1、BSI Standards PublicationBS ISO 12154:2014Determination of densityby volumetric displacement Skeleton density by gaspycnometryBS ISO 12154:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 12154:2014.The UK participation in its preparation was entrusted to T
2、echnicalCommittee LBI/37, Particle characterization including sieving.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 correctapplicat
3、ion. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 79043 0ICS 19.120Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on
4、30 April 2014.Amendments issued since publicationDate Text affectedBS ISO 12154:2014 ISO 2014Determination of density by volumetric displacement Skeleton density by gas pycnometryDtermination de la masse volumique par dplacement volumtrique Masse volumique du squelette mesure par pycnomtrie gazINTER
5、NATIONAL STANDARDISO12154First edition2014-04-01Reference numberISO 12154:2014(E)BS ISO 12154:2014ISO 12154:2014(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
6、in any form or by any means, electronic or mechanical, including photocopying, or 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 po
7、stale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 12154:2014ISO 12154:2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14
8、Symbols and abbreviated terms . 25 Principle of the method . 26 Apparatus and procedure . 36.1 Apparatus 36.2 Sample pre-treatment and determination of sample mass 46.3 Determination of the solid skeleton volume of the sample 56.4 Calculation of skeleton density . 66.5 Calibration procedure . 67 Tes
9、t report . 8Annex A (informative) Interferences . 9Bibliography .11BS ISO 12154:2014ISO 12154:2014(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally
10、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. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the wo
11、rk. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the diff
12、erent 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/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document m
13、ay 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 the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/pate
14、nts). 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 of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO princip
15、les in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 24, Particle characterization including sieving, Subcommittee SC 4, Particle characterization.iv ISO 2014 All rights reservedBS ISO 12154:2014
16、ISO 12154:2014(E)IntroductionThe true solid state density of a material is defined as the ratio of the mass to the volume occupied by that mass. Therefore, the contribution to the volume made by pores or internal voids and also interparticle voids (in the case of granulated or highly dispersed sampl
17、es) shall be subtracted when calculating the true density.If the material has no porosity, the true density can be measured by displacement of any fluid in which the solid remains inert. The accuracy of the method is limited by the accuracy with which the fluid volume can be determined. Usually, how
18、ever, the pores, cracks, or crevices of the material will not easily be completely penetrated by a displaced liquid. In these instances, the true density can be measured by using a gas as the displaced fluid if the material does not contain closed pores, which cannot be penetrated by the analysis ga
19、s. Therefore, the density experimentally determined by gas pycnometry generally is the so called skeleton density of the material which equals the true solid state density only for samples without closed pores.Apparatus used to measure solid volumes are often referred to as pyknometers or pycnometer
20、s after the Greek “pyknos”, meaning thick or dense. With gas pycnometry, materials of irregular shape can be analysed.Once the volume of solid skeleton of the sample and the sample mass have been determined, the skeleton density is readily calculated. ISO 2014 All rights reserved vBS ISO 12154:2014B
21、S ISO 12154:2014Determination of density by volumetric displacement Skeleton density by gas pycnometry1 ScopeThis International Standard specifies a method for rapid and efficient determination of the skeleton density of solid material samples of regular or irregular shape, whether powdered or in on
22、e piece, by means of a gas displacement pycnometer.2 Normative referencesThe 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 editi
23、on of the referenced document (including any amendments) applies.ISO 14488, Particulate materials Sampling and sample splitting for the determination of particulate propertiesISO 9277, Determination of the specific surface area of solids by gas adsorption BET methodISO 15901-3, Pore size distributio
24、n and porosity of solid materials by mercury porosimetry and gas adsorption Part 3: Analysis of micropores by gas adsorption3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1densityratio of the mass of a certain amount of a sample to the volume oc
25、cupied by that mass3.2true solid state densityratio of the sample mass to the volume of the compact solid skeleton of the sample which excludes the volume of open and closed pores or internal voids and also interparticle voids as in the case of granulated or highly dispersed samples3.3skeleton densi
26、tyratio between sample mass and the volume of the sample including the volume of closed pores (if present) but excluding the volumes of open pores as well as that of void spaces between particles within the bulk sample3.4closed porepore totally enclosed by its walls and hence not interconnecting wit
27、h other pores and not accessible to fluids3.5open porepore not totally enclosed by its walls and open to the surface either directly or by interconnecting with other pores and therefore accessible to fluidsINTERNATIONAL STANDARD ISO 12154:2014(E) ISO 2014 All rights reserved 1BS ISO 12154:2014ISO 12
28、154:2014(E)3.6gauge pressure sensorbecause gauge pressure is defined relative to atmospheric conditions, the signal or reading of a gauge pressure sensor is the total pressure minus atmospheric pressure3.7absolute pressure sensorabsolute pressure sensor measures the pressure relative to an absolute
29、vacuum that means the reference is full vacuum (zero pressure)4 Symbols and abbreviated termsTable 1 SymbolsSymbol Name Unitsskeleton density g cm-3mssample mass gVsskeleton volume of the sample cm3Vcellsample chamber volume cm3Vrefreference chamber volume cm3Vcalvolume of the calibrated reference s
30、ample cm3p1equilibrated gauge pressure prior to expansion aPap2equilibrated gauge pressure after expansion aPapA1equilibrated gauge pressure before expansion (calibration step A) aPapA2equilibrated gauge pressure after expansion (calibration step A) aPapB1equilibrated gauge pressure before expansion
31、 (2nd calibration step) aPapB2equilibrated gauge pressure after expansion (2nd calibration step) aPapapycnometer pressure at start of analysis Papipycnometer absolute gas pressure i (i = 1, 2, A1, A2, B1, or B2) Papipycnometer excess gas pressure i (i = 1, 2, A1, A2, B1, or B2) Paagauge pressure (ex
32、cess gas pressure) piis defined as the difference between the absolute pressure piand the pycnometer pressure paat start of analysis, i.e. pppii=a(see 3.6, 3.7, and 6.3.2.1)5 Principle of the methodThe skeleton density will be determined volumetrically in a gas expansion pycnometer. This technique i
33、s based on the displacement of a volume of gas by the solid space. The measurement is performed by expanding gas from one chamber to another (see Figure 1) under isothermal conditions. First, the weight of the dry sample is to be determined and the sample loaded into the sample chamber. The sample c
34、hamber then is pressurized to a set value when using the experimental configuration 1 of Figure 1. In a further step, the analysis gas will be expanded into a second chamber, the reference volume. The equilibrated pressures for both steps will be recorded by the instrument. Density is calculated usi
35、ng these values.For gas pycnometers according to the experimental configuration 2 of Figure 1, the first step consists in pressurizing the reference chamber to a set value followed by the expansion into the sample chamber having a lower initial pressure than the set value. It is important for both e
36、xperimental pycnometer configurations, that every chamber of the pycnometer is at the same pressure paprior to starting the 2 ISO 2014 All rights reservedBS ISO 12154:2014ISO 12154:2014(E)analysis steps (see Clause 6) Furthermore, all parts of the pycnometer shall have the same controlled temperatur
37、e.The analysis gas of sufficient purity (see 6.1) shall be nonreactive and also non-adsorbing onto the solid sample. It has to behave as ideally as possible. Therefore, helium is used for most applications. Another reason for the preferred use of helium as the analysis gas for gas pycnometry is that
38、 it is able to penetrate even the smallest pores or cracks of a material.NOTE 1 Because of its pronounced ability to permeate thin inner walls of samples with closed cells, helium can cause difficulties if permeable samples are to be analysed. Therefore, as described in Annex A.6, gas pycnometric me
39、asurements using helium can be erroneous in the case of organic samples like cellulose and cellular polymers with low density. For density measurements of those samples, the use of alternative inert gases such as nitrogen, argon, or sulfur hexafluoride as well as dry air is recommended.NOTE 2 If the
40、 sample contains no closed pores, then the volume measured by gas pycnometry is the true volume. To test the presence of closed pores, after a first density determination the sample can be powdered revealing any possible closed pores accessible to the test gas. An increased density value of the grou
41、nd sample material indicates closed pores in the original sample.6 Apparatus and procedure6.1 Apparatus6.1.1 Gas expansion pycnometer, with fixed-volume sample chamber (see Figure 1).1 2 36.1.2 Calibrated reference sample, (in general calibration spheres made of stainless steel with known traceable
42、volume).6.1.3 Analysis gas, in general helium (see Clause 5) with a minimum purity of 99,996 % (by volume).6.1.4 Analytical balance.6.1.5 Drying oven, for pre-treatment of samples preferably with the option of purging during heating or heating in a vacuum.Figure 1 is a schematic diagram of the two p
43、rincipal configurations of automatic gas expansion pycnometers having fixed sample chamber size. Main components of such instruments are two chambers connected by tubes (a sample chamber which can be sealed for inserting the sample or the calibration spheres and a reference chamber), a pressure-meas
44、uring sensor, and three valves. The difference between the pycnometer configurations is in the sequence of the sample chamber and the reference chamber.Sample volumes of commercially available gas expansion pycnometers vary from 0,1 cm3to about 500 cm3. This is accomplished either by having fixed-vo
45、lume sample chambers of different sizes, or by means of volume-filling inserts placed into a sample chamber. These variations in sample chamber ISO 2014 All rights reserved 3BS ISO 12154:2014ISO 12154:2014(E)volume are necessary because the accuracy of the pycnometric measurement is related to the p
46、ercent of total capacity the sample material occupies in the sample chamber.Configuration 1Configuration 2Key1 valve 1, gas inlet 4 reference chamber2 valve 2 5 sample chamber3 valve 3, gas outlet 6 pressure sensorNOTE The pressure sensor can be either an absolute pressure sensor or a gauge sensor.F
47、igure 1 Two principal experimental gas pycnometer configurations6.2 Sample pre-treatment and determination of sample massPreparing the sample is the first step in obtaining accurate results from the pycnometer. Samples shall be free of moisture in order to obtain true sample mass and to avoid the di
48、storting effect of water vapour on the volume measurement. The following procedures are recommended, however, modifications may be necessary for some materials.Sampling shall be carried out in accordance with ISO 14488. Removing the atmospheric gases from the sample can be carried out by timed evacu
49、ation, timed flow of purge gas, or repetitive pulsing (think multiple rinses) of purge gas. External oven drying of wet samples is recommended.Heat sensitive materials can be dried by long-time exposure to silica gel, freeze drying, etc. Materials having a low melting point can be dried using the purge process. In this case, do not weigh the sample and cup until after the purge and analysis have been completed.NOTE Outgassing can be considered complete when the results of duplicate skeleton density analyses are found within th
