1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7955:1999 ICS 13.340.2
2、0 91.220 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Containment nets and sheets on construction works Specification for performance and test methodsThis British Standard, having been prepared under the direction of the Building and Civil Engineering Sector Committee, was
3、published under the authority of the Standards Committee and comes into effect on 15 December 1999 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference B/514/27 Draft for comment 96/107981 DC ISBN 0 580 33087 7 BS 7955:1999 Amendments issued since publica
4、tion Amd. No. Date Comments Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee B/514/27, Nets and sheets, upon which the following bodies were represented: Construction Confederation Construction Health and Safety Group Cons
5、truction Industry Training Board Cordage Manufacturers Institute English Net Manufacturers Association Health and Safety Executive Institution of Structural Engineers Made-Up Textiles Association National Association of Scaffolding Contractors National Federation of Roofing ContractorsBS 7955:1999 B
6、SI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Tests 1 5 Performance requirements 1 6 Flammability 4 7 Permeability 4 8 Light transmission 4 9 Marking 4 Annex A (normative) Impact test 5 Annex B (normative) Punctu
7、re test 8 Annex C (normative) Flammability 9 Annex D (normative) Wind tunnel test to establish the permeability of nets used for cladding 11 Bibliography 13 Figure 1 Attachment point strength test 2 Figure 2 Tie strength test 3 Figure A.1 Preparation of sample sheet or net for impact test 5 Figure A
8、.2 Impact test Test rig 6 Figure A.3 Impact test Test apparatus 7 Figure B.1 Preparation of sample sheet or net for puncture test 8 Figure B.2 Puncture test Test apparatus 9 Figure C.1 Arrangement for flammable liquid test 11 Figure D.1 Log 10 permeability v log 10 form factor 12ii BSI 12-1999 BS 79
9、55:1999 Foreword This British Standard has been prepared by Technical Committee B/514, Nets and sheets, and supersedes performance specifications contained within BS 8093:1991 annexes D and E. It supersedes the recommended perfomance specification for containment nets and sheeting contained in BS 80
10、93. The flammability tests given in annex C are reproduced verbatim from the Loss Prevention Council Standard (LPS) LPS 1215. 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. Complianc
11、e with a British Standard 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, pages 1 to 13 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last
12、 issued. BSI 12-1999 1 BS 7955:1999 1 Scope This British Standard specifies requirements and test methods for containment nets and sheets intended for use on construction works. It covers flame retardant and non-flame retardant containment nets and sheets. It also specifies test methods and performa
13、nce specifications for ties used in conjunction with nets and sheets. It does not cover safety nets, barrier nets or temporary roofs. It does not cover installation and use. This British Standard does not specify ageing requirements. 2 Normative references This British Standard incorporates, by date
14、d or undated reference, provisions from other publications. These normative references are cited at the appropriate place in the text and the publications are listed hereafter. For dated references, only the edition cited applies; any subsequent amendments to or revisions of any of these publication
15、s apply to this British Standard only when incorporated in it by amendments or revision. For undated references the latest edition of the publication referred to apply. BS 476-12:1991, Method of test for ignitability of products by direct flame impingement. BS 2576:1986, Method for determination of
16、breaking strength and elongation (strip method) of woven fabrics. BS EN ISO 13468-1:1997, Single-beam instrument. 3 Definitions For the purpose of this British Standard, the following definitions apply. 3.1 containment net net intended to restrain small objects, or tools and debris, to restrict dust
17、, to reduce the effects of weather, to provide protection for persons from falling objects and to reduce the risk of persons falling from scaffold platforms 3.2 containment sheet impervious sheet intended to protect a structure from inclement weather, to contain dust and other pollution, to prevent
18、small objects, tools and debris from falling, and to reduce the risk of persons falling from scaffold platforms 3.3 ties means used to join nets or sheets into larger configurations and to secure them in position 3.4 attachment points designated points within nets and sheets through which ties can b
19、e threaded 3.5 form factor constant factor, characteristic of each different containment material, relating the wind speed to the wind pressure that would be exerted on the material 4 Tests 4.1 Impact test The net or sheet and tie shall be tested in accordance with annex A. 4.2 Puncture test The net
20、 or sheet and tie shall be tested in accordance with annex B. 4.3 Tensile strength The tensile strength of the net or sheet shall be determined in both directions by testing in accordance with BS 2576. Samples for testing shall be cut from the same roll as used for samples tested in annexes A and B.
21、 4.4 Attachment point strength The tensile strength of the attachment points shall be determined in accordance with BS 2576:1986. Samples for testing shall be cut from the same roll as used for samples tested in annexes A and B. The net or sheet shall be attached to the test apparatus as shown in Fi
22、gure 1. 4.5 Tie strength The tensile strength of the ties shall be determined in accordance with BS 2576:1986. Samples for testing shall be of the same type and specification as those used for tests given in annexes A and B. The tie shall be attached to the test apparatus as shown in Figure 2. 5 Per
23、formance requirements 5.1 General The nets or sheets shall meet the following requirements. a) When tested in accordance with annex A, the length of either 50 mm conditioning cut shall not increase in length to more than 100 mm. b) When tested in accordance with annex A and annex B, here shall be no
24、 failure, except that described in a).2 BSI 12-1999 BS 7955:1999 Figure 1 Attachment point strength test BSI 12-1999 3 BS 7955:1999 Figure 2 Tie strength test4 BSI 12-1999 BS 7955:1999 1) If the net is of a blue colour, then the band should be in red. 5.2 Tensile strength When tested in accordance w
25、ith 4.3, nets or sheets shall have a minimum tensile strength of 630 N. The actual performance shall be stated. 5.3 Attachment point strength When tested in accordance with annex A and annex B, the attachment point shall maintain the connection between tie and net/sheet. When tested in accordance wi
26、th 4.4, the minimum tensile strength shall be 500 N. The actual performance shall be stated. 5.4 Tie strength When tested in accordance with annex A and annex B, the tie shall not fail. When tested in accordance with 4.5, the minimum tensile strength shall be 500 N. The actual performance shall be s
27、tated. 6 Flammability When tested in accordance with annex C, the nets and sheets shall be resistant to fire at a rate set by the appropriate flame tests. Nets and sheets conforming to annex C shall be regarded as flame retardant. 7 Permeability When tested in accordance with annex D, the nets shall
28、 have a form factor of not less than 0.4. 8 Light transmission When tested in accordance with BS EN ISO 13468-1:1997, light transmission properties shall conform to the requirements in that standard and shall be designated in accordance with Table 1 of that standard. 9 Marking 9.1 Nets and sheets 9.
29、1.1 Nets and sheets Nets and sheets shall be either marked directly or manufactured with the relevant identification strand or tape as stated in a) and b) as follows. a) If marked directly, this shall be with letters not less than 25 mm high. The information shall be repeated at regular intervals al
30、ong the entire length of the roll. The marking shall not be obscured by any overlapping sections, when fixed according to the manufacturers recommendations. The following information shall be stated: 1) the manufacturers or suppliers name, trade mark or identification mark; 2) the number and year of
31、 this British Standard, BS 7955:1999. b) If manufactured with a strand or tape, this shall be a Royal blue 1) identification strand or tape supported by an attached label. The strand and tape shall be continuous along the entire length of the roll and shall not be obscured by overlapping sections wh
32、en fixed according to the manufacturers recommendations. Fire resistance nets shall have two tapes. The minimum width of the tapes shall be 25 mm. The distance between the two tapes shall be 25 mm. The following information shall be stated: 1) the manufacturers or suppliers name, trade mark or ident
33、ification mark; 2) the number and year of this British Standard, BS 7955:1999. 9.1.2 The following information shall be stated on the packaging: a) the manufacturers or suppliers name, trade mark or identification mark; b) the number and year of this British Standard, BS 7955:1999; c) the dimensions
34、 of the net or sheet; d) the weight of the net or sheet; e) the manufacturers or suppliers recommended type of tie; f) designated attachment points. 9.2 Ties The following information shall be stated on a label attached to the product or its packaging: a) the manufacturers or suppliers name, trade m
35、ark or identification mark; b) the number and year of this British Standard, BS 7955:1999; c) the net or sheet with which the tie has been tested in clauses 4 and 5 of this British Standard. 9.3 Additional information The following additional information shall be supplied on the packaging or separat
36、ely on an information sheet: a) tensile strength of net or sheet, determined by the test in 4.3; b) tensile strength of the attachment point, determined by the test in 4.4; c) tensile strength of the tie, determined by the test in 4.5; d) flame retardancy, determined by the tests in annex C; e) ligh
37、t transmission, determined by testing, as described in clause 8; f) for nets, the wind coefficient, determined by the test in clause 7.BS 7955:1999 BSI 12-1999 5 Figure A.1 Preparation of sample sheet or net for impact test Annex A (normative) Impact test A.1 Principle The net or sheet is subjected
38、to impact from a soft body impactor, capable of being swung at the sample to determine the resistance to impact. A.2 Sampling Test specimens for any given material shall be identical in type, construction, composition, nominal thickness and manufacture to the material to be assessed. A test sample s
39、hall contain 5 net or sheet test specimens and sufficient ties as described in A.5 for each test. A.3 Preparation of test specimens Prior to the test the net or sheet and ties shall have been stored at a relative humidity of (50 5) % and an air temperature of (23 2)8C for 24 h. Each net or sheet tes
40、t specimen shall be rectangular, with nominal dimensions of 1 000 mm wide3 2 000 mm high, as shown in Figure A.1. The actual size shall be calculated from the eyelet positions nearest to the nominal size. The actual dimensions of the test specimen shall be a minimum of 150 mm beyond the eyelet, or t
41、he edge of the net or sheet, if this dimension is less than 150 mm at the time of manufacture. One long side of the test specimen shall be the manufactured edge of the net or sheet (see Figure A.1). Each net or sheet test specimen shall be prepared by cutting two 50 mm long cuts in the material at t
42、he point of impact as described in A.4 and as shown in Figure A.1. One cut shall be made in the machine direction of the material, the other in the transverse direction. The two cuts shall intersect at their central point. Where nets or sheets are manufactured by welding or otherwise joining togethe
43、r, the test specimen shall be prepared from a section containing a joint where each piece either side of the joint is of approximate equal dimensions. The sample shall be installed on the test frame hand tight without any slack.6 BSI 12-1999 BS 7955:1999 Figure A.2 Impact test Test rig A.4 Test appa
44、ratus The test apparatus shall consist of the following. A.4.1 A test frame, constructed from standard scaffolding components (see Figures A.2 and A.3), of a construction suitable for the test specimen to be attached in the same manner as it would be fixed on site and in accordance with the manufact
45、urers recommendations. A.4.2 A bag, of (50 1) kg capacity, the largest diameter of which, when hanging at rest, is not more than 25 mm from the surface of the test specimen and which is suspended from an overhead support. A.4.3 An overhead support, the length of which is to be adjusted so that the b
46、ag, at its greatest diameter, is of equal distance from the top and bottom eyelets of the test specimen and equal distance from each side eyelet. A.4.4 Means to prop up the bag at an angle to the test specimen, to allow a calculated impact force to be applied to the test specimen. BSI 12-1999 7 BS 7
47、955:1999 NOTE Cable C 1 should be made as light as possible. Figure A.3 Impact test Test apparatus A.5 Test procedure Perform the test at a temperature of (20 5)8C. Fix the test specimen to the frame. Use the minimum number and type of ties, and means of fixing these, as recommended by the manufactu
48、rer or supplier of the sample. Fix the test specimen to the frame on the opposite side to that of the bag. Raise the bag using the winch to a drop height H, calculated to produce a minimum energy of 150 Nm, and secure the line. NOTE A 50 kg bag from a drop height of 306 mm imparts a kinetic energy o
49、f approximately 150 Nm. Release the line allowing the bag to impact the test specimen. Repeat the test on the remaining four test specimens. A.6 Test report The test report shall include at least the following information: a) identification of the net or sheet; b) identification of the tie used; c) date of sampling; d) a reference to this standard and method used; e) failure of any tie; f) failure of any eyelet; g) the amount of any increase in length of the two cuts; h) failure of the net or sheet material except as
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