Department of Trade and Industry Department of Trade and Industry Laboratory of the Government Chemist* Fertilizer Manufacturers Association Lt

4、d. Institute of Vitreous Enamellers Institution of Gas Engineers Ministry of Agriculture, Fisheries and Food National Sulphuric Acid Association Royal Institute of Public Health and Hygiene Soap and Detergent Industry Association The Government department and industrial organization marked with an a

5、sterisk in the above list, together with the following, were directly represented on the committee entrusted with the formulation of the United Kingdom point of view in the international work leading to the publication of this British Standard: British Plastics Federation Dyers and Cleaners Research

6、 Organization Fire Extinguishers Trades Association Institute of Metal Finishing Institute of Refrigeration Man-made Fibre Producers Committee Ministry of Defence, Army Department Ministry of Defence, Navy Department Oil and Colour Chemists Association Paintmakers Association of Great Britain Pharma

7、ceutical Society of Great Britain Research Association of British Paint, Colour and Varnish Manufacturers Royal Institute of Chemistry Society of Chemical Industry Society of Motor Manufacturers and Traders Ltd. Amendments issued since publication Amd. No. Date CommentsBS4774:1972 BSI 12-1999 i Cont

8、ents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Determination of distillation characteristics 1 3 Determination of density at 20 C 1 4 Determination of residue on evaporation 1 5 Determination of water content 1 6 Determination of acidity 1 7 Measurement of colour 2 8

9、 Test report 2 Figure 1 Apparatus for determination of residue on evaporation 3BS4774:1972 ii BSI 12-1999 Foreword This standard makes reference to the following British Standards: BS 593, Laboratory thermometers. BS 1792, One-mark volumetric flasks. BS 2511, Determination of water (Karl Fischer met

10、hod). BS 3978, Water for laboratory use. BS 4522, Method for the determination of density of liquids at 20 C. BS 4591, Method for the determination of distillation characteristics. For some years the United Kingdom has participated in the work of preparing methods of test for halogenated hydrocarbon

11、s for industrial use, carried out within Working Group6 of Technical Committee47 Chemistry, of the International Organization for Standardization (ISO). As international agreement is reached on the methods of test for each product, it is proposed to publish them as British Standards. This British St

12、andard is technically identical with ISO Recommendation R1870, “Chloroform for industrial use Methods of test”, and is published at the same time as three other British Standards similarly produced: BS 4775, “Methods of test for 1, 4-dichlorobenzene for industrial use”. BS 4776, “Methods of test for

13、 4-chlorotoluene for industrial use” and BS 4777, “Methods of test for 2-chlorotoluene for industrial use”. 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. Compliance with a British S

14、tandard 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, pages1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorp

15、orated. This will be indicated in the amendment table on the inside front cover.BS4774:1972 BSI 12-1999 1 1 Scope This British Standard describes methods of test for chloroform for industrial use. NOTEThe titles of the British Standards referred to in this standard are listed on pageii. 2 Determinat

16、ion of distillation characteristics Use the method described in BS4591:1971, subject to the following additional details and modifications appropriate for chloroform. 2.1 Principle (see1 of BS4591:1971). This determination indicates the difference between the temperatures corresponding to the collec

17、tion of two volumes of distillate, A and B. These two volumes will be indicated in the specifications for the product agreed between the interested parties. 2.2 Thermometer (see3.2 of BS4591:1971). Use a thermometer including the interval59 C to71 C (see BS593). 2.3 Distillation rate (see6.2 of BS45

18、91:1971). Carry out the distillation at a rate of4ml to5ml per minute. 2.4 Temperature correction. The temperature correction, which is necessary only when the scope of the determination is to ascertain the two temperatures corresponding to the volumes of distillate A and B, is equal to0.040(760p) C

19、 where p is the barometric pressure in millimetres of mercury. This correction shall be added to the observed temperatures. 3 Determination of density at 20 C Use the method described in BS4522. 4 Determination of residue on evaporation 4.1 Principle. The principle of this method is weighing of the

20、residue obtained after evaporation of the test portion at its boiling point and drying at110 C to constant mass. CAUTION. This test should be carried out in a fume cupboard with a good draught. 4.2 Apparatus. The following apparatus is used. 1) Platinum dish or, in the absence of this, a borosilicat

21、e glass dish, of approximately140ml capacity and85mm diameter. 2) Apparatus for heating the dish by transmission of heat obtained by boiling chloroform under reflux. Figure 1 shows an example of such an arrangement. 3) Oven, controlled at110 2 C. 4.3 Procedure. Weigh the dish to the nearest0.2mg, af

22、ter heating for 30min in the oven at110 C and cooling in a desiccator, for30min in the case of a platinum dish or for45min in the case of a borosilicate glass dish. Introduce100.0ml of the test sample. Place the dish on the heating apparatus, taking care to place an inverted funnel over it for prote

23、ction against the deposition of dust. Wait until all the liquid has evaporated, then place the dish, containing the residue, in the oven with the temperature previously set at110 2 C. Dry until the mass is constant to within 0.2mg, leaving the dish and contents to cool in a desiccator before each we

24、ighing for the same time as when weighing out. 4.4 Expression of results. Residue on evaporation is expressed as a percentage (m/m) by the formula: where m is the mass of the weighed residue (g); 20 is the density of the test sample at20 C (g/ml); V is the volume of the test portion,i.e.100.0ml. 5 D

25、etermination of water content Use any of the methods described in BS2511. 6 Determination of acidity 6.1 Principle. The principle of this method is titration of the acidity of the aqueous extract separated from a test portion with standard sodium hydroxide solution, using bromocresol green as indica

26、tor. 6.2 Apparatus. Ordinary laboratory apparatus is to be used. 6.3 Reagents. The following reagents are to be used. 1) Sodium hydroxide. Approximately0.01N solution, standardized against 0.01N hydrochloric acid solution under the same conditions as in the determination. 2) Bromocresol green. 1g/l

27、solution in95% (v/v) ethanol. 3) Distilled water neutral to bromocresol green. Add distilled water contained in a conical flask fitted with a ground glass stopper, 1% (v/v) of the bromocresol green solution 6.3 2) and neutralize with the standard sodium hydroxide solution6.3 1) until the colour beco

28、mes a clear blue.BS4774:1972 2 BSI 12-1999 NOTEAttention is drawn to BS3978, “Water for laboratory use”. 6.4 Procedure 6.4.1 Test portion. Take50.0ml of the laboratory sample. 6.4.2 Determination. Place in a250ml separating funnel, 100.0ml of neutral distilled water 6.3 3) at approximately20 C. Add

29、the test portion (6.4.1) and agitate for exactly3min, measured with the aid of a chronometer. Allow to settle. If the sample is acid, the aqueous phase will be yellow in colour. Carefully take50.0ml of this phase and transfer to a250ml conical flask. Titrate with the sodium hydroxide solution 6.3 1)

30、 until a clear blue colour is obtained. 6.5 Calculation. The acidity, expressed in milli-equivalents per litre, is given by the formula: where V is the volume, in millilitres, of the standard sodium hydroxide solution used for the titration. 7 Measurement of colour 7.1 Principle. The principle of th

31、is method is comparison of the colour of the sample with coloured standards, expressing the result in Hazen (platinum-cobalt) units. NOTEThe Hazen unit is by definition, the colour of a solution containing 1part per million of platinum in the form of chloroplatinic acid, in the presence of2parts per

32、 million of cobaltous chloride hexahydrate (CoCl 2 .6H 2 O). 7.2 Apparatus. Use the following apparatus. 1) Ordinary laboratory apparatus, and 2) Matched flat bottom colorimetric tubes, (two) with a graduation mark at least100mm from the base. 7.3 Reagents. Use only distilled water or water of equiv

33、alent purity throughout the analysis. The following reagents are to be used. 1) Cobaltous chloride, hexahydrate. 2) Hydrochloric acid, concentrated36%(m/m) (11N). 3) Either a) Chloroplatinic acid reagent. Dissolve250mg of platinum in a small quantity of aqua regia contained in a glass or porcelain b

34、asin by heating on a water bath. When the metal has dissolved evaporate the solution to dryness. Add1ml of the hydrochloric acid 7.3 2) and again evaporate to dryness. Repeat this operation twice more. or b) Potassium chloroplatinate. 7.4 Preparation of colour standard. Dissolve0.50g of the cobaltou

35、s chloride hexahydrate 7.3 1) and either the whole of the chloroplatinic acid (prepared as described in7.3 3)a) or0.623g of the potassium chloroplatinate 7.3 3)b), in50ml of the hydrochloric acid 7.3 2). Warm if necessary to obtain a clear solution and after cooling, pour into a500ml one-mark volume

36、tric flask. Dilute with water to the mark. NOTEAttention is drawn to BS3978, “Water for laboratory use”, and to BS1792, “One-mark volumetric flasks”. From this solution prepare a series of colour standards ranging from0Hazen colour units upwards at intervals of10units. For each10units pipette5.0ml o

37、f the solution into a250ml one-mark volumetric flask and dilute with water to the mark. These diluted solutions shall always be freshly prepared. 7.5 Procedure. Fill one of the colorimetric tubes7.2 2) to the mark with the sample, and the other with the selected colour standard. Using a white backgr

38、ound compare the colours, viewing vertically. Repeat with other colour standards, if necessary, until the closest match is obtained. If the colour of the sample does not match that of any of the colour standards, report if possible an approximate value or give a description of the colour with an app

39、ropriate note. 8 Test report For each test state the following in the report: 1) the reference of the method used,i.e. “in accordance with BS4774”; 2) the results and the method of expression used; 3) any unusual features noted during the determination; 4) any operation not included in this standard

40、 or those to which reference is made or regarded as optional.BS4774:1972 BSI 12-1999 3 Figure 1 Apparatus for determination of residue on evaporation4 blankBS4774:1972 BSI 12-1999 British Standards The following are available on application: YEARBOOK Including subject index and numerical list of Bri

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44、d steel (SL 24) Laboratory apparatus (SL 23) Leather, plastics, rubber (SL 12) Local authority purchasing officers guide (SL 28) Machine tools (SL 20) Mechanical engineering (SL 6) Nomenclature, symbols and abbreviations (SL 29) Non-ferrous metals (SL 19) Nuclear energy (SL 36) Packaging and contain

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