EN ISO 18472:2018

SLOVENSKI STANDARD
01-december-2018
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SIST EN ISO 18472:2006
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3UHVNXVQDRSUHPD,62
Sterilization of health care products - Biological and chemical indicators - Test equipment
(ISO 18472:2018)
Sterilisation von Produkten für die Gesundheitsfürsorge - Biologische und chemische
Indikatoren - Prüfausrüstung (ISO 18472:2018)
Stérilisation des produits de santé - Indicateurs biologiques et chimiques - Appareillage
d'essai (ISO 18472:2018)
Ta slovenski standard je istoveten z: EN ISO 18472:2018
ICS:
11.080.01 Sterilizacija in dezinfekcija na Sterilization and disinfection
splošno in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 18472
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2018
EUROPÄISCHE NORM
ICS 11.080.01 Supersedes EN ISO 18472:2006
English Version
Sterilization of health care products - Biological and
chemical indicators - Test equipment (ISO 18472:2018)
Stérilisation des produits de santé - Indicateurs Sterilisation von Produkten für die
biologiques et chimiques - Appareillage d'essai (ISO Gesundheitsfürsorge - Biologische und chemische
18472:2018) Indikatoren - Prüfausrüstung (ISO 18472:2018)
This European Standard was approved by CEN on 9 May 2018.

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, Serbia, 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: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 18472:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 18472:2018) has been prepared by Technical Committee ISO/TC 198
"Sterilization of health care products" in collaboration with Technical Committee CEN/TC 102
“Sterilizers and associated equipment for processing of medical devices” the secretariat of which is held
by DIN.
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 March 2019, and conflicting national standards shall
be withdrawn at the latest by March 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 18472:2006.
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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 18472:2018 has been approved by CEN as EN ISO 18472:2018 without any modification.

INTERNATIONAL ISO
STANDARD 18472
Second edition
2018-08
Sterilization of health care products —
Biological and chemical indicators —
Test equipment
Stérilisation des produits de santé — Indicateurs biologiques et
chimiques — Appareillage d'essai
Reference number
ISO 18472:2018(E)
©
ISO 2018
ISO 18472:2018(E)
© ISO 2018
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 18472:2018(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Performance requirements for resistometers . 4
4.1 Intended use . 4
4.2 Test methods . 4
4.3 Air leakage test. 4
4.4 Steam resistometer performance requirements . 5
4.4.1 Measurement accuracy . 5
4.4.2 Data . 5
4.4.3 Process control . 5
4.4.4 General steam resistometer requirements . 6
4.4.5 Air leakage test . 7
4.4.6 Operation of steam resistometer . 7
4.5 Ethylene oxide gas resistometer performance requirements . 7
4.5.1 Measurement accuracy . 7
4.5.2 Data . 8
4.5.3 Process control . 8
4.5.4 General ethylene oxide gas resistometer requirements . 9
4.5.5 Air leakage test .10
4.5.6 Operation of ethylene oxide gas resistometer .10
4.6 Dry heat (heated air) resistometer performance requirements .10
4.6.1 Measurement accuracy .10
4.6.2 Data .11
4.6.3 Process control .11
4.6.4 General dry heat (heated air) resistometer requirements .12
4.6.5 Operation of dry heat (heated air) resistometer .12
4.7 Vaporized hydrogen peroxide resistometer performance requirements .13
4.7.1 Measurement accuracy .13
4.7.2 Recording interval .13
4.7.3 Process control .13
4.7.4 General vaporized hydrogen peroxide resistometer requirements .14
4.7.5 Air leakage test .15
4.7.6 Operation of vaporized hydrogen peroxide resistometer .15
5 Calibration .15
Annex A (informative) Additional performance characterization — Steam .16
Annex B (informative) Additional performance characterization — Ethylene oxide gas .19
Annex C (informative) Additional performance characterization — Dry heat.22
Annex D (informative) Resistometer documentation and derivations .24
Bibliography .30
ISO 18472:2018(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 198, Sterilization of health care products.
This second edition cancels and replaces the first edition (ISO 18472:2006), which has been technically
revised.
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 2018 – All rights reserved

ISO 18472:2018(E)
Introduction
To test the performance of biological and chemical indicators, specific test equipment is required.
This document specifies the performance requirements for the test equipment to be used to establish
the response of biological and chemical indicators to critical process variables. This document does
not apply to test equipment for indicators used in irradiation, isolator/room biodecontamination (at
atmospheric pressure), or low temperature steam and formaldehyde processes.
Resistometers constitute test equipment designed to create precise and repeatable sterilizing
environments, allowing the evaluation of their effect on biological inactivation kinetics, chemical
reactions, material degradation and product bioburden. Resistometers allow precise variation of the
environmental conditions and cycle sequences in order to produce controlled physical studies. When
used with the defined test methods given in the appropriate parts of ISO 11138 for biological indicators
and ISO 11140 for chemical indicators, the results of these studies can be used to demonstrate
conformance of biological indicators and chemical indicators to these standards.
Resistometers differ from conventional sterilizers. Instrumentation selection and control requirements
for resistometers are based upon mathematical models in which rates of reaction, measurement
accuracy and process control requirements are evaluated to quantify the effects induced by test
equipment-controlled variables. The requirements for accurate measurement, precise control,
and rapid rates of change approach limits of commercially available process control and calibration
instrumentation measurement accuracy. The measurement and control requirements often prohibit
practical validation of a resistometer using procedures that might be employed in a conventional heat
or chemical sterilization system. Resistometers are considered test equipment rather than sterilizers;
therefore, an understanding of instrumentation and process design is critical in clarifying requirements
on precision and measurement accuracy. Practical design takes the following into consideration:
— achievable measurement and control;
— acceptable equipment induced variation in test results;
— economic design (utilizing tight process controls only where required);
— test method correlation with intended use;
— historical knowledge applied to test procedures and an understanding of micro-environmental
physical phenomena;
— testing and analysis alternatives, when accurate quantitative determinations exceed physical
measurement/control limits.
INTERNATIONAL STANDARD ISO 18472:2018(E)
Sterilization of health care products — Biological and
chemical indicators — Test equipment
1 Scope
This document specifies the requirements for test equipment to be used to:
— test biological indicators for steam, ethylene oxide gas and dry heat sterilization processes for
conformity to the requirements given in ISO 11138 series;
— test chemical indicators for steam, ethylene oxide gas, dry heat and vaporized hydrogen peroxide
sterilization processes for conformity to the requirements given in ISO 11140-1:2014.
This document also provides informative methods useful in characterizing the performance of
biological and chemical indicators for intended use and for routine quality control testing.
This document does not specify requirements for test equipment for processes specifically for testing
chemical and biological indicators intended to monitor isolator and room biodecontamination processes
at atmospheric pressure.
ISO 11138-2:2017, ISO 11138-3:2017, ISO 11138-4:2017 and ISO 11140-1:2014 require the use of
resistometers specified in this document, and these resistometers are used in conjunction with the test
methods specified in the appropriate parts of ISO 11138 series and ISO 11140 series.
Resistometers for low temperature steam and formaldehyde indicators are not included in this
document. Test methods using laboratory apparatus for low temperature steam and formaldehyde are
included in ISO 11138-5:2017.
Test equipment for testing Type 2 (e.g. Bowie Dick) chemical indicators are specified in ISO 11140-3:2007,
ISO 11140-4:2007, and ISO 11140-5:2007.
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 11138-1:2017, Sterilization of health care products — Biological indicators — Part 1: General
requirements
ISO 11138-2:2017, Sterilization of health care products — Biological indicators — Part 2: Biological
indicators for ethylene oxide sterilization processes
ISO 11138-3:2017, Sterilization of health care products — Biological indicators — Part 3: Biological
indicators for moist heat sterilization processes
ISO 11138-4:2017, Sterilization of health care products — Biological indicators — Part 4: Biological
indicators for dry heat sterilization processes
ISO 11138-5:2017, Sterilization of health care products — Biological indicators — Part 5: Biological
indicators for low-temperature steam and formaldehyde sterilization processes
ISO 11140-1:2014, Sterilization of health care products — Chemical indicators — Part 1: General
requirements
ISO 18472:2018(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11138-1:2017, ISO 11138-2:2017,
ISO 11138-3:2017, ISO 11138-4:2017, ISO 11138-5:2017, and ISO 11140-1:2014 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
biological indicator
test system containing viable microorganisms providing a specified resistance to a specified
sterilization process
[SOURCE: ISO 11139:2018, 3.29]
3.2
calibration
operation that, under specified conditions, in a first step, establishes a relation between the quantity
values with measurement uncertainties provided by the measurement standards and corresponding
indications with associated measurement uncertainties and, in a second step, uses this information to
establish a relation for obtaining a measurement result from an indication
[SOURCE: ISO/IEC Guide 99:2007, 2.39, modified — NOTE 1, 2, and 3 have been deleted.]
3.3
chemical indicator
test system that reveals change in one or more pre-specified process variables based on a chemical or
physical change resulting from exposure to a process
[SOURCE: ISO 11139:2018, 3.43]
3.4
come-down period
time elapsed from the termination of the exposure period to an established null
reaction point
[SOURCE: ISO 11139:2018, 3.56]
3.5
come-up period
time elapsed from the introduction of the sterilizing agent to the attainment of the
specified conditions
[SOURCE: ISO 11139:2018, 3.57]
3.6
indicator exposure period
duration between the initial attainment to the termination of the specified exposure conditions
[SOURCE: ISO 11139:2018, 3.140]
3.7
measurement accuracy
closeness of the agreement between a measured quantity value and a true quantity value of a measurand
Note 1 to entry: “Accuracy” is a qualitative concept.
Note 2 to entry: The term “precision” should not be used for “accuracy”.
2 © ISO 2018 – All rights reserved

ISO 18472:2018(E)
[SOURCE: ISO/IEC Guide 99:2007, 2.13, modified — The terms “accuracy of measurement” and
“accuracy” have been deleted. NOTE 1 and 2 have been modified. NOTE 3 has been deleted.]
3.8
measurement precision
closeness of agreement between indications or measured quantity values obtained by replicate
measurements on the same or similar objects under specified conditions
Note 1 to entry: Measurement precision is usually expressed numerically by measures of imprecision, such as
standard deviation, variance, or coefficient of variation under the specified conditions of measurement.
Note 2 to entry: The ‘specified conditions’ can be, for example, repeatability conditions of measurement,
intermediate precision conditions of measurement, or reproducibility conditions of measurement.
Note 3 to entry: Measurement precision is used to define “measurement repeatability”, “intermediate
measurement precision”, and “measurement reproducibility”.
Note 4 to entry: Sometimes “measurement precision” is erroneously used to mean measurement accuracy.
[SOURCE: ISO/IEC Guide 99:2007, 2.15, modified — The term “precision” has been deleted. The NOTEs
have been modified.]
3.9
null reaction point
terminating set of conditions that have no significant effect on the indicator
3.10
record, verb
collect, store and make accessible
[SOURCE: ISO 11139:2018, 3.223]
3.11
reference standard
measurement standard designated for the calibration of other measurement standards for quantities of
a given kind in a given organization or at a given location
[SOURCE: ISO/IEC Guide 99:2007, 5.6, modified — The term name has been simplified.]
3.12
resistometer
test equipment designed to create specified combinations of the physical and/or chemical parameters
of a sterilization process
[SOURCE: ISO 11139:2018, 3.233]
3.13
response time
τ
period required for a 90 % change in sensor output when exposed to a step change in the
variable being measured
Note 1 to entry: It may be necessary to determine the sensor response time using a faster data sampling rate
than the minimum for the equipment specified in this document. Documentary evidence from the sensor
manufacturer's stated response time is equally acceptable as proof of conformance.
[SOURCE: ISO 11139:2018, 3.234, modified — Note 1 to entry has been added.]
3.14
saturated steam
water vapour in a state of equilibrium between its liquid and gas phases
[SOURCE: ISO 11139:2018, 3.241]
ISO 18472:2018(E)
3.15
stabilization period
elapsed time from the attainment of the minimum specified exposure conditions until the end of the
specified time to achieve steady state conditions
[SOURCE: ISO 11139:2018, 3.261]
3.16
steady state period
portion of the exposure period which begins after the stabilization period and terminates
at the end of the exposure period
[SOURCE: ISO 11139:2018, 3.266]
3.17
sterilant
chemical or combination of chemicals used to generate a sterilizing agent
[SOURCE: ISO 11139:2018, 3.268]
4 Performance requirements for resistometers
4.1 Intended use
The resistometer is intended to be used to expose test samples under stated test conditions, and
therefore shall be capable of producing cycle sequences as required for specific test methods.
Depending upon the test methods defined in ISO 11138-2:2017, ISO 11138-3:2017, ISO 11138-4:2017
and ISO 11140-1:2014, the resistometer utilized need only verify those limits necessary to characterize
the chemical or biological indicators being tested.
NOTE 1 The following requirements define the conditions to be achieved in the vessel in which the sample is
to be placed, but the means by which these conditions are to be controlled are not addressed.
NOTE 2 Piping connected to the chamber can modify the total volume of the chamber.
4.2 Test methods
The equipment specified in this document shall be used with the detailed test methods given in
ISO 11138-1:2017, ISO 11138-2:2017, ISO 11138-3:2017, ISO 11138-4:2017, and ISO 11140-1:2014.
The performance of resistometers can be influenced by the nature of the load being used. The
performance requirements listed in Tables 2, 4, 6, and 8 shall be met during testing of indicators as well
as during empty chamber conditions.
NOTE Tolerances might be compounded when taking into consideration the tolerances designated for the
performance of the resistometer and the tolerances for performance testing of biological (ISO 11138-1:2017,
ISO 11138-2:2017, ISO 11138-3:2017, ISO 11138-4:2017) and chemical (ISO 11140-1:2014) indicators.
4.3 Air leakage test
4.3.1 With the temperature stabilized and the chamber empty (except for fixed furniture and necessary
monitoring sensors) start the test cycle. When the pressure in the chamber has reached or is below the
value corresponding to the lowest operating vacuum of the test cycle air removal stages, close all the
valves connected to the chamber and stop the vacuum pump. Observe and record the time, t , and the
absolute pressure, p . Allow evaporation of condensate in the chamber for 300 s ± 10 s and then observe
4 © ISO 2018 – All rights reserved

ISO 18472:2018(E)
and record the absolute pressure, p , in the chamber and the time, t . After a further 600 s ± 10 s, again
2 2
observe and record the absolute pressure, p , and the time, t .
3 3
The resistometer may be equipped with a test cycle for air leakage that will carry out this procedure
automatically and display the air leakage in kPa/min (mbar/min).
4.3.2 At the end of the test calculate the rate of pressure rise for the 600 s period.
NOTE 1 If the value of (p − p ) is greater than 2 kPa (20 mbar), this could be due to the initial presence of
2 1
excessive condensate in the sterilizer chamber.
NOTE 2 In a closed vessel at 4 kPa pressure, the pressure changes by approximately 0,1 kPa (1 mbar) for each
10 °C change in temperature; over the range 20 °C to 140 °C; at 7 kPa (70 mbar) the change is approximately
0,2 kPa (2 mbar). The test can be compromised if the temperature changes by more than 10 °C during the period
in which the chamber pressure is monitored.
NOTE 3 The leak test is relevant for steam, ethylene oxide gas and vaporized hydrogen peroxide resistometers.
4.4 Steam resistometer performance requirements
4.4.1 Measurement accuracy
The sensors used to measure temperature and pressure from within the steam resistometer shall have
a response time as specified in Table 1. For temperature this step change shall be from 20 °C to 90 °C and
for pressure this step change shall be from 10 kPa to 100 kPa. The measurement chains used to record
time, temperature and pressure from within the steam resistometer shall be capable of operation with
a resolution and measurement accuracy within the scale range specified in Table 1.
The measurement chains used may operate beyond the scale range specified as long as the limiting
values within the scale range specified in Table 1 are attained.
These requirements shall apply to complete measurement chains including sensors and data processing.
Table 1 — Steam resistometer instrumentation requirements (measurement and recording)
Sensor re-
Measurement
sponse
Measurement Unit Scale range Resolution accuracy b
time
a
(+/−)
ms
Time HH:MM:SS Selectable 00:00:01 00:00:01 —
Temperature °C 110 to 145 0,01 0,5 ≤500
kPa 0 to ≤100 0,01 1,0 ≤200
Pressure
kPa >100 to 420 0,01 1,6 ≤200
a
Measurement accuracy over the test condition range (see 3.7 and 4.1).
b
See 3.13.
4.4.2 Data
Data from the measurements specified in Table 1 shall be provided at a sampling interval of not less
than one data point per second and may be electronically archived.
If this data is required to be recorded, the recording interval is at the user's discretion.
4.4.3 Process control
The steam resistometer process control shall control the parameters to the tolerances as specified in
Table 2.
ISO 18472:2018(E)
Table 2 — Steam resistometer physical conditions
Tolerance
Parameter Unit Range
(+/−)
Time HH:MM:SS Selectable 00:00:01
a d
Temperature °C 110 to 145 0,5 , 1,0
a,c
kPa >100 to 420 3,5
Pressure
kPa 3 to ≤100 1,0
Time to achieve vacuum
b
HH:MM:SS ≤00:02:00 –
set point
Come-up period HH:MM:SS ≤00:00:11 –
Come-down period HH:MM:SS ≤00:00:11 –
Stabilization period (PS) HH:MM:SS ≤00:00:10 –
a
During steady-state period (PSS) (see Figure 1).
b
Some indicators can be adversely affected by prolonged exposure to dry heat and vacuum. The minimum practicable
settings for evacuation should be used. The time taken should be as consistent as possible in order to minimize potential
variability (e.g. desiccation can occur).
c
Tolerance is at 121 °C. Tolerance will increase at higher temperatures based on steam tables, (i.e. 4,5 kPa at 132 °C,
tolerances at other temperatures may be interpolated or extrapolated.)
d
During stabilization period.
Key
PS stabilization period PNR null reaction point example
PSS steady-state period SP set point
PE exposure period TS stabilization tolerance
PCU come-up period TSS steady-state tolerance
Figure 1 — Stabilization time for temperature for steam resistometer
4.4.4 General steam resistometer requirements
4.4.4.1 The chamber shall be supplied with dry saturated steam with dryness of 0,9 or greater from a
source external to the chamber.
6 © ISO 2018 – All rights reserved

ISO 18472:2018(E)
NOTE A method to determine steam dryness which can be modified for use in steam resistometers is
specified in EN 285.
4.4.4.2 Air admitted at the end of the cycle shall be filtered through a filter having the capability of
removing not less than 99,5 % of 0,5 µm particles.
4.4.4.3 The sample holder shall allow the indicator to be exposed to the test conditions in the manner
intended by the indicator manufacturer.
The various types of indicator may require customized sample holders. Sample holders might have
to be constructed to hold test items in different vertical and horizontal attitudes to test performance
differences.
NOTE Consult the indicator manufacturer for guidance when verifying label claim performance.
4.4.4.4 The null reaction point shall be specified and demonstrated by experimentation or by
calculation using published data.
4.4.5 Air leakage test
4.4.5.1 When determined by the method given in 4.3, for vessels less than or equal to 55 l, the air
leakage rate shall not be greater than 0,13 kPa/min.
4.4.5.2 When determined by the method given in 4.3, for vessels greater than 55 l, the air leakage rate
shall not be greater than 0,13 kPa/min × (54,8/V ) where V is chamber volume in l.
c c
4.4.6 Operation of steam resistometer
4.4.6.1 The chamber shall be designed such that the formation of condensate during any stage of the
operating cycle does not adversely affect the required test conditions. To avoid excessive condensate
formation during the operating cycle it might be necessary to provide thermostatic control of the inner
surfaces of the resistometer so that they can be maintained at a specified temperature (e.g. the exposure
period temperature).
4.4.6.2 Before initiating a test cycle, the inner surface of the chamber shall be heated to the test
temperature.
4.4.6.3 The equipment shall be provided with means to evacuate the chamber to the vacuum set point
to permit adequate air removal prior to admission of steam.
Steam admission/gravity displacement shall not be used to effect air removal from the chamber.
4.4.6.4 Data from controlled values shall be provided at an interface for recording purposes within a
minimum frequency of 1 s.
NOTE 1 For additional applications of steam resistometers, see Annex A.
NOTE 2 For examples of resistometer test cycle documentation, see D.4.
4.5 Ethylene oxide gas resistometer performance requirements
4.5.1 Measurement accuracy
The sensors used to measure temperature, pressure and relative humidity from within the EO gas
resistometer shall have a response time as specified in Table 3. For temperature this step change shall
be from 20 °C to 90 °C and for pressure this step change shall be from 10 kPa to 100 kPa. The system
ISO 18472:2018(E)
used to record time, temperature, vacuum, pressure, relative humidity and EO gas concentration
from within the EO gas resistometer shall be capable of operation with a resolution and measurement
accuracy within the scale range specified in Table 3.
The measurement systems used may operate beyond the scale range specified as long as the limiting
values within the scale range specified in Table 3 are attained.
These requirements shall apply to complete measurement chains including sensors and data processing.
Table 3 — EO gas resistometer instrumentation requirements (measurement and recording)
Measurement
Response time
Measurement Unit Scale range Resolution accuracy
a ms
(+/−)
Time HH:MM:SS Selectable 00:00:01 00:00:01 —
Temperature °C 25 to 80 0,1 0,5 ≤500
Pressure kPa 0 to 100 0,1 ±3,5 ≤30
b
Relative humidity % RH 20 to 90 1 5 15 000
5 % of the concen-
EO gas concentration mg/l 25 to 1 200 — —
tration targeted
a
Measurement accuracy over the test condition range (see 4.1).
b
If relative humidity is not determined by partial pressure.
4.5.2 Data
Data from the measurements specified in Table 3 shall be provided at a sampling interval of not less
than one data point per second and may be electronically archived.
If this data are required to be recorded, the recording interval is at the user's discretion.
The percentage of relative humidity and ethylene oxide gas concentration shall be directly measured by
using a suitable sensor, or determined from pressure measurements during steady-state stages of the
operating cycle.
4.5.3 Process control
The EO gas resistometer process control shall control the parameters to the tolerances as specified in
Table 4.
NOTE For calculation of EO gas concentration and relative humidity, see D.2 and D.3.
Table 4 — EO gas resistometer physical design/control specifications
Tolerance
Parameter Units Range
(+/−)
Time HH:MM:SS Selectable 00:00:01
Pressure kPa 100 to 200 3,5
Pressure kPa 4 to 100 1,0
EO gas concentration mg/l 200 to 1 200 5 % of the targeted
a
>45 to 65 ±1
Temperature °C
b
29 to ≤45 ±3
Relative humidity % RH 30 to 80 10
Time to achieve vacuum set point HH:MM:SS ≤00:01:00 —
a
During steady-state period (see Figure 2).
b
During stabilization period.
8 © ISO 2018 – All rights reserved

ISO 18472:2018(E)
Table 4 (continued)
Tolerance
Parameter Units Range
(+/−)
Come-up period HH:MM:SS ≤00:01:00 —
Come-down period HH:MM:SS ≤00:01:00 —
Stabilization period HH:MM:SS ≤00:02:00 —-
a
During steady-state period (see Figure 2).
b
During stabilization period.
Key
PS stabilization period PNR null reaction point example
PSS steady-state period SP set point
PE exposure period TS stabilization tolerance
PCU come-up period TSS steady-state tolerance
Figure 2 — Stabilization time for temperature for ethylene oxide gas resistometer
4.5.4 General ethylene oxide gas resistometer requirements
4.5.4.1 Means shall be provided to ensure that test samples are not contacted by liquid ethylene oxide
or particles of polymer entering the chamber. Due to the potential for stratification, a mixing device may
be used to facilitate homogeneous conditions within the chamber.
4.5.4.2 The test system including the chamber and door shall be provided with a means of maintaining
the temperature of the inner surfaces above the dew point for the test temperature and relative humidity.
The chamber environment shall be at thermal equilibrium control conditions before a cycle is initiated.
4.5.4.3 Air admitted at the end of the cycle shall be filtered through a filter having the capability of
removing not less than 99,5 % of 0,5 µm particles.
ISO 18472:2018(E)
4.5.4.4 The sample holder should allow the indicator to be exposed to the test conditions in the manner
intended by the indicator manufacturer.
The various types of indicator may require customized sample holders. Sample holders might have to be
constructed to hold test items in different vertical and horizontal attitudes in order to test performance
differences.
NOTE The indicator manufacturer can be consulted for guidance when verifying label claim performance.
4.5.4.5 The null reaction point shall be specified and demonstrated by experimentation or by
calculation using published data.
4.5.5 Air leakage test
When determined by the method given in 4.3, the air leakage rate shall not be greater than 0,13 kPa/min.
4.5.6 Operation of ethylene oxide gas resistometer
4.5.6.1 The chamber shall be designed such that the formation of condensate during any stage of the
operating cycle does not adversely affect the required test conditions. In order to avoid condensation
during the operating cycle it might be necessary to provide thermostatic control of the inner surfaces of
the resistometer so that they can be maintained at a specified temperature above the dew point.
4.5.6.2 Before initiating a test cycle, the inner surface of the chamber shall be heated to the test
temperature.
NOTE See Table 4 and Figure 2.
4.5.6.3 The equipment shall be provided with a means of evacuating the chamber to less than the vacuum
set point to permit adequate air removal prior to admission of water vapour and ethylene oxide gas.
4.5.6.4 Data from controlled values shall be provided at an interface to record with a minimum
frequency of 1 s.
NOTE 1 For additional applications of EO gas resistometers, see Annex B.
NOTE 2 For examples of resistometer test cycle documentation, see D.4.
4.6 Dry heat (heated air) resistometer performance requirements
4.6.1 Measurement accuracy
The sensors used to measure temperature from within the dry heat resistometer shall have a response
time as specified in Table 5. For temperature this step change shall be from 20 °C to 90 °C and
for pressure this step change shall be from 10 kPa to 100 kPa. The system used to record time and
temperature from within the dry heat resistometer shall be capable of operation with a resolution and
measurement accuracy within the scale range specified in Table 5.
The measurement systems used may operate beyond the scale range specified as long as the limiting
values within the scale range specified in Table 5 are attained.
These requirements shall apply to complete measurement chains including sensors and data processing.
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ISO 18472:2018(E)
Table 5 — Dry heat resistometer instrumentation requirements (measurement and recording)
Measurement
Response time
Measurement Unit Scale range Resolution accuracy
a ms
(+/−)
Time HH:MM:SS Selectable 00:00:01 00:00:01 —
Temperature °C 120 to 200 0,1 0,5 ≤500
a
The measurement accuracy over the test condition range (see 4.1).
4.6.2 Data
Data from the measurements specified in Table 5 shall be provided at a sampling interval of not less
than one data point per second and may be electronically archived.
If this data is required to be recorded, the recording interval is at the user's discretion.
4.6.3 Process control
The dry heat resistometer process control shall control the parameters to the tolerances as specified in
Table 6.
Table 6 — Dry heat resistometer physical design/control specifications
Parameter Units Range Tolerance
(+/−)
Time HH:MM:SS Selectable 00:00:02
a
Temperature °C 120 to 200 2,5
Come-up period HH:MM:SS ≤00:01:00 —
Come-down period HH:MM:SS ≤00:01:00 —
Stabilization period HH:MM:SS ≤00:02:00 —
a
After a 2 min stabilization time (see Figure 3).
ISO 18472:2018(E)
Key
PS stabilization period PNR null reaction point example
PSS steady-state period SP set point
PE exposure period TS stabilization tolerance
PCU come-up period TSS steady-state tolerance
Figure 3 — Stabilization time for temperature tolerance for dry heat resistometer
4.6.4 General dry heat (heated air) resistometer requirements
4.6.4.1 Test samples shall be loaded on to a suitable sample holder. The sample holder sha
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