ISO 12154:2014
(Main)Determination of density by volumetric displacement — Skeleton density by gas pycnometry
Determination of density by volumetric displacement — Skeleton density by gas pycnometry
ISO 12154:2014 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 one piece, by means of a gas displacement pycnometer.
Détermination de la masse volumique par déplacement volumétrique — Masse volumique du squelette mesurée par pycnométrie à gaz
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INTERNATIONAL ISO
STANDARD 12154
First edition
2014-04-01
Determination of density by
volumetric displacement — Skeleton
density by gas pycnometry
Détermination de la masse volumique par déplacement
volumétrique — Masse volumique du squelette mesurée par
pycnométrie à gaz
Reference number
©
ISO 2014
© ISO 2014
All 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 posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Principle of the method . 2
6 Apparatus and procedure . 3
6.1 Apparatus . 3
6.2 Sample pre-treatment and determination of sample mass . 4
6.3 Determination of the solid skeleton volume of the sample . 5
6.4 Calculation of skeleton density . 6
6.5 Calibration procedure . 6
7 Test report . 8
Annex A (informative) Interferences . 9
Bibliography .11
Foreword
ISO (the International Organization for Standardization) 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 represented 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 develop 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/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 the 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 of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 24, Particle characterization including sieving,
Subcommittee SC 4, Particle characterization.
iv © ISO 2014 – All rights reserved
Introduction
The 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 samples) 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, however, 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 gas. 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 pycnometers 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.
INTERNATIONAL STANDARD ISO 12154:2014(E)
Determination of density by volumetric displacement —
Skeleton density by gas pycnometry
1 Scope
This 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 one piece, by
means of a gas displacement pycnometer.
2 Normative references
The 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 14488, Particulate materials — Sampling and sample splitting for the determination of particulate
properties
ISO 9277, Determination of the specific surface area of solids by gas adsorption — BET method
ISO 15901-3, Pore size distribution and porosity of solid materials by mercury porosimetry and gas
adsorption — Part 3: Analysis of micropores by gas adsorption
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
density
ratio of the mass of a certain amount of a sample to the volume occupied by that mass
3.2
true solid state density
ratio 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 samples
3.3
skeleton density
ratio 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 sample
3.4
closed pore
pore totally enclosed by its walls and hence not interconnecting with other pores and not accessible to
fluids
3.5
open pore
pore not totally enclosed by its walls and open to the surface either directly or by interconnecting with
other pores and therefore accessible to fluids
3.6
gauge pressure sensor
because gauge pressure is defined relative to atmospheric conditions, the signal or reading of a gauge
pressure sensor is the total pressure minus atmospheric pressure
3.7
absolute pressure sensor
absolute pressure sensor measures the pressure relative to an absolute vacuum that means the reference
is full vacuum (zero pressure)
4 Symbols and abbreviated terms
Table 1 — Symbols
Symbol Name Unit
-3
ρ skeleton density g cm
s
m sample mass g
s
V skeleton volume of the sample cm
s
V sample chamber volume cm
cell
V reference chamber volume cm
ref
V volume of the calibrated reference sample cm
cal
a
p equilibrated gauge pressure prior to expansion Pa
a
p equilibrated gauge pressure after expansion Pa
a
p equilibrated gauge pressure before expansion (calibration step A) Pa
A1
a
p equilibrated gauge pressure after expansion (calibration step A) Pa
A2
a
p equilibrated gauge pressure before expansion (2nd calibration step) Pa
B1
a
p equilibrated gauge pressure after expansion (2nd calibration step) Pa
B2
p pycnometer pressure at start of analysis Pa
a
∗
pycnometer absolute gas pressure i (i = 1, 2, A1, A2, B1, or B2) Pa
p
i
p pycnometer excess gas pressure i (i = 1, 2, A1, A2, B1, or B2) Pa
i
∗
a
gauge pressure (excess gas pressure) p is defined as the difference between the absolute pressure p and the
i
i
∗
pycnometer pressure p at start of analysis, i.e. pp=−p (see 3.6, 3.7, and 6.3.2.1)
a
ii a
5 Principle of the method
The skeleton density will be determined volumetrically in a gas expansion pycnometer. This technique
is 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
chamber 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 using
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 experimental pycnometer
configurations, that every chamber of the pycnometer is at the same pressure p prior to starting the
a
2 © ISO 2014 – All rights reserved
analysis steps (see Clause 6) Furthermore, all parts of the pycnometer shall have the same controlled
temperature.
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 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
measurements 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 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 ground sample
material indicates closed pores in the original sample.
6 Apparatus and procedure
6.1 Apparatus
[1] [2] [3]
6.1.1 Gas expansion pycnometer, with fixed-volume sample chamber (see Figure 1).
6.1.2 Calibrated reference sample, (in general calibration spheres made of stainless steel with
known traceable 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.
Fi
...
INTERNATIONAL ISO
STANDARD 12154
First edition
2014-04-01
Determination of density by
volumetric displacement — Skeleton
density by gas pycnometry
Détermination de la masse volumique par déplacement
volumétrique — Masse volumique du squelette mesurée par
pycnométrie à gaz
Reference number
©
ISO 2014
© ISO 2014
All 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 posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Principle of the method . 2
6 Apparatus and procedure . 3
6.1 Apparatus . 3
6.2 Sample pre-treatment and determination of sample mass . 4
6.3 Determination of the solid skeleton volume of the sample . 5
6.4 Calculation of skeleton density . 6
6.5 Calibration procedure . 6
7 Test report . 8
Annex A (informative) Interferences . 9
Bibliography .11
Foreword
ISO (the International Organization for Standardization) 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 represented 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 develop 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/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 the 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 of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 24, Particle characterization including sieving,
Subcommittee SC 4, Particle characterization.
iv © ISO 2014 – All rights reserved
Introduction
The 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 samples) 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, however, 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 gas. 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 pycnometers 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.
INTERNATIONAL STANDARD ISO 12154:2014(E)
Determination of density by volumetric displacement —
Skeleton density by gas pycnometry
1 Scope
This 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 one piece, by
means of a gas displacement pycnometer.
2 Normative references
The 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 14488, Particulate materials — Sampling and sample splitting for the determination of particulate
properties
ISO 9277, Determination of the specific surface area of solids by gas adsorption — BET method
ISO 15901-3, Pore size distribution and porosity of solid materials by mercury porosimetry and gas
adsorption — Part 3: Analysis of micropores by gas adsorption
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
density
ratio of the mass of a certain amount of a sample to the volume occupied by that mass
3.2
true solid state density
ratio 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 samples
3.3
skeleton density
ratio 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 sample
3.4
closed pore
pore totally enclosed by its walls and hence not interconnecting with other pores and not accessible to
fluids
3.5
open pore
pore not totally enclosed by its walls and open to the surface either directly or by interconnecting with
other pores and therefore accessible to fluids
3.6
gauge pressure sensor
because gauge pressure is defined relative to atmospheric conditions, the signal or reading of a gauge
pressure sensor is the total pressure minus atmospheric pressure
3.7
absolute pressure sensor
absolute pressure sensor measures the pressure relative to an absolute vacuum that means the reference
is full vacuum (zero pressure)
4 Symbols and abbreviated terms
Table 1 — Symbols
Symbol Name Unit
-3
ρ skeleton density g cm
s
m sample mass g
s
V skeleton volume of the sample cm
s
V sample chamber volume cm
cell
V reference chamber volume cm
ref
V volume of the calibrated reference sample cm
cal
a
p equilibrated gauge pressure prior to expansion Pa
a
p equilibrated gauge pressure after expansion Pa
a
p equilibrated gauge pressure before expansion (calibration step A) Pa
A1
a
p equilibrated gauge pressure after expansion (calibration step A) Pa
A2
a
p equilibrated gauge pressure before expansion (2nd calibration step) Pa
B1
a
p equilibrated gauge pressure after expansion (2nd calibration step) Pa
B2
p pycnometer pressure at start of analysis Pa
a
∗
pycnometer absolute gas pressure i (i = 1, 2, A1, A2, B1, or B2) Pa
p
i
p pycnometer excess gas pressure i (i = 1, 2, A1, A2, B1, or B2) Pa
i
∗
a
gauge pressure (excess gas pressure) p is defined as the difference between the absolute pressure p and the
i
i
∗
pycnometer pressure p at start of analysis, i.e. pp=−p (see 3.6, 3.7, and 6.3.2.1)
a
ii a
5 Principle of the method
The skeleton density will be determined volumetrically in a gas expansion pycnometer. This technique
is 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
chamber 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 using
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 experimental pycnometer
configurations, that every chamber of the pycnometer is at the same pressure p prior to starting the
a
2 © ISO 2014 – All rights reserved
analysis steps (see Clause 6) Furthermore, all parts of the pycnometer shall have the same controlled
temperature.
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 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
measurements 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 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 ground sample
material indicates closed pores in the original sample.
6 Apparatus and procedure
6.1 Apparatus
[1] [2] [3]
6.1.1 Gas expansion pycnometer, with fixed-volume sample chamber (see Figure 1).
6.1.2 Calibrated reference sample, (in general calibration spheres made of stainless steel with
known traceable 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.
Fi
...
DRAFT INTERNATIONAL STANDARD ISO/DIS 12154
ISO/TC 24/SC 4 Secretariat: DIN
Voting begins on Voting terminates on
2012-05-04 2012-10-04
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Determination of density by volumetric displacement —
Skeleton density by gas pycnometry
Détermination de la masse volumique par déplacement volumétrique — Masse volumique du squelette
mesurée par pycnométrie à gaz
ICS 19.120
To expedite distribution, this document is circulated as received from the committee
secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at
publication stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
© International Organization for Standardization, 2012
ISO/DIS 12154
Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted
under the applicable laws of the user’s country, neither this ISO draft nor any extract from it may be
reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic,
photocopying, recording or otherwise, without prior written permission being secured.
Requests for permission to reproduce should be addressed to either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Reproduction may be subject to royalty payments or a licensing agreement.
Violators may be prosecuted.
ii © ISO 2012 – All rights reserved
ISO/DIS 12154
Contents Page
Foreword . iv
Introduction . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Principle of the method . 2
6 Apparatus and procedure . 3
6.1 Apparatus . 3
6.2 Sample pre-treatment and determination of sample mass . 4
6.3 Determination of the solid skeleton volume of the sample . 5
6.3.1 Pycnometric measurement . 5
6.3.2 Calculation of the skeleton volume of the sample . 6
6.4 Calculation of skeleton density . 6
6.5 Calibration procedure . 6
6.5.1 General remarks . 6
6.5.2 Calibration of pycnometer configuration 1 . 7
6.5.3 Calibration of pycnometer configuration 2 . 7
7 Test report . 8
Annex A (informative) Interferences . 9
A.1 Improper sample quantity. 9
A.2 Thermal effects and pressure stability . 9
A.3 Influence of humidity and adsorbed gases . 9
A.4 Leaks . 9
A.5 Permeable samples . 10
A.6 Compressible samples . 10
A.7 Thermally sensitive samples . 10
A.8 High surface area samples . 10
A.9 Finely ground samples . 10
Bibliography . 11
ISO/DIS 12154
Foreword
ISO (the International Organization for Standardization) 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 represented 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.
International Standards are drafted in accordance with the 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 by 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 12154 was prepared by Technical Committee ISO/TC 24, Particle characterization including sieving,
Subcommittee SC 4, Particle characterization.
This second/third/. edition cancels and replaces the first/second/. edition (), [clause(s) / subclause(s) /
table(s) / figure(s) / annex(es)] of which [has / have] been technically revised.
iv © ISO 2012 – All rights reserved
ISO/DIS 12154
Introduction
The 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 samples) must 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, however, 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 gas.
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 pycnometers 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.
DRAFT INTERNATIONAL STANDARD ISO/DIS 12154
Determination of density by volumetric displacement —
Skeleton density by gas pycnometry
1 Scope
This 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 one piece by means of a gas displacement
pycnometer.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 14488, Particulate materials — Sampling and sample splitting for the determination of particulate
properties
ISO 9277, Determination of the specific surface area of solids by gas adsorption — BET method
ISO 15901-3, Pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption
— Part 3: Analysis of micropores by gas adsorption
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
density
ratio of the mass of a certain amount of a sample to the volume occupied by that mass
3.2
true solid state density
ratio 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 samples
3.3
skeleton density
ratio 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 sample
3.4
closed pore
a pore totally enclosed by its walls and hence not interconnecting with other pores and not accessible to fluids
3.5
open pore
a pore not totally enclosed by its walls and open to the surface either directly or by interconnecting with other
pores and therefore accessible to fluids
ISO/DIS 12154
3.6
gauge pressure sensor
because gauge pressure is defined relative to atmospheric conditions, the signal or reading of a gauge
pressure sensor is the total pressure minus atmospheric pressure
3.7
absolute pressure sensor
an absolute pressure sensor measures the pressure relative to an absolute vacuum that means the reference
is full vacuum (zero pressure)
4 Symbols and abbreviated terms
Table 1 — Symbols
Symbol Name Unit
-3
skeleton density
ρ g cm
s
m
sample mass g
s
V skeleton volume of the sample
cm
s
V
sample chamber volume
cm
cell
V reference chamber volume
cm
ref
V
volume of the calibrated reference sample
cm
cal
a
p equilibrated gauge pressure prior to expansion Pa
a
p equilibrated gauge pressure after expansion Pa
a
p equilibrated gauge pressure before expansion (calibration step A) Pa
A1
a
p equilibrated gauge pressure after expansion (calibration step A) Pa
A2
a
p Pa
equilibrated gauge pressure before expansion (2nd calibration step)
B1
a
p equilibrated gauge pressure after expansion (2nd calibration step) Pa
B2
p pycnometer pressure at start of analysis Pa
a
∗
p pycnometer absolute gas pressure i (i = 1, 2, A1, A2, B1, or B2) Pa
i
p
pycnometer excess gas pressure i (i = 1, 2, A1, A2, B1, or B2) Pa
i
a ∗
gauge pressure (gas excess pressure) p is defined as the difference between the absolute pressure and the pycnometer
p
i
i
∗
at start of analysis, i.e. (see Subclauses 3.6, 3.7, and 6.3.2.1)
pressure p p = p − p
a i i a
5 Principle of the method
The skeleton density will be determined volumetrically in a gas expansion pycnometer. This technique is
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 chamber
then is pressurised 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 instrumen
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