1、BRITISH STANDARD BS 4840-2: 1994 Rigid polyurethane (PUR) foam in slab form Part 2: Specification for PUR foam for use in refrigerator cabinets, cold rooms and storesBS4840-2:1994 This British Standard, having been prepared under the directionof the Plastics and Rubber Standards Policy Committee, wa
2、s published underthe authority of the Standards Board and comes into effect on 15 January 1994 BSI 07-1999 First published June 1985 Second edition January 1994 The following BSI references relate to the work on this standard: Committee reference PRM/72 Draft for comment 92/46316 DC ISBN 0 580 22377
3、 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/72, upon which the following bodies were represented: Association of Building Component Manufacturers Br
4、ick Development Association British Board of Agrment British Plastics Federation British Rigid Urethane Foam Manufacturers Association Calcium Silicate Brick Association Limited Cavity Foam Bureau Department of the Environment (Building Research Establishment) Department of the Environment (Construc
5、tion Industries Directorate) Engineering Equipment and Materials Users Association European Phenolic Foam Association Flat Roofing Contractors Advisory Board Ministry of Defence National Federation of Roofing Contractors National House-building Council Polyethylene Foam Insulation Association Royal
6、Institute of British Architects The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Ceramic Research Ltd. British Urethane Foam Contractors Association (BUFCA) RAPRA Technology Ltd. Amendments issued since publication Amd. No. Date Co
7、mmentsBS4840-2:1994 BS 07-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Designation 1 4 Composition and form 1 5 Sampling 1 6 Physical properties 1 7 Dimensional tolerances 2 8 Marking 2 Annex A (informative) Guidance for designers 3 Annex B (i
8、nformative) Burning properties of PUR foam and recommendationsregarding its use 3 Annex C (informative) Guidance intended to minimize fire hazards 3 Annex D (normative) Method for the determination of apparent water absorption 4 Table 1 Designation codes for thermal conductivity 1 Table 2 Physical p
9、roperty requirements 2 Table 3 Dimensional tolerances for lengths, widths and diagonals 2 List of references Inside back coverBS4840-2:1994 ii BSI 07-1999 Foreword This Part of BS4840 has been prepared under the direction of the Plastics and Rubber Standards Policy Committee. It supersedes BS4840-2:
10、1985, which is withdrawn. The 1985 revision of BS4840:1973 resulted in the separation of the standard into two Parts to reflect more accurately the existing technology and use of rigid polyurethane (PUR) foam in slab form. This edition introduces technical changes, but it does not reflect a full rev
11、iew or revision of the standard. It is envisaged that this standard will be replaced by a European Standard in due course and that the European Standard will be adopted in the BS EN series. Requirements have been included for thermal conductivity to be designated by the manufacturer. Although this P
12、art is intended primarily for quality assurance uses, guidance has been included for those involved in design work (Annex A). This Part also contains guidelines (Annex B and Annex C) on burning properties and fire hazards. These guidelines are in accordance with the principles recommended in BS6336:
13、1982. Attention is drawn to BS2501:1992 and BS2502:1979 which specify constructional requirements for commercial refrigeration cabinets, cold rooms and cold stores. Attention is also drawn to BS3456-202.24:1990 which specifies requirements for domestic refrigeration appliances. A British Standard do
14、es 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 legal obligations. Summary of pages This document comprises a front cover, an ins
15、ide front cover, pages i and ii, pages1 to 6, 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 inside front cover.BS4840-2:1994 BSI 07-1999 1 1 Scope This Part of
16、BS4840 specifies requirements for the composition, physical properties and dimensional tolerances of rigid polyurethane (PUR) foam in the form of slabs (blocks, boards and sheets) for the thermal insulation of refrigerator cabinets (domestic and commercial), cold rooms and cold stores. 2 References
17、2.1 Normative references This Part of BS4840 incorporates, by reference, provisions from specific editions of other publications. These normative references are cited at the appropriates points in the text and the publications are listed on the inside back cover. Subsequent amendments to, or revisio
18、ns of, any of these publications apply to this Part of BS4840 only when incorporated in it by updating or revision. 2.2 Informative references This Part of BS4840 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this st
19、andard are listed on the inside back cover, but references should be made to the latest editions. 3 Designation The material specified in this Part of BS4840 is defined as type2. The designation shall consist of a three-component code comprising the following items, in the order presented: a) the nu
20、mber and date of this British Standard, i.e. BS4840/2:1994; b) a number indicating the foam type, i.e.2; c) a double-digit number to indicate the thermal conductivity selected in accordance withTable 1. An example of the designation for a type2 foam with a thermal conductivity of0.020W/(mK) is as fo
21、llows: BS 4840/2:1994/2/20 4 Composition and form The slabs shall consist of rigid polyurethane (PUR) foam, shall be flat and shall have a uniform cellular structure. NOTENo requirement for odour is included as its assessment is largely subjective. However, it is recommended that the material should
22、 be supplied free from objectionable odour. The slabs should also be supplied free from irregular surface skin. Table 1 Designation codes for thermal conductivity 5 Sampling In cases of doubt or dispute as to whether a consignment of slabs conforms to this standard, one slab shall be selected at ran
23、dom for test from each five hundred slabs of any consignment supplied, or from the total if this is less than five hundred. In the even of non-conformity of any slab to the requirements of this standard, two more slabs shall be tested from the same group of five hundred. If either of these fails, th
24、e consignment shall be considered not to conform to the requirements of this standard. 6 Physical properties 6.1 Thermal conductivity Thermal conductivity shall be determined by either method7A or method7B of BS4370-2:1993 at a mean temperature of10 C, (30 2) days after manufacture. Materials shall
25、be conditioned throughout this period at (23 2) C and(50 5)%r.h. NOTESee guidance inAnnex A concerning3-day values and design values of thermal conductivity. 6.2 Other properties The other physical properties shall conform to the requirements given inTable 2. Thermal conductivity a(see6.1) W/(mK) Co
26、de 0.015 15 0.016 16 0.017 17 0.018 18 0.019 19 0.020 20 0.021 21 0.022 22 0.023 23 0.024 24 0.025 25 0.026 26 0.027 27 0.028 28 0.029 29 0.030 30 0.031 31 0.032 32 a CAUTION. These values are30-day values for quality control purposes. For corresponding long-term design values, the manufacturers adv
27、ice should be sought (seeAnnex A).BS4840-2:1994 2 BSI 07-1999 Table 2 Physical property requirements 7 Dimensional tolerances The permissible deviation of thickness shall be 1.5mm. Other dimensional tolerances shall conform to the requirements given inTable 3. Table 3 Dimensional tolerances for leng
28、ths,widths and diagonals 8 Marking The product, packages or invoice shall be marked with at least the following information: a) manufacturers name or trademark; b) product designation in accordance with clause3 1) ; c) manufacturers description and/or product reference. Physical property Test requir
29、ement Test method Minimum compressive strength normal to the major plane of the slab,kPa 175 Method 3 of BS 4370-1:1988 Apply force normal to the major plane of the slab. Dimensional stability: maximum mean linear change, % Method 5A as described in5.2 of BS4370-1:1988 Cut the length and width of th
30、e test specimen parallel to the major plane of the slab. Test conditions: 24 h at ( 15 2) C 24 h at (100 2) C 24 h at (70 2) C and (95 5) % r.h. 1 2 3 Maximum water vapour permeability normal to the major plane of the slab, ng/(Pasm) 5.5 Method 8 as described in clause3 of BS4370-2:1993 Carry out th
31、e test at (38 0.5) C and(88 2)% r.h. on one face of the test specimen and at(38 0.5) C and 0 % r.h. onthe other. Cut the cylindrical test specimens (25 5)mm thick such that their plane faces are parallel to the major plane of the slab. Maximum apparent water absorption by volume, % 6.5 Annex D Minim
32、um closed cell content apparent volume, % 85 Method 10 as described in clause5 of BS 4370-2:1993 Burning characteristics a Extent of burning not to exceed 125 mm BS 4735:1974 a CAUTION. The small-scale laboratory test described in BS4735 is solely for assistance in monitoring consistency of producti
33、on and is not for use as a means of assessing the potential fire hazard of a material in use. (SeeAnnex B and Annex C). Lengths or widths Permissible deviations of lengths or widths Maximum difference between the longest diagonals of rectangular slabs mm mm mm Up to and including 100 1 3 Over 100 up
34、 to and including 1000 1.5 5 Over 1000 up to and including 2000 2.5 7 Over 2000 up to and including 4000 5 13 Over 4000 10 25 1) Marking BS4840/2:1994 on or in relation to a product represents a manufacturers declaration of conformity, i.e. a claim by or on behalf of the manufacturer that the produc
35、t meets the requirements of the standard. The accuracy of the claim is solely the claimants responsibility. Such a declaration is not to be confused with third party certification of conformity, which may also be desirable.BS4840-2:1994 BSI 07-1999 3 Annex A (informative) Guidance for designers PUR
36、slabstock foams of apparent densities28kg/m 3to35kg/m 3are normally suitable for refrigerator cabinets, cold rooms and stores. The attention of designers is drawn specifically to the following points: a) In addition to the30-day maximum thermal conductivity value which forms the specification value
37、for the purposes of this standard, two related maximum thermal conductivity values have practical importance, and should be obtained for the product from the manufacturer as follows. 1) Design value of thermal conductivity. This value takes into account the limited diffusion of gases which can be us
38、ed as a basis for user calculations. Generally this will be higher than or equal to the30-day value. 2) The 3-day value of thermal conductivity. This value is often used in manufacturing control operations, to ensure that the quality of product is regularly maintained. Generally it will be lower tha
39、n or equal to the30-day value. b) the need for water and moisture vapour barriers on the surfaces of the PUR foam; c) the possibility of corrosion at the interface of PUR foam and metal surfaces in the presence of water vapour; d) the possible deleterious effects, including odour, of some adhesives;
40、 e) the fire performance of the complete structure, which is largely determined by the facings applied to the foam and the design of the component or structure (seeAnnex B); where Fire Regulations apply, these usually specify given ratings for Standard Fire Tests on specimens of the completed struct
41、ure and should be considered at an early stage. Annex B (informative) Burning properties of PUR foam and recommendations regarding its use The fire performance of the finished structure or article which contains PUR foam is most relevant when considering the possible fire hazard associated with PUR
42、foam. PUR foam is an organic material and hence is combustible. Care should be taken to avoid its ignition, particularly since the burning rate of the PUR foam, if exposed, can be significantly greater than that of wood. The risk of ignition and fire growth associated with PUR foam in building const
43、ruction, industry, transport, etc., should be assessed in accordance with the recommendations of BS6336:1982, i.e.consideration should be given to the design of the end product formed from, or incorporating, the PUR foam and to the risks to which it might be exposed. Recommendations on the provision
44、 of suitable protective measures, together with references to appropriate regulatory requirements, are given in the British Standards for the end products. In general, the performance of the end product is primarily controlled by the type of finish or facing used in conjunction with the foam and the
45、 way in which the composite is used. This standard is concerned only with the specification of PUR foam as a basic material, formulated so that under certain well-defined conditions, its tendency to burn is reduced to a given level, when tested as described in BS4735:1974. Whilst formulation to this
46、 specification can prevent sustained ignition of PUR foam by small energy sources such as a match or small burner flame, this is no longer true if the severity of the source is increased. Once the early ignition phase of the fire has passed, many other factors are involved in the development of the
47、fire, and the requirement for extent of burning given inTable 2 ceases to be relevant; in fact, any modification in formulation introduced to satisfy the requirement may adversely affect the level of smoke generated in a fully-developed fire. Care should be taken during the construction or repair of
48、 any structure or article which contains PUR foam. The use of heat sources such as welding torches in the vicinity of the foam should be avoided unless precise instructions are available on safety measures appropriate to the individual construction. Annex C (informative) Guidance intended to minimiz
49、e fire hazards The following practices are recommended wherever PUR foam is manufactured, stored, fabricated or installed. a) Maintain good housekeeping standards. b) Observe stringent fire precautions, especially in respect of welding operations. Prohibition of smoking, except in designated areas, is advised. c) Ensure that employees are fully aware of the potential fire hazards presented by these materials.BS4840-2:1994 4 BSI 07-1999 d) Consult the Health and Safety Executive for advice in respect of fire precau
