1、BRITISH STANDARD BS 4674:1971 Incorporating Amendment No.1 Methods for The determination of the breaking load and knot breaking load of netting yarns for fishing netsBS4674:1971 This British Standard, having been approved by the Ropes andCordage Industry Standards Committee, was published underthe a
2、uthority of the Executive Board on 15 February1971 BSI10-1999 The following BSI references relate to the work on this standard: Committee reference RCT/8 Draft for comment69/4509 ISBN 580 06327 5 Co-operating organizations The Ropes and Cordage Industry Standards Committee, under whose supervision t
3、his British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: British Railways Board British Tug Owners Association Chamber of Shipping of the United Kingdom Cotton Twine Manufacturers Association Council of Brit
4、ish Manufacturers of Petroleum Equipment Crown Agents for Oversea Governments and Administrations Department of Employment and Productivity Docks and Harbour Authorities Association Federation of Soft Fibre Associations* Hard Fibre Cordage Institute* Lloyds Register of Shipping London Master Stevedo
5、res Association Ministry of Defence (Air Force Dept.) Ministry of Defence (Army Dept.) Ministry of Defence (Navy Dept.) Ministry of Technology Synthetic Cordage Manufacturers Association The industrial organizations marked with an asterisk in the above list, together with the following, were directl
6、y represented on the committee entrusted with the preparation of this British Standard: British Man-made Fibres Federation British Trawlers Federation Ltd. Department of Agriculture and Fisheries for Scotland Federation of British Trawler Owners Grimsby Net Manufacturers Association Herring Industry
7、 Board Ministry of Agriculture, Fisheries and Food Scottish Inshore White Fish Producers Association Scottish Trawlers Federation Amendments issued since publication Amd. No. Date of issue Comments 2991 May 1979 Indicated by a sideline in the marginBS4674:1971 BSI 10-1999 i Contents Page Co-operatin
8、g organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Principle 1 4 Apparatus 1 5 Atmosphere for conditioning and testing 2 6 Sampling 3 7 Preparation of specimens 3 8 Requirements for testing 3 9 Number of tests 3 10 Testing procedure 3 11 Calculation and expression of results
9、4 12 Report 5 Appendix A Sampling 6 Figure 1 Holding devices for the testing of netting yarns without knots 2 Figure 2 Weavers knot 4BS4674:1971 ii BSI 10-1999 Foreword This standard makes reference to the following British Standards: BS 1051, Glossary of terms relating to the conditioning and testi
10、ng of textiles. BS 1610, Methods for the load verification of testing machines. BS 4406, Designation in the tex system of netting yarns for fishing nets. Technical Committee38, “Textiles”, of the International Organization for Standardization (ISO) agreed at its meeting in1960 to a proposal from Ger
11、many that a specialist sub-committee be appointed to deal with textile products for fishing nets. This action arose from the increasing interest in standards matters being evinced by the Food and Agriculture Organization of the United Nations and other international bodies concerned with deep sea fi
12、shing. It had become evident that there was a need for ISO to examine the subject of fishing nets and produce such recommendations as were required to co-ordinate, on an international basis, the activities of the fishing industries of the maritime nations. The ISO sub-committee decided that urgent a
13、ttention should be given to terminology, designation of nets and netting yarns and to methods of hanging nets and cutting them to shape. The Ropes and Cordage Industry Standards Committee appointed a technical committee to organize the UK contribution to the ISO work and to develop as British Standa
14、rds such ISO Recommendations as were relevant to the UK industry. This British Standard is based on ISO1805 (with which it is in complete conformity) and is one of a number that will cover the aspects being investigated by the ISO sub-committee. A British Standard does not purport to include all the
15、 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 inside front cover, pagesi andii, pa
16、ges1 to6 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.BS4674:1971 BSI 10-1999 1 1 Scope This British Standard deals with the determination of breaking load and k
17、not breaking load of netting yarns for fishing nets. Tests may be carried out in both the dry and wet state, but tests in the wet state on the knotted yarn are considered to be particularly appropriate in indicating the behaviour of the yarn in use. 2 Definitions 1) For the purposes of this British
18、Standard the following definitions apply: 2.1 breaking load the maximum load observed during a breaking test, applicable to: 1) dry yarn, 2) wet yarn, 3) dry knot, 4) wet knot. 2.2 load at rupture the final load at the moment that the specimen or the first component of the specimen breaks when, or a
19、fter, the breaking load has been reached. The load at rupture is usually, but not always, identical with the breaking load 2.3 tenacity the breaking load per unit resultant linear density of the unstrained specimen in the conditioned state 2.4 breaking length the calculated length of a yarn whose co
20、nditioned weight exercises a force equal to its breaking load. It is expressed in km 2.5 time-to-break the time in seconds, taken to reach the breaking load measured from the moment of application of the load 3 Principle A test specimen is extended in a dry or wet state until it reaches the load at
21、rupture, by suitable apparatus that records or indicates the applied load. 4 Apparatus 4.1 Tensile testing machines. Testing machines of any of the following types may be used: 1) constant rate of extension, 2) constant rate of load, 3) constant rate of traverse. Preference should be given to consta
22、nt rate of extension machines. 4.1.1 All tensile testing machines shall include a pair of suitable devices to hold the specimen, a means of loading or elongating the specimen at suitable rates (see8.4) and a load indicating mechanism which will indicate or record, continuously the load applied to th
23、e specimen. For determining the breaking load of netting yarns without knots, the specimens should be mounted in special holding devices, e.g.of the types shown in Figure 1, to avoid slipping of the specimens or breaking due to damage caused by the holding devices. 1) Symbolic abbreviations of the p
24、arameters defined have been omitted pending discussion by ISO/TC38 of the general subject.BS4674:1971 2 BSI 10-1999 4.1.2 The maximum error of the indicated load at any point in the range in which the machine is used shall not exceed 1% in accordance with BS1610 2) , Grade A. Check the accuracy of t
25、he graduated scale of the apparatus dynamically, for example, by means of calibrated springs of appropriate characteristics. 4.1.3 The testing machine shall be capable of testing specimens having a nominal gauge length of at least250mm. 4.1.4 All testing machines shall include facilities for produci
26、ng different rates of loading in order to break specimens in the specified average time-to-break. 4.2 Equipment for producing and maintaining the standard atmosphere for testing (see8.1). 4.3 Equipment in which specimens can be immersed in water preparatory to wet testing. 4.4 Stopwatch or interval
27、timer. 5 Atmosphere for conditioning and testing The atmosphere to be used shall be the standard atmosphere for testing as described in BS1051 3) , i.e.6.52% relative humidity at a temperature of20 2 C. Figure 1 Holding devices for the testing of netting yarns without knots 2) BS1610, “Methods for t
28、he load verification of testing machines”. 3) BS1051, “Glossary of terms relating to the conditioning and testing of textiles”.BS4674:1971 BSI 10-1999 3 6 Sampling Sampling shall be carried out in accordance with the procedure given in Appendix A, or by agreement between the parties concerned. 7 Pre
29、paration of specimens The specimens shall be removed from the package, before exposure in the standard atmosphere, or before immersing in water, in such a manner that there is no alteration in the twist. 8 Requirements for testing 8.1 Testing in the dry state. Specimens to be tested in the dry state
30、 shall be exposed to the standard atmosphere for testing described in Clause5 until they have reached equilibrium. For netting yarns of man-made fibres a period of24h exposure is generally sufficient. Where it is not possible to carry out the tests in the standard atmosphere the tests shall be carri
31、ed out immediately after removal of the samples from the standard atmosphere. 8.2 Testing in the wet state 8.2.1 All specimens to be tested in the wet state shall be immersed in tap water without wetting agents:at20 2 C for a period of not less than12h. Surplus water shall be shaken off. 8.2.2 By ag
32、reement between the parties concerned, a shorter wetting time with the addition of a wetting agent may be used. The specimens are immersed for one hour in a2% solution of wetting agent in water at a temperature of20 2 C. A shorter period of immersion is allowed if the specimen is completely wetted i
33、n less than one hour. 8.3 Distance between the holding devices. The free length of the sample shall be at least250mm. 8.4 Time-to-break. The mean duration of the test should be203s. It is to determined by preliminary tests. Where this time cannot be obtained due to limitations of the apparatus and/o
34、r holding devices, the duration of the test may be30 3s or606s. This should be recorded in the test report. 9 Number of tests At least20 single valid tests on each sample package are to be carried out. If a distinct confidence interval for the main value is prescribed, as many additional tests are t
35、o be carried out as necessary to secure this confidence interval. 10 Test procedure 10.1 General 10.1.1 Check that the distance between the holding devices is not less than250mm (see8.3). 10.1.2 Mount the specimen in the testing machine so that the axis of the specimen is parallel and coincidental t
36、o the direction of the applied force. 10.1.3 Wet samples shall be tested immediately after removal from the water (see8.2.1). 10.1.4 Apply the force to reach the prescribed mean time-to-break. 10.1.5 Discard all observations, obtained on specimens which slip between the holding devices or break due
37、to damage-caused by the holding devices. 10.1.6 If any component breaks before the breaking load is reached, this should be reported. 10.2 Knotted netting yarns in the dry and wet state 10.2.1 All knots shall be made immediately before testing and gently tightened by hand. Precautions should be take
38、n to ensure that the twist is not altered. 10.2.2 Specimens should be tested with the weavers knot. All four ends of the weavers knot should be fastened in the holding devices. Each holding device holds the two ends of the same yarn of approximately the same length (see Figure 2). 10.2.3 If a sample
39、 does not break at the knot, this test is discarded.BS4674:1971 4 BSI 10-1999 11 Calculation and expression of results 11.1 Average breaking load is equal to breaking load being expressed in newtons 4) . Calculate the average breaking load to four significant figures and round it off to three signif
40、icant figures. 11.2 Tenacity. Average tenacity in milli-newtons per tex is equal to Calculate the average tenacity to four significant figures and round it off to three significant figures. 11.3 If necessary the coefficient of variation and the confidence interval may be calculated by recognized sta
41、tistical methods. Figure 2 Weavers knot 4) 9.80665N (newton)=1Kgf. sum of observed breaking loads number of observations - Average breaking load expressed in milli-newtons Average resultant linear density (in tex) of conditioned sample -BS4674:1971 BSI 10-1999 5 12 Report 12.1 The report shall provi
42、de information on the following points and should state that the tests were performed in accordance with this British Standard. The date of the test should be stated. 12.2 Type, size and direction of final twist of the netting yarn (see BS4406 5) ). 12.3 Type and capacity of testing machine used, th
43、e type of holding devices employed and the ranges of indication. 12.4 The sampling method employed. 12.5 The number of specimens tested. 12.6 The number of irregular tests. 12.7 The kind and time of wetting (with or without wetting agents). 12.8 The average breaking load in newtons. 12.9 Any deviati
44、on of the test procedure. If required, the report should also state: 12.10 The coefficient of variation of the breaking load and confidence interval. 12.11 The average tenacity in milli-newtons per tex. 12.12 The average breaking length in km. 5) BS4406, “The designation in the tex system of netting
45、 yarns for fishing nets”.BS4674:1971 6 BSI 10-1999 Appendix A Sampling Samples, each to provide the required number of test specimens, should be taken from the consignment or delivery being tested by a convenient and representative system of sampling. The number of samples taken should be agreed bet
46、ween the purchaser and the supplier, so as to ensure satisfactory representation of the consignment, but shall be not less than10 unless agreed between the purchaser and the supplier.blankBS4674:1971 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent natio
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