1、BRITISH STANDARD BS 6751:1986 Guide for Protection of machine tools intended for use in extreme environmental conditions UDC 621.9.022:62-7BS6751:1986 This British Standard, having been prepared under the directionof the Machine, Engineers and Hand Tools Standards Committee, waspublished under theau
2、thorityofthe BoardofBSIand comesintoeffect on 28 November1986 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference MTE/1 Draft for comment 85/70428 DC ISBN 0 580 15474 2 Committees responsible for this British Standard The preparation of this British Stan
3、dard was entrusted by the Machine, Engineers and Hand Tools Standards Committee (MTE/-) to Technical Committee MTE/1 upon which the following bodies were represented: Department of Trade and Industry (Mechanical and Electrical EngineeringDivision) Federation of British Engineers Tool Manufacturers G
4、AMBICA (BEAMA Ltd) Health and Safety Executive Institution of Production Engineers Machine Tool Industry Research Association Ministry of Defence University of Aston in Birmingham Coopted members Amendments issued since publication Amd. No. Date of issue CommentsBS6751:1986 BSI 12-1999 i Contents Pa
5、ge Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Guidance regarding climatic conditions 1 Appendix A Questionnaire 6 Appendix B Types of climate 9 Appendix C Bibliography 10 Table 1 Guidance for environmental conditions 2 Table 2 Types of climate by annual extreme
6、 values 9 Publications referred to Inside back coverBS6751:1986 ii BSI 12-1999 Foreword This British Standard has been prepared under the direction of the Machine, Engineers and Hand Tools Standards Committee and is based on a draft submitted by the Machine Tool Industry Research Association. It has
7、 long been recognized that a machine tool built for use in a temperate area such as the United Kingdom may require some modification before operation in tropical or arctic conditions. It is hoped that this standard will lead to a common approach to environmental conditions that may be encountered. S
8、ome machine tool manufacturers may wish to obtain details of the environmental conditions in which their products are likely to be used by supplying the customer or his representative with a formal request about climatic conditions, electric supply characteristics, altitude, etc. An example of a que
9、stionnaire suitable for this purpose is given in Appendix A. 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 Standard does not of itself confer immunity from
10、 legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesiandii, pages1to12, 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 tab
11、le on the inside front cover.BS6751:1986 BSI 12-1999 1 1 Scope This British Standard provides guidance on the protection of machine tools intended for use in extreme environmental conditions. Examples of types of climate are given in Appendix B. A bibliography is included as Appendix C. NOTEThe titl
12、es of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard the following definitions apply. 2.1 working environment local conditions in the machine shop (which may be air conditioned or heated, etc.) and not the ex
13、ternal or “open air” conditions 2.2 non-working environment 1) Conditions where the machine is stored at site prior to installation. 2) Conditions where the machine is not in use, e.g. overnight shut-down or holiday period. 2.3 atmospheric contamination contamination by dusts, fumes, vapours, corros
14、ive gases and salt laden moisture or spray 2.4 biological contamination contamination by insects, rodents, fungi and moulds and bacteria 2.5 shock or vibration vibration from neighbouring machinery, road and rail traffic, earth tremors and blasting operations 3 Guidance regarding climatic conditions
15、 Guidance regarding the steps to be taken to protect a machine tool in varied climatic conditions is given inTable 1. NOTEIn order to obtain the required information, observe the number(s) in the box formed by the intersection of a vertical column containing the environment factor and a horizontal c
16、olumn containing the machine item category. Then consult the appropriate number reference in the notes which followTable 1. Repeat as necessary for other environmental factors.BS 6751:1986 2 BSI 12-1999 Table 1 Guidance for environmental conditions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Item Non-workin
17、g environment a Working environment a Ambient temperature Ambient temperature Humidity Altitude above 1000 m Atmospheric contamination a Biological contamination a Shock or vibration a Electrical interference orradiation Below 0 C 0 C to 45 C Above 45 C Below 5 C 5 Cto 30 C Above 30 C 0 % r.h. to 80
18、% r.h. no condensation Above 80 % r.h. or with condensation Construction Materials 1 49 8 11 11 11 49 23 49 49 49 49 43 Finishes 2 2 2 2 2 2 2 2, 24 49 2, 31 2 49 49 Foundations 1 49 49 49 49 49 49 49 49 49 49 39 49 Electrical/Electronic Electrical control gear, wiring, ducting 3 8, 49 8 12 12 12, 1
19、8, 19 49 25, 26, 27 30 28, 32 28, 37 40, 41 45 Electronic and ancillary instrumented systems 49 8, 49 8, 9 13, 14 14 14, 18 49 25, 26, 27 30 28, 32, 33 28, 37 40, 41 44, 45, 46 Motors 49 49 49 49 49 20 49 28 20 28 28 49 45, 47 Fluid systems Electrical components 4, 5 4, 8 4, 5 15 49 15 49 27 49 28 2
20、8, 37 41 49 Non-electrical components 4, 5 4, 8 4, 5 15 49 15 49 49 49 49 49 49 49 Reservoir equipment 4 4 4 16 49 21 49 49 49 34 49 49 49 Seals and hoses 5 49 5 17 49 17 49 49 49 35 37 49 49 Fittings and pipework 4 4 4 15 49 15 49 49 49 31 49 42 49 Hydraulic fluids 6 49 49 6, 16 49 21 49 29 49 49 3
21、8 49 49 Lubricants 7 7 10, 7 15 49 10, 21 49 49 49 34 38 49 48 Cutting fluids 6 49 49 6 49 22 49 49 49 36 38 49 49 NOTEThe numbers in columns 3 to 15 refer to items in the explanatory notes to the table. a See clause 2.BS6751:1986 BSI 12-1999 3 Explanatory notes to Table 1 1. At temperatures below0
22、C there is possibility of damage to structures if moisture is present. 2. Some countries may insist on particular specifications for surface treatments; if these are not sufficiently detailed, the advice of paint manufacturers should be sought. BS5493 contains useful information. 3. Electrical and e
23、lectronic equipment should be capable of withstanding temperatures down to 25 C. At very low temperatures there is a risk of cable insulation or flexible conduit jackets developing cracks during transportation, installation or usage. Consult the equipment manufacturer. 1) 4. If equipment is to be ou
24、t of action for a long period, the system should be run with an inhibitor in the oil, prior to shut down, in order to protect the internal working surfaces from corrosion. 5. Synthetic rubber materials (nitrile, acrylic, etc.) have a temperature range 20 C to +100 C. Outside this range consult the m
25、anufacturer. 6. Where temperatures may drop below0 C water based fluids may freeze or be degraded. Fluid manufacturers recommendations should be sought. 1)7. Greases may degenerate during storage or long-term shut-down, showing a tendency towards separation of soap and oil. For temperatures below40
26、C consult manufacturer. 8. The adhesive properties of bonding agents can be permanently affected by temperatures above45 C particularly when moisture is present. Check adhesive manufacturers specification. 9. Electrical and electronic equipment should be capable of withstanding temperatures up to55
27、C and for short periods not exceeding24h up to70 C. Consult the equipment manufacturer. 10. Water contained in lime soap greases may evaporate through exposure to heat and separation of ingredients can occur above60 C. 11. Changes in temperature cause dimensional variations and alignments can be aff
28、ected. Where high accuracy is important a temperature controlled environment should be considered. 12. Factory built assemblies are suitable for operation in a temperature range 5 C to +40 C (or average of35 C over24h). However, components such as relays, meters, electronic equipment, etc. may requi
29、re to be heated to ensure that their operating temperatures do not fall below+5 C. If there is a risk of ice formation leading to malfunctioning when starting up, the provision of heating should be considered. 1) 13. Memory retention problems may occur while temperature is below5 C until it is raise
30、d by self-heating of the circuitry. Liquid crystal displays may not operate below0 C. Consult the equipment manufacturer about internal heaters. 14. Disc drives may be limited to operation within a temperature range of 10 C to40 C. If necessary, consult the manufacturer. 15. No specific precautions
31、are necessary; normal ambient temperatures are between 20 C and+70 C. 16. At temperatures below5 C, consider the use of immersion heaters in the oil reservoir in order to prevent the oil viscosity exceeding that specified for components such as pumps, control valves, etc. 17. No specific precautions
32、 are required; normal working temperatures are between 40 C and+100 C. 18. Electrical and electronic equipment should be capable of operating in an ambient temperature up to40 C (average over24h not exceeding35 C). However, where equipment generates heat the local operating temperature will rise abo
33、ve the ambient. Some components have an operating limit of70 C above which they must be de-rated. It may therefore be necessary to select higher rated components or to arrange for suitable ventilation and/or cooling. Consult the equipment manufacturer. 19. Above30 C the current ratings of cables are
34、 reduced; correction factors are given in Appendix9of the IEE Regulations for Electrical Installation, IEC287and AppendixBof IEC204-1:1981. 20. At high temperatures or at altitudes above1000m motors may require de-rating due to loss of cooling efficiency; BS4999-32refers. Consult the motor manufactu
35、rer. 1) Contains advice which may continue to be applicable after the machine tool has been commissioned. In such cases notes should be included in the instruction manual supplied with the machine tool and the supplier should ensure that the user is made aware of them.BS6751:1986 4 BSI 12-1999 21. A
36、t ambient temperatures above30 C consider the use of air blast or water coolers to cool the oil. In extreme cases, refrigeration units may be required. 22. For precision machines and for heavy duty cutting operations it may be necessary to force cool the cutting fluid. 23. Above80% humidity or where
37、 condensation is present, polyamides (e.g. nylon) may absorb moisture and change dimensionally. This could result in seizure of gears or bearings. Check suitability of material with the manufacturer. 24. It may be necessary to use “anti-condensation” paint. Consult the paint manufacturer. 25. Above8
38、0% humidity, or where condensation is present, electrical current leakage is a hazard. Consider special measures such as local heating of cabinets and/or protective measures such as hermetic sealing, use of desiccants and varnish insulation. 26. Above80% humidity, or where condensation is present, e
39、nsure conduits, trunkings, etc. are self-ventilating and adequately drained. 27. Above80% humidity, or where condensation is present, push buttons and switchgear may need protection; the manufacturer should be consulted. Encapsulated solenoids, switches, etc. and waterproof plugs and sockets may be
40、required. 28. BS4999-20 classifies the nature of enclosure required to protect against ingress of solid bodies, dust and water. Where corrosive vapours, fungi, insect or vermin attack are possible the manufacturer should be consulted. Attention is also drawn to BS5420. 29. If the system is open to t
41、he atmosphere and exposed to high humidity, avoid the use of hydraulic fluids with ZDDP additives which will hydrolyse to form acidic by-products. 30. Above1000m for electronic equipment, or2000m for electrical equipment, it may be necessary to derate to take account of the reduction of the electric
42、 strength and cooling effect of the air. The manufacturer should be consulted. 31. If there are corrosive gases or vapours in the immediate vicinity, it will be necessary to use a chemically resistant paint or a metallic finish in order to obtain adequate protection (see BS5493). 32. Sealed and pres
43、surized or sealed and non-ventilated cabinets are preferred where atmospheric contamination is present. If ventilation is used adequate filtration should be provided and blocked filter indication is advisable. Special precautions are necessary in cases of conductive dusts. 33. Disc drives are extrem
44、ely sensitive to dust and have to be protected. Consult the manufacturer. 34. In all dusty environments ensure that reservoir filtration equipment for tank breathing is adequate. 35. Certain atmospheric contaminants (vapours, fluids, etc.) may attack the outside of rubber or synthetic hoses. The man
45、ufacturer should be consulted. 36. Contamination of neat soluble oils with water can result in unstable solutions. 37. Many synthetic materials are attractive to insects and rodents. Ensure that paint or surface treatments are applied to suppliers specifications and that wiring, insulating and seali
46、ng materials, etc. are shielded from attack by vermin. 2) 38. Biological contamination of water based fluid is possible particularly in soluble oil emulsions. Commercial fluids are available which are formulated with biocides to control the problem. Alternatively biocides which are compatible may be
47、 added at the dilution recommended by the manufacturer of the fluid. Excessively high concentrations can cause operator skin problems. 39. Machines for producing high surface finishes, e.g. grinders, can be adversely affected by floorborne vibration caused by traffic and neighbouring machinery, etc.
48、 Where such vibration is likely, these machines should be isolated using appropriate resilient materials or foundation systems. Engineering Design Guide No. 13 “Vibration Isolation” refers (see Appendix C) and advice should also be sought from manufacturers of anti-vibration mounting systems. Some c
49、ountries require machines to withstand earthquakes but may not provide information as to what protection is required. Most machines should not suffer from seismic shock, but for machines which require rigid foundations, the design of the foundation should ensure that the risk of severe deformation arising from sudden local subsidence is minimized. NOTEMachines cannot be reasonably protected against damage caused by falling objects and an exclusion clause to this effect should be included. 2) Contains advice which may con
