1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 728 : 1997 BS 2782
2、: Part 11 : Method 1103D : 1997 ICS 23.040.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Plastics piping and ducting systems Polyolefin pipes and fittings Determination of oxidation induction time The European Standard EN 728 : 1997 has the status of a British StandardBS
3、EN 728 : 1997 This British Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 July 1997 BSI 1997 The following BSI references relate to the work on this standard: Com
4、mittee reference PRI/61 Draft for comment 92/41379 DC ISBN 0 580 27392 X Amendments issued since publication Amd. No. Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PRI/61, Plastics piping systems and
5、components, upon which the following bodies were represented: British Gas plc British Plastics Federation British Plumbing Fittings Manufacturers Association British Valve and Actuator Manufacturers Association Chartered Institution of Water and Environment Management Department of the Environment (
6、British Board of Agre ment) Department of the Environment (Building Research Establishment) Department of Transport Electricity Association Health and Safety Executive Institute of Building Control Institute of Materials Institution of Civil Engineers Institution of Gas Engineers National Associatio
7、n of Plumbing, Heating and Mechanical Services Contractors Pipeline Industries Guild Plastics Land Drainage Manufacturers Association Society of British Gas Industries Society of British Water Industries Water Companies Association Water Services Association of England and Wales The following bodies
8、 were also represented in the drafting of this standard, through subcommittees and panels: ERA Technology Ltd. Engineering Equipment and Materials Users Association RAPRA Technology Ltd.BS EN 728 : 1997 BSI 1997 i Contents Page Committees responsible Inside front cover National foreword ii Foreword
9、2 Method 3 1 Scope 3 2 Normative references 3 3 Principle 3 4 Materials 3 5 Apparatus 3 6 Test pieces 5 7 Procedure 5 8 Interpretation of results 6 9 Test report 6 Figures 1 Typical calibration curve 4 2 Typical thermogram for polyethylene exhibiting an endothermic reaction 6ii BSI 1997 BS EN 728 :
10、1997 1) Under preparation. National foreword This British Standard has been prepared by Technical Committee PRI/61 and is the English language version of EN 728 : 1997 Plastics piping and ducting systems Polyolefin pipes and fittings Determination of oxidation induction time, published by the Europe
11、an Committee for Standardization (CEN). It is incorporated into BS 2782 Methods of testing plastics : Part 11 : Thermoplastics pipes, fittings and valves, as Method 1103D : 1997, for association with related test methods for plastics materials and plastics piping components. This test method has bee
12、n prepared for reference by other standards under preparation by CEN for specification of plastics piping and ducting systems and components. It has been implemented to enable experience of the method to be gained and for use for other fresh applications. It is also for use for the revision or amend
13、ment of other national standards as practicable, but it should not be presumed to apply to any existing standard or specification which contains or makes reference to a different test method until that standard/specification has been amended or revised to make reference to this method and adjust any
14、 requirements as appropriate. Cross-references Publication referred to Corresponding British Standard ISO 293 BS 2782 : Part 9 : Method 901A : 1988 Methods of testing plastics : Part 9 Sampling and test specimen preparation : Method 901A Compression moulding test specimens of thermoplastics material
15、s ISO 1133 BS 2782 : Part 7 : Method 720A : 1997 1) Methods of testing plastics : Part 7 : Rheological properties : Method 720A Determination of melt flow rate of thermoplastics NOTE 1. For other applications, attention is drawn to BS 2782 : Part 1 : Methods 134A and 134B : 1992 Determination of the
16、 oxidation induction time of thermoplastics. NOTE 2. Attention is drawn to the use in figure 1 of D to designate the horizontal axis, for temperature and in figure 2 of F to designate the time axis. This is inconsistent with ISO/TR 10837 : 1991, and with other test methods prepared by CEN/TC 155 and
17、 ISO/TC 138, which generally use T to designate a temperature axis and time or t to designate the time axis. F is generally used to designate a force. Hence the use of D and F as presented in EN 728 : 1997 should not be copied into other contexts if it can be avoided. Warning note. This British Stan
18、dard, which is identical with EN 728 : 1997, does not necessarily detail all the precautions necessary to meet the requirements of the Health and Safety at Work etc. Act 1974. Attention should be paid to any appropriate safety precautions and the method should be operated only by trained personnel.
19、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, pages i and ii, the EN title page, pages 2 to 6, an inside back cover and a back cover.CEN European Committee for Standardizati
20、on Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 Copyright reserved to CEN members Ref. No. EN 728 : 1997 E EUROPEAN STANDARD EN 728 NORME EUROPE ENNE EUROPA ISCHE NORM January 1997 ICS 83.140.30 Descriptors: Plasti
21、c tubes, thermoplastic resins, polyolefins, pipe fittings, tests, determination, thermal stability, oxidation English version Plastics piping and ducting systems Polyolefin pipes and fittings Determination of oxidation induction time Syste mes de canalisations et de gaines en plastiques Tubes et rac
22、cords en polyole fine Determination du temps dinduction a loxydation Kunststoff-Rohrleitungs- und Schutzrohrsysteme Rohre und Formstu cke aus Polyolefinen Bestimmung der Oxidations-Induktionszeit This European Standard was approved by CEN on 1996-10-27. CEN members are bound to comply with the CEN/C
23、ENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to an
24、y CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. C
25、EN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 728 : 1997 BSI 1997 Foreword This European Standard has been prepar
26、ed by Technical Committee CEN/TC 155, Plastics piping systems and ducting systems, the secretariat of which is held by NNI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 1997, and conflicti
27、ng national standards shall be withdrawn at the latest by July 1997. This standard is based on ISO/TR 10837 : 1991 Determination of the thermal stability of polyethylene (PE) for use in gas pipes and fittings, published by the International Organization for Standardization (ISO). It is a modificatio
28、n of ISO/TR 10837 : 1991 for reasons of applicability to other plastics materials and/or other test conditions and alignment with texts of other standards on test methods. The modifications are: advice is provided on possible application of the method to additional thermoplastics; test parameters, e
29、xcept those common to all plastics, are omitted; no material-dependent requirements are given; editorial changes have been introduced. The material-dependent parameters and/or performance requirements are incorporated in the System Standard(s) concerned. This standard is one of a series of standards
30、 on test methods which support System Standards for plastics piping systems and ducting systems. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, Franc
31、e, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.Page 3 EN 728 : 1997 BSI 1997 1 Scope This standard specifies a method for measuring the oxidation induction time in oxygen at a specified temperature of polyolef
32、in materials for or from pipes or fittings. It may be used for assessing the thermal stability of either raw materials or finished products. 2 Normative references This standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at th
33、e appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publicat
34、ion referred to applies. ISO 293 Plastics Compression moulding test pieces of thermoplastic materials ISO 1133 Plastics Determination of the melt mass-flow rate (MFR) and the melt volume-flow rate (MVR) of thermoplastics 3 Principle It is assumed that a polyolefin material for manufacture of pipe an
35、d/or fittings will incorporate an additive package which includes one or more antioxidants or other stabilizers. The time for which the material, with its additive package consisting of antioxidant, stabilizers and other additives present in a test piece, inhibits oxidation is measured while the tes
36、t piece is held isothermally at a specified temperature in a stream of oxygen. The progress of the oxidation is monitored by measuring the difference in energy flow (D )o r Q o temperature (DT) between the test piece pan and reference pan of a thermal analyser and recording this difference against t
37、ime. The oxidation induction time (OIT) is then derived from this record as the period during which the difference in energy flow or temperature remains constant (see figure 2) between the test piece pan and reference pan. This time can be indicative of the effective residual antioxidant level and r
38、eflects the time the test piece can be exposed in pure oxygen at the test temperature before the onset of thermal degradation. In normal atmospheric conditions this time will be longer. Depending upon the material and the pipe or fitting processing, dimensions and service conditions, the methods of
39、sample and test piece preparation may be crucial to the consistency of the results and their significance. NOTE. It is assumed that the following test parameters are set by the standard making reference to this standard: a) the test temperature, T, for the reference pan (see 5.1); b) the methods of
40、sample and test piece preparation (see 6.2) and, if applicable, the moulding temperature see a) of 6.1; c) the number of test pieces (see 6.3). It is recommended to choose a temperature which normally results in induction times of at least 10 min. 4 Materials 4.1 Oxygen An oxygen supply with a purit
41、y of at least 99,5 %. 4.2 Nitrogen A nitrogen supply with a purity of 99,998 %. 4.3 Reference materials Two or more temperature reference materials (calibration standards) of high purity metal having melting temperatures in the vicinity of the testing temperature, T see a) of the note to clause 3. W
42、hen T lies between 190 C and 220 C (typical for testing polyolefins), the calibration metals shall be as follows: indium (melting point 156,6 C) with a purity grade of at least 99,99 %; tin (melting point 231,9 C) with a purity grade of at least 99,99 %; where the melting point is derived from the o
43、nset in the DSC diagram (shown as A in figure 1). 4.4 Solvent A solvent of appropriate composition (see 7.2), analytical grade. 5 Apparatus 5.1 Differential scanning calorimeter (DSC) or differential thermal analyser (DTA), capable of: a) recording the difference in energy flow,D ,o ri n Q o tempera
44、ture,DT, between the test piece pan and the reference pan against time (see clause 7); b) exposing a test piece in an open or ventilated aluminium pan to a flow of 50 ml/min 10 % of nitrogen and 50 ml/min 10 % of oxygen in turn so that each gas changeover is effected in not more than 1 min. The pan
45、shall have a flat, smooth base capable of making good contact with the cell base and with a test piece respectively;Page 4 EN 728 : 1997 BSI 1997 DQ o Difference in energy flow A Onset temperature (melting point) C Melting point D Temperature Figure 1. Typical calibration curve c) increasing the tem
46、perature over the range of 140 C to 250 C at a rate of (1 0,1) C/min when the cell contains either a temperature calibration device or a calibration metal (see 4.3 and 7.1); d) increasing the test piece pan temperature T over the range from 50 C to the test temperature at a rate of (20 2) C/min (see
47、 7.2); e) stabilizing the temperature at (T 0,3) C within 3 min of first reaching (T 0,3) C; f) maintaining the test temperature, T, within 0,3 C for the duration of the test (see 7.2). NOTE. The design of the instrument oven should ensure that the test piece compartment is exposed to the required g
48、as flow see b). 5.2 Temperature measurement device, capable of continuously monitoring the test piece pan temperature with a resolution of 0,1 C. NOTE 1. Test piece pan temperatures are used as the values for test results. NOTE 2. This device can be integral with the DSC or DTA apparatus (see 5.1),
49、but this is not essential. A high impedance digital voltmeter with a resolution of 1 mV has been found suitable when connected to a thermocouple and the associated cold junction, or cold compensator, of the thermal analyser. 5.3 Analytical balance, capable of weighing a test piece (see clause 6) to a limit of error of 0,1 mg. 5.4 Gas flow control and measuring devices, capable of providing the required flow rate (see 7.1 and 7.2). Rotameters are suitable, if they are c
