Assistive products for tissue integrity when lying down

This document lists the terminology and common test methods used by manufacturers and laboratories to quantify the performance of a foam material. It also and gives information to users or buyers of these products to make an educated assessment of the relevance of the physical characteristics between various products offered to them. This document summarizes/gives information about the tests for —   polyurethane foams – typically polyether (polyether polyurethane foam) or polyester based (polyester polyurethane foam) – produced by either slabstock (slabstock foam) or moulded foam process, and —   latex foams produced by either the Dunlop process or Talalay process. The physical properties addressed in this document are a) resilience, b) hysteresis, c) support/SAG factor, d) density, e) hardness, f) compression set, g) tensile strength, h) tear strength, i) air flow/permeability, j) resistance to fatigue, and k) microbial resistance. NOTE      The test methods presented in this document do not necessarily simulate conditions of use in practice. The use of resulting data is therefore restricted to a broad comparative assessment between different foam products. This document addresses only the characterization and performance of foam materials used in APTIs. It does not address the design, construction method or other factors relating to the final clinical efficiency of the product. Test methods for characterizing the physical properties of any coverings, or the effects of any coverings on the physical properties of the foams, are not addressed in this document.

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Status
Published
Publication Date
17-Aug-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
30-Jun-2021
Completion Date
30-Jun-2021
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TECHNICAL ISO/TR
REPORT 20342-7
First edition
2021-08
Assistive products for tissue integrity
when lying down —
Part 7:
Foam properties, characteristics and
performance
Reference number
ISO/TR 20342-7:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TR 20342-7:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 20342-7:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Test samples and foam properties ..................................................................................................................................................... 4

4.1 General ........................................................................................................................................................................................................... 4

4.2 Test samples .............................................................................................................................................................................................. 4

4.3 Presale literature ................................................................................................................................................................................... 5

4.4 Composite APTIs ................................................................................................................................................................................... 5

4.5 Foam density and hardness ......................................................................................................................................................... 5

4.6 Aging effects .............................................................................................................................................................................................. 5

5 Test methods ............................................................................................................................................................................................................. 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 Determination of foam type ......................................................................................................................................................... 6

5.2.1 Resilience (ball rebound) ......................................................................................................................................... 6

5.2.2 Hysteresis ............................................................................................................................................................................... 6

5.2.3 Support/SAG factor ....................................................................................................................................................... 6

5.3 Characterization of foam durability ...................................................................................................................................... 6

5.3.1 Density (core or apparent)...................................................................................................................................... 6

5.3.2 Tensile strength and elongation ......................................................................................................................... 7

5.3.3 Tear strength ....................................................................................................................................................................... 7

5.3.4 Compression set (wet and/or dry) .................................................................................................................. 7

5.4 Characterization of foam hardness ........................................................................................................................................ 7

5.4.1 General...................................................................................................................................................................................... 7

5.4.2 Indentation hardness ................................................................................................................................................... 8

5.4.3 Compression hardness ............................................................................................................................................... 8

5.5 Characterization of other properties ................................................................................................................................... 8

5.5.1 Dynamic Fatigue Test (Pounding) ..................................................................................................................... 8

5.5.2 Dynamic Fatigue Test (Roller) .............................................................................................................................. 8

5.5.3 Air flow/permeability ................................................................................................................................................. 8

5.5.4 Flammability ....................................................................................................................................................................... 8

5.5.5 Microbial resistance ...................................................................................................................................................... 9

5.5.6 Restricted substances .................................................................................................................................................. 9

Annex A (informative) Cross-reference guide between related ISO, ASTM, CEN and JIS standards .10

Bibliography .............................................................................................................................................................................................................................11

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/TR 20342-7:2021(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 of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 173 Assistive products, in collaboration

with the European Committee for Standardization (CEN) Technical Committee CEN/TC 293, Assistive

products and accessibility, in accordance with the Agreement on technical cooperation between ISO and

CEN (Vienna Agreement).
A list of all parts in the ISO 20342 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TR 20342-7:2021(E)
Introduction

Although the phrase ‘high specification foam mattress’ has been common in the industry for several

decades, its continued use today is now a cause for concern.

The first ‘high specification foam mattresses’ were introduced around the 1990s. These incorporated

multiple construct layers of different foams, some of which might be castellated and/or shaped, and

then enveloped in stretch covers to provide improved pressure reducing properties when compared

with the then, ‘standard hospital mattress’, which was essentially a single rectangular block of foam

protected by a non-stretch cover. Over time these more advanced, complicated multi-layer constructs

have themselves now become the norm, completely replacing the old product in most modern hospitals.

Continued use of the ‘high specification’ terminology creates the risk of confusion and allows

manufacturers to lay claim to providing a ‘high specification foam mattress’ without an agreed

benchmark against which to justify this claim. The continued use of this phrase also takes the focus

away from the principles of holistic care and the correct risk assessment leading hopefully to the

selection of the mattress that will most likely deliver the desired outcome depending on the needs of

the patient.

Looking at the different clinical requirements and physical properties for foam mattresses, different

properties and their values come into play depending on the identified needs. A single property that

might be considered ‘high’ specification or highly desirable in relation to one patient or healthcare

environment could well be deemed ‘low’ or somewhat unimportant when considered against the needs

of the next patient in a different environment. Ultimately, it is the performance of the mattress as a

whole, within its environment, rather than any individual component part of it, that is important.

Understanding the characteristics of foam can help inform and potentially aid in the choice when

several products are available. However, it is the performance of the complete product, based on the

individual’s assessed needs, which is critical to ensure optimal patient care.

Without knowing the current (and often evolving) clinical needs of every particular user, it is not

possible to define clearly a nominal or minimal/maximal performance specification that needs to be

met or surpassed by the final product.

Additional safety standards, such as fire resistance at a component and/or final product level, exist

in relation to the foam product addressed in this document. The minimum level of resistance legally

required potentially differs depending on the application environment, for example domestic versus

hospital use. The flammability requirements and test methods used currently differ depending on the

country or state of use.

The manufacturer is required to explain and corroborate any claims made concerning the important

features of their product and how these features assure the clinical efficiency of their product over its

expected lifetime.

Based on this information and/or local, national or international requirements, it remains, however,

the responsibility of the user to determine if the foam proposed provides merely adequate behaviour or

exceeds by a significant amount the performance required.

Not all of the proposed tests need to be carried out to give an indication of a foam's performance and

some of the proposed tests will not be considered relevant for some types of foam.

These test methods can be used to identify differing performance characteristics between products

thus indicating the potential superior performance of one foam over another.

It is emphasized that the test methods specified in this document do not necessarily simulate conditions

of use in practice. The use of resulting data is therefore restricted to a broad comparative assessment

between different foam products.
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/TR 20342-7:2021(E)

It is recommended that no single result be taken in isolation. The clinical efficiency of the final product

will also be the result of many different contributory factors, a large number of which will not be related

to the foam’s physical properties.

The type of cover (fabric or other) used on the APTI can have a significant effect on overall clinical

performance of the final product. An incorrectly fitted cover, or changing the cover to a product other

than that specified by the manufacturer, will possibly affect product safety, performance and durability.

Continued use of a damaged cover can result in penetration of liquids into the foam, not only potentially

affecting its performance, but also increasing the risk of cross contamination.

The type of bedframe, or support, onto which the APTI is placed potentially affects the performance of

the final product. Overall product dimensions need to be taken into account not only to ensure that the

APTI can function correctly, but also to ensure that no entrapment hazards are created between the

frame and the APTI.
vi © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
TECHNICAL REPORT ISO/TR 20342-7:2021(E)
Assistive products for tissue integrity when lying down —
Part 7:
Foam properties, characteristics and performance
1 Scope

This document lists the terminology and common test methods used by manufacturers and laboratories

to quantify the performance of a foam material. It also and gives information to users or buyers of these

products to make an educated assessment of the relevance of the physical characteristics between

various products offered to them.
This document summarizes/gives information about the tests for

— polyurethane foams – typically polyether (polyether polyurethane foam) or polyester based

(polyester polyurethane foam) – produced by either slabstock (slabstock foam) or moulded foam

process, and
— latex foams produced by either the Dunlop process or Talalay process.
The physical properties addressed in this document are
a) resilience,
b) hysteresis,
c) support/SAG factor,
d) density,
e) hardness,
f) compression set,
g) tensile strength,
h) tear strength,
i) air flow/permeability,
j) resistance to fatigue, and
k) microbial resistance.

NOTE The test methods presented in this document do not necessarily simulate conditions of use in practice.

The use of resulting data is therefore restricted to a broad comparative assessment between different foam

products.

This document addresses only the characterization and performance of foam materials used in APTIs. It

does not address the design, construction method or other factors relating to the final clinical efficiency

of the product.

Test methods for characterizing the physical properties of any coverings, or the effects of any coverings

on the physical properties of the foams, are not addressed in this document.
© ISO 2021 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/TR 20342-7:2021(E)
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 20342-1, Assistive products for tissue integrity when lying down — Part 1: General requirements

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20342-1 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
assistive product for tissue integrity
APTI

surface intended to protect body tissue, designed to interface with the body when lying down or in

adjusted position
[SOURCE: ISO 20342-1:2019, 3.5]
3.2
bottoming out

insufficient support provided by an assistive product for tissue integrity (3.1) for the mass of patient

concerned, at the place where the assistive product for tissue integrity is no longer capable of

redistributing the pressure applied

Note 1 to entry: Localized pressure risks are now placed onto the patient by the bed frame or support surface

onto which the assistive product for tissue integrity has been placed.
3.3
destructive test
test method resulting in damage or destruction of the sample being tested

Note 1 to entry: The preparation of this test part renders an assistive product for tissue integrity (3.1) unsuitable

for use afterwards.
3.4
Dunlop process

action where foamed liquid latex is poured into a mould before vulcanization (3.10)

Note 1 to entry: Continuous production [see slabstock foam (3.11.6)] using the Dunlop process is also possible.

3.5
elongation
length of elongation at the rupture point as a percentage of the original length
3.6
tensile strength
force necessary to rupture the foam (3.11) when pulled by opposite forces
3.7
hydrolysis

chemical reaction in which the interaction of a compound with water results in the gradual

decomposition of that compound
2 © ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/TR 20342-7:2021(E)
3.8
non-destructive test
test method that can be carried out without damaging the sample being tested

Note 1 to entry: An assistive product for tissue integrity (3.1) is not significantly altered by the test and is deemed

suitable for use afterwards.
3.9
Talalay process

action where foamed liquid latex is poured into a mould then placed under vacuum before vulcanization

(3.10)
3.10
vulcanization

chemical cross linking of rubber-based polymers to increase product rigidity and durability

3.11
foam

flexible cellular material in which the cells are all or partly intercommunicating

3.11.1
high resilience foam
HR foam

foam (3.11) characterized by higher elasticity, measured by ball rebound or comfort factor (SAG factor),

as compared with standard polyether polyurethane foams

Note 1 to entry: Special high resilience polyols are used frequently in combination with methylene diphenyl di-

isocyanate (MDI) rather than toluene di-isocyanate.

Note 2 to entry: The higher elasticity is attributed to a more irregular cell structure than that present in standard

ether based foams.
3.11.2
latex foam

flexible cellular material made from natural or synthetic latex (3.11.2.2), in which the cells are all or

partly intercommunicating
3.11.2.1
natural latex
latex produced from the sap of the Hevea Brasiliensis rubber tree
3.11.2.2
synthetic latex
petroleum based alternative to natural latex (3.
...

TECHNICAL ISO/TR
REPORT 20342-7
First edition
Assistive products for tissue integrity
when lying down —
Part 7:
Foam properties, characteristics and
performance
PROOF/ÉPREUVE
Reference number
ISO/TR 20342-7:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TR 20342-7:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 20342-7:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Test samples and foam properties ..................................................................................................................................................... 4

4.1 General ........................................................................................................................................................................................................... 4

4.2 Test samples .............................................................................................................................................................................................. 4

4.3 Presale literature ................................................................................................................................................................................... 5

4.4 Composite APTIs ................................................................................................................................................................................... 5

4.5 Foam density and hardness ......................................................................................................................................................... 5

4.6 Aging effects .............................................................................................................................................................................................. 5

5 Test methods ............................................................................................................................................................................................................. 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 Determination of foam type ......................................................................................................................................................... 6

5.2.1 Resilience (ball rebound) ......................................................................................................................................... 6

5.2.2 Hysteresis ............................................................................................................................................................................... 6

5.2.3 Support/SAG factor ....................................................................................................................................................... 6

5.3 Characterization of foam durability ...................................................................................................................................... 6

5.3.1 Density (core or apparent)...................................................................................................................................... 6

5.3.2 Tensile strength and elongation ......................................................................................................................... 7

5.3.3 Tear strength ....................................................................................................................................................................... 7

5.3.4 Compression set (wet and/or dry) .................................................................................................................. 7

5.4 Characterization of foam hardness ........................................................................................................................................ 7

5.4.1 General...................................................................................................................................................................................... 7

5.4.2 Indentation hardness ................................................................................................................................................... 8

5.4.3 Compression hardness ............................................................................................................................................... 8

5.5 Characterization of other properties ................................................................................................................................... 8

5.5.1 Dynamic Fatigue Test (Pounding) ..................................................................................................................... 8

5.5.2 Dynamic Fatigue Test (Roller) .............................................................................................................................. 8

5.5.3 Air flow/permeability ................................................................................................................................................. 8

5.5.4 Flammability ....................................................................................................................................................................... 8

5.5.5 Microbial resistance ...................................................................................................................................................... 9

5.5.6 Restricted substances .................................................................................................................................................. 9

Annex A (informative) Cross-reference guide between related ISO, ASTM, and JIS standards .............10

Bibliography .............................................................................................................................................................................................................................11

© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/TR 20342-7:2021(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 of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 173 Assistive products, in collaboration

with the European Committee for Standardization (CEN) Technical Committee CEN/TC 293, Assistive

products and accessibility, in accordance with the Agreement on technical cooperation between ISO and

CEN (Vienna Agreement).
A list of all parts in the ISO 20342 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TR 20342-7:2021(E)
Introduction

Although the phrase ‘high specification foam mattress’ has been common in the industry for several

decades, its continued use today is now a cause for concern.

The first ‘high specification foam mattresses’ were introduced around the 1990s. These incorporated

multiple construct layers of different foams, some of which might be castellated and/or shaped, and

then enveloped in stretch covers to provide improved pressure reducing properties when compared

with the then, ‘standard hospital mattress’, which was essentially a single rectangular block of foam

protected by a non-stretch cover. Over time these more advanced, complicated multi-layer constructs

have themselves now become the norm, completely replacing the old product in most modern hospitals.

Continued use of the ‘high specification’ terminology creates the risk of confusion and allows

manufacturers to lay claim to providing a ‘high specification foam mattress’ without an agreed

benchmark against which to justify this claim. The continued use of this phrase also takes the focus

away from the principles of holistic care and the correct risk assessment leading hopefully to the

selection of the mattress that will most likely deliver the desired outcome depending on the needs of

the patient.

Looking at the different clinical requirements and physical properties for foam mattresses, different

properties and their values come into play depending on the identified needs. A single property that

might be considered ‘high’ specification or highly desirable in relation to one patient or healthcare

environment could well be deemed ‘low’ or somewhat unimportant when considered against the needs

of the next patient in a different environment. Ultimately, it is the performance of the mattress as a

whole, within its environment, rather than any individual component part of it, that is important.

Understanding the characteristics of foam can help inform and potentially aid in the choice when

several products are available. However, it is the performance of the complete product, based on the

individual’s assessed needs, which is critical to ensure optimal patient care.

Without knowing the current (and often evolving) clinical needs of every particular user, it is not

possible to define clearly a nominal or minimal/maximal performance specification that needs to be

met or surpassed by the final product.

Additional safety standards, such as fire resistance at a component and/or final product level, exist

in relation to the foam product addressed in this document. The minimum level of resistance legally

required potentially differs depending on the application environment, for example domestic versus

hospital use. The flammability requirements and test methods used currently differ depending on the

country or state of use.

The manufacturer is required to explain and corroborate any claims made concerning the important

features of their product and how these features assure the clinical efficiency of their product over its

expected lifetime.

Based on this information and/or local, national or international requirements, it remains, however,

the responsibility of the user to determine if the foam proposed provides merely adequate behaviour or

exceeds by a significant amount the performance required.

Not all of the proposed tests need to be carried out to give an indication of a foam's performance and

some of the proposed tests will not be considered relevant for some types of foam.

These test methods can be used to identify differing performance characteristics between products

thus indicating the potential superior performance of one foam over another.

It is emphasized that the test methods specified in this document do not necessarily simulate conditions

of use in practice. The use of resulting data is therefore restricted to a broad comparative assessment

between different foam products.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE v
---------------------- Page: 5 ----------------------
ISO/TR 20342-7:2021(E)

It is recommended that no single result be taken in isolation. The clinical efficiency of the final product

will also be the result of many different contributory factors, a large number of which will not be related

to the foam’s physical properties.

The type of cover (fabric or other) used on the APTI can have a significant effect on overall clinical

performance of the final product. An incorrectly fitted cover, or changing the cover to a product other

than that specified by the manufacturer, will possibly affect product safety, performance and durability.

Continued use of a damaged cover can result in penetration of liquids into the foam, not only potentially

affecting its performance, but also increasing the risk of cross contamination.

The type of bedframe, or support, onto which the APTI is placed potentially affects the performance of

the final product. Overall product dimensions need to be taken into account not only to ensure that the

APTI can function correctly, but also to ensure that no entrapment hazards are created between the

frame and the APTI.
vi PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
TECHNICAL REPORT ISO/TR 20342-7:2021(E)
Assistive products for tissue integrity when lying down —
Part 7:
Foam properties, characteristics and performance
1 Scope

This document lists the terminology and common test methods used by manufacturers and laboratories

to quantify the performance of a foam material. It also and gives information to users or buyers of these

products to make an educated assessment of the relevance of the physical characteristics between

various products offered to them.
This document summarizes/gives information about the tests for

— polyurethane foams – typically polyether (polyether polyurethane foam) or polyester based

(polyester polyurethane foam) – produced by either slabstock (slabstock foam) or moulded foam

process, and
— latex foams produced by either the Dunlop process or Talalay process.
The physical properties addressed in this document are
a) resilience,
b) hysteresis,
c) support/SAG factor,
d) density,
e) hardness,
f) compression set,
g) tensile strength,
h) tear strength,
i) air flow/permeability,
j) resistance to fatigue, and
k) microbial resistance.

NOTE The test methods presented in this document do not necessarily simulate conditions of use in practice.

The use of resulting data is therefore restricted to a broad comparative assessment between different foam

products.

This document addresses only the characterization and performance of foam materials used in APTIs. It

does not address the design, construction method or other factors relating to the final clinical efficiency

of the product.

Test methods for characterizing the physical properties of any coverings, or the effects of any coverings

on the physical properties of the foams, are not addressed in this document.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 1
---------------------- Page: 7 ----------------------
ISO/TR 20342-7:2021(E)
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 20342-1, Assistive products for tissue integrity when lying down — Part 1: General requirements

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20342-1 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
assistive product for tissue integrity
APTI

surface intended to protect body tissue, designed to interface with the body when lying down or in

adjusted position
[SOURCE: ISO 20342-1:2019, 3.5]
3.2
bottoming out

insufficient support provided by an assistive product for tissue integrity (3.1) for the mass of patient

concerned, at the place where the assistive product for tissue integrity is no longer capable of

redistributing the pressure applied

Note 1 to entry: Localized pressure risks are now placed onto the patient by the bed frame or support surface

onto which the assistive product for tissue integrity has been placed.
3.3
destructive test
test method resulting in damage or destruction of the sample being tested

Note 1 to entry: The preparation of this test part renders an assistive product for tissue integrity (3.1) unsuitable

for use afterwards.
3.4
Dunlop process

action where foamed liquid latex is poured into a mould before vulcanization (3.10)

Note 1 to entry: Continuous production [see slabstock foam (3.11.6)] using the Dunlop process is also possible.

3.5
elongation
length of elongation at the rupture point as a percentage of the original length
3.6
tensile strength
force necessary to rupture the foam (3.11) when pulled by opposite forces
3.7
hydrolysis

chemical reaction in which the interaction of a compound with water results in the gradual

decomposition of that compound
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ISO/TR 20342-7:2021(E)
3.8
non-destructive test
test method that can be carried out without damaging the sample being tested

Note 1 to entry: An assistive product for tissue integrity (3.1) is not significantly altered by the test and is deemed

suitable for use afterwards.
3.9
Talalay process

action where foamed liquid latex is poured into a mould then placed under vacuum before vulcanization

(3.10)
3.10
vulcanization

chemical cross linking of rubber-based polymers to increase product rigidity and durability

3.11
foam

flexible cellular material in which the cells are all or partly intercommunicating

3.11.1
high resilience foam
HR foam

foam (3.11) characterized by higher elasticity, measured by ball rebound or comfort factor (SAG factor),

as compared with standard polyether polyurethane foams

Note 1 to entry: Special high resilience polyols are used frequently in combination with methylene diphenyl di-

isocyanate (MDI) rather than toluene di-isocyanate.

Note 2 to entry: The higher elasticity is attributed to a more irregular cell structure than that present in standard

ether based foams.
3.11.2
latex foam

flexible cellular material made from natural or synthetic latex (3.11.2.2), in which the cells are all or

partly intercommunicating
3.11.2.1
natural latex
latex produced from the sap of the Hevea Brasiliensis rubber tree
3.11.2.2
synthetic latex
petroleum based alternative to natural latex (3.11.2.1)
3.11.3
moulded foam
cellular foam (3.11) p
...

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