Draft for Public Comment

Transcription

1 Draft for Public Comment Form 36 Version 6.1 DPC: 07/ DC Head Office 389 Chiswick High Road London W4 4AL Telephone: +44(0) Fax: +44(0) Date: 15 January 2007 Origin: National Latest date for receipt of comments: 30 March 2007 Project no.: 2006/02306 Responsible committee: GEL/31/19 Gas detectors Interested committees: Title: Draft BS BS 8494 Portable apparatus designed to detect and measure carbon dioxide in ambi ent air or extraction systems Supersession information: If this document is published as a standard, the UK implementation of it will supersede NONE and partially supersede NONE. If you are aware of a current national standard which may be affected, please notify the secretary (contact details below). WARNING: THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH STANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30 March This draft is issued to allow comments from interested parties; all comments will be given consideration prior to publication. No acknowledgement will normally be sent. See overleaf for information on commenting. No copying is allowed, in any form, without prior written permission from BSI except as permitted under the Copyright, Designs and Patent Act 1988 or for circulation within a nominating organization for briefing purposes. Electronic circulation is limited to dissemination by within such an organization by committee members. Further copies of this draft may be purchased from BSI Customer Services, Tel: +44(0) or orders@bsi-global.com. British, International and foreign standards are also available from BSI Customer Services. British Standards on CD or Online are available from British Standards Publishing Sales Limited. Tel: or bsonline@techindex.co.uk. Information on the co-operating organizations represented on the committees referenced above may be obtained from the responsible committee secretary. Cross-references The British Standards which implement International or European publications referred to in this draft may be found via the British Standards Online Service on the BSI web site Responsible Committee Secretary: Miss K Chambers (BSI) Direct tel: karen.chambers@bsi-global.com a

2 Introduction Your comments on this draft are welcome and will assist in the preparation of the consequent British Standard. If no comments are received to the contrary, this draft may be implemented unchanged as a British Standard. Submission The guidance given below is intended to ensure that all comments receive efficient and appropriate attention by the responsible BSI committee. Annotated drafts are not acceptable and will be rejected. All comments must be submitted, preferably electronically, to the Responsible Committee Secretary at the address given on the front cover. Comments should be compatible with Version 6.0 or Version 97 of Microsoft Word for Windows, if possible; otherwise comments in ASCII text format are acceptable. Any comments not submitted electronically should still adhere to these format requirements. All comments submitted should be presented as given in the example below. Further information on submitting comments and how to obtain a blank electronic version of a comment form are available from the BSI web site at: Template for comments and secretariat observations Date: xx/xx/200x Document: ISO/DIS xxxxx 1 2 (3) 4 5 (6) (7) MB Clause No./ Subclause No./ Annex (e.g. 3.1) Paragraph/ Figure/Table/ Note (e.g. Table 1) Type of comment Comment (justification for change) by the MB Proposed change by the MB Secretariat observations on each comment submitted 3.1 Definition 1 ed Definition is ambiguous and needs clarifying. 6.4 Paragraph 2 te The use of the UV photometer as an alternative cannot be supported as serious problems have been encountered in its use in the UK. Amend to read... so that the mains connector to which no connection... Delete reference to UV photometer. Microsoft and MS-DOS are registered trademarks, and Windows is a trademark of Microsoft Corporation. b

3 Draft BS 8494:2007 BRITISH STANDARD Electronic portable apparatus designed to detect and measure carbon dioxide in indoor ambient air ICS x.xxx.xx NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW 1 of 15

4 Draft BS 8494:2007 Publishing and copyright information The BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2007 ISBN XXXXX X The following BSI references relate to the work on this standard: Committee reference GEL/31/19 Draft for comment 06/ DC Publication history (Publishing history if applicable) Amendments issued since publication Amd. No. Date Text affected 2 of 15

5 Contents 1 Scope 5 2 Normative references 5 3 Terms and definitions 5 4 Construction, labelling and instructions 7 5 Performance 9 Bibliography 14 List of tables Table 1 CO 2 test gases 10 3 of 15

6 Foreword Publishing information This British Standard is published by BSI and came into effect on XX Month 200X. It was prepared by Subcommittee GEL/31/19, Gas detectors, under the authority of Technical Committee GEL/31, Equipment for explosive atmospheres. A list of organizations represented on this committee can be obtained on request to its secretary. Information about this document This is a new standard, which has been written to fill a need for the standardization of electronic portable apparatus designed to detect and measure carbon dioxide. Hazard warnings WARNING. This British Standard calls for the use of substances and/or procedures that can be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. Use of this document Any user claiming compliance with this British Standard is expected to be able to justify any course of action that deviates from its recommendations. It has been assumed in the preparation of this British Standard that the execution of its provisions will be entrusted to appropriately qualified and experienced people, for whose use it has been produced. Presentational conventions The provisions of this standard are presented in roman (i.e. upright) type. Its requirements are expressed in sentences in which the principal auxiliary verb is shall. Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element. Contractual and legal considerations This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. 4 of 15

7 1 Scope This British Standard specifies requirements for the construction, testing and performance of electronic portable apparatus for the detection and measurement of carbon dioxide (CO 2 ) in indoor ambient air, which includes air entering mechanical ventilation systems in dwellings, commercial premises and industrial premises. NOTE 1 The CO 2 measuring capabilities of indoor air quality apparatus is covered by this standard. NOTE 2 The measurement capabilities of electronic portable apparatus that are additional to the measurement of CO 2 are not covered in this standard. Other standards that cover these additional measurement capabilities include, for example, BS EN for electronic portable combustion gas analysers and BS EN for toxic gas detection apparatus having an alarm function for alerting an operator to an unsafe workplace atmosphere. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. BS , Technical manuals Part 1: Specification for presentation of essential information BS EN , Environmental testing Part 2: Tests Test Fc: Vibration (sinusoidal) BS EN :2004, Electrical apparatus for explosive gas atmospheres Part 0: General requirements BS EN , Household and similar electrical appliances Safety Part 1: General requirements BS EN 60529:1992, Degrees of protection provided by enclosures (IP code) BS EN 50270, Electromagnetic compatibility Electrical apparatus for the detection and measurement of combustible gases, toxic gases or oxygen 3 Terms and definitions For the purposes of this British Standard, the following terms and definitions apply: 3.1 aspirated apparatus gas detection apparatus that obtains the gas by drawing it through a sample line to the gas sensor, for example, by means of a hand-operated or electric pump [BS EN :2000, definition 2.2.2] 3.2 battery-powered apparatus designed to be energized from batteries alone, whether disposable or rechargeable 3.3 calibration process of determining the deviation of a measuring apparatus relative to a standard and subsequent adjustment, if necessary, to achieve the manufacturer s stated specification 5 of 15

8 3.4 clean air air that contains carbon dioxide at outdoor air concentrations but is free of other gases and vapours to which the sensing element is sensitive or which influence the performance of the sensing element 3.5 diffusion apparatus apparatus in which the transfer of gas from the atmosphere to the gas sensor takes place by random molecular movement, i.e. under conditions in which there is no aspirated flow [BS EN :2000, definition 2.2.4] 3.6 dwellings unit of residential accommodation including residential park homes, flats, bed-sits, maisonettes, terraced, semi-detached and detached houses (including all such residential accommodation situated within or forming part of commercial or industrial or agricultural premises), leisure accommodation and boats, excluding vessels with an international load line certificate NOTE It is recognised that the guidance can be applied to premises other than dwellings, such as those supplying a small number of clients on a bed and breakfast basis. [BS :2005, definition 3.1] 3.7 electronic portable combustion gas analyser electronic apparatus that will detect and measure the presence of combustion gases and clearly display the result [BS :2005, definition 3.4] 3.8 gas concentration amount of CO 2 present expressed as parts per million or percent by volume NOTE Parts per million (ppm) measurements can be expressed as parts per million (volume) (ppm v ). 3.9 indoor air quality apparatus apparatus used to determine the health and comfort of the air inside buildings, often used for analysing the efficiency of air filtration and ventilation systems NOTE The apparatus can be designed to measure a number of different factors, such as gaseous composition, temperature, relative humidity and airborne contaminant levels probe part of the measuring system that is placed in ambient air including air entering a mechanical ventilation system for the purpose of sampling the gas 3.11 response time (t 90 ) time interval with the apparatus in a warmed-up condition, between the time when an instantaneous variation of the parameter to be measured is produced at the apparatus inlet, and the time when the response reaches and remains beyond 90% of the final indication [BS EN :2004, definition 3.16] 6 of 15

9 3.12 sensor assembly in which the sensing element is housed, and which can contain associated electronic components 3.13 warm up period time taken for the apparatus to reach the manufacturer s specified operating performance from switch on, or following power failure in the case of mains powered equipment 4 Construction, labelling and instructions 4.1 Construction General All parts of the apparatus, including the sensors and probe, shall be constructed of materials that will not be affected by vapours and gases or chemical substances typically found in the environment in which it is intended to be used [see 4.2.2c)] The design of the apparatus shall be such that all materials used in the construction and all components, including electrical and electronic components, shall be within the manufacturer s ratings or limits, as specified by the material or components supplier, unless otherwise certified by the manufacturer of the apparatus Degree of mechanical strength and protection The apparatus shall conform to BS EN 60529:1992, IP42. The sampling system shall be so constructed as to prevent damage to the sensors and pump by such particulate matter and liquids that may be expected in the application The resistance to impact of the apparatus shall be tested in accordance with BS EN :2004, and be capable of withstanding a low impact resistance for Group II apparatus in accordance with BS EN :2004, Table 8. If mechanical protection such as a carrying case is provided, this test shall be carried out with the apparatus assembled in the form in which it is intended to be used It shall not be possible to make external adjustments that affect the performance of the apparatus. Any regular checks and calibrations shall either be achieved automatically or via limited access adjustment controls Power supplies For battery-powered apparatus, the batteries specified by the manufacturer shall have sufficient capacity to enable accurate readings of gas concentration and other measurement parameters, if provided, for at least 4 h of continuous usage. When the battery capacity falls below a preset level a visual warning shall be given, following which the apparatus shall operate to the performance specification for at least a further 30 min Apparatus provided with the means of connection to the mains supply shall conform to relevant British Standards Indicators Indicators shall be provided to show: a) measured parameter, values and units of measurement; b) low battery warning for battery-powered apparatus; 7 of 15

10 c) mode of operation or apparatus status (e.g. warm-up and measurement); and d) when values lie outside the indicating range All values shall be indicated on a display with characters not less than 8 mm high, unless adequate provision is made for enhancing the legibility (e.g. backlighting), in which case the minimum character height shall be 4 mm Range and resolution The apparatus shall indicate gas concentrations of CO 2 : a) at least across a range of (0 to 5 000) ppm with a resolution of 50 ppm or better; and/or NOTE Apparatus with this range may be considered suitable, for example, when monitoring indoor air quality or measuring CO 2 concentrations in commercial laundry and kitchen environments. b) across a range of (5 000 to ) ppm with a resolution of 2% of the displayed reading or better. NOTE Apparatus with this range may be considered suitable, for example, when assessing the safe operation of open flue appliances installed in compartments) Printer or data transfer facility When the apparatus is provided with a printer or data transfer facility, it shall print or communicate the date, time, unique apparatus identification, measured parameter, values and units of measurement specified in taken at the time of the measurement. 4.2 Labelling and instructions Labelling Durable labels shall be carried on the apparatus, or moulded into the casing, giving: a) the manufacturer s or supplier s name, trademark or other means of identification; b) the type of apparatus, e.g. CO 2 gas analyser, and model name or number; c) the number and year of this British Standard, i.e. BS 8494:2007; d) the manufacturer s serial number or other unique apparatus identification; e) the replacement battery and mains power requirements if relevant; NOTE Attention is drawn to the requirements for markings and instructions given in the EC directive on waste electrical and electronic equipment (WEEE) [1] Item b) shall be clearly visible during normal operation Item e) shall be clearly visible if the batteries are being changed The durability of any external label shall be tested in accordance with BS EN :2002, 7.6 and 7.14 after which the label shall not be removable and shall be legible with no curling Instructions The apparatus shall be provided with an instruction booklet or leaflet, conforming to BS This shall give complete, clear and accurate instructions for the safe and proper operation, handling and regular checking of the apparatus, and shall include: a) the correct battery types and method of replacing or recharging batteries for battery powered units, details of mains voltage, frequency and fuse rating, if relevant, and warning of the possible hazards of electric shock or malfunction, if tampered with; 8 of 15

11 b) an explanation of all warning and other indications; c) a list of commonly occurring materials, vapours or gases (e.g. cleaning fluids, polishes, paints and cooking operations) that may affect the operation or reliability of the apparatus in the short or long term; d) guidance on the life expectancy of the apparatus and batteries; e) details of the operational limitations including temperature, humidity and pressure ranges; f) details of the storage limitations including temperature and humidity ranges; g) details of procedure for switch on, including warm up period; h) instructions for checking, testing and/or calibration and adjustment of the apparatus on a routine basis; i) instructions for the disposal of the apparatus at the end of its working life. 5 Performance 5.1 General Sample and sequence of tests For the purposes of type testing, one sample of the apparatus shall be subjected to the tests given in to NOTE The tests in to may be performed in a sequence chosen at the discretion of the test house If the apparatus consists of separate measuring and display elements they shall be considered as a single unit for the purposes of these tests Preparation of sample apparatus The sample apparatus shall be prepared in accordance with the manufacturer s instructions (see 4.2.2) If the apparatus has the facility to zero in ambient air, the apparatus shall be zeroed in ambient air before each test Test chamber The apparatus shall be tested in a suitable test chamber and gas delivery system to present test gases to the sensor. The construction of the test chamber and gas delivery system shall be such as to ensure that the gas sensor is exposed to a specific concentration of test gas in a reproducible manner Labels After the full sequence of tests has been carried out, any external labels shall be checked again for legibility. 5.2 Conditions for tests Test gas The apparatus shall be tested with single gases, of known concentration as laid out in Table 1. 9 of 15

12 Table 1 CO 2 test gases Level CO 2 concentration range, balance air ppm 1st nd rd th (only where the apparatus covers this range) Total uncertainty of test gas concentrations shall be within ±2% relative Speed of test gas The speed of air or test gas in the test chamber shall be between 0.1 m/s and 0.5 m/s. NOTE In the case of a mask, the requirements of apply Power supply Unless otherwise specified for the particular test, the mains voltage shall be within either ±2% of the nominal value or the range of values quoted by the manufacturer. Battery powered apparatus shall be fitted with new or fully charged battery/batteries at the start of each test Temperature Unless otherwise specified for the particular test, the ambient air and test gas shall be at the same constant temperature of ±2% C and within a range of (15 to 25) C for the duration of each test Humidity Unless otherwise specified for the particular test, the ambient air shall be at a constant relative humidity ±10% r.h., within the range 30% r.h. to 70% r.h for the duration of each test The test gas shall be at a constant relative humidity of less than 10% r.h., except during the humidity test in Pressure The test shall be performed at any ambient atmospheric pressure between 97 kpa and 108 kpa and shall be recorded during each test with a total uncertainty of not greater than ±1 kpa. 5.3 Test methods General The displayed reading shall be within ±10% of the concentration of the test gas. Unless otherwise stated, all tests shall be carried out in test gas Unless otherwise stated, each test condition shall be varied separately, while the others remain as defined in The test procedure to be used for to is as follows. a) Switch on the apparatus and its pump (if fitted) and allow it to stabilize for warm up period recommended by the manufacturer. b) Expose the apparatus to: 1) the first level test gas for (180 ± 10) s; 2) clean air for at least 180 s to purge the apparatus back to ambient conditions; 10 of 15

13 3) repeat until all relevant levels of test gases have been applied 4) repeat 1) Unpowered storage The apparatus (including the battery, if the manufacturer supplies this item with the product) shall be exposed sequentially to a temperature of ( 10 ± 2) C for 24 h, (20 ± 2) C for 24 h, (40 ± 2) C for 24 h and (20 ± 2) C for 24 h. The apparatus shall then be energized, and tested in accordance with Supply voltage For mains powered apparatus, stabilize with a power supply voltage of 207 V r.m.s. and test in accordance with Repeat with a power supply voltage of 253 V r.m.s Temperature Steady state The apparatus shall be tested in accordance with 5.3.1, at ( 5 ± 2) C after being exposed to that temperature for at least 1 h. The apparatus shall then be allowed to stabilize at (20 ± 2) C for at least 1 h, before being tested again in accordance with at (40 ± 2) C, after being exposed to that temperature for at least 1 h Transient test for battery-powered apparatus The apparatus shall be switched on and stabilized at (20 ± 2) C for the warm up period. Transfer the apparatus, within 5 s, into a test chamber at (40 ± 2) C. Apply test gas 2. Take a reading at 3 min and 10 min after application of the test gas. Both readings shall be within ±20% of the concentration of the test gas Humidity Steady state The apparatus shall then be tested in accordance with at (90 ± 5)% r.h. and (40 ± 2) C, after being exposed to that temperature and relative humidity for at least 1 h. NOTE Low temperature, low humidity tests are a part of Transient test for battery-powered apparatus The apparatus shall be switched on and stabilized at (40 ± 10)% r.h. and (20 ± 2) C for the warm up period. Transfer the apparatus, within 5 s, into a test chamber at (90 to 95)% r.h. and (40 ± 2) C. Apply test gas 2. Take a reading at 3 min and 10 min after application of the test gas. Both readings shall be within ±20% of the concentration of the test gas Pressure The apparatus shall be switched on and stabilized in the test chamber at ambient conditions as specified in 5.2 for the warm up period. Apply test gas 2 for sufficient time to flush the chamber and stabilize the displayed reading. Increase the pressure in the test chamber by (10 ± 1) kpa within 30 s. Take a reading at 3 min after pressure is stable. The reading shall be within ±20% of the concentration of the test gas Low battery warning For battery powered apparatus, fit new or fully charged batteries and switch the apparatus on. Check that the low battery warning is not activated within 4 h. When the low 11 of 15

14 battery warning is activated wait a further 30 min, and measure the battery voltage, to be further referred to as VL With the battery removed, connect the apparatus to a variable power supply. Decrease the supply voltage to VL. Maintain the supply voltage at this level and test in accordance with Vibration The appropriate test, as defined in BS EN shall be applied along all three axes with: a) a frequency range of (10 to 150) Hz; b) a vibration amplitude of 0.35 mm; c) a duration of endurance of 10 sweep cycles per axis After return to normal test conditions, test in accordance with Drop The apparatus including the probe and any interconnecting wiring and tubing, shall be dropped in its normal orientation from a fall height of 0.5 m onto concrete. If the apparatus is normally used in its carrying case, then it shall be installed in its case for the test to be carried out and the apparatus shall show no signs of mechanical damage after the drop test. After return to normal test conditions, test in accordance with EMC The apparatus, including the probe and any interconnecting wiring and tubing, shall be tested in clean air for electromagnetic compatibility in accordance with BS EN Battery reversal For battery powered apparatus, attempt to insert the battery/batteries the wrong way around. Switch the apparatus on for 1 min. Afterwards, remove the battery/batteries and reinsert in correct polarity and then power the apparatus and test in accordance with Printer and data transfer facility Where there is a printer or data transfer facility, test it to confirm that the printout or transfer repeats the displayed readings and date and time Operational stability Continuous operation If the apparatus is intended for temporary continuous monitoring (i.e. for periods exceeding 24 hours during which it will not be zeroed), it shall be subjected to a stability test, where the test procedure in shall be repeated after every 24 hours of continuously powered operation for a period of 5 days, and then a subsequent test 1 week later Intermittent operation If the apparatus is intended for intermittent monitoring (i.e. for periods of less than 24 hours), it shall be turned on and off in clean air 100 times. The duration of each operation shall be equal to the manufacturer s stated warm-up time; 1 min shall elapse after each operation. At the end of the 100 operations, the apparatus shall be exposed to the highest concentration of test gas used in of 15

15 Sample flow failure For aspirated apparatus with an integral flow indicator, the sample line shall be blocked. Operation of the apparatus shall be checked by visual inspection of the flow indicator to ensure that a warning of the blockage is given Cross sensitivity and specificity Unless applies, the apparatus shall be subjected to test gas concentrations of 200 ppm carbon monoxide in air, 1% ethylene oxide in air and 2% nitrous oxide in air in turn and the displayed reading shall be within ±5% of the previous ambient air reading Where it is known that the apparatus cannot conform to (for example if it uses infrared sensing technology) the apparatus need not be tested in accordance with , however, where this is this case the instruction booklet or leaflet shall include a warning about the possibility of cross sensitivity to these gases causing a higher reading (for example when the apparatus is used for medical applications) Response time Expose the apparatus to a step change from ambient air to the test gas with the highest concentration used in 5.3. Aspirated apparatus shall have a response time (t 90 ) of not greater than 50 s. Diffusion apparatus shall have a response time (t 90 ) of 120 s Air velocity Apparatus with sensors that operate by diffusion shall be tested in a flow chamber under conditions of no forced ventilation and at a speed of 6 m/s. This shall be performed using: a) ambient air; and b) the test gas with the highest concentration used in 5.3. The orientation of the sensor in relation to the direction of the flow shall be such that the flow reaches the apparatus from each of three mutually perpendicular directions, while the orientation of the apparatus is kept constant. NOTE Directions of flow which are not likely to occur in practice, due to the design of the apparatus, or which are expressly prohibited by the manufacturer shall not be tested. 13 of 15

16 Bibliography Standards publication BS :2005, Carbon monoxide in dwellings and the combustion performance of gas-fired appliances Part 1: Guide for identifying and managing sources of fumes, smells, spillage/leakage of combustion products and carbon monoxide detector activation BS EN (all parts) Workplace atmospheres Electrical apparatus used for the direct detection and direct concentration measurement of toxic gases and vapours BS EN (all parts), Specification for portable electrical apparatus designed to measure combustion flue gas parameters of heating appliances BS EN :2000, Electrical apparatus for the detection and measurement of flammable gases Part 1: General requirements and test methods Other publications [1] EUROPEAN PARLIAMENT. Directive 2002/96/EC of the European Parliament and of the Council of 27 January 2003 on waste electrical and electronic equipment (WEEE) (as amended by Directive 2003/108/EC). 14 of 15

17 Draft BS 8494:2007 BSI British Standards Institution 389 Chiswick High Road London W4 4AL BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: +44 (0) Fax: +44 (0) BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tel: +44 (0) Fax: +44 (0) Standards are also available from the BSI website at In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service. Various BSI electronic information services are also available which give details on all its products and services. Contact the Information Centre. Tel: +44 (0) Fax: +44 (0) info@bsi-global.com. Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards. For details of these and other benefits contact Membership Administration. Tel: +44 (0) Fax: +44 (0) membership@bsi-global.com. Information regarding online access to British Standards via British Standards Online can be found at Further information about BSI is available on the BSI website at Copyright Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the publications of the international standardization bodies. Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, photocopying, recording or otherwise without prior written permission from BSI. This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained. Details and advice can be obtained from the Copyright & Licensing Manager. Tel: +44 (0) Fax: +44 (0) copyright@bsi-global.com.