Rigid cellular plastics - Determination of the volume percentage of open cells and of closed cells (ISO 4590:2016)

This International Standard specifies a general procedure for the determination of the volume
percentage of open and of closed cells of rigid cellular plastics, by measurement first of the geometrical
volume and then of the air-impenetrable volume of test specimens.
The procedure includes the correction of the apparent open-cell volume by taking into account the
surface cells opened by cutting during specimen preparation. Three alternative methods (method 1,
method 2a and method 2b), and corresponding apparatus, are specified for the measurement of the
impenetrable volume.

Harte Schaumstoffe - Bestimmung des Volumenanteils offener und geschlossener Zellen (ISO 4590:2016)

Diese Internationale Norm legt ein allgemeines Verfahren zur Bestimmung des Volumenanteils offener und geschlossener Zellen von harten Schaumstoffen durch Messung des geometrischen Volumens und anschließender Messung des gasdichten Volumens der Probekörper fest.
Dieses Verfahren schließt eine Korrektur des scheinbaren Volumens offener Zellen ein, indem die durch Anschneiden bei der Herstellung der Probekörper geöffneten Zellen berücksichtigt werden. Für die Messung des gasdichten Volumens werden drei alternative Verfahren (Verfahren 1, Verfahren 2a und Verfahren 2b) sowie die entsprechende Prüfeinrichtung festgelegt.

Plastiques alvéolaires rigides - Détermination du pourcentage volumique de cellules ouvertes et de cellules fermées (ISO 4590:2016)

L'ISO 4590 :2016 spécifie un mode opératoire général permettant de déterminer le pourcentage volumique des cellules ouvertes et fermées de plastiques alvéolaires rigides par mesurage, en premier lieu, du volume géométrique d'éprouvettes de ces plastiques, puis du volume impénétrable à l'air de ces éprouvettes.
Le mode opératoire permet d'effectuer une correction du volume apparent des cellules ouvertes en tenant compte des cellules de surface ouvertes par la découpe des éprouvettes. Trois méthodes alternatives (méthode 1, méthode 2a et méthode 2b) et les appareillages correspondants sont spécifiés pour le mesurage du volume impénétrable.

Trdi penjeni polimerni materiali - Določanje prostorninskega deleža odprtih in zaprtih celic (ISO 4590:2016)

Ta mednarodni standard določa splošni postopek za določanje prostorninskega deleža
odprtih in zaprtih celic v trdih penjenih polimernih materialih na podlagi merjenja najprej geometrijske prostornine in nato še zračno neprepustne prostornine preskušancev.
Postopek vključuje popravek navidezne prostornine odprtih celic ob upoštevanju površinskih celic, odprtih pri rezanju med pripravo preskušanca. Za merjenje neprepustne prostornine so določene tri alternativne metode (1, 2a in 2b) ter ustrezna naprava.

General Information

Status
Published
Public Enquiry End Date
17-Aug-2014
Publication Date
22-Aug-2016
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
19-Aug-2016
Due Date
24-Oct-2016
Completion Date
23-Aug-2016

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SLOVENSKI STANDARD
SIST EN ISO 4590:2016
01-oktober-2016
1DGRPHãþD
SIST EN ISO 4590:2003
7UGLSHQMHQLSROLPHUQLPDWHULDOL'RORþDQMHSURVWRUQLQVNHJDGHOHåDRGSUWLKLQ
]DSUWLKFHOLF ,62

Rigid cellular plastics - Determination of the volume percentage of open cells and of

closed cells (ISO 4590:2016)

Harte Schaumstoffe - Bestimmung des Volumenanteils offener und geschlossener Zellen

(ISO 4590:2016)

Plastiques alvéolaires rigides - Détermination du pourcentage volumique de cellules

ouvertes et de cellules fermées (ISO 4590:2016)
Ta slovenski standard je istoveten z: EN ISO 4590:2016
ICS:
83.100 Penjeni polimeri Cellular materials
SIST EN ISO 4590:2016 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 4590:2016
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SIST EN ISO 4590:2016
EN ISO 4590
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2016
EUROPÄISCHE NORM
ICS 83.100 Supersedes EN ISO 4590:2003
English Version
Rigid cellular plastics - Determination of the volume
percentage of open cells and of closed cells (ISO
4590:2016)

Plastiques alvéolaires rigides - Détermination du Harte Schaumstoffe - Bestimmung des Volumenanteils

pourcentage volumique de cellules ouvertes et de offener und geschlossener Zellen (ISO 4590:2016)

cellules fermées (ISO 4590:2016)
This European Standard was approved by CEN on 1 July 2016.

CEN members are bound to comply with the CEN/CENELEC 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 CEN-CENELEC Management Centre or to any 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 CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4590:2016 E

worldwide for CEN national Members.
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SIST EN ISO 4590:2016
EN ISO 4590:2016 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 4590:2016
EN ISO 4590:2016 (E)
European foreword

This document (EN ISO 4590:2016) has been prepared by Technical Committee ISO/TC 61 “Plastics” in

collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by NBN.

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 February 2017, and conflicting national standards

shall be withdrawn at the latest by February 2017.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent

rights.
This document supersedes EN ISO 4590:2003.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 4590:2016 has been approved by CEN as EN ISO 4590:2016 without any modification.

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SIST EN ISO 4590:2016
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SIST EN ISO 4590:2016
INTERNATIONAL ISO
STANDARD 4590
Third edition
2016-07-15
Rigid cellular plastics — Determination
of the volume percentage of open cells
and of closed cells
Plastiques alvéolaires rigides — Détermination du pourcentage
volumique de cellules ouvertes et de cellules fermées
Reference number
ISO 4590:2016(E)
ISO 2016
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Test specimens........................................................................................................................................................................................................ 2

5.1 Number .......................................................................................................................................................................................................... 2

5.2 Preparation ................................................................................................................................................................................................ 3

5.3 Dimensions ................................................................................................................................................................................................. 3

5.4 Sectioning of test specimens ....................................................................................................................................................... 3

6 Conditioning and test atmospheres .................................................................................................................................................. 3

7 Measurement of surface area S and geometrical volume V ................................................................................... 3

8 Determination of impenetrable volume V by method 1: pressure variation (pyknometer) 4

8.1 Principle of method 1 ........................................................................................................................................................................ 5

8.2 Description of apparatus for method 1 .............................................................................................................................. 5

8.3 Calibration of pyknometer apparatus ................................................................................................................................. 7

8.4 Procedure for method 1 .................................................................................................................................................................. 8

8.5 Calculation for method 1 ................................................................................................................................................................ 9

9 Determination of impenetrable volume V by method 2: volume expansion ........................................9

9.1 Principle of method 2 ........................................................................................................................................................................ 9

9.2 Description of apparatus for method 2a ........................................................................................................................10

9.3 Calibration of apparatus for method 2a .........................................................................................................................11

9.4 Procedure and calculation for method 2a ....................................................................................................................14

9.5 Description of apparatus for method 2b .......................................................................................................................14

9.6 Calibration of apparatus for method 2b .........................................................................................................................15

9.7 Test procedure for method 2b ................................................................................................................................................15

9.8 Test sequence for method 2b ......... ..........................................................................................................................................16

9.9 Calculations and expression of results for method 2b ......................................................................................17

10 Correction for specimen surface cells opened during specimen preparation ..................................17

10.1 For the pressure-variation method (see Clause 8) ...............................................................................................17

10.2 For the volume-expansion method (see Clause 9) ................................................................................................17

11 Expression of results .....................................................................................................................................................................................18

11.1 Apparent volume percentage of open cells .................................................................................................................18

11.2 Corrected volume percentage of open cells ................................................................................................................18

12 Precision ....................................................................................................................................................................................................................19

13 Test report ................................................................................................................................................................................................................20

Annex A (normative) Notes on procedure ...................................................................................................................................................21

© ISO 2016 – All rights reserved iii
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
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 61, Plastics, Subcommittee SC 10, Cellular

plastics.

This third edition cancels and replaces the second edition (ISO 4590:2002), which has been technically

revised with the following changes:
— changes on Clause 2;

— introduction of a new test method based on the variation of the volume which is named 2b and is

explained under 9.5 to 9.7;

— references to the test methods have been revised consequently and the cross references;

— some editorial updates have been introduced.
iv © ISO 2016 – All rights reserved
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
Introduction

The method 2b is included in order to update the basics of the method with the modern apparatus.

This International Standard kept the same measurement equipment since the first version of 1981 and

new test equipment has been included in accordance with the technical advances. The equipment, its

performance and calibration, and the calculation of the new method are described in 9.5 to 9.9.

© ISO 2016 – All rights reserved v
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SIST EN ISO 4590:2016
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SIST EN ISO 4590:2016
INTERNATIONAL STANDARD ISO 4590:2016(E)
Rigid cellular plastics — Determination of the volume
percentage of open cells and of closed cells
1 Scope

This International Standard specifies a general procedure for the determination of the volume

percentage of open and of closed cells of rigid cellular plastics, by measurement first of the geometrical

volume and then of the air-impenetrable volume of test specimens.

The procedure includes the correction of the apparent open-cell volume by taking into account the

surface cells opened by cutting during specimen preparation. Three alternative methods (method 1,

method 2a and method 2b), and corresponding apparatus, are specified for the measurement of the

impenetrable volume.
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 1923, Cellular plastics and rubbers — Determination of linear dimensions
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
surface area

total surface area of the test specimen determined by measuring its geometrical dimensions

3.2
geometrical volume
volume of the test specimen determined by measuring its geometrical dimensions
3.3
surface/volume ratio
ratio for the test specimen
3.4
impenetrable volume

volume of the test specimen into which air cannot penetrate and from which gas cannot escape, under

the test conditions
© ISO 2016 – All rights reserved 1
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
3.5
apparent volume percentage of open cells
ratio
VV−
×100

Note 1 to entry: It includes the volume of the cells opened during cutting of the test specimen, and depends on the

nature of the cellular plastic under test and on the surface/volume ratio r of the test specimen.

3.6
corrected volume percentage of open cells

apparent volume percentage of cells ω , corrected to take into account the surface cells opened by

cutting during preparation of the test specimen

Note 1 to entry: It is the limit of the apparent volume percentage of open cells ω , as the surface/volume ratio r

approaches zero.
3.7
corrected volume percentage of closed cells

volume percentage remaining after accounting for the corrected volume percentage of open cells

ψω=−100
Note 1 to entry: This percentage includes the volume of the cell walls.
4 Principle

The surface area S and geometrical volume V of a number of test specimens, each having a different

geometrical surface/volume ratio r, is determined.
The impenetrable volume V is determined by either of two methods, namely
a) method 1 — by pressure variation (pyknometer), and
b) method 2 — by volume expansion.

The determination of the impenetrable volume V is based on the application of the Boyle-Mariotte law

to a gas confined in an indeformable chamber, first in the absence and then in the presence of a test

specimen.

The apparent volume percentage of open cells ω of the test specimen is calculated by plotting the curve

ω = f(r) and extrapolating to r = 0, followed by calculation of the corrected volume percentage of open

cells ω and the corrected volume percentage of closed cells ψ .
5 Test specimens
5.1 Number

A minimum of three test specimens shall be prepared for each test. A total of three tests shall be carried

out per test specimen.
2 © ISO 2016 – All rights reserved
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
5.2 Preparation

Cut test specimens out with a band saw and machine them if necessary, taking care that there is no

deformation to the original cell structure other than at the surface. The specimens shall be free of dust,

voids and moulding skins.
Hot-wire cutting shall not be used.
5.3 Dimensions

The required test specimen dimensions depend on the specific method used to measure the

impenetrable volume V . Initial specimen sizes shall be as follows.
— Method 1: Pressure variation (pyknometer) and method 2b
length: (25 ± 1) mm
width: (25 ± 1) mm
thickness: (25 ± 1) mm
— Method 2a: Volume expansion
length: (100 ± 1) mm
width: (30 ± 1) mm
thickness: (30 ± 1) mm
5.4 Sectioning of test specimens

All three methods require that specimens r and r of each set be further sectioned as shown in Figure 1

2 3
to provide a range of surface/volume ratios for testing.
6 Conditioning and test atmospheres

The test specimens shall be conditioned for not less than 16 h at (23 ± 2) °C and (50 ± 5) % relative

humidity prior to testing. It is important that the test be conducted at (23 ± 2) °C and preferably at

controlled and moderate humidity, i.e. (50 ± 5) %.
7 Measurement of surface area S and geometrical volume V

7.1 Determine the linear dimensions of each test specimen in accordance with ISO 1923, except that

measurements shall be made to the nearest 0,05 mm. The locations of the measurement points shall be

as shown in Figure 2.

7.2 Calculate the average linear dimensions, the surface area S and the geometrical volume V ,

retaining all significant figures for test specimens r (one parallelepiped), r (two parallelepipeds) and

1 2

r (four parallelepipeds). Round off the final values for surface area S to the nearest 0,01 cm and for the

geometrical volume V to the nearest 0,01 cm .
© ISO 2016 – All rights reserved 3
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
(r ) (r ) (r )
1 2 3
Figure 1 — Pattern for cutting test specimens
a) Thick specimen b) Thin specimen
Figure 2 — Locations of measurement points
8 Determination of impenetrable volume V by method 1: pressure variation
(pyknometer)

NOTE The impenetrable volume V is determined by either method 1 or method 2. The principle, description

of apparatus, calibration, procedure and calculation for these two methods are specified in this Clause and

Clause 9, respectively.
4 © ISO 2016 – All rights reserved
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
8.1 Principle of method 1

The following characteristics are determined for an atmospheric pressure p and a pressure

amb
reduction p in the test chamber in relation to p :
e amb

a) the corresponding change in volume δV of the test chamber in the absence of a test specimen; this

determination constitutes the calibration of the apparatus;

b) the corresponding change in volume δV of the test chamber in the presence of a test specimen.

The impenetrable volume V of the test specimen is given by Formula (1):
δδVV−
A1 A2
V = p (1)
i B
where
p is equal to p + .
B amb pe
In practice (see 8.2.2), V is calculated from the equivalent Formula (2):
ll−
V = p (2)
i B
−Kp
where
l is the pyknometer scale reading corresponding to KδV ;
1 A1
l is the pyknometer scale reading corresponding to KδV ;
2 A2

K is a constant relating the pyknometer scale readings to volume change in the chamber.

8.2 Description of apparatus for method 1

8.2.1 The apparatus consists of an air pyknometer that permits instant reading of the difference

between internal pressure and atmospheric pressure. A schematic diagram of the apparatus is shown in

Figure 3. It consists essentially of the following items:

a) test chamber A, including a removable measurement chamber D of volume approximately 50 cm ,

which fits to the main part of chamber A by means of an appropriate mechanical device, a filter F

and an airtight circular joint G, to ensure impermeability and reproducibility of the geometrical

volume of this part of the test chamber;
b) chamber B to create the reduced pressure.

8.2.2 The two chambers A and B are linked in parallel by means of tubing fitted with a valve T , which

can connect or disconnect them, and a differential manometer M . The tubing can be connected directly

to atmosphere by means of valve T .

When chamber D is connected to chamber A by means of the airtight joint G and the valve T is closed,

the volume V of the combined chambers (including the free volume of the chambers and of the tubing

connected to the manometer M and to the valve T ) can be modified by moving piston P by means of

1 1 A
crank C .
© ISO 2016 – All rights reserved 5
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
Key
A test chamber H test specimen
B reduced-pressure chamber I indicator
C , C cranks J scale
A B
D measurement chamber M , M differential manometers
1 2
E , E endpoints for displacement of pistons P , P pistons
A B A B
F filter T to T valves
1 5
G airtight joint

Figure 3 — Schematic diagram of apparatus for determination of impenetrable volume V by

method 1
6 © ISO 2016 – All rights reserved
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SIST EN ISO 4590:2016
ISO 4590:2016(E)

The indicator I of the displacement of piston P permits reading directly on a scale J, with a precision of

0,25 %, a value l which has been precalibrated by the manufacturer to some corresponding change δV ,

starting from an initial reference value V .

NOTE The relationship between l and δV is defined by a proportionality constant K (l = KδV ) as provided

A A

by the equipment manufacturer or by calibration from standard volumes. The proper value for K is obtained only

if the zero reading on scale J is previously adjusted during the setting up of the air pyknometer in accordance

with the manufacturer’s instructions. The value of K for one commercially available air pyknometer is 2,0.

8.2.3 Chamber B can be connected directly to the atmosphere by means of valve T . Moreover, it is

connected by means of tubing and valve T to a differential manometer M which indicates the pressure

4 2

reduction that can be imposed at any time on the internal volume of chamber B with respect to the

ambient atmosphere. The manometer M shall permit the reading of the pressure reduction to 0,25 %

(i.e. a pressure reduction p of −200 mmH O shall be read to within ±0,5 mmH O).
e 2 2

The pressure in chamber B is adjustable (when valves T and T are closed) by moving piston P by

1 3 B

means of crank C . The difference p (negative in the procedure for method 1) between the pressure p in

B e B

chamber B and the atmospheric pressure p is indicated on the manometer M when valve T is open:

amb 2 4
pp=− p (3)
eB amb
8.3 Calibration of pyknometer apparatus

Determine, in accordance with the test procedure specified in 8.4 and for the atmospheric pressure p

amb

prevailing at the moment of test, the reading l corresponding to a pressure change p = −200 mmH O

1 e 2
in relation to p .
amb

NOTE 1 In order to eliminate the need to determine l each time the barometric pressure p changes, it can

1 amb

be desirable to establish a calibration curve of l = f(p ) for a given value of p . This can be accomplished as

1 amb e

shown in Figure 4 by repeating the calibration procedure over a period of several days over which p varies.

amb

NOTE 2 If it is desired, for some cellular materials, to determine the impenetrable volume of the test specimens

at another pressure reduction p ′, for example, −300 mmH O, it will be necessary to plot a calibration curve for p ′.

e 2 e
© ISO 2016 – All rights reserved 7
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SIST EN ISO 4590:2016
ISO 4590:2016(E)
Key
l scale reading
p (KPa) atmospheric pressure
amb
Figure 4 — Calibration graph for method 1 (p = −200 mmH O)
e 2
8.4 Procedure for method 1

8.4.1 Prior to testing, move pistons P and P along the whole available distance to change completely

A B

the air in chambers A and B and the tubing. For this, all the valves will have to be open. In order to

obtain greater homogeneity between the internal and external environments, it is advisable to repeat the

operation several times.
Determine the atmospheric pressure p to the nearest 10 Pa .
amb
8.4.2 Verify the zero readings of manometers M and M .
1 2
8.4.3 Place chamber D (containing the test specimen, if applicable) in position.

8.4.4 Again change the air in the apparatus by moving pistons P and P in the appropriate way.

A B

8.4.5 Adjust piston P so as to obtain a reading l = 0 on scale J. Position piston P to enable the desired

A B
pressure reduction to be achieved.

8.4.6 Close valves T , T and then T . Wait a few seconds. Both manometers M and M should indicate

3 2 1 1 2

zero. If such is not the case, re-open valves T , T and T , repeat the operation specified in 8.4.4 and then

1 3 2

proceed in accordance with 8.4.5. If the manometers continue to show instability, measurements are

impossible due to anomalies discussed in Annex A (see A.4, A.5 and A.6).
1) 10 Pa ≈ 1 mmH O
8 © ISO 2016 – All rights reserved
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SIST EN ISO 4590:2016
ISO 4590:2016(E)

8.4.7 When the differential manometers are stable, lower the internal pressure by progressively

moving piston P and, almost simultaneously, piston P to maintain the indicator on manometer M

B A 1
close to zero, while observing the pressure reduction on manometer M .
Never move piston P backwards during this operation.

8.4.8 Proceed as specified in 8.4.7 until the pressure reduction p = −200 mmH O. The equilibrium

e 2

shall be stable. If such is not the case, there exists one of the anomalies discussed in Annex A (s

...

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