BS ISO 23714-2014 Pulps Determination of water retention value (WRV)《纸浆 保水值(WRV)的测定》.pdf

1、BSI Standards PublicationBS ISO 23714:2014Pulps Determination ofwater retention value (WRV)BS ISO 23714:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 23714:2014. Itsupersedes BS ISO 23714:2007 which is withdrawn.The UK participation in its preparation wa

2、s entrusted to TechnicalCommittee PAI/11, Methods of test for paper, board and pulps.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its

3、correctapplication. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 77829 2ICS 85.040Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strateg

4、y Committee on 31 January 2014.Amendments issued since publicationDate Text affectedBS ISO 23714:2014 ISO 2014Pulps Determination of water retention value (WRV)Ptes Dtermination de la valeur de rtention deau (VRE)INTERNATIONAL STANDARDISO23714Second edition2014-02-01Reference numberISO 23714:2014(E)

5、BS ISO 23714:2014ISO 23714:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or

6、 posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyr

7、ightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 23714:2014ISO 23714:2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Reagents 16 Apparatus . 27 Sampling 38 Preparation of sample 39 Proc

8、edure. 39.1 General . 39.2 Forming in a Bchner funnel 39.3 Centrifuging the test pad 310 Calculation 411 Test report . 4Annex A (informative) Test-pad-holding units. 5Annex B (informative) Precision . 7BS ISO 23714:2014ISO 23714:2014(E)ForewordISO (the International Organization for Standardization)

9、 is a worldwide federation of 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 repre

10、sented on that committee. International 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.The procedures used to devel

11、op this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/

12、IEC Directives, Part 2 (see www.iso.org/directives).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. Details of any patent rights identified during th

13、e development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning o

14、f ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 6, Paper,

15、 board and pulps.This second edition cancels and replaces the first edition (ISO 23714:2007) which has been revised to add a new precision statement that complies with the requirements of ISO/TR 24498.iv ISO 2014 All rights reservedBS ISO 23714:2014ISO 23714:2014(E)IntroductionThe water retention va

16、lue (WRV) is an empirical measure of the capacity of a test pad of fibres to hold water. The WRV increases with increasing beating because of internal fibrillation, a widening of the small internal pores, and delaminations, which has been called “swelling” and which occurs concurrently with the deve

17、lopment of external fibrils, which also serve to hold additional water.This test can be useful for the pulp producer as a guide to the influence of the pulping process on the fibre produced and the papermaking potential of the pulp. It is also useful for the papermaker as a measure of the efficiency

18、 of pulping and refining. ISO 2014 All rights reserved vBS ISO 23714:2014BS ISO 23714:2014Pulps Determination of water retention value (WRV)1 ScopeThis International Standard specifies a procedure for the determination of the water retention value (WRV) of all kinds of pulp.2 Normative referencesThe

19、 following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 5263-1,

20、 Pulps Laboratory wet disintegration Part 1: Disintegration of chemical pulpsISO 5263-2, Pulps Laboratory wet disintegration Part 2: Disintegration of mechanical pulps at 20 CISO 5263-3, Pulps Laboratory wet disintegration Part 3: Disintegration of mechanical pulps at 85 CISO 7213, Pulps Sampling fo

21、r testingISO 14487, Pulps Standard water for physical testing3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1water retention valueratio of the mass of water retained after centrifugation under specified conditions by a wet pulp sample to the ove

22、n-dry mass of the same pulp sample4 PrincipleA test pad consisting of pulp fibres is formed by dewatering a pulp suspension on a glass-fibre filter. The test pad is centrifuged under a specified centrifugal force for a specified time, weighed, dried, and weighed again. The WRV is calculated from the

23、 wet mass of the centrifuged test pad and the dry mass of the test pad.NOTE The results obtained from a rewetted pulp will not be the same as those from a corresponding never-dried pulp.5 Reagents5.1 Standard water, as specified in ISO 14487.If any other type of water is used, this shall be reported

24、.INTERNATIONAL STANDARD ISO 23714:2014(E) ISO 2014 All rights reserved 1BS ISO 23714:2014ISO 23714:2014(E)6 Apparatus6.1 Laboratory centrifuge, with a swing-out head and buckets, made of an inert material such as steel or anodized aluminium, about 100 ml in volume, and about 45 mm in inner diameter.

25、The centrifugal force shall be (3 000 50) g (g is the acceleration due to gravity, i.e. 9,81 m/s2) at the position of the test pad, approximately 15 mm from the bottom of the bucket. The centrifuge shall be equipped with a timer and a brake.It is desirable that the centrifuge should maintain a worki

26、ng temperature of (23 3) C.NOTE If g is the acceleration due to gravity, i.e. 9,81 m/s2, then the rotational frequency is obtained using Formula (1):NZr=89612(1)whereN is the rotational frequency, in min1or r/min;Z is the centrifugal force, (3 000 50) g;r is the distance between the centre of rotati

27、on and the filtration plane of the glass filter (radius of gyra-tion), in metres.6.2 Bchner funnel or similar funnel, made of non-corrosive material, the perforated bottom of which shall be flat, and having an internal diameter larger than 30 mm.6.3 Wire cloth, of glass-fibre filter, e.g. Whatman gr

28、ade GF/C filter or equivalent.6.4 Suction flask, connected to a water suction pump or similar device for vacuum filtration applied to the Bchner funnel.6.5 Set of test-pad-holding units.The holding unit is a metal tube, (30 5) mm in inner diameter, with a phosphor-bronze wire screen attached to one

29、end. The wire screen shall have a nominal size of aperture of 125 m and a preferred diameter of the wire of 90 m. The centrifuge tube should be capped with a hole in the centre to prevent moisture loss.The design of the holding unit depends on the design of the centrifuge and is therefore not specif

30、ied in this International Standard. The unit shall fit into the centrifuge buckets in such a way that the test pad in the test-pad-holding unit will not be rewetted after centrifugation. Two examples of test-pad-holding units are described in Annex A.The number of test-pad-holding units required dep

31、ends on the design of the centrifuge. All units shall have the same mass.6.6 Weighing bottles with lids, having a volume of 25 ml.6.7 Oven, capable of maintaining (105 2) C.2 ISO 2014 All rights reservedBS ISO 23714:2014ISO 23714:2014(E)7 SamplingIf the test is being carried out to evaluate a pulp l

32、ot, the sample shall be selected in accordance with ISO 7213. If the test is made on another type of sample, report the source of the sample and, if possible, the sampling procedure used.Make sure that the test portions taken are representative of the pulp sample.8 Preparation of sampleIf the pulp s

33、ample is in dried form, disintegrate the pulp in standard water (5.1) in accordance with ISO 5263-1 or ISO 5263-2.If a mechanical pulp has been disintegrated at a temperature higher than 85 C, in accordance with ISO 5263-3 to remove latency effects, then before proceeding further, the diluted stock

34、sample shall be allowed to cool to (23 3) C.If the sample has been disintegrated, the disintegration method shall be stated in the test report.Dilute the stock in standard water (5.1) to give a concentration in the range from 2 g/l to 5 g/l. For samples that drain slowly, use the highest concentrati

35、on.It shall be stated in the test report whether the sample is rewetted or never-dried, since there could be significant differences in the results.9 Procedure9.1 GeneralFrom the diluted and well-stirred stock, take samples and carry out WRV determinations at (23 3) C in duplicate. Carry out all det

36、erminations as soon as possible after sampling.If, for practical reasons, WRV determinations are carried out a day or more after sampling, the WRV will be somewhat higher (normally less than 0,03 g/g) than it would have been if the determination had been carried out the same day. Any significant del

37、ay in carrying out the WRV tests shall be reported.9.2 Forming in a Bchner funnelConnect the Bchner funnel (6.2) to the suction flask (6.4). Put the glass-fibre filter in the funnel, moisten, and then start the suction. Add to the Bchner funnel a volume of the stock, so chosen that the test pad form

38、ed will have an oven-dry grammage of (1 700 100) g/m2, when placed in the test-pad-holding unit (6.5).For the volume of stock chosen, 100 ml of this volume should be filtered and then the suction stopped. If necessary (if the retention of fines is too low), add this initial filtrate to the remainder

39、 of the stock volume to be filtered.Stop the suction when all the surface water has directly disappeared. The dry-matter content of the test pad should then be between 5 % and 15 %.Remove the pad from the Bchner funnel and place it in a test-pad holder.9.3 Centrifuging the test padPlace the complete

40、 test-pad-holding unit with the test pad in a centrifuge bucket (see 6.1). Centrifuge at a speed that gives a centrifugal force of (3 000 50) g at the bottom of the pad for 30 min 30 s. This period shall include neither acceleration nor retardation. ISO 2014 All rights reserved 3BS ISO 23714:2014ISO

41、 23714:2014(E)The temperature of the test pad during the centrifugation can influence the result, and it is therefore recommended that the centrifuge be able to maintain a working temperature of (23 3) C. Otherwise, the temperature of centrifugation should be included in the report. If multiple cent

42、rifuging tests are to be run, then some time should be allowed for the centrifuge to cool between each run, to be within the proper temperature range.Immediately after the centrifuge has stopped, transfer the test pad to a preweighed weighing bottle (6.6). Weigh it to the nearest 1 mg. Place the ope

43、n weighing bottle together with its lid in a drying oven (6.7) and dry to constant mass at a temperature of (105 2) C (normally overnight). Close the weighing bottle and allow it to cool in a desiccator, raise the lid briefly to achieve pressure equalization, and weigh the closed bottle to the neare

44、st 1 mg.10 CalculationCalculate the WRV, in grams per gram, using Formula (2):WRV=mm121 (2)wherem1is the mass of the centrifuged wet test pad, in grams;m2is the mass of the dry test pad, in grams.Calculate the mean of the duplicates and report the result to two decimal places.The results of the para

45、llel determinations shall not differ by more than 5 % from their mean.11 Test reportThe test report shall include the following information:a) a reference to this International Standard (i.e. ISO 23714);b) all information necessary for complete identification of the sample;c) the date and place of t

46、esting;d) rewetted or never-dried pulp used;e) the results, as specified in Clause 10;f) any departure from this International Standard, or any other circumstances or influences regarded as optional, that could have affected the results.4 ISO 2014 All rights reservedBS ISO 23714:2014ISO 23714:2014(E

47、)Annex A (informative) Test-pad-holding unitsThis informative annex describes examples of the design of two different test-pad-holding units.A.1 Test-pad-holding unit, to hang on the rim of the centrifuge bucketThis kind of test-pad-holding unit (shown in Figure A.1) has four parts: (2) is the test-

48、pad basket with its wire (3). The wire is not soldered to the tube but is fixed in position by pushing the tube (2) into the vessel (4), which has a perforated bottom. The lid (1) fits into the tube (2) and forms a cover. It has a small hole to allow air to pass through. All parts are machined to fi

49、t tightly to each other. During centrifugation, the unit hangs on the rim of the centrifuge bucket, leaving enough space underneath to accommodate drained water.The parts (2), (3), and (4) are assembled before adding the sample. The lid (1) is placed in position before centrifugation.A.2 Test-pad-holding unit, to rest on the bottom of the centrifuge bucketThis kind of test-pad-holding unit (shown in Figure A.2) has the test-pad basket (2) and its wire screen soldered to the tube.