1、BRITISH STANDARD BS ISO 9852:2007 Unplasticized poly(vinyl chloride) (PVC-U) pipes Dichloromethane resistance at specified temperature (DCMT) Test method ICS 23.040.20 BS ISO 9852:2007 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 June 2
2、007 BSI 2007 ISBN 978 0 580 52918 4 National foreword This British Standard was published by BSI. It is the UK implementation of ISO 9852:2007. The UK participation in its preparation was entrusted by Technical Committee PRI/88, Plastics piping systems, to Subcommittee PRI/88/4, Test methods. A list
3、 of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from lega
4、l obligations. Amendments issued since publication Amd. No. Date Comments Reference number ISO 9852:2007(E)INTERNATIONAL STANDARD ISO 9852 Second edition 2007-05-01 Unplasticized poly(vinyl chloride) (PVC-U) pipes Dichloromethane resistance at specified temperature (DCMT) Test method Tubes en poly(c
5、hlorure de vinyle) non plastifi (PVC-U) Rsistance au dichloromthane une temprature spcifie (DCMT) Mthode dessai BS ISO 9852:2007ii iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Principle. 1 3 Reagent 1 4 Apparatus 2 5 Preparation of test pieces 2 6 Immersion conditions. 3 7 Procedure 3
6、8 Expression of results . 3 9 Test report . 4 Annex A (informative) Description of attack 5 Annex B (informative) Example of small container placed in an existing (larger) container . 6 BS ISO 9852:2007iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of
7、national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. Inte
8、rnational organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with th
9、e rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval b
10、y at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 9852 was prepared by Technical Committee ISO
11、/TC 138, Plastics pipes, fittings and valves for the transport of fluids, Subcommittee SC 5, General properties of pipes, fittings and valves of plastic materials and their accessories Test methods and basic specifications. This second edition cancels and replaces the first edition (ISO 9852:1995),
12、which has been revised to align it with EN 580:2003. The principal modifications are the following: the wall thickness ranges “8 u e u 16” and “e 16” in Table 1 have been changed to “8 u e 16” and “16 u e”, respectively, to align them with those in EN 580:2003; the surface of the dichloromethane lay
13、er has been reduced to the minimum and the thickness of the water layer covering the dichloromethane increased (see 6.2); after immersion in the dichloromethane, the test piece is held in the water layer to allow it to “drip” before final drying and inspection (see 7.4); in the event of the pipe bei
14、ng attacked (see 8.2), giving a description of the attack has become optional, dealt with in a new Annex A (informative). the lower limit for the test temperature (12 C) has been moved to 6.3, and Annex A, “Basic specification”, has been deleted; a typical test arrangement, with the deeper water lay
15、er (acting both as a block to evaporation and as a “drip” zone), is shown in a new Annex B. These modifications allow the consumption of dichloromethane to be reduced, thus improving the environment for the staff conducting the test without reducing the number of tests. Experience has shown that thi
16、s modified procedure and test arrangement can result in a reduction of dichloromethane consumption of more than 90 %. BS ISO 9852:2007 v Introduction The maximum temperature at which unplasticized poly(vinyl chloride) (PVC-U) pipe is not attacked by dichloromethane gives an indication of the level a
17、nd homogeneity of gelation of the PVC material in the pipe. This characteristic is related to the mechanical properties and, in particular, the long-term performance of the pipe. BS ISO 9852:2007blank 1 Unplasticized poly(vinyl chloride) (PVC-U) pipes Dichloromethane resistance at specified temperat
18、ure (DCMT) Test method 1 Scope This International Standard specifies a method for determining the resistance of unplasticized poly(vinyl chloride) (PVC-U) pipes to dichloromethane at a specified temperature (DCMT). It is applicable to all PVC-U pipes, irrespective of their intended use. The method c
19、an be used as a rapid means of quality control during manufacture. NOTE The temperature of the dichloromethane up to which the pipe shall not be attacked is specified in the referring standard. 2 Principle A piece of PVC-U pipe, of specified length, chamfered at one end to an angle dependent on its
20、thickness, is immersed for (30 1) min in dichloromethane, at a temperature T specified by the referring standard, to verify that the PVC-U is not attacked at that temperature. For safety reasons, the surface area of the dichloromethane is kept to the minimum and the dichloromethane is covered by a d
21、eep layer of water to reduce evaporation. After immersion in the dichloromethane, the test piece is held in the water layer to allow it to “drip” before final drying and inspection. NOTE 1 If the PVC-U has not sufficiently gelled, whitening of the surface will occur and, in the worst case, a precipi
22、tate will be observed. NOTE 2 It is assumed that the following test parameters are set by the standard making reference to this International Standard: a) the temperature T of the dichloromethane (see 4.3 and 6.3); b) the minimum wall thickness for which the test can be used; c) the number of test p
23、ieces, if appropriate (see 5.1). 3 Reagent 3.1 Dichloromethane, technical grade. NOTE Technical-grade dichloromethane contains small quantities (at the most, 1 % of each) of chloromethane (CH 3 Cl), trichloromethane (CHCl 3 ) and tetrachloromethane (CCl 4 ). It has been noted that, even if the level
24、 of these impurities reaches 5 % in total, the results are not significantly affected. WARNING The boiling point of dichloromethane is low (40 C). Consequently, it has a high vapour pressure at ambient temperature. Further, it can be toxic by absorption through the skin and eyes. It is therefore nec
25、essary to take precautions when handling dichloromethane or test pieces which have been immersed in it. The vapour is also toxic, the threshold limit value (TLV) corresponding to the maximum admissible concentration (MAC) being 100 ml/m 3 (ppm). Ventilation of the room or area in which the container
26、 is located and where the test pieces are dried is therefore essential. BS ISO 9852:20072 4 Apparatus 4.1 Chamfering machine (see 5.2). 4.2 Glass or stainless-steel container, of suitable dimensions to accommodate at least one test piece (see Clause 5), with a grating maintained at a depth approxima
27、tely 10 mm above the bottom of the container, a lid to limit evaporation of the liquid (see 6.1 and 6.2) and temperature-control equipment, with a stirrer, capable of maintaining the temperature of the liquid at (T 0,5) C with the help of the cooling equipment (4.3). NOTE It is recommended that a cy
28、lindrical container be used of a suitable small diameter, e.g. slightly greater than 315 mm but chosen to suit the dimensions of the most frequently produced pipe size (larger pipes can be cut into a number of longitudinal sections to be fitted into the container, see 5.1). In laboratories which pre
29、viously used a larger container for this test, the container specified here can be placed in the old container, which can be filled with water (see Annex B). Provided the new container is sufficiently small and made from a heat-conducting material like stainless steel, the temperature-control equipm
30、ent and stirrer can be located in the old vessel. The grating shall be designed so it can be positioned at two different levels as follows: a) with the appropriate parts of the test pieces or test piece sections immersed in the dichloromethane; b) with the parts of the test pieces or test piece sect
31、ions which were immersed in the dichloromethane completely surrounded by water but not in contact with the dichloromethane. 4.3 Cooling equipment, capable of cooling the dichloromethane to the temperature specified in the referring standard. 4.4 Hood fitted with a fume extraction system, mounted for
32、 safety reasons (see warning in Clause 3) over the container (4.2). 5 Preparation of test pieces 5.1 Cut from the pipe to be tested test pieces 160 mm in length, such that the cut ends are perpendicular to the axis of the pipe. Unless otherwise specified by the referring standard, the number of test
33、 pieces shall be three. The wall thickness of the pipe shall be greater than the minimum thickness specified for this test by the referring standard see item b) of Note 2 to Clause 2. 5.2 Chamfer, by cutting (see Note) without producing any appreciable heating effect, one of the ends of each test pi
34、ece over its entire wall thickness (see Figure A.1). The angle of chamfer shall be chosen as a function of the wall thickness of the pipe as specified in Table 1. NOTE The term “cutting” has been used to exclude grinding. Table 1 Angles of chamfer Pipe wall thickness, e mm Angle of chamfer, degrees
35、e 8 10 8 u e 16 20 16 u e 30 BS ISO 9852:2007 3 5.3 If the test pieces are larger than the diameter of the container, cut each test piece into a number of longitudinal sections. The maximum width of the saw blade used shall be 2,5 mm. The number of sections into which each test piece is cut shall be
36、 the lowest possible number, i.e. the maximum possible size, allowed by the size of the container. 5.4 Cool the test pieces or test piece sections to ambient temperature. 6 Immersion conditions 6.1 Fill the container with dichloromethane of known refractive index to a depth sufficient to completely
37、cover the chamfered zone of the test pieces or test piece sections. 6.2 Cover the dichloromethane with a layer of water preferably 250 mm to 300 mm deep, but not less than 20 mm deep. 6.3 Using the temperature control, cooling equipment and stirrer, establish and maintain the temperature of the dich
38、loromethane in the container at (T 0,5) C see item a) of Note 2 to Clause 2. This temperature shall not be less than 12 C. 6.4 Between tests, add dichloromethane as necessary to maintain the level of the dichloromethane in the container. 6.5 Ensure that the refractive index of the dichloromethane do
39、es not vary during use by more than 0,002 from its initial value. NOTE In practice, the refractive index varies by about 0,000 5 every 3 months if some 700 to 800 tests are carried out per month. A check on the quality of the bath every 3 months should suffice therefore. 7 Procedure 7.1 For the dura
40、tion of the test, avoid touching the test pieces or test piece sections with the fingers (see warning in Clause 3), e.g. by using tongs and gloves. 7.2 Place each test piece or test piece section in the liquid so that the chamfered zone is completely immersed in the dichloromethane. 7.3 Leave the te
41、st pieces or test piece sections for (30 1) min in the dichloromethane. 7.4 After this immersion time, raise the grating to the level described in 4.2 b) for 10 min to 15 min to allow the dichloromethane to “drip” from the test pieces or test piece sections (see Figure B.1). 7.5 Remove the test piec
42、es or test piece sections from the container and leave them to dry in the air until the water has evaporated, but for at least 15 min, in a well-ventilated area or under a hood equipped with a ventilation system. 7.6 Examine the test pieces or test piece sections and determine the result in accordan
43、ce with Clause 8. 7.7 Repeat the procedure for any remaining test pieces or test piece sections. 8 Expression of results 8.1 If a test piece or the sections making up a test piece show no sign of attack anywhere (other than swelling), express the result as “No attack”. BS ISO 9852:20074 8.2 If a tes
44、t piece or the sections making up a test piece show signs of attack anywhere, express the result as “Attacked” and, if required, describe the appearance and location(s) of the attacks. NOTE An example of the way in which attack on the chamfer can be described is given in Annex A. 9 Test report The t
45、est report shall include the following information: a) a reference to this International Standard and to the referring standard; b) all details necessary for complete identification of the pipe under test; c) the temperature T of the dichloromethane bath; d) the number of test pieces tested and, if
46、the test pieces were cut into sections, the number of sections into which each was cut; e) the results of the test and any additional information associated with the results; f) any factors which could have affected the results, such as any incidents or any procedural details not specified in this I
47、nternational Standard; g) the date of the test. BS ISO 9852:2007 5 Annex A (informative) Description of attack If a test piece or the sections making up a test piece are attacked, it is possible to express the result as a percentage of the total chamfer surface (see Figure A.1) in two ways: a) perce
48、ntage attack expressed in terms of the width of the chamfer surface, i.e. Percentage attack 1 100 a c = where a is the (statistical) average dimension of the attacked zone(s) across the width of the chamfer surface, c is the width of the chamfer; b) percentage attack in the circumferential direction
49、, i.e. Percentage attack 2 100 b D = where b is the (statistical) average dimension of the attacked zone(s) in the circumferential direction round the chamfer, D is the outside diameter of the pipe. The rounding interval for the result is 5. Figure A.1 Calculation of percentage attack BS ISO 9852:20076 Annex B (informative) Example of small container placed in an existing (larger) container Figure B.1 shows an exam
