1、BRITISH STANDARD BS1747-6: 1983 ISO4219:1979 Methods for Measurement of air pollution Part6: Sampling equipment used for the determination of gaseous sulphur compounds in ambient air ISO title: Air quality Determination of gaseous sulphur compounds in ambient air Sampling equipment UDC551.510.42:614
2、.72:551.508.95:546.22-13BS1747-6:1983 This British Standard, having been prepared under the directionof the Environment andPollution Standards Committee, was published underthe authority of the BoardofBSI and comes into effect on 31January1983 BSI 08-1999 The following BSI references relate to the w
3、ork on this standard: Committee reference EPC/35 Draft for comment77/52934DC ISBN 0 580 13121 1 Cooperating organizations The Environment and Pollution Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following: Association of County
4、 Councils British Gas Corporation* British Industrial Measuring and Control Apparatus Manufacturers Association (BEAMA) British Paper and Board Industry Federation (PIF) British Railways Board British Steel Corporation* Chemical Industries Association Confederation of British Industry Consumer Stand
5、ards Advisory Committee of BSI Council of Engineering Institutions Council of Environmental Conservation Department of Industry (Laboratory of the Government Chemist)* Department of Industry (Warren Spring Laboratory)* Department of the Environment (Water Directorate) Department of Transport Electri
6、city Supply Industry in England and Wales* Engineering Equipment Users Association Greater London Council Health and Safety Executive* Institute of Petroleum* Medical Research Council Ministry of Agriculture, Fisheries and Food National Coal Board* National Water Council Royal Society of Chemistry S
7、cottish Office Trades Union Congress The organizations marked with an asterisk in the above list, together with the following, were directly represented on the Technical Committee entrusted with the preparation of this British Standard: Cement Makers Federation Department of Health and Social Securi
8、ty Institution of Environmental Health Officers Institution of Gas Engineers Lead Development Association National Industrial Fuel Efficiency Service National Society for Clean Air Amendments issued since publication Amd. No. Date of issue CommentsBS1747-6:1983 BSI 08-1999 i Contents Page Cooperatin
9、g organizations Inside front cover National foreword ii 0 Introduction 1 1 Scope 1 2 Field of application 1 3 Definition 1 4 Principle 1 5 Equipment 1 6 Installation 4 Figure 1 Block diagram of sampling equipment 2 Figure 2 Air intake with protecting funnel 2 Publications referred to Inside back cov
10、erBS1747-6:1983 ii BSI 08-1999 National foreword This Part of this British Standard, which has been prepared under the direction of the Environment and Pollution Standards Committee, is identical with ISO4219:1979 “Air quality Determination of gaseous sulphur compounds in ambient air Sampling equipm
11、ent”. The International Standard was prepared by Technical Committee146, Air quality, and published by the International Organization for Standardization (ISO) as a result of discussion in which the UK participated. This Part of this British Standard is one of a series relating to air quality arisin
12、g from UK participation in the work of ISO/TC146. Methods for the determination of particular constituents of ambient air will be published as further Parts of this standard. Topics relating to air quality characteristics will be published as Parts of BS6069 “Methods for characterization of air qual
13、ity”. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is especially drawn to the follo
14、wing. The comma has been used as a decimal marker. It is current practice in British Standards to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. ISO4220, to which refer
15、ence is made in clauses0, 2 and3, is still in course of preparation. When it is published, consideration will be given to publishing it as a dual numbered British Standard. Additional information.3 Definition. The definition for “gaseous sulphur compounds” is liable to misinterpretation and the foll
16、owing has been reported to ISO in a proposal to amend the text of the International Standard. “gaseous sulphur compounds: Sulphurdioxide and other gaseous sulphur compounds, and, in addition, water-soluble acidic gases determined according to the method in ISO4220.” A British Standard does not purpo
17、rt to include 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. Cross-references International Standard Corresponding British Standard ISO
18、4221:1980 BS1747 Methods for measurement of air pollution Part7:1982 Determination of mass concentration of sulphur dioxide in ambient air: Thorin spectrophotometricmethod (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside b
19、ack 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.BS1747-6:1983 BSI 08-1999 1 0 Introduction The determination of gaseous sulphur compounds in ambient atmos
20、pheres requires as a first step the collection of a sample of air and the absorption of the constituents to be determined in a suitable liquid medium. The specific absorption media and some of the sampling conditions may vary according to the methods. This International Standard provides details of
21、the equipment required thus obviating the necessity for specification in detail of the equipment in each of the separate International Standards concerned with methods of determination of gaseous sulphur compounds. The method of sampling is covered in ISO4220 and4221. 1 Scope This International Stan
22、dard specifies general requirements for the equipment for the sampling of ambient air in order to determine gaseous sulphur compounds, particularly sulphurdioxide. 2 Field of application This International Standard is applicable to ambient air. It is applicable to the sampling of air for sulphurdiox
23、ide and other gaseous sulphur compounds as defined in clause3. It is primarily intended to be used in conjunction with the following International Standards: 1) ISO4220, Air quality Determination of a gaseous acid pollution index Titrimetric method with indicator or potentiometric end-point detectio
24、n. ISO4221, Air quality Determination of mass concentration of sulphurdioxide in ambient air Thorin spectrophotometric method. which specify supplementary details relating to the sampling equipment, the absorbing solution and the sampling procedure. The sampling equipment specified may also be used
25、for determinations other than gaseous sulphur compounds. 3 Definition gaseous sulphur compounds sulpurdioxide, other gaseous sulphur compounds and water-soluble acidic gases determined according to the method of ISO4220 4 Principle Drawing of ambient air through an absorber to trap the gaseous sulph
26、ur compounds being determined. Under certain circumstances, detailed in the relevant International Standard, filtration of the air to remove interfering particulates. 5 Equipment Because gaseous sulphur compounds are very reactive, the use of the correct materials for all parts of the sampling equip
27、ment coming into contact with the air containing these compounds is essential. Materials used shall not absorb any of the constituents to be determined and shall not react with them to produce a reaction product that might interfere with subsequent determination or to reduce the concentration of the
28、 constituents. The equipment shall consist essentially of the following components, each of which is separately described in5.1 to5.7: air intake; connecting tubing; particulate filter and filter holder; absorber; protection filter; 1) An International Standard specifying a tetrachloromercurate (TCM
29、) pararosaniline spectrophotometric method for the determination of the mass concentration of sulphurdioxide in ambient air is in preparation.BS1747-6:1983 2 BSI 08-1999 sampling pump; gas meter or air-flow regulator. A schematic layout of a typical assembly system is shown in Figure 1: 5.1 Air inta
30、ke No particular design of air intake is required for this International Standard concerning determination of gaseous sulphur compounds only. If the air intake may be exposed to precipitation, an inverted funnel may be used as protection, as shown in Figure 2. If it is intended to carry out other de
31、terminations, e.g.concentration of black smoke with the same equipment (see clause2), the air must be drawn in through an air intake of appropriate diameter. 5.2 Connecting tubing 5.2.1 Dimensions The internal diameter of the tubing shall be6 to8mm and the internal surface shall be smooth. Figure 1
32、Block diagram of sampling equipment Figure 2 Air intake with protecting funnelBS1747-6:1983 BSI 08-1999 3 5.2.2 Material In addition to the general requirements for materials, plastics materials used shall be protected from actinic activity and preferably should be covered with a material having a l
33、ow thermal conductivity. All tubing shall be airtight. Regular cleaning of the tubing is recommended. The following materials, in order of preference according to descending effectiveness, may be used: a) Polytetrafluorethylene (PTFE). Although chemically inert, PTFE is not flexible and difficulty m
34、ay be experienced in making connections. Connections with PTFE can be made successfully using connectors which are available in PTFE. In addition, in view of the inflexibility of PTFE, there is no need to use PTFE downstream of the sample absorber. Rubber vacuum hose should be the preferred material
35、 since it is flexible, makes good seals and will not affect the sample because the components of interest have already been removed. b) Glass. Glass is fragile. It is suggested that connections to components be made using butt joints with flexible PVC tubing. c) Polypropylene (polyethylene). Agents
36、used for cleaning tubing shall be sulphur free. 5.3 Particulate filter The assembly shall be airtight in use; hence, an appropriate clamping device shall be used together with an annular seal. Air shall be drawn upwards through the filter. 5.3.1 Filter material The material of the filter shall be ch
37、emically inert with respect to sulphur compounds, and shall not be hygroscopic. The filter shall possess high efficiency(99%) for particles above0,34m. If the filter is being used simply to remove particulate matter (which interferes with some methods of analysis), a suitable filter is a pad of poly
38、styrene fibres 2) . This filter has excellent efficiency and low pressure drop, and the material is inert. Other kinds of inert filter can also be used. The use of glass fibre filter material is not recommended as it is too reactive (seefirst paragraph). NOTEUnder conditions of high humidity, the pa
39、rticulate filter may become damp and thus absorb some sulphur compounds from the air passing through it. These conditions should be noted in the test report. The heating of the filter under such conditions is not recommended due to the possibility of side reactions. However, under some climatic cond
40、itions, it is found necessary to warm the filter above the dew point. 5.3.2 Filter holder The filter holder shall be made from inert material, for an example an inert form of PVC. 5.4 Absorber The design of the absorption bottle, in which the absorption solution is contained, is dependent on the par
41、ticular analysis to be employed and on the sampling flow rate. The relevant International Standards shall be consulted. 5.5 Protection filter If a liquid absorbent is employed, it may be necessary to insert a trap between the absorption bottle and the gas meter (or the air-flow regulator) to protect
42、 the latter from absorbing solution droplets and/or harmful gases. The design of the trap is not critical, provided that air is not allowed to enter the system through leakage (it will normally be under slight suction). 5.6 Gas meter or air-flow regulator In order to calculate the relevant concentra
43、tion, the volume of air sampled must be known. The volume is best measured by an integrating method, for example by using a dry-gas meter. This shall be able to record the volume of sampled air to a sufficient accuracy at the flow rate used. A flow-regulating system based on the use of a critical or
44、ifice may alternatively be used. The flow shall then be checked at the beginning and end of the sampling period at the air intake with a device such as a variable-area flow meter to ensure that the flow rate has not changed because of partial plugging of the orifice. Calibration of these meters or o
45、rifices may be carried out by comparison with a laboratory wet-gas meter which has itself been subjected to primary calibration within the preceding2years. 2) For example, Microsorban.BS1747-6:1983 4 BSI 08-1999 5.7 Sampling pump The most suitable device for sampling is a constant-flow air pump. The
46、 type of pump should preferably be chosen for the intended air flow rate as it is not good practice to control a pump flow rate by voltage variations. Unless the pump is placed after the gas meter, it shall be leak proof. 6 Installation Install the equipment in an environment in which it is not expo
47、sed to extreme temperatures or to direct sunlight for long periods. Arrange the air intake(5.1) so that it is at least1m from all obstacles, including sampling equipment, and more than3m above the nearest large area of horizontal surface. The tubing or funnel shall point vertically downwards. Take c
48、are to avoid placing the air intake anywhere near local sources of pollution, such as a low-level chimney or an exhaust vent. NOTEThe choice of a site which is representative of the relevant concentration in a given geographical area, and the number of sites required for adequate coverage of a given
49、 area, will be the subject of other International Standards. Arrange the connecting tubing(5.2) in such a way that there are no loops in which water may collect and no radii less than50mm. The latter condition is particularly important if a black smoke index is being determined with the same equipment. The total length of tubing between air intake and absorber(5.4) shall be as short as possible and in any case shall be less than6m. Check that all connections between the components of the equipment are airtight.BS1747-6:1983 BSI 08-19
